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Diffstat (limited to 'third_party/rust/itertools/src')
47 files changed, 11467 insertions, 0 deletions
diff --git a/third_party/rust/itertools/src/adaptors/coalesce.rs b/third_party/rust/itertools/src/adaptors/coalesce.rs new file mode 100644 index 0000000000..3df7cc5823 --- /dev/null +++ b/third_party/rust/itertools/src/adaptors/coalesce.rs @@ -0,0 +1,235 @@ +use std::fmt; +use std::iter::FusedIterator; + +use crate::size_hint; + +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct CoalesceBy<I, F, T> +where + I: Iterator, +{ + iter: I, + last: Option<T>, + f: F, +} + +impl<I: Clone, F: Clone, T: Clone> Clone for CoalesceBy<I, F, T> +where + I: Iterator, +{ + clone_fields!(last, iter, f); +} + +impl<I, F, T> fmt::Debug for CoalesceBy<I, F, T> +where + I: Iterator + fmt::Debug, + T: fmt::Debug, +{ + debug_fmt_fields!(CoalesceBy, iter); +} + +pub trait CoalescePredicate<Item, T> { + fn coalesce_pair(&mut self, t: T, item: Item) -> Result<T, (T, T)>; +} + +impl<I, F, T> Iterator for CoalesceBy<I, F, T> +where + I: Iterator, + F: CoalescePredicate<I::Item, T>, +{ + type Item = T; + + fn next(&mut self) -> Option<Self::Item> { + // this fuses the iterator + let last = self.last.take()?; + + let self_last = &mut self.last; + let self_f = &mut self.f; + Some( + self.iter + .try_fold(last, |last, next| match self_f.coalesce_pair(last, next) { + Ok(joined) => Ok(joined), + Err((last_, next_)) => { + *self_last = Some(next_); + Err(last_) + } + }) + .unwrap_or_else(|x| x), + ) + } + + fn size_hint(&self) -> (usize, Option<usize>) { + let (low, hi) = size_hint::add_scalar(self.iter.size_hint(), self.last.is_some() as usize); + ((low > 0) as usize, hi) + } + + fn fold<Acc, FnAcc>(self, acc: Acc, mut fn_acc: FnAcc) -> Acc + where + FnAcc: FnMut(Acc, Self::Item) -> Acc, + { + if let Some(last) = self.last { + let mut f = self.f; + let (last, acc) = self.iter.fold((last, acc), |(last, acc), elt| { + match f.coalesce_pair(last, elt) { + Ok(joined) => (joined, acc), + Err((last_, next_)) => (next_, fn_acc(acc, last_)), + } + }); + fn_acc(acc, last) + } else { + acc + } + } +} + +impl<I: Iterator, F: CoalescePredicate<I::Item, T>, T> FusedIterator for CoalesceBy<I, F, T> {} + +/// An iterator adaptor that may join together adjacent elements. +/// +/// See [`.coalesce()`](crate::Itertools::coalesce) for more information. +pub type Coalesce<I, F> = CoalesceBy<I, F, <I as Iterator>::Item>; + +impl<F, Item, T> CoalescePredicate<Item, T> for F +where + F: FnMut(T, Item) -> Result<T, (T, T)>, +{ + fn coalesce_pair(&mut self, t: T, item: Item) -> Result<T, (T, T)> { + self(t, item) + } +} + +/// Create a new `Coalesce`. +pub fn coalesce<I, F>(mut iter: I, f: F) -> Coalesce<I, F> +where + I: Iterator, +{ + Coalesce { + last: iter.next(), + iter, + f, + } +} + +/// An iterator adaptor that removes repeated duplicates, determining equality using a comparison function. +/// +/// See [`.dedup_by()`](crate::Itertools::dedup_by) or [`.dedup()`](crate::Itertools::dedup) for more information. +pub type DedupBy<I, Pred> = CoalesceBy<I, DedupPred2CoalescePred<Pred>, <I as Iterator>::Item>; + +#[derive(Clone)] +pub struct DedupPred2CoalescePred<DP>(DP); + +impl<DP> fmt::Debug for DedupPred2CoalescePred<DP> { + debug_fmt_fields!(DedupPred2CoalescePred,); +} + +pub trait DedupPredicate<T> { + // TODO replace by Fn(&T, &T)->bool once Rust supports it + fn dedup_pair(&mut self, a: &T, b: &T) -> bool; +} + +impl<DP, T> CoalescePredicate<T, T> for DedupPred2CoalescePred<DP> +where + DP: DedupPredicate<T>, +{ + fn coalesce_pair(&mut self, t: T, item: T) -> Result<T, (T, T)> { + if self.0.dedup_pair(&t, &item) { + Ok(t) + } else { + Err((t, item)) + } + } +} + +#[derive(Clone, Debug)] +pub struct DedupEq; + +impl<T: PartialEq> DedupPredicate<T> for DedupEq { + fn dedup_pair(&mut self, a: &T, b: &T) -> bool { + a == b + } +} + +impl<T, F: FnMut(&T, &T) -> bool> DedupPredicate<T> for F { + fn dedup_pair(&mut self, a: &T, b: &T) -> bool { + self(a, b) + } +} + +/// Create a new `DedupBy`. +pub fn dedup_by<I, Pred>(mut iter: I, dedup_pred: Pred) -> DedupBy<I, Pred> +where + I: Iterator, +{ + DedupBy { + last: iter.next(), + iter, + f: DedupPred2CoalescePred(dedup_pred), + } +} + +/// An iterator adaptor that removes repeated duplicates. +/// +/// See [`.dedup()`](crate::Itertools::dedup) for more information. +pub type Dedup<I> = DedupBy<I, DedupEq>; + +/// Create a new `Dedup`. +pub fn dedup<I>(iter: I) -> Dedup<I> +where + I: Iterator, +{ + dedup_by(iter, DedupEq) +} + +/// An iterator adaptor that removes repeated duplicates, while keeping a count of how many +/// repeated elements were present. This will determine equality using a comparison function. +/// +/// See [`.dedup_by_with_count()`](crate::Itertools::dedup_by_with_count) or +/// [`.dedup_with_count()`](crate::Itertools::dedup_with_count) for more information. +pub type DedupByWithCount<I, Pred> = + CoalesceBy<I, DedupPredWithCount2CoalescePred<Pred>, (usize, <I as Iterator>::Item)>; + +#[derive(Clone, Debug)] +pub struct DedupPredWithCount2CoalescePred<DP>(DP); + +impl<DP, T> CoalescePredicate<T, (usize, T)> for DedupPredWithCount2CoalescePred<DP> +where + DP: DedupPredicate<T>, +{ + fn coalesce_pair( + &mut self, + (c, t): (usize, T), + item: T, + ) -> Result<(usize, T), ((usize, T), (usize, T))> { + if self.0.dedup_pair(&t, &item) { + Ok((c + 1, t)) + } else { + Err(((c, t), (1, item))) + } + } +} + +/// An iterator adaptor that removes repeated duplicates, while keeping a count of how many +/// repeated elements were present. +/// +/// See [`.dedup_with_count()`](crate::Itertools::dedup_with_count) for more information. +pub type DedupWithCount<I> = DedupByWithCount<I, DedupEq>; + +/// Create a new `DedupByWithCount`. +pub fn dedup_by_with_count<I, Pred>(mut iter: I, dedup_pred: Pred) -> DedupByWithCount<I, Pred> +where + I: Iterator, +{ + DedupByWithCount { + last: iter.next().map(|v| (1, v)), + iter, + f: DedupPredWithCount2CoalescePred(dedup_pred), + } +} + +/// Create a new `DedupWithCount`. +pub fn dedup_with_count<I>(iter: I) -> DedupWithCount<I> +where + I: Iterator, +{ + dedup_by_with_count(iter, DedupEq) +} diff --git a/third_party/rust/itertools/src/adaptors/map.rs b/third_party/rust/itertools/src/adaptors/map.rs new file mode 100644 index 0000000000..cf5e5a00d5 --- /dev/null +++ b/third_party/rust/itertools/src/adaptors/map.rs @@ -0,0 +1,124 @@ +use std::iter::FromIterator; +use std::marker::PhantomData; + +#[derive(Clone, Debug)] +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct MapSpecialCase<I, F> { + iter: I, + f: F, +} + +pub trait MapSpecialCaseFn<T> { + type Out; + fn call(&mut self, t: T) -> Self::Out; +} + +impl<I, R> Iterator for MapSpecialCase<I, R> +where + I: Iterator, + R: MapSpecialCaseFn<I::Item>, +{ + type Item = R::Out; + + fn next(&mut self) -> Option<Self::Item> { + self.iter.next().map(|i| self.f.call(i)) + } + + fn size_hint(&self) -> (usize, Option<usize>) { + self.iter.size_hint() + } + + fn fold<Acc, Fold>(self, init: Acc, mut fold_f: Fold) -> Acc + where + Fold: FnMut(Acc, Self::Item) -> Acc, + { + let mut f = self.f; + self.iter.fold(init, move |acc, v| fold_f(acc, f.call(v))) + } + + fn collect<C>(self) -> C + where + C: FromIterator<Self::Item>, + { + let mut f = self.f; + self.iter.map(move |v| f.call(v)).collect() + } +} + +impl<I, R> DoubleEndedIterator for MapSpecialCase<I, R> +where + I: DoubleEndedIterator, + R: MapSpecialCaseFn<I::Item>, +{ + fn next_back(&mut self) -> Option<Self::Item> { + self.iter.next_back().map(|i| self.f.call(i)) + } +} + +impl<I, R> ExactSizeIterator for MapSpecialCase<I, R> +where + I: ExactSizeIterator, + R: MapSpecialCaseFn<I::Item>, +{ +} + +/// An iterator adapter to apply a transformation within a nested `Result::Ok`. +/// +/// See [`.map_ok()`](crate::Itertools::map_ok) for more information. +pub type MapOk<I, F> = MapSpecialCase<I, MapSpecialCaseFnOk<F>>; + +/// See [`MapOk`]. +#[deprecated(note = "Use MapOk instead", since = "0.10.0")] +pub type MapResults<I, F> = MapOk<I, F>; + +impl<F, T, U, E> MapSpecialCaseFn<Result<T, E>> for MapSpecialCaseFnOk<F> +where + F: FnMut(T) -> U, +{ + type Out = Result<U, E>; + fn call(&mut self, t: Result<T, E>) -> Self::Out { + t.map(|v| self.0(v)) + } +} + +#[derive(Clone)] +pub struct MapSpecialCaseFnOk<F>(F); + +impl<F> std::fmt::Debug for MapSpecialCaseFnOk<F> { + debug_fmt_fields!(MapSpecialCaseFnOk,); +} + +/// Create a new `MapOk` iterator. +pub fn map_ok<I, F, T, U, E>(iter: I, f: F) -> MapOk<I, F> +where + I: Iterator<Item = Result<T, E>>, + F: FnMut(T) -> U, +{ + MapSpecialCase { + iter, + f: MapSpecialCaseFnOk(f), + } +} + +/// An iterator adapter to apply `Into` conversion to each element. +/// +/// See [`.map_into()`](crate::Itertools::map_into) for more information. +pub type MapInto<I, R> = MapSpecialCase<I, MapSpecialCaseFnInto<R>>; + +impl<T: Into<U>, U> MapSpecialCaseFn<T> for MapSpecialCaseFnInto<U> { + type Out = U; + fn call(&mut self, t: T) -> Self::Out { + t.into() + } +} + +#[derive(Clone, Debug)] +pub struct MapSpecialCaseFnInto<U>(PhantomData<U>); + +/// Create a new [`MapInto`] iterator. +pub fn map_into<I, R>(iter: I) -> MapInto<I, R> { + MapSpecialCase { + iter, + f: MapSpecialCaseFnInto(PhantomData), + } +} diff --git a/third_party/rust/itertools/src/adaptors/mod.rs b/third_party/rust/itertools/src/adaptors/mod.rs new file mode 100644 index 0000000000..1695bbd655 --- /dev/null +++ b/third_party/rust/itertools/src/adaptors/mod.rs @@ -0,0 +1,1151 @@ +//! Licensed under the Apache License, Version 2.0 +//! <https://www.apache.org/licenses/LICENSE-2.0> or the MIT license +//! <https://opensource.org/licenses/MIT>, at your +//! option. This file may not be copied, modified, or distributed +//! except according to those terms. + +mod coalesce; +mod map; +mod multi_product; +pub use self::coalesce::*; +pub use self::map::{map_into, map_ok, MapInto, MapOk}; +#[allow(deprecated)] +pub use self::map::MapResults; +#[cfg(feature = "use_alloc")] +pub use self::multi_product::*; + +use std::fmt; +use std::iter::{Fuse, Peekable, FromIterator, FusedIterator}; +use std::marker::PhantomData; +use crate::size_hint; + +/// An iterator adaptor that alternates elements from two iterators until both +/// run out. +/// +/// This iterator is *fused*. +/// +/// See [`.interleave()`](crate::Itertools::interleave) for more information. +#[derive(Clone, Debug)] +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct Interleave<I, J> { + a: Fuse<I>, + b: Fuse<J>, + flag: bool, +} + +/// Create an iterator that interleaves elements in `i` and `j`. +/// +/// [`IntoIterator`] enabled version of `[Itertools::interleave]`. +pub fn interleave<I, J>(i: I, j: J) -> Interleave<<I as IntoIterator>::IntoIter, <J as IntoIterator>::IntoIter> + where I: IntoIterator, + J: IntoIterator<Item = I::Item> +{ + Interleave { + a: i.into_iter().fuse(), + b: j.into_iter().fuse(), + flag: false, + } +} + +impl<I, J> Iterator for Interleave<I, J> + where I: Iterator, + J: Iterator<Item = I::Item> +{ + type Item = I::Item; + #[inline] + fn next(&mut self) -> Option<Self::Item> { + self.flag = !self.flag; + if self.flag { + match self.a.next() { + None => self.b.next(), + r => r, + } + } else { + match self.b.next() { + None => self.a.next(), + r => r, + } + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + size_hint::add(self.a.size_hint(), self.b.size_hint()) + } +} + +impl<I, J> FusedIterator for Interleave<I, J> + where I: Iterator, + J: Iterator<Item = I::Item> +{} + +/// An iterator adaptor that alternates elements from the two iterators until +/// one of them runs out. +/// +/// This iterator is *fused*. +/// +/// See [`.interleave_shortest()`](crate::Itertools::interleave_shortest) +/// for more information. +#[derive(Clone, Debug)] +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct InterleaveShortest<I, J> + where I: Iterator, + J: Iterator<Item = I::Item> +{ + it0: I, + it1: J, + phase: bool, // false ==> it0, true ==> it1 +} + +/// Create a new `InterleaveShortest` iterator. +pub fn interleave_shortest<I, J>(a: I, b: J) -> InterleaveShortest<I, J> + where I: Iterator, + J: Iterator<Item = I::Item> +{ + InterleaveShortest { + it0: a, + it1: b, + phase: false, + } +} + +impl<I, J> Iterator for InterleaveShortest<I, J> + where I: Iterator, + J: Iterator<Item = I::Item> +{ + type Item = I::Item; + + #[inline] + fn next(&mut self) -> Option<Self::Item> { + let e = if self.phase { self.it1.next() } else { self.it0.next() }; + if e.is_some() { + self.phase = !self.phase; + } + e + } + + #[inline] + fn size_hint(&self) -> (usize, Option<usize>) { + let (curr_hint, next_hint) = { + let it0_hint = self.it0.size_hint(); + let it1_hint = self.it1.size_hint(); + if self.phase { + (it1_hint, it0_hint) + } else { + (it0_hint, it1_hint) + } + }; + let (curr_lower, curr_upper) = curr_hint; + let (next_lower, next_upper) = next_hint; + let (combined_lower, combined_upper) = + size_hint::mul_scalar(size_hint::min(curr_hint, next_hint), 2); + let lower = + if curr_lower > next_lower { + combined_lower + 1 + } else { + combined_lower + }; + let upper = { + let extra_elem = match (curr_upper, next_upper) { + (_, None) => false, + (None, Some(_)) => true, + (Some(curr_max), Some(next_max)) => curr_max > next_max, + }; + if extra_elem { + combined_upper.and_then(|x| x.checked_add(1)) + } else { + combined_upper + } + }; + (lower, upper) + } +} + +impl<I, J> FusedIterator for InterleaveShortest<I, J> + where I: FusedIterator, + J: FusedIterator<Item = I::Item> +{} + +#[derive(Clone, Debug)] +/// An iterator adaptor that allows putting back a single +/// item to the front of the iterator. +/// +/// Iterator element type is `I::Item`. +pub struct PutBack<I> + where I: Iterator +{ + top: Option<I::Item>, + iter: I, +} + +/// Create an iterator where you can put back a single item +pub fn put_back<I>(iterable: I) -> PutBack<I::IntoIter> + where I: IntoIterator +{ + PutBack { + top: None, + iter: iterable.into_iter(), + } +} + +impl<I> PutBack<I> + where I: Iterator +{ + /// put back value `value` (builder method) + pub fn with_value(mut self, value: I::Item) -> Self { + self.put_back(value); + self + } + + /// Split the `PutBack` into its parts. + #[inline] + pub fn into_parts(self) -> (Option<I::Item>, I) { + let PutBack{top, iter} = self; + (top, iter) + } + + /// Put back a single value to the front of the iterator. + /// + /// If a value is already in the put back slot, it is overwritten. + #[inline] + pub fn put_back(&mut self, x: I::Item) { + self.top = Some(x); + } +} + +impl<I> Iterator for PutBack<I> + where I: Iterator +{ + type Item = I::Item; + #[inline] + fn next(&mut self) -> Option<Self::Item> { + match self.top { + None => self.iter.next(), + ref mut some => some.take(), + } + } + #[inline] + fn size_hint(&self) -> (usize, Option<usize>) { + // Not ExactSizeIterator because size may be larger than usize + size_hint::add_scalar(self.iter.size_hint(), self.top.is_some() as usize) + } + + fn count(self) -> usize { + self.iter.count() + (self.top.is_some() as usize) + } + + fn last(self) -> Option<Self::Item> { + self.iter.last().or(self.top) + } + + fn nth(&mut self, n: usize) -> Option<Self::Item> { + match self.top { + None => self.iter.nth(n), + ref mut some => { + if n == 0 { + some.take() + } else { + *some = None; + self.iter.nth(n - 1) + } + } + } + } + + fn all<G>(&mut self, mut f: G) -> bool + where G: FnMut(Self::Item) -> bool + { + if let Some(elt) = self.top.take() { + if !f(elt) { + return false; + } + } + self.iter.all(f) + } + + fn fold<Acc, G>(mut self, init: Acc, mut f: G) -> Acc + where G: FnMut(Acc, Self::Item) -> Acc, + { + let mut accum = init; + if let Some(elt) = self.top.take() { + accum = f(accum, elt); + } + self.iter.fold(accum, f) + } +} + +#[derive(Debug, Clone)] +/// An iterator adaptor that iterates over the cartesian product of +/// the element sets of two iterators `I` and `J`. +/// +/// Iterator element type is `(I::Item, J::Item)`. +/// +/// See [`.cartesian_product()`](crate::Itertools::cartesian_product) for more information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct Product<I, J> + where I: Iterator +{ + a: I, + a_cur: Option<I::Item>, + b: J, + b_orig: J, +} + +/// Create a new cartesian product iterator +/// +/// Iterator element type is `(I::Item, J::Item)`. +pub fn cartesian_product<I, J>(mut i: I, j: J) -> Product<I, J> + where I: Iterator, + J: Clone + Iterator, + I::Item: Clone +{ + Product { + a_cur: i.next(), + a: i, + b: j.clone(), + b_orig: j, + } +} + +impl<I, J> Iterator for Product<I, J> + where I: Iterator, + J: Clone + Iterator, + I::Item: Clone +{ + type Item = (I::Item, J::Item); + + fn next(&mut self) -> Option<Self::Item> { + let elt_b = match self.b.next() { + None => { + self.b = self.b_orig.clone(); + match self.b.next() { + None => return None, + Some(x) => { + self.a_cur = self.a.next(); + x + } + } + } + Some(x) => x + }; + self.a_cur.as_ref().map(|a| (a.clone(), elt_b)) + } + + fn size_hint(&self) -> (usize, Option<usize>) { + let has_cur = self.a_cur.is_some() as usize; + // Not ExactSizeIterator because size may be larger than usize + let (b_min, b_max) = self.b.size_hint(); + + // Compute a * b_orig + b for both lower and upper bound + size_hint::add( + size_hint::mul(self.a.size_hint(), self.b_orig.size_hint()), + (b_min * has_cur, b_max.map(move |x| x * has_cur))) + } + + fn fold<Acc, G>(mut self, mut accum: Acc, mut f: G) -> Acc + where G: FnMut(Acc, Self::Item) -> Acc, + { + // use a split loop to handle the loose a_cur as well as avoiding to + // clone b_orig at the end. + if let Some(mut a) = self.a_cur.take() { + let mut b = self.b; + loop { + accum = b.fold(accum, |acc, elt| f(acc, (a.clone(), elt))); + + // we can only continue iterating a if we had a first element; + if let Some(next_a) = self.a.next() { + b = self.b_orig.clone(); + a = next_a; + } else { + break; + } + } + } + accum + } +} + +impl<I, J> FusedIterator for Product<I, J> + where I: FusedIterator, + J: Clone + FusedIterator, + I::Item: Clone +{} + +/// A “meta iterator adaptor”. Its closure receives a reference to the iterator +/// and may pick off as many elements as it likes, to produce the next iterator element. +/// +/// Iterator element type is *X*, if the return type of `F` is *Option\<X\>*. +/// +/// See [`.batching()`](crate::Itertools::batching) for more information. +#[derive(Clone)] +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct Batching<I, F> { + f: F, + iter: I, +} + +impl<I, F> fmt::Debug for Batching<I, F> where I: fmt::Debug { + debug_fmt_fields!(Batching, iter); +} + +/// Create a new Batching iterator. +pub fn batching<I, F>(iter: I, f: F) -> Batching<I, F> { + Batching { f, iter } +} + +impl<B, F, I> Iterator for Batching<I, F> + where I: Iterator, + F: FnMut(&mut I) -> Option<B> +{ + type Item = B; + #[inline] + fn next(&mut self) -> Option<Self::Item> { + (self.f)(&mut self.iter) + } +} + +/// An iterator adaptor that steps a number elements in the base iterator +/// for each iteration. +/// +/// The iterator steps by yielding the next element from the base iterator, +/// then skipping forward *n-1* elements. +/// +/// See [`.step()`](crate::Itertools::step) for more information. +#[deprecated(note="Use std .step_by() instead", since="0.8.0")] +#[allow(deprecated)] +#[derive(Clone, Debug)] +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct Step<I> { + iter: Fuse<I>, + skip: usize, +} + +/// Create a `Step` iterator. +/// +/// **Panics** if the step is 0. +#[allow(deprecated)] +pub fn step<I>(iter: I, step: usize) -> Step<I> + where I: Iterator +{ + assert!(step != 0); + Step { + iter: iter.fuse(), + skip: step - 1, + } +} + +#[allow(deprecated)] +impl<I> Iterator for Step<I> + where I: Iterator +{ + type Item = I::Item; + #[inline] + fn next(&mut self) -> Option<Self::Item> { + let elt = self.iter.next(); + if self.skip > 0 { + self.iter.nth(self.skip - 1); + } + elt + } + + fn size_hint(&self) -> (usize, Option<usize>) { + let (low, high) = self.iter.size_hint(); + let div = |x: usize| { + if x == 0 { + 0 + } else { + 1 + (x - 1) / (self.skip + 1) + } + }; + (div(low), high.map(div)) + } +} + +// known size +#[allow(deprecated)] +impl<I> ExactSizeIterator for Step<I> + where I: ExactSizeIterator +{} + +pub trait MergePredicate<T> { + fn merge_pred(&mut self, a: &T, b: &T) -> bool; +} + +#[derive(Clone, Debug)] +pub struct MergeLte; + +impl<T: PartialOrd> MergePredicate<T> for MergeLte { + fn merge_pred(&mut self, a: &T, b: &T) -> bool { + a <= b + } +} + +/// An iterator adaptor that merges the two base iterators in ascending order. +/// If both base iterators are sorted (ascending), the result is sorted. +/// +/// Iterator element type is `I::Item`. +/// +/// See [`.merge()`](crate::Itertools::merge_by) for more information. +pub type Merge<I, J> = MergeBy<I, J, MergeLte>; + +/// Create an iterator that merges elements in `i` and `j`. +/// +/// [`IntoIterator`] enabled version of [`Itertools::merge`](crate::Itertools::merge). +/// +/// ``` +/// use itertools::merge; +/// +/// for elt in merge(&[1, 2, 3], &[2, 3, 4]) { +/// /* loop body */ +/// } +/// ``` +pub fn merge<I, J>(i: I, j: J) -> Merge<<I as IntoIterator>::IntoIter, <J as IntoIterator>::IntoIter> + where I: IntoIterator, + J: IntoIterator<Item = I::Item>, + I::Item: PartialOrd +{ + merge_by_new(i, j, MergeLte) +} + +/// An iterator adaptor that merges the two base iterators in ascending order. +/// If both base iterators are sorted (ascending), the result is sorted. +/// +/// Iterator element type is `I::Item`. +/// +/// See [`.merge_by()`](crate::Itertools::merge_by) for more information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct MergeBy<I, J, F> + where I: Iterator, + J: Iterator<Item = I::Item> +{ + a: Peekable<I>, + b: Peekable<J>, + fused: Option<bool>, + cmp: F, +} + +impl<I, J, F> fmt::Debug for MergeBy<I, J, F> + where I: Iterator + fmt::Debug, J: Iterator<Item = I::Item> + fmt::Debug, + I::Item: fmt::Debug, +{ + debug_fmt_fields!(MergeBy, a, b); +} + +impl<T, F: FnMut(&T, &T)->bool> MergePredicate<T> for F { + fn merge_pred(&mut self, a: &T, b: &T) -> bool { + self(a, b) + } +} + +/// Create a `MergeBy` iterator. +pub fn merge_by_new<I, J, F>(a: I, b: J, cmp: F) -> MergeBy<I::IntoIter, J::IntoIter, F> + where I: IntoIterator, + J: IntoIterator<Item = I::Item>, + F: MergePredicate<I::Item>, +{ + MergeBy { + a: a.into_iter().peekable(), + b: b.into_iter().peekable(), + fused: None, + cmp, + } +} + +impl<I, J, F> Clone for MergeBy<I, J, F> + where I: Iterator, + J: Iterator<Item = I::Item>, + Peekable<I>: Clone, + Peekable<J>: Clone, + F: Clone +{ + clone_fields!(a, b, fused, cmp); +} + +impl<I, J, F> Iterator for MergeBy<I, J, F> + where I: Iterator, + J: Iterator<Item = I::Item>, + F: MergePredicate<I::Item> +{ + type Item = I::Item; + + fn next(&mut self) -> Option<Self::Item> { + let less_than = match self.fused { + Some(lt) => lt, + None => match (self.a.peek(), self.b.peek()) { + (Some(a), Some(b)) => self.cmp.merge_pred(a, b), + (Some(_), None) => { + self.fused = Some(true); + true + } + (None, Some(_)) => { + self.fused = Some(false); + false + } + (None, None) => return None, + } + }; + if less_than { + self.a.next() + } else { + self.b.next() + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + // Not ExactSizeIterator because size may be larger than usize + size_hint::add(self.a.size_hint(), self.b.size_hint()) + } +} + +impl<I, J, F> FusedIterator for MergeBy<I, J, F> + where I: FusedIterator, + J: FusedIterator<Item = I::Item>, + F: MergePredicate<I::Item> +{} + +/// An iterator adaptor that borrows from a `Clone`-able iterator +/// to only pick off elements while the predicate returns `true`. +/// +/// See [`.take_while_ref()`](crate::Itertools::take_while_ref) for more information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct TakeWhileRef<'a, I: 'a, F> { + iter: &'a mut I, + f: F, +} + +impl<'a, I, F> fmt::Debug for TakeWhileRef<'a, I, F> + where I: Iterator + fmt::Debug, +{ + debug_fmt_fields!(TakeWhileRef, iter); +} + +/// Create a new `TakeWhileRef` from a reference to clonable iterator. +pub fn take_while_ref<I, F>(iter: &mut I, f: F) -> TakeWhileRef<I, F> + where I: Iterator + Clone +{ + TakeWhileRef { iter, f } +} + +impl<'a, I, F> Iterator for TakeWhileRef<'a, I, F> + where I: Iterator + Clone, + F: FnMut(&I::Item) -> bool +{ + type Item = I::Item; + + fn next(&mut self) -> Option<Self::Item> { + let old = self.iter.clone(); + match self.iter.next() { + None => None, + Some(elt) => { + if (self.f)(&elt) { + Some(elt) + } else { + *self.iter = old; + None + } + } + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (0, self.iter.size_hint().1) + } +} + +/// An iterator adaptor that filters `Option<A>` iterator elements +/// and produces `A`. Stops on the first `None` encountered. +/// +/// See [`.while_some()`](crate::Itertools::while_some) for more information. +#[derive(Clone, Debug)] +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct WhileSome<I> { + iter: I, +} + +/// Create a new `WhileSome<I>`. +pub fn while_some<I>(iter: I) -> WhileSome<I> { + WhileSome { iter } +} + +impl<I, A> Iterator for WhileSome<I> + where I: Iterator<Item = Option<A>> +{ + type Item = A; + + fn next(&mut self) -> Option<Self::Item> { + match self.iter.next() { + None | Some(None) => None, + Some(elt) => elt, + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (0, self.iter.size_hint().1) + } +} + +/// An iterator to iterate through all combinations in a `Clone`-able iterator that produces tuples +/// of a specific size. +/// +/// See [`.tuple_combinations()`](crate::Itertools::tuple_combinations) for more +/// information. +#[derive(Clone, Debug)] +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct TupleCombinations<I, T> + where I: Iterator, + T: HasCombination<I> +{ + iter: T::Combination, + _mi: PhantomData<I>, +} + +pub trait HasCombination<I>: Sized { + type Combination: From<I> + Iterator<Item = Self>; +} + +/// Create a new `TupleCombinations` from a clonable iterator. +pub fn tuple_combinations<T, I>(iter: I) -> TupleCombinations<I, T> + where I: Iterator + Clone, + I::Item: Clone, + T: HasCombination<I>, +{ + TupleCombinations { + iter: T::Combination::from(iter), + _mi: PhantomData, + } +} + +impl<I, T> Iterator for TupleCombinations<I, T> + where I: Iterator, + T: HasCombination<I>, +{ + type Item = T; + + fn next(&mut self) -> Option<Self::Item> { + self.iter.next() + } +} + +impl<I, T> FusedIterator for TupleCombinations<I, T> + where I: FusedIterator, + T: HasCombination<I>, +{} + +#[derive(Clone, Debug)] +pub struct Tuple1Combination<I> { + iter: I, +} + +impl<I> From<I> for Tuple1Combination<I> { + fn from(iter: I) -> Self { + Tuple1Combination { iter } + } +} + +impl<I: Iterator> Iterator for Tuple1Combination<I> { + type Item = (I::Item,); + + fn next(&mut self) -> Option<Self::Item> { + self.iter.next().map(|x| (x,)) + } +} + +impl<I: Iterator> HasCombination<I> for (I::Item,) { + type Combination = Tuple1Combination<I>; +} + +macro_rules! impl_tuple_combination { + ($C:ident $P:ident ; $($X:ident)*) => ( + #[derive(Clone, Debug)] + pub struct $C<I: Iterator> { + item: Option<I::Item>, + iter: I, + c: $P<I>, + } + + impl<I: Iterator + Clone> From<I> for $C<I> { + fn from(mut iter: I) -> Self { + Self { + item: iter.next(), + iter: iter.clone(), + c: iter.into(), + } + } + } + + impl<I: Iterator + Clone> From<I> for $C<Fuse<I>> { + fn from(iter: I) -> Self { + Self::from(iter.fuse()) + } + } + + impl<I, A> Iterator for $C<I> + where I: Iterator<Item = A> + Clone, + I::Item: Clone + { + type Item = (A, $(ignore_ident!($X, A)),*); + + fn next(&mut self) -> Option<Self::Item> { + if let Some(($($X),*,)) = self.c.next() { + let z = self.item.clone().unwrap(); + Some((z, $($X),*)) + } else { + self.item = self.iter.next(); + self.item.clone().and_then(|z| { + self.c = self.iter.clone().into(); + self.c.next().map(|($($X),*,)| (z, $($X),*)) + }) + } + } + } + + impl<I, A> HasCombination<I> for (A, $(ignore_ident!($X, A)),*) + where I: Iterator<Item = A> + Clone, + I::Item: Clone + { + type Combination = $C<Fuse<I>>; + } + ) +} + +// This snippet generates the twelve `impl_tuple_combination!` invocations: +// use core::iter; +// use itertools::Itertools; +// +// for i in 2..=12 { +// println!("impl_tuple_combination!(Tuple{arity}Combination Tuple{prev}Combination; {idents});", +// arity = i, +// prev = i - 1, +// idents = ('a'..'z').take(i - 1).join(" "), +// ); +// } +// It could probably be replaced by a bit more macro cleverness. +impl_tuple_combination!(Tuple2Combination Tuple1Combination; a); +impl_tuple_combination!(Tuple3Combination Tuple2Combination; a b); +impl_tuple_combination!(Tuple4Combination Tuple3Combination; a b c); +impl_tuple_combination!(Tuple5Combination Tuple4Combination; a b c d); +impl_tuple_combination!(Tuple6Combination Tuple5Combination; a b c d e); +impl_tuple_combination!(Tuple7Combination Tuple6Combination; a b c d e f); +impl_tuple_combination!(Tuple8Combination Tuple7Combination; a b c d e f g); +impl_tuple_combination!(Tuple9Combination Tuple8Combination; a b c d e f g h); +impl_tuple_combination!(Tuple10Combination Tuple9Combination; a b c d e f g h i); +impl_tuple_combination!(Tuple11Combination Tuple10Combination; a b c d e f g h i j); +impl_tuple_combination!(Tuple12Combination Tuple11Combination; a b c d e f g h i j k); + +/// An iterator adapter to filter values within a nested `Result::Ok`. +/// +/// See [`.filter_ok()`](crate::Itertools::filter_ok) for more information. +#[derive(Clone)] +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct FilterOk<I, F> { + iter: I, + f: F +} + +impl<I, F> fmt::Debug for FilterOk<I, F> +where + I: fmt::Debug, +{ + debug_fmt_fields!(FilterOk, iter); +} + +/// Create a new `FilterOk` iterator. +pub fn filter_ok<I, F, T, E>(iter: I, f: F) -> FilterOk<I, F> + where I: Iterator<Item = Result<T, E>>, + F: FnMut(&T) -> bool, +{ + FilterOk { + iter, + f, + } +} + +impl<I, F, T, E> Iterator for FilterOk<I, F> + where I: Iterator<Item = Result<T, E>>, + F: FnMut(&T) -> bool, +{ + type Item = Result<T, E>; + + fn next(&mut self) -> Option<Self::Item> { + loop { + match self.iter.next() { + Some(Ok(v)) => { + if (self.f)(&v) { + return Some(Ok(v)); + } + }, + Some(Err(e)) => return Some(Err(e)), + None => return None, + } + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (0, self.iter.size_hint().1) + } + + fn fold<Acc, Fold>(self, init: Acc, fold_f: Fold) -> Acc + where Fold: FnMut(Acc, Self::Item) -> Acc, + { + let mut f = self.f; + self.iter.filter(|v| { + v.as_ref().map(&mut f).unwrap_or(true) + }).fold(init, fold_f) + } + + fn collect<C>(self) -> C + where C: FromIterator<Self::Item> + { + let mut f = self.f; + self.iter.filter(|v| { + v.as_ref().map(&mut f).unwrap_or(true) + }).collect() + } +} + +impl<I, F, T, E> FusedIterator for FilterOk<I, F> + where I: FusedIterator<Item = Result<T, E>>, + F: FnMut(&T) -> bool, +{} + +/// An iterator adapter to filter and apply a transformation on values within a nested `Result::Ok`. +/// +/// See [`.filter_map_ok()`](crate::Itertools::filter_map_ok) for more information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct FilterMapOk<I, F> { + iter: I, + f: F +} + +impl<I, F> fmt::Debug for FilterMapOk<I, F> +where + I: fmt::Debug, +{ + debug_fmt_fields!(FilterMapOk, iter); +} + +fn transpose_result<T, E>(result: Result<Option<T>, E>) -> Option<Result<T, E>> { + match result { + Ok(Some(v)) => Some(Ok(v)), + Ok(None) => None, + Err(e) => Some(Err(e)), + } +} + +/// Create a new `FilterOk` iterator. +pub fn filter_map_ok<I, F, T, U, E>(iter: I, f: F) -> FilterMapOk<I, F> + where I: Iterator<Item = Result<T, E>>, + F: FnMut(T) -> Option<U>, +{ + FilterMapOk { + iter, + f, + } +} + +impl<I, F, T, U, E> Iterator for FilterMapOk<I, F> + where I: Iterator<Item = Result<T, E>>, + F: FnMut(T) -> Option<U>, +{ + type Item = Result<U, E>; + + fn next(&mut self) -> Option<Self::Item> { + loop { + match self.iter.next() { + Some(Ok(v)) => { + if let Some(v) = (self.f)(v) { + return Some(Ok(v)); + } + }, + Some(Err(e)) => return Some(Err(e)), + None => return None, + } + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (0, self.iter.size_hint().1) + } + + fn fold<Acc, Fold>(self, init: Acc, fold_f: Fold) -> Acc + where Fold: FnMut(Acc, Self::Item) -> Acc, + { + let mut f = self.f; + self.iter.filter_map(|v| { + transpose_result(v.map(&mut f)) + }).fold(init, fold_f) + } + + fn collect<C>(self) -> C + where C: FromIterator<Self::Item> + { + let mut f = self.f; + self.iter.filter_map(|v| { + transpose_result(v.map(&mut f)) + }).collect() + } +} + +impl<I, F, T, U, E> FusedIterator for FilterMapOk<I, F> + where I: FusedIterator<Item = Result<T, E>>, + F: FnMut(T) -> Option<U>, +{} + +/// An iterator adapter to get the positions of each element that matches a predicate. +/// +/// See [`.positions()`](crate::Itertools::positions) for more information. +#[derive(Clone)] +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct Positions<I, F> { + iter: I, + f: F, + count: usize, +} + +impl<I, F> fmt::Debug for Positions<I, F> +where + I: fmt::Debug, +{ + debug_fmt_fields!(Positions, iter, count); +} + +/// Create a new `Positions` iterator. +pub fn positions<I, F>(iter: I, f: F) -> Positions<I, F> + where I: Iterator, + F: FnMut(I::Item) -> bool, +{ + Positions { + iter, + f, + count: 0 + } +} + +impl<I, F> Iterator for Positions<I, F> + where I: Iterator, + F: FnMut(I::Item) -> bool, +{ + type Item = usize; + + fn next(&mut self) -> Option<Self::Item> { + while let Some(v) = self.iter.next() { + let i = self.count; + self.count = i + 1; + if (self.f)(v) { + return Some(i); + } + } + None + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (0, self.iter.size_hint().1) + } +} + +impl<I, F> DoubleEndedIterator for Positions<I, F> + where I: DoubleEndedIterator + ExactSizeIterator, + F: FnMut(I::Item) -> bool, +{ + fn next_back(&mut self) -> Option<Self::Item> { + while let Some(v) = self.iter.next_back() { + if (self.f)(v) { + return Some(self.count + self.iter.len()) + } + } + None + } +} + +impl<I, F> FusedIterator for Positions<I, F> + where I: FusedIterator, + F: FnMut(I::Item) -> bool, +{} + +/// An iterator adapter to apply a mutating function to each element before yielding it. +/// +/// See [`.update()`](crate::Itertools::update) for more information. +#[derive(Clone)] +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct Update<I, F> { + iter: I, + f: F, +} + +impl<I, F> fmt::Debug for Update<I, F> +where + I: fmt::Debug, +{ + debug_fmt_fields!(Update, iter); +} + +/// Create a new `Update` iterator. +pub fn update<I, F>(iter: I, f: F) -> Update<I, F> +where + I: Iterator, + F: FnMut(&mut I::Item), +{ + Update { iter, f } +} + +impl<I, F> Iterator for Update<I, F> +where + I: Iterator, + F: FnMut(&mut I::Item), +{ + type Item = I::Item; + + fn next(&mut self) -> Option<Self::Item> { + if let Some(mut v) = self.iter.next() { + (self.f)(&mut v); + Some(v) + } else { + None + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + self.iter.size_hint() + } + + fn fold<Acc, G>(self, init: Acc, mut g: G) -> Acc + where G: FnMut(Acc, Self::Item) -> Acc, + { + let mut f = self.f; + self.iter.fold(init, move |acc, mut v| { f(&mut v); g(acc, v) }) + } + + // if possible, re-use inner iterator specializations in collect + fn collect<C>(self) -> C + where C: FromIterator<Self::Item> + { + let mut f = self.f; + self.iter.map(move |mut v| { f(&mut v); v }).collect() + } +} + +impl<I, F> ExactSizeIterator for Update<I, F> +where + I: ExactSizeIterator, + F: FnMut(&mut I::Item), +{} + +impl<I, F> DoubleEndedIterator for Update<I, F> +where + I: DoubleEndedIterator, + F: FnMut(&mut I::Item), +{ + fn next_back(&mut self) -> Option<Self::Item> { + if let Some(mut v) = self.iter.next_back() { + (self.f)(&mut v); + Some(v) + } else { + None + } + } +} + +impl<I, F> FusedIterator for Update<I, F> +where + I: FusedIterator, + F: FnMut(&mut I::Item), +{} diff --git a/third_party/rust/itertools/src/adaptors/multi_product.rs b/third_party/rust/itertools/src/adaptors/multi_product.rs new file mode 100644 index 0000000000..0b38406987 --- /dev/null +++ b/third_party/rust/itertools/src/adaptors/multi_product.rs @@ -0,0 +1,230 @@ +#![cfg(feature = "use_alloc")] + +use crate::size_hint; +use crate::Itertools; + +use alloc::vec::Vec; + +#[derive(Clone)] +/// An iterator adaptor that iterates over the cartesian product of +/// multiple iterators of type `I`. +/// +/// An iterator element type is `Vec<I>`. +/// +/// See [`.multi_cartesian_product()`](crate::Itertools::multi_cartesian_product) +/// for more information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct MultiProduct<I>(Vec<MultiProductIter<I>>) + where I: Iterator + Clone, + I::Item: Clone; + +impl<I> std::fmt::Debug for MultiProduct<I> +where + I: Iterator + Clone + std::fmt::Debug, + I::Item: Clone + std::fmt::Debug, +{ + debug_fmt_fields!(CoalesceBy, 0); +} + +/// Create a new cartesian product iterator over an arbitrary number +/// of iterators of the same type. +/// +/// Iterator element is of type `Vec<H::Item::Item>`. +pub fn multi_cartesian_product<H>(iters: H) -> MultiProduct<<H::Item as IntoIterator>::IntoIter> + where H: Iterator, + H::Item: IntoIterator, + <H::Item as IntoIterator>::IntoIter: Clone, + <H::Item as IntoIterator>::Item: Clone +{ + MultiProduct(iters.map(|i| MultiProductIter::new(i.into_iter())).collect()) +} + +#[derive(Clone, Debug)] +/// Holds the state of a single iterator within a `MultiProduct`. +struct MultiProductIter<I> + where I: Iterator + Clone, + I::Item: Clone +{ + cur: Option<I::Item>, + iter: I, + iter_orig: I, +} + +/// Holds the current state during an iteration of a `MultiProduct`. +#[derive(Debug)] +enum MultiProductIterState { + StartOfIter, + MidIter { on_first_iter: bool }, +} + +impl<I> MultiProduct<I> + where I: Iterator + Clone, + I::Item: Clone +{ + /// Iterates the rightmost iterator, then recursively iterates iterators + /// to the left if necessary. + /// + /// Returns true if the iteration succeeded, else false. + fn iterate_last( + multi_iters: &mut [MultiProductIter<I>], + mut state: MultiProductIterState + ) -> bool { + use self::MultiProductIterState::*; + + if let Some((last, rest)) = multi_iters.split_last_mut() { + let on_first_iter = match state { + StartOfIter => { + let on_first_iter = !last.in_progress(); + state = MidIter { on_first_iter }; + on_first_iter + }, + MidIter { on_first_iter } => on_first_iter + }; + + if !on_first_iter { + last.iterate(); + } + + if last.in_progress() { + true + } else if MultiProduct::iterate_last(rest, state) { + last.reset(); + last.iterate(); + // If iterator is None twice consecutively, then iterator is + // empty; whole product is empty. + last.in_progress() + } else { + false + } + } else { + // Reached end of iterator list. On initialisation, return true. + // At end of iteration (final iterator finishes), finish. + match state { + StartOfIter => false, + MidIter { on_first_iter } => on_first_iter + } + } + } + + /// Returns the unwrapped value of the next iteration. + fn curr_iterator(&self) -> Vec<I::Item> { + self.0.iter().map(|multi_iter| { + multi_iter.cur.clone().unwrap() + }).collect() + } + + /// Returns true if iteration has started and has not yet finished; false + /// otherwise. + fn in_progress(&self) -> bool { + if let Some(last) = self.0.last() { + last.in_progress() + } else { + false + } + } +} + +impl<I> MultiProductIter<I> + where I: Iterator + Clone, + I::Item: Clone +{ + fn new(iter: I) -> Self { + MultiProductIter { + cur: None, + iter: iter.clone(), + iter_orig: iter + } + } + + /// Iterate the managed iterator. + fn iterate(&mut self) { + self.cur = self.iter.next(); + } + + /// Reset the managed iterator. + fn reset(&mut self) { + self.iter = self.iter_orig.clone(); + } + + /// Returns true if the current iterator has been started and has not yet + /// finished; false otherwise. + fn in_progress(&self) -> bool { + self.cur.is_some() + } +} + +impl<I> Iterator for MultiProduct<I> + where I: Iterator + Clone, + I::Item: Clone +{ + type Item = Vec<I::Item>; + + fn next(&mut self) -> Option<Self::Item> { + if MultiProduct::iterate_last( + &mut self.0, + MultiProductIterState::StartOfIter + ) { + Some(self.curr_iterator()) + } else { + None + } + } + + fn count(self) -> usize { + if self.0.is_empty() { + return 0; + } + + if !self.in_progress() { + return self.0.into_iter().fold(1, |acc, multi_iter| { + acc * multi_iter.iter.count() + }); + } + + self.0.into_iter().fold( + 0, + |acc, MultiProductIter { iter, iter_orig, cur: _ }| { + let total_count = iter_orig.count(); + let cur_count = iter.count(); + acc * total_count + cur_count + } + ) + } + + fn size_hint(&self) -> (usize, Option<usize>) { + // Not ExactSizeIterator because size may be larger than usize + if self.0.is_empty() { + return (0, Some(0)); + } + + if !self.in_progress() { + return self.0.iter().fold((1, Some(1)), |acc, multi_iter| { + size_hint::mul(acc, multi_iter.iter.size_hint()) + }); + } + + self.0.iter().fold( + (0, Some(0)), + |acc, &MultiProductIter { ref iter, ref iter_orig, cur: _ }| { + let cur_size = iter.size_hint(); + let total_size = iter_orig.size_hint(); + size_hint::add(size_hint::mul(acc, total_size), cur_size) + } + ) + } + + fn last(self) -> Option<Self::Item> { + let iter_count = self.0.len(); + + let lasts: Self::Item = self.0.into_iter() + .map(|multi_iter| multi_iter.iter.last()) + .while_some() + .collect(); + + if lasts.len() == iter_count { + Some(lasts) + } else { + None + } + } +} diff --git a/third_party/rust/itertools/src/combinations.rs b/third_party/rust/itertools/src/combinations.rs new file mode 100644 index 0000000000..68a59c5e4d --- /dev/null +++ b/third_party/rust/itertools/src/combinations.rs @@ -0,0 +1,128 @@ +use std::fmt; +use std::iter::FusedIterator; + +use super::lazy_buffer::LazyBuffer; +use alloc::vec::Vec; + +/// An iterator to iterate through all the `k`-length combinations in an iterator. +/// +/// See [`.combinations()`](crate::Itertools::combinations) for more information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct Combinations<I: Iterator> { + indices: Vec<usize>, + pool: LazyBuffer<I>, + first: bool, +} + +impl<I> Clone for Combinations<I> + where I: Clone + Iterator, + I::Item: Clone, +{ + clone_fields!(indices, pool, first); +} + +impl<I> fmt::Debug for Combinations<I> + where I: Iterator + fmt::Debug, + I::Item: fmt::Debug, +{ + debug_fmt_fields!(Combinations, indices, pool, first); +} + +/// Create a new `Combinations` from a clonable iterator. +pub fn combinations<I>(iter: I, k: usize) -> Combinations<I> + where I: Iterator +{ + let mut pool = LazyBuffer::new(iter); + pool.prefill(k); + + Combinations { + indices: (0..k).collect(), + pool, + first: true, + } +} + +impl<I: Iterator> Combinations<I> { + /// Returns the length of a combination produced by this iterator. + #[inline] + pub fn k(&self) -> usize { self.indices.len() } + + /// Returns the (current) length of the pool from which combination elements are + /// selected. This value can change between invocations of [`next`](Combinations::next). + #[inline] + pub fn n(&self) -> usize { self.pool.len() } + + /// Returns a reference to the source iterator. + #[inline] + pub(crate) fn src(&self) -> &I { &self.pool.it } + + /// Resets this `Combinations` back to an initial state for combinations of length + /// `k` over the same pool data source. If `k` is larger than the current length + /// of the data pool an attempt is made to prefill the pool so that it holds `k` + /// elements. + pub(crate) fn reset(&mut self, k: usize) { + self.first = true; + + if k < self.indices.len() { + self.indices.truncate(k); + for i in 0..k { + self.indices[i] = i; + } + + } else { + for i in 0..self.indices.len() { + self.indices[i] = i; + } + self.indices.extend(self.indices.len()..k); + self.pool.prefill(k); + } + } +} + +impl<I> Iterator for Combinations<I> + where I: Iterator, + I::Item: Clone +{ + type Item = Vec<I::Item>; + fn next(&mut self) -> Option<Self::Item> { + if self.first { + if self.k() > self.n() { + return None; + } + self.first = false; + } else if self.indices.is_empty() { + return None; + } else { + // Scan from the end, looking for an index to increment + let mut i: usize = self.indices.len() - 1; + + // Check if we need to consume more from the iterator + if self.indices[i] == self.pool.len() - 1 { + self.pool.get_next(); // may change pool size + } + + while self.indices[i] == i + self.pool.len() - self.indices.len() { + if i > 0 { + i -= 1; + } else { + // Reached the last combination + return None; + } + } + + // Increment index, and reset the ones to its right + self.indices[i] += 1; + for j in i+1..self.indices.len() { + self.indices[j] = self.indices[j - 1] + 1; + } + } + + // Create result vector based on the indices + Some(self.indices.iter().map(|i| self.pool[*i].clone()).collect()) + } +} + +impl<I> FusedIterator for Combinations<I> + where I: Iterator, + I::Item: Clone +{} diff --git a/third_party/rust/itertools/src/combinations_with_replacement.rs b/third_party/rust/itertools/src/combinations_with_replacement.rs new file mode 100644 index 0000000000..0fec9671ac --- /dev/null +++ b/third_party/rust/itertools/src/combinations_with_replacement.rs @@ -0,0 +1,109 @@ +use alloc::vec::Vec; +use std::fmt; +use std::iter::FusedIterator; + +use super::lazy_buffer::LazyBuffer; + +/// An iterator to iterate through all the `n`-length combinations in an iterator, with replacement. +/// +/// See [`.combinations_with_replacement()`](crate::Itertools::combinations_with_replacement) +/// for more information. +#[derive(Clone)] +pub struct CombinationsWithReplacement<I> +where + I: Iterator, + I::Item: Clone, +{ + indices: Vec<usize>, + pool: LazyBuffer<I>, + first: bool, +} + +impl<I> fmt::Debug for CombinationsWithReplacement<I> +where + I: Iterator + fmt::Debug, + I::Item: fmt::Debug + Clone, +{ + debug_fmt_fields!(Combinations, indices, pool, first); +} + +impl<I> CombinationsWithReplacement<I> +where + I: Iterator, + I::Item: Clone, +{ + /// Map the current mask over the pool to get an output combination + fn current(&self) -> Vec<I::Item> { + self.indices.iter().map(|i| self.pool[*i].clone()).collect() + } +} + +/// Create a new `CombinationsWithReplacement` from a clonable iterator. +pub fn combinations_with_replacement<I>(iter: I, k: usize) -> CombinationsWithReplacement<I> +where + I: Iterator, + I::Item: Clone, +{ + let indices: Vec<usize> = alloc::vec![0; k]; + let pool: LazyBuffer<I> = LazyBuffer::new(iter); + + CombinationsWithReplacement { + indices, + pool, + first: true, + } +} + +impl<I> Iterator for CombinationsWithReplacement<I> +where + I: Iterator, + I::Item: Clone, +{ + type Item = Vec<I::Item>; + fn next(&mut self) -> Option<Self::Item> { + // If this is the first iteration, return early + if self.first { + // In empty edge cases, stop iterating immediately + return if !(self.indices.is_empty() || self.pool.get_next()) { + None + // Otherwise, yield the initial state + } else { + self.first = false; + Some(self.current()) + }; + } + + // Check if we need to consume more from the iterator + // This will run while we increment our first index digit + self.pool.get_next(); + + // Work out where we need to update our indices + let mut increment: Option<(usize, usize)> = None; + for (i, indices_int) in self.indices.iter().enumerate().rev() { + if *indices_int < self.pool.len()-1 { + increment = Some((i, indices_int + 1)); + break; + } + } + + match increment { + // If we can update the indices further + Some((increment_from, increment_value)) => { + // We need to update the rightmost non-max value + // and all those to the right + for indices_index in increment_from..self.indices.len() { + self.indices[indices_index] = increment_value; + } + Some(self.current()) + } + // Otherwise, we're done + None => None, + } + } +} + +impl<I> FusedIterator for CombinationsWithReplacement<I> +where + I: Iterator, + I::Item: Clone, +{} diff --git a/third_party/rust/itertools/src/concat_impl.rs b/third_party/rust/itertools/src/concat_impl.rs new file mode 100644 index 0000000000..f022ec90af --- /dev/null +++ b/third_party/rust/itertools/src/concat_impl.rs @@ -0,0 +1,23 @@ +use crate::Itertools; + +/// Combine all an iterator's elements into one element by using [`Extend`]. +/// +/// [`IntoIterator`]-enabled version of [`Itertools::concat`]. +/// +/// This combinator will extend the first item with each of the rest of the +/// items of the iterator. If the iterator is empty, the default value of +/// `I::Item` is returned. +/// +/// ```rust +/// use itertools::concat; +/// +/// let input = vec![vec![1], vec![2, 3], vec![4, 5, 6]]; +/// assert_eq!(concat(input), vec![1, 2, 3, 4, 5, 6]); +/// ``` +pub fn concat<I>(iterable: I) -> I::Item + where I: IntoIterator, + I::Item: Extend<<<I as IntoIterator>::Item as IntoIterator>::Item> + IntoIterator + Default +{ + #[allow(deprecated)] //TODO: once msrv hits 1.51. replace `fold1` with `reduce` + iterable.into_iter().fold1(|mut a, b| { a.extend(b); a }).unwrap_or_default() +} diff --git a/third_party/rust/itertools/src/cons_tuples_impl.rs b/third_party/rust/itertools/src/cons_tuples_impl.rs new file mode 100644 index 0000000000..ae0f48f349 --- /dev/null +++ b/third_party/rust/itertools/src/cons_tuples_impl.rs @@ -0,0 +1,64 @@ + +macro_rules! impl_cons_iter( + ($_A:ident, $_B:ident, ) => (); // stop + + ($A:ident, $($B:ident,)*) => ( + impl_cons_iter!($($B,)*); + #[allow(non_snake_case)] + impl<X, Iter, $($B),*> Iterator for ConsTuples<Iter, (($($B,)*), X)> + where Iter: Iterator<Item = (($($B,)*), X)>, + { + type Item = ($($B,)* X, ); + fn next(&mut self) -> Option<Self::Item> { + self.iter.next().map(|(($($B,)*), x)| ($($B,)* x, )) + } + + fn size_hint(&self) -> (usize, Option<usize>) { + self.iter.size_hint() + } + fn fold<Acc, Fold>(self, accum: Acc, mut f: Fold) -> Acc + where Fold: FnMut(Acc, Self::Item) -> Acc, + { + self.iter.fold(accum, move |acc, (($($B,)*), x)| f(acc, ($($B,)* x, ))) + } + } + + #[allow(non_snake_case)] + impl<X, Iter, $($B),*> DoubleEndedIterator for ConsTuples<Iter, (($($B,)*), X)> + where Iter: DoubleEndedIterator<Item = (($($B,)*), X)>, + { + fn next_back(&mut self) -> Option<Self::Item> { + self.iter.next().map(|(($($B,)*), x)| ($($B,)* x, )) + } + } + + ); +); + +impl_cons_iter!(A, B, C, D, E, F, G, H, I, J, K, L,); + +/// An iterator that maps an iterator of tuples like +/// `((A, B), C)` to an iterator of `(A, B, C)`. +/// +/// Used by the `iproduct!()` macro. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +#[derive(Debug)] +pub struct ConsTuples<I, J> + where I: Iterator<Item=J>, +{ + iter: I, +} + +impl<I, J> Clone for ConsTuples<I, J> + where I: Clone + Iterator<Item=J>, +{ + clone_fields!(iter); +} + +/// Create an iterator that maps for example iterators of +/// `((A, B), C)` to `(A, B, C)`. +pub fn cons_tuples<I, J>(iterable: I) -> ConsTuples<I::IntoIter, J> + where I: IntoIterator<Item=J> +{ + ConsTuples { iter: iterable.into_iter() } +} diff --git a/third_party/rust/itertools/src/diff.rs b/third_party/rust/itertools/src/diff.rs new file mode 100644 index 0000000000..1731f0639f --- /dev/null +++ b/third_party/rust/itertools/src/diff.rs @@ -0,0 +1,61 @@ +//! "Diff"ing iterators for caching elements to sequential collections without requiring the new +//! elements' iterator to be `Clone`. +//! +//! - [`Diff`] (produced by the [`diff_with`] function) +//! describes the difference between two non-`Clone` iterators `I` and `J` after breaking ASAP from +//! a lock-step comparison. + +use crate::free::put_back; +use crate::structs::PutBack; + +/// A type returned by the [`diff_with`] function. +/// +/// `Diff` represents the way in which the elements yielded by the iterator `I` differ to some +/// iterator `J`. +pub enum Diff<I, J> + where I: Iterator, + J: Iterator +{ + /// The index of the first non-matching element along with both iterator's remaining elements + /// starting with the first mis-match. + FirstMismatch(usize, PutBack<I>, PutBack<J>), + /// The total number of elements that were in `J` along with the remaining elements of `I`. + Shorter(usize, PutBack<I>), + /// The total number of elements that were in `I` along with the remaining elements of `J`. + Longer(usize, PutBack<J>), +} + +/// Compares every element yielded by both `i` and `j` with the given function in lock-step and +/// returns a [`Diff`] which describes how `j` differs from `i`. +/// +/// If the number of elements yielded by `j` is less than the number of elements yielded by `i`, +/// the number of `j` elements yielded will be returned along with `i`'s remaining elements as +/// `Diff::Shorter`. +/// +/// If the two elements of a step differ, the index of those elements along with the remaining +/// elements of both `i` and `j` are returned as `Diff::FirstMismatch`. +/// +/// If `i` becomes exhausted before `j` becomes exhausted, the number of elements in `i` along with +/// the remaining `j` elements will be returned as `Diff::Longer`. +pub fn diff_with<I, J, F>(i: I, j: J, is_equal: F) + -> Option<Diff<I::IntoIter, J::IntoIter>> + where I: IntoIterator, + J: IntoIterator, + F: Fn(&I::Item, &J::Item) -> bool +{ + let mut i = i.into_iter(); + let mut j = j.into_iter(); + let mut idx = 0; + while let Some(i_elem) = i.next() { + match j.next() { + None => return Some(Diff::Shorter(idx, put_back(i).with_value(i_elem))), + Some(j_elem) => if !is_equal(&i_elem, &j_elem) { + let remaining_i = put_back(i).with_value(i_elem); + let remaining_j = put_back(j).with_value(j_elem); + return Some(Diff::FirstMismatch(idx, remaining_i, remaining_j)); + }, + } + idx += 1; + } + j.next().map(|j_elem| Diff::Longer(idx, put_back(j).with_value(j_elem))) +} diff --git a/third_party/rust/itertools/src/duplicates_impl.rs b/third_party/rust/itertools/src/duplicates_impl.rs new file mode 100644 index 0000000000..28eda44a97 --- /dev/null +++ b/third_party/rust/itertools/src/duplicates_impl.rs @@ -0,0 +1,216 @@ +use std::hash::Hash; + +mod private { + use std::collections::HashMap; + use std::hash::Hash; + use std::fmt; + + #[derive(Clone)] + #[must_use = "iterator adaptors are lazy and do nothing unless consumed"] + pub struct DuplicatesBy<I: Iterator, Key, F> { + pub(crate) iter: I, + pub(crate) meta: Meta<Key, F>, + } + + impl<I, V, F> fmt::Debug for DuplicatesBy<I, V, F> + where + I: Iterator + fmt::Debug, + V: fmt::Debug + Hash + Eq, + { + debug_fmt_fields!(DuplicatesBy, iter, meta.used); + } + + impl<I: Iterator, Key: Eq + Hash, F> DuplicatesBy<I, Key, F> { + pub(crate) fn new(iter: I, key_method: F) -> Self { + DuplicatesBy { + iter, + meta: Meta { + used: HashMap::new(), + pending: 0, + key_method, + }, + } + } + } + + #[derive(Clone)] + pub struct Meta<Key, F> { + used: HashMap<Key, bool>, + pending: usize, + key_method: F, + } + + impl<Key, F> Meta<Key, F> + where + Key: Eq + Hash, + { + /// Takes an item and returns it back to the caller if it's the second time we see it. + /// Otherwise the item is consumed and None is returned + #[inline(always)] + fn filter<I>(&mut self, item: I) -> Option<I> + where + F: KeyMethod<Key, I>, + { + let kv = self.key_method.make(item); + match self.used.get_mut(kv.key_ref()) { + None => { + self.used.insert(kv.key(), false); + self.pending += 1; + None + } + Some(true) => None, + Some(produced) => { + *produced = true; + self.pending -= 1; + Some(kv.value()) + } + } + } + } + + impl<I, Key, F> Iterator for DuplicatesBy<I, Key, F> + where + I: Iterator, + Key: Eq + Hash, + F: KeyMethod<Key, I::Item>, + { + type Item = I::Item; + + fn next(&mut self) -> Option<Self::Item> { + let DuplicatesBy { iter, meta } = self; + iter.find_map(|v| meta.filter(v)) + } + + #[inline] + fn size_hint(&self) -> (usize, Option<usize>) { + let (_, hi) = self.iter.size_hint(); + let hi = hi.map(|hi| { + if hi <= self.meta.pending { + // fewer or equally many iter-remaining elements than pending elements + // => at most, each iter-remaining element is matched + hi + } else { + // fewer pending elements than iter-remaining elements + // => at most: + // * each pending element is matched + // * the other iter-remaining elements come in pairs + self.meta.pending + (hi - self.meta.pending) / 2 + } + }); + // The lower bound is always 0 since we might only get unique items from now on + (0, hi) + } + } + + impl<I, Key, F> DoubleEndedIterator for DuplicatesBy<I, Key, F> + where + I: DoubleEndedIterator, + Key: Eq + Hash, + F: KeyMethod<Key, I::Item>, + { + fn next_back(&mut self) -> Option<Self::Item> { + let DuplicatesBy { iter, meta } = self; + iter.rev().find_map(|v| meta.filter(v)) + } + } + + /// A keying method for use with `DuplicatesBy` + pub trait KeyMethod<K, V> { + type Container: KeyXorValue<K, V>; + + fn make(&mut self, value: V) -> Self::Container; + } + + /// Apply the identity function to elements before checking them for equality. + #[derive(Debug)] + pub struct ById; + impl<V> KeyMethod<V, V> for ById { + type Container = JustValue<V>; + + fn make(&mut self, v: V) -> Self::Container { + JustValue(v) + } + } + + /// Apply a user-supplied function to elements before checking them for equality. + pub struct ByFn<F>(pub(crate) F); + impl<F> fmt::Debug for ByFn<F> { + debug_fmt_fields!(ByFn,); + } + impl<K, V, F> KeyMethod<K, V> for ByFn<F> + where + F: FnMut(&V) -> K, + { + type Container = KeyValue<K, V>; + + fn make(&mut self, v: V) -> Self::Container { + KeyValue((self.0)(&v), v) + } + } + + // Implementors of this trait can hold onto a key and a value but only give access to one of them + // at a time. This allows the key and the value to be the same value internally + pub trait KeyXorValue<K, V> { + fn key_ref(&self) -> &K; + fn key(self) -> K; + fn value(self) -> V; + } + + #[derive(Debug)] + pub struct KeyValue<K, V>(K, V); + impl<K, V> KeyXorValue<K, V> for KeyValue<K, V> { + fn key_ref(&self) -> &K { + &self.0 + } + fn key(self) -> K { + self.0 + } + fn value(self) -> V { + self.1 + } + } + + #[derive(Debug)] + pub struct JustValue<V>(V); + impl<V> KeyXorValue<V, V> for JustValue<V> { + fn key_ref(&self) -> &V { + &self.0 + } + fn key(self) -> V { + self.0 + } + fn value(self) -> V { + self.0 + } + } +} + +/// An iterator adapter to filter for duplicate elements. +/// +/// See [`.duplicates_by()`](crate::Itertools::duplicates_by) for more information. +pub type DuplicatesBy<I, V, F> = private::DuplicatesBy<I, V, private::ByFn<F>>; + +/// Create a new `DuplicatesBy` iterator. +pub fn duplicates_by<I, Key, F>(iter: I, f: F) -> DuplicatesBy<I, Key, F> +where + Key: Eq + Hash, + F: FnMut(&I::Item) -> Key, + I: Iterator, +{ + DuplicatesBy::new(iter, private::ByFn(f)) +} + +/// An iterator adapter to filter out duplicate elements. +/// +/// See [`.duplicates()`](crate::Itertools::duplicates) for more information. +pub type Duplicates<I> = private::DuplicatesBy<I, <I as Iterator>::Item, private::ById>; + +/// Create a new `Duplicates` iterator. +pub fn duplicates<I>(iter: I) -> Duplicates<I> +where + I: Iterator, + I::Item: Eq + Hash, +{ + Duplicates::new(iter, private::ById) +} + diff --git a/third_party/rust/itertools/src/either_or_both.rs b/third_party/rust/itertools/src/either_or_both.rs new file mode 100644 index 0000000000..ef3985f757 --- /dev/null +++ b/third_party/rust/itertools/src/either_or_both.rs @@ -0,0 +1,254 @@ +use crate::EitherOrBoth::*; + +use either::Either; + +/// Value that either holds a single A or B, or both. +#[derive(Clone, PartialEq, Eq, Hash, Debug)] +pub enum EitherOrBoth<A, B> { + /// Both values are present. + Both(A, B), + /// Only the left value of type `A` is present. + Left(A), + /// Only the right value of type `B` is present. + Right(B), +} + +impl<A, B> EitherOrBoth<A, B> { + /// If `Left`, or `Both`, return true, otherwise, return false. + pub fn has_left(&self) -> bool { + self.as_ref().left().is_some() + } + + /// If `Right`, or `Both`, return true, otherwise, return false. + pub fn has_right(&self) -> bool { + self.as_ref().right().is_some() + } + + /// If Left, return true otherwise, return false. + /// Exclusive version of [`has_left`](EitherOrBoth::has_left). + pub fn is_left(&self) -> bool { + match *self { + Left(_) => true, + _ => false, + } + } + + /// If Right, return true otherwise, return false. + /// Exclusive version of [`has_right`](EitherOrBoth::has_right). + pub fn is_right(&self) -> bool { + match *self { + Right(_) => true, + _ => false, + } + } + + /// If Right, return true otherwise, return false. + /// Equivalent to `self.as_ref().both().is_some()`. + pub fn is_both(&self) -> bool { + self.as_ref().both().is_some() + } + + /// If `Left`, or `Both`, return `Some` with the left value, otherwise, return `None`. + pub fn left(self) -> Option<A> { + match self { + Left(left) | Both(left, _) => Some(left), + _ => None, + } + } + + /// If `Right`, or `Both`, return `Some` with the right value, otherwise, return `None`. + pub fn right(self) -> Option<B> { + match self { + Right(right) | Both(_, right) => Some(right), + _ => None, + } + } + + /// If Both, return `Some` tuple containing left and right. + pub fn both(self) -> Option<(A, B)> { + match self { + Both(a, b) => Some((a, b)), + _ => None, + } + } + + /// Converts from `&EitherOrBoth<A, B>` to `EitherOrBoth<&A, &B>`. + pub fn as_ref(&self) -> EitherOrBoth<&A, &B> { + match *self { + Left(ref left) => Left(left), + Right(ref right) => Right(right), + Both(ref left, ref right) => Both(left, right), + } + } + + /// Converts from `&mut EitherOrBoth<A, B>` to `EitherOrBoth<&mut A, &mut B>`. + pub fn as_mut(&mut self) -> EitherOrBoth<&mut A, &mut B> { + match *self { + Left(ref mut left) => Left(left), + Right(ref mut right) => Right(right), + Both(ref mut left, ref mut right) => Both(left, right), + } + } + + /// Convert `EitherOrBoth<A, B>` to `EitherOrBoth<B, A>`. + pub fn flip(self) -> EitherOrBoth<B, A> { + match self { + Left(a) => Right(a), + Right(b) => Left(b), + Both(a, b) => Both(b, a), + } + } + + /// Apply the function `f` on the value `a` in `Left(a)` or `Both(a, b)` variants. If it is + /// present rewrapping the result in `self`'s original variant. + pub fn map_left<F, M>(self, f: F) -> EitherOrBoth<M, B> + where + F: FnOnce(A) -> M, + { + match self { + Both(a, b) => Both(f(a), b), + Left(a) => Left(f(a)), + Right(b) => Right(b), + } + } + + /// Apply the function `f` on the value `b` in `Right(b)` or `Both(a, b)` variants. + /// If it is present rewrapping the result in `self`'s original variant. + pub fn map_right<F, M>(self, f: F) -> EitherOrBoth<A, M> + where + F: FnOnce(B) -> M, + { + match self { + Left(a) => Left(a), + Right(b) => Right(f(b)), + Both(a, b) => Both(a, f(b)), + } + } + + /// Apply the functions `f` and `g` on the value `a` and `b` respectively; + /// found in `Left(a)`, `Right(b)`, or `Both(a, b)` variants. + /// The Result is rewrapped `self`'s original variant. + pub fn map_any<F, L, G, R>(self, f: F, g: G) -> EitherOrBoth<L, R> + where + F: FnOnce(A) -> L, + G: FnOnce(B) -> R, + { + match self { + Left(a) => Left(f(a)), + Right(b) => Right(g(b)), + Both(a, b) => Both(f(a), g(b)), + } + } + + /// Apply the function `f` on the value `a` in `Left(a)` or `Both(a, _)` variants if it is + /// present. + pub fn left_and_then<F, L>(self, f: F) -> EitherOrBoth<L, B> + where + F: FnOnce(A) -> EitherOrBoth<L, B>, + { + match self { + Left(a) | Both(a, _) => f(a), + Right(b) => Right(b), + } + } + + /// Apply the function `f` on the value `b` + /// in `Right(b)` or `Both(_, b)` variants if it is present. + pub fn right_and_then<F, R>(self, f: F) -> EitherOrBoth<A, R> + where + F: FnOnce(B) -> EitherOrBoth<A, R>, + { + match self { + Left(a) => Left(a), + Right(b) | Both(_, b) => f(b), + } + } + + /// Returns a tuple consisting of the `l` and `r` in `Both(l, r)`, if present. + /// Otherwise, returns the wrapped value for the present element, and the supplied + /// value for the other. The first (`l`) argument is used for a missing `Left` + /// value. The second (`r`) argument is used for a missing `Right` value. + /// + /// Arguments passed to `or` are eagerly evaluated; if you are passing + /// the result of a function call, it is recommended to use [`or_else`], + /// which is lazily evaluated. + /// + /// [`or_else`]: EitherOrBoth::or_else + /// + /// # Examples + /// + /// ``` + /// # use itertools::EitherOrBoth; + /// assert_eq!(EitherOrBoth::Both("tree", 1).or("stone", 5), ("tree", 1)); + /// assert_eq!(EitherOrBoth::Left("tree").or("stone", 5), ("tree", 5)); + /// assert_eq!(EitherOrBoth::Right(1).or("stone", 5), ("stone", 1)); + /// ``` + pub fn or(self, l: A, r: B) -> (A, B) { + match self { + Left(inner_l) => (inner_l, r), + Right(inner_r) => (l, inner_r), + Both(inner_l, inner_r) => (inner_l, inner_r), + } + } + + /// Returns a tuple consisting of the `l` and `r` in `Both(l, r)`, if present. + /// Otherwise, returns the wrapped value for the present element, and the [`default`](Default::default) + /// for the other. + pub fn or_default(self) -> (A, B) + where + A: Default, + B: Default, + { + match self { + EitherOrBoth::Left(l) => (l, B::default()), + EitherOrBoth::Right(r) => (A::default(), r), + EitherOrBoth::Both(l, r) => (l, r), + } + } + + /// Returns a tuple consisting of the `l` and `r` in `Both(l, r)`, if present. + /// Otherwise, returns the wrapped value for the present element, and computes the + /// missing value with the supplied closure. The first argument (`l`) is used for a + /// missing `Left` value. The second argument (`r`) is used for a missing `Right` value. + /// + /// # Examples + /// + /// ``` + /// # use itertools::EitherOrBoth; + /// let k = 10; + /// assert_eq!(EitherOrBoth::Both("tree", 1).or_else(|| "stone", || 2 * k), ("tree", 1)); + /// assert_eq!(EitherOrBoth::Left("tree").or_else(|| "stone", || 2 * k), ("tree", 20)); + /// assert_eq!(EitherOrBoth::Right(1).or_else(|| "stone", || 2 * k), ("stone", 1)); + /// ``` + pub fn or_else<L: FnOnce() -> A, R: FnOnce() -> B>(self, l: L, r: R) -> (A, B) { + match self { + Left(inner_l) => (inner_l, r()), + Right(inner_r) => (l(), inner_r), + Both(inner_l, inner_r) => (inner_l, inner_r), + } + } +} + +impl<T> EitherOrBoth<T, T> { + /// Return either value of left, right, or the product of `f` applied where `Both` are present. + pub fn reduce<F>(self, f: F) -> T + where + F: FnOnce(T, T) -> T, + { + match self { + Left(a) => a, + Right(b) => b, + Both(a, b) => f(a, b), + } + } +} + +impl<A, B> Into<Option<Either<A, B>>> for EitherOrBoth<A, B> { + fn into(self) -> Option<Either<A, B>> { + match self { + EitherOrBoth::Left(l) => Some(Either::Left(l)), + EitherOrBoth::Right(r) => Some(Either::Right(r)), + _ => None, + } + } +} diff --git a/third_party/rust/itertools/src/exactly_one_err.rs b/third_party/rust/itertools/src/exactly_one_err.rs new file mode 100644 index 0000000000..c54ae77ca9 --- /dev/null +++ b/third_party/rust/itertools/src/exactly_one_err.rs @@ -0,0 +1,110 @@ +#[cfg(feature = "use_std")] +use std::error::Error; +use std::fmt::{Debug, Display, Formatter, Result as FmtResult}; + +use std::iter::ExactSizeIterator; + +use either::Either; + +use crate::size_hint; + +/// Iterator returned for the error case of `IterTools::exactly_one()` +/// This iterator yields exactly the same elements as the input iterator. +/// +/// During the execution of `exactly_one` the iterator must be mutated. This wrapper +/// effectively "restores" the state of the input iterator when it's handed back. +/// +/// This is very similar to `PutBackN` except this iterator only supports 0-2 elements and does not +/// use a `Vec`. +#[derive(Clone)] +pub struct ExactlyOneError<I> +where + I: Iterator, +{ + first_two: Option<Either<[I::Item; 2], I::Item>>, + inner: I, +} + +impl<I> ExactlyOneError<I> +where + I: Iterator, +{ + /// Creates a new `ExactlyOneErr` iterator. + pub(crate) fn new(first_two: Option<Either<[I::Item; 2], I::Item>>, inner: I) -> Self { + Self { first_two, inner } + } + + fn additional_len(&self) -> usize { + match self.first_two { + Some(Either::Left(_)) => 2, + Some(Either::Right(_)) => 1, + None => 0, + } + } +} + +impl<I> Iterator for ExactlyOneError<I> +where + I: Iterator, +{ + type Item = I::Item; + + fn next(&mut self) -> Option<Self::Item> { + match self.first_two.take() { + Some(Either::Left([first, second])) => { + self.first_two = Some(Either::Right(second)); + Some(first) + }, + Some(Either::Right(second)) => { + Some(second) + } + None => { + self.inner.next() + } + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + size_hint::add_scalar(self.inner.size_hint(), self.additional_len()) + } +} + + +impl<I> ExactSizeIterator for ExactlyOneError<I> where I: ExactSizeIterator {} + +impl<I> Display for ExactlyOneError<I> + where I: Iterator, +{ + fn fmt(&self, f: &mut Formatter) -> FmtResult { + let additional = self.additional_len(); + if additional > 0 { + write!(f, "got at least 2 elements when exactly one was expected") + } else { + write!(f, "got zero elements when exactly one was expected") + } + } +} + +impl<I> Debug for ExactlyOneError<I> + where I: Iterator + Debug, + I::Item: Debug, +{ + fn fmt(&self, f: &mut Formatter) -> FmtResult { + match &self.first_two { + Some(Either::Left([first, second])) => { + write!(f, "ExactlyOneError[First: {:?}, Second: {:?}, RemainingIter: {:?}]", first, second, self.inner) + }, + Some(Either::Right(second)) => { + write!(f, "ExactlyOneError[Second: {:?}, RemainingIter: {:?}]", second, self.inner) + } + None => { + write!(f, "ExactlyOneError[RemainingIter: {:?}]", self.inner) + } + } + } +} + +#[cfg(feature = "use_std")] +impl<I> Error for ExactlyOneError<I> where I: Iterator + Debug, I::Item: Debug, {} + + diff --git a/third_party/rust/itertools/src/extrema_set.rs b/third_party/rust/itertools/src/extrema_set.rs new file mode 100644 index 0000000000..ae128364c5 --- /dev/null +++ b/third_party/rust/itertools/src/extrema_set.rs @@ -0,0 +1,48 @@ +use std::cmp::Ordering; + +/// Implementation guts for `min_set`, `min_set_by`, and `min_set_by_key`. +pub fn min_set_impl<I, K, F, Compare>( + mut it: I, + mut key_for: F, + mut compare: Compare, +) -> Vec<I::Item> +where + I: Iterator, + F: FnMut(&I::Item) -> K, + Compare: FnMut(&I::Item, &I::Item, &K, &K) -> Ordering, +{ + match it.next() { + None => Vec::new(), + Some(element) => { + let mut current_key = key_for(&element); + let mut result = vec![element]; + it.for_each(|element| { + let key = key_for(&element); + match compare(&element, &result[0], &key, ¤t_key) { + Ordering::Less => { + result.clear(); + result.push(element); + current_key = key; + } + Ordering::Equal => { + result.push(element); + } + Ordering::Greater => {} + } + }); + result + } + } +} + +/// Implementation guts for `ax_set`, `max_set_by`, and `max_set_by_key`. +pub fn max_set_impl<I, K, F, Compare>(it: I, key_for: F, mut compare: Compare) -> Vec<I::Item> +where + I: Iterator, + F: FnMut(&I::Item) -> K, + Compare: FnMut(&I::Item, &I::Item, &K, &K) -> Ordering, +{ + min_set_impl(it, key_for, |it1, it2, key1, key2| { + compare(it2, it1, key2, key1) + }) +} diff --git a/third_party/rust/itertools/src/flatten_ok.rs b/third_party/rust/itertools/src/flatten_ok.rs new file mode 100644 index 0000000000..21ae1f7223 --- /dev/null +++ b/third_party/rust/itertools/src/flatten_ok.rs @@ -0,0 +1,165 @@ +use crate::size_hint; +use std::{ + fmt, + iter::{DoubleEndedIterator, FusedIterator}, +}; + +pub fn flatten_ok<I, T, E>(iter: I) -> FlattenOk<I, T, E> +where + I: Iterator<Item = Result<T, E>>, + T: IntoIterator, +{ + FlattenOk { + iter, + inner_front: None, + inner_back: None, + } +} + +/// An iterator adaptor that flattens `Result::Ok` values and +/// allows `Result::Err` values through unchanged. +/// +/// See [`.flatten_ok()`](crate::Itertools::flatten_ok) for more information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct FlattenOk<I, T, E> +where + I: Iterator<Item = Result<T, E>>, + T: IntoIterator, +{ + iter: I, + inner_front: Option<T::IntoIter>, + inner_back: Option<T::IntoIter>, +} + +impl<I, T, E> Iterator for FlattenOk<I, T, E> +where + I: Iterator<Item = Result<T, E>>, + T: IntoIterator, +{ + type Item = Result<T::Item, E>; + + fn next(&mut self) -> Option<Self::Item> { + loop { + // Handle the front inner iterator. + if let Some(inner) = &mut self.inner_front { + if let Some(item) = inner.next() { + return Some(Ok(item)); + } + + // This is necessary for the iterator to implement `FusedIterator` + // with only the original iterator being fused. + self.inner_front = None; + } + + match self.iter.next() { + Some(Ok(ok)) => self.inner_front = Some(ok.into_iter()), + Some(Err(e)) => return Some(Err(e)), + None => { + // Handle the back inner iterator. + if let Some(inner) = &mut self.inner_back { + if let Some(item) = inner.next() { + return Some(Ok(item)); + } + + // This is necessary for the iterator to implement `FusedIterator` + // with only the original iterator being fused. + self.inner_back = None; + } else { + return None; + } + } + } + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + let inner_hint = |inner: &Option<T::IntoIter>| { + inner + .as_ref() + .map(Iterator::size_hint) + .unwrap_or((0, Some(0))) + }; + let inner_front = inner_hint(&self.inner_front); + let inner_back = inner_hint(&self.inner_back); + // The outer iterator `Ok` case could be (0, None) as we don't know its size_hint yet. + let outer = match self.iter.size_hint() { + (0, Some(0)) => (0, Some(0)), + _ => (0, None), + }; + + size_hint::add(size_hint::add(inner_front, inner_back), outer) + } +} + +impl<I, T, E> DoubleEndedIterator for FlattenOk<I, T, E> +where + I: DoubleEndedIterator<Item = Result<T, E>>, + T: IntoIterator, + T::IntoIter: DoubleEndedIterator, +{ + fn next_back(&mut self) -> Option<Self::Item> { + loop { + // Handle the back inner iterator. + if let Some(inner) = &mut self.inner_back { + if let Some(item) = inner.next_back() { + return Some(Ok(item)); + } + + // This is necessary for the iterator to implement `FusedIterator` + // with only the original iterator being fused. + self.inner_back = None; + } + + match self.iter.next_back() { + Some(Ok(ok)) => self.inner_back = Some(ok.into_iter()), + Some(Err(e)) => return Some(Err(e)), + None => { + // Handle the front inner iterator. + if let Some(inner) = &mut self.inner_front { + if let Some(item) = inner.next_back() { + return Some(Ok(item)); + } + + // This is necessary for the iterator to implement `FusedIterator` + // with only the original iterator being fused. + self.inner_front = None; + } else { + return None; + } + } + } + } + } +} + +impl<I, T, E> Clone for FlattenOk<I, T, E> +where + I: Iterator<Item = Result<T, E>> + Clone, + T: IntoIterator, + T::IntoIter: Clone, +{ + clone_fields!(iter, inner_front, inner_back); +} + +impl<I, T, E> fmt::Debug for FlattenOk<I, T, E> +where + I: Iterator<Item = Result<T, E>> + fmt::Debug, + T: IntoIterator, + T::IntoIter: fmt::Debug, +{ + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("FlattenOk") + .field("iter", &self.iter) + .field("inner_front", &self.inner_front) + .field("inner_back", &self.inner_back) + .finish() + } +} + +/// Only the iterator being flattened needs to implement [`FusedIterator`]. +impl<I, T, E> FusedIterator for FlattenOk<I, T, E> +where + I: FusedIterator<Item = Result<T, E>>, + T: IntoIterator, +{ +} diff --git a/third_party/rust/itertools/src/format.rs b/third_party/rust/itertools/src/format.rs new file mode 100644 index 0000000000..d87cee9503 --- /dev/null +++ b/third_party/rust/itertools/src/format.rs @@ -0,0 +1,113 @@ +use std::fmt; +use std::cell::RefCell; + +/// Format all iterator elements lazily, separated by `sep`. +/// +/// The format value can only be formatted once, after that the iterator is +/// exhausted. +/// +/// See [`.format_with()`](crate::Itertools::format_with) for more information. +#[derive(Clone)] +pub struct FormatWith<'a, I, F> { + sep: &'a str, + /// FormatWith uses interior mutability because Display::fmt takes &self. + inner: RefCell<Option<(I, F)>>, +} + +/// Format all iterator elements lazily, separated by `sep`. +/// +/// The format value can only be formatted once, after that the iterator is +/// exhausted. +/// +/// See [`.format()`](crate::Itertools::format) +/// for more information. +#[derive(Clone)] +pub struct Format<'a, I> { + sep: &'a str, + /// Format uses interior mutability because Display::fmt takes &self. + inner: RefCell<Option<I>>, +} + +pub fn new_format<I, F>(iter: I, separator: &str, f: F) -> FormatWith<'_, I, F> + where I: Iterator, + F: FnMut(I::Item, &mut dyn FnMut(&dyn fmt::Display) -> fmt::Result) -> fmt::Result +{ + FormatWith { + sep: separator, + inner: RefCell::new(Some((iter, f))), + } +} + +pub fn new_format_default<I>(iter: I, separator: &str) -> Format<'_, I> + where I: Iterator, +{ + Format { + sep: separator, + inner: RefCell::new(Some(iter)), + } +} + +impl<'a, I, F> fmt::Display for FormatWith<'a, I, F> + where I: Iterator, + F: FnMut(I::Item, &mut dyn FnMut(&dyn fmt::Display) -> fmt::Result) -> fmt::Result +{ + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + let (mut iter, mut format) = match self.inner.borrow_mut().take() { + Some(t) => t, + None => panic!("FormatWith: was already formatted once"), + }; + + if let Some(fst) = iter.next() { + format(fst, &mut |disp: &dyn fmt::Display| disp.fmt(f))?; + iter.try_for_each(|elt| { + if !self.sep.is_empty() { + f.write_str(self.sep)?; + } + format(elt, &mut |disp: &dyn fmt::Display| disp.fmt(f)) + })?; + } + Ok(()) + } +} + +impl<'a, I> Format<'a, I> + where I: Iterator, +{ + fn format<F>(&self, f: &mut fmt::Formatter, mut cb: F) -> fmt::Result + where F: FnMut(&I::Item, &mut fmt::Formatter) -> fmt::Result, + { + let mut iter = match self.inner.borrow_mut().take() { + Some(t) => t, + None => panic!("Format: was already formatted once"), + }; + + if let Some(fst) = iter.next() { + cb(&fst, f)?; + iter.try_for_each(|elt| { + if !self.sep.is_empty() { + f.write_str(self.sep)?; + } + cb(&elt, f) + })?; + } + Ok(()) + } +} + +macro_rules! impl_format { + ($($fmt_trait:ident)*) => { + $( + impl<'a, I> fmt::$fmt_trait for Format<'a, I> + where I: Iterator, + I::Item: fmt::$fmt_trait, + { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + self.format(f, fmt::$fmt_trait::fmt) + } + } + )* + } +} + +impl_format!{Display Debug + UpperExp LowerExp UpperHex LowerHex Octal Binary Pointer} diff --git a/third_party/rust/itertools/src/free.rs b/third_party/rust/itertools/src/free.rs new file mode 100644 index 0000000000..19e3e28694 --- /dev/null +++ b/third_party/rust/itertools/src/free.rs @@ -0,0 +1,286 @@ +//! Free functions that create iterator adaptors or call iterator methods. +//! +//! The benefit of free functions is that they accept any [`IntoIterator`] as +//! argument, so the resulting code may be easier to read. + +#[cfg(feature = "use_alloc")] +use std::fmt::Display; +use std::iter::{self, Zip}; +#[cfg(feature = "use_alloc")] +type VecIntoIter<T> = alloc::vec::IntoIter<T>; + +#[cfg(feature = "use_alloc")] +use alloc::{ + string::String, +}; + +use crate::Itertools; +use crate::intersperse::{Intersperse, IntersperseWith}; + +pub use crate::adaptors::{ + interleave, + merge, + put_back, +}; +#[cfg(feature = "use_alloc")] +pub use crate::put_back_n_impl::put_back_n; +#[cfg(feature = "use_alloc")] +pub use crate::multipeek_impl::multipeek; +#[cfg(feature = "use_alloc")] +pub use crate::peek_nth::peek_nth; +#[cfg(feature = "use_alloc")] +pub use crate::kmerge_impl::kmerge; +pub use crate::zip_eq_impl::zip_eq; +pub use crate::merge_join::merge_join_by; +#[cfg(feature = "use_alloc")] +pub use crate::rciter_impl::rciter; + +/// Iterate `iterable` with a particular value inserted between each element. +/// +/// [`IntoIterator`] enabled version of [`Iterator::intersperse`]. +/// +/// ``` +/// use itertools::intersperse; +/// +/// itertools::assert_equal(intersperse((0..3), 8), vec![0, 8, 1, 8, 2]); +/// ``` +pub fn intersperse<I>(iterable: I, element: I::Item) -> Intersperse<I::IntoIter> + where I: IntoIterator, + <I as IntoIterator>::Item: Clone +{ + Itertools::intersperse(iterable.into_iter(), element) +} + +/// Iterate `iterable` with a particular value created by a function inserted +/// between each element. +/// +/// [`IntoIterator`] enabled version of [`Iterator::intersperse_with`]. +/// +/// ``` +/// use itertools::intersperse_with; +/// +/// let mut i = 10; +/// itertools::assert_equal(intersperse_with((0..3), || { i -= 1; i }), vec![0, 9, 1, 8, 2]); +/// assert_eq!(i, 8); +/// ``` +pub fn intersperse_with<I, F>(iterable: I, element: F) -> IntersperseWith<I::IntoIter, F> + where I: IntoIterator, + F: FnMut() -> I::Item +{ + Itertools::intersperse_with(iterable.into_iter(), element) +} + +/// Iterate `iterable` with a running index. +/// +/// [`IntoIterator`] enabled version of [`Iterator::enumerate`]. +/// +/// ``` +/// use itertools::enumerate; +/// +/// for (i, elt) in enumerate(&[1, 2, 3]) { +/// /* loop body */ +/// } +/// ``` +pub fn enumerate<I>(iterable: I) -> iter::Enumerate<I::IntoIter> + where I: IntoIterator +{ + iterable.into_iter().enumerate() +} + +/// Iterate `iterable` in reverse. +/// +/// [`IntoIterator`] enabled version of [`Iterator::rev`]. +/// +/// ``` +/// use itertools::rev; +/// +/// for elt in rev(&[1, 2, 3]) { +/// /* loop body */ +/// } +/// ``` +pub fn rev<I>(iterable: I) -> iter::Rev<I::IntoIter> + where I: IntoIterator, + I::IntoIter: DoubleEndedIterator +{ + iterable.into_iter().rev() +} + +/// Converts the arguments to iterators and zips them. +/// +/// [`IntoIterator`] enabled version of [`Iterator::zip`]. +/// +/// ## Example +/// +/// ``` +/// use itertools::zip; +/// +/// let mut result: Vec<(i32, char)> = Vec::new(); +/// +/// for (a, b) in zip(&[1, 2, 3, 4, 5], &['a', 'b', 'c']) { +/// result.push((*a, *b)); +/// } +/// assert_eq!(result, vec![(1, 'a'),(2, 'b'),(3, 'c')]); +/// ``` +#[deprecated(note="Use [std::iter::zip](https://doc.rust-lang.org/std/iter/fn.zip.html) instead", since="0.10.4")] +pub fn zip<I, J>(i: I, j: J) -> Zip<I::IntoIter, J::IntoIter> + where I: IntoIterator, + J: IntoIterator +{ + i.into_iter().zip(j) +} + + +/// Takes two iterables and creates a new iterator over both in sequence. +/// +/// [`IntoIterator`] enabled version of [`Iterator::chain`]. +/// +/// ## Example +/// ``` +/// use itertools::chain; +/// +/// let mut result:Vec<i32> = Vec::new(); +/// +/// for element in chain(&[1, 2, 3], &[4]) { +/// result.push(*element); +/// } +/// assert_eq!(result, vec![1, 2, 3, 4]); +/// ``` +pub fn chain<I, J>(i: I, j: J) -> iter::Chain<<I as IntoIterator>::IntoIter, <J as IntoIterator>::IntoIter> + where I: IntoIterator, + J: IntoIterator<Item = I::Item> +{ + i.into_iter().chain(j) +} + +/// Create an iterator that clones each element from &T to T +/// +/// [`IntoIterator`] enabled version of [`Iterator::cloned`]. +/// +/// ``` +/// use itertools::cloned; +/// +/// assert_eq!(cloned(b"abc").next(), Some(b'a')); +/// ``` +pub fn cloned<'a, I, T: 'a>(iterable: I) -> iter::Cloned<I::IntoIter> + where I: IntoIterator<Item=&'a T>, + T: Clone, +{ + iterable.into_iter().cloned() +} + +/// Perform a fold operation over the iterable. +/// +/// [`IntoIterator`] enabled version of [`Iterator::fold`]. +/// +/// ``` +/// use itertools::fold; +/// +/// assert_eq!(fold(&[1., 2., 3.], 0., |a, &b| f32::max(a, b)), 3.); +/// ``` +pub fn fold<I, B, F>(iterable: I, init: B, f: F) -> B + where I: IntoIterator, + F: FnMut(B, I::Item) -> B +{ + iterable.into_iter().fold(init, f) +} + +/// Test whether the predicate holds for all elements in the iterable. +/// +/// [`IntoIterator`] enabled version of [`Iterator::all`]. +/// +/// ``` +/// use itertools::all; +/// +/// assert!(all(&[1, 2, 3], |elt| *elt > 0)); +/// ``` +pub fn all<I, F>(iterable: I, f: F) -> bool + where I: IntoIterator, + F: FnMut(I::Item) -> bool +{ + iterable.into_iter().all(f) +} + +/// Test whether the predicate holds for any elements in the iterable. +/// +/// [`IntoIterator`] enabled version of [`Iterator::any`]. +/// +/// ``` +/// use itertools::any; +/// +/// assert!(any(&[0, -1, 2], |elt| *elt > 0)); +/// ``` +pub fn any<I, F>(iterable: I, f: F) -> bool + where I: IntoIterator, + F: FnMut(I::Item) -> bool +{ + iterable.into_iter().any(f) +} + +/// Return the maximum value of the iterable. +/// +/// [`IntoIterator`] enabled version of [`Iterator::max`]. +/// +/// ``` +/// use itertools::max; +/// +/// assert_eq!(max(0..10), Some(9)); +/// ``` +pub fn max<I>(iterable: I) -> Option<I::Item> + where I: IntoIterator, + I::Item: Ord +{ + iterable.into_iter().max() +} + +/// Return the minimum value of the iterable. +/// +/// [`IntoIterator`] enabled version of [`Iterator::min`]. +/// +/// ``` +/// use itertools::min; +/// +/// assert_eq!(min(0..10), Some(0)); +/// ``` +pub fn min<I>(iterable: I) -> Option<I::Item> + where I: IntoIterator, + I::Item: Ord +{ + iterable.into_iter().min() +} + + +/// Combine all iterator elements into one String, separated by `sep`. +/// +/// [`IntoIterator`] enabled version of [`Itertools::join`]. +/// +/// ``` +/// use itertools::join; +/// +/// assert_eq!(join(&[1, 2, 3], ", "), "1, 2, 3"); +/// ``` +#[cfg(feature = "use_alloc")] +pub fn join<I>(iterable: I, sep: &str) -> String + where I: IntoIterator, + I::Item: Display +{ + iterable.into_iter().join(sep) +} + +/// Sort all iterator elements into a new iterator in ascending order. +/// +/// [`IntoIterator`] enabled version of [`Itertools::sorted`]. +/// +/// ``` +/// use itertools::sorted; +/// use itertools::assert_equal; +/// +/// assert_equal(sorted("rust".chars()), "rstu".chars()); +/// ``` +#[cfg(feature = "use_alloc")] +pub fn sorted<I>(iterable: I) -> VecIntoIter<I::Item> + where I: IntoIterator, + I::Item: Ord +{ + iterable.into_iter().sorted() +} + diff --git a/third_party/rust/itertools/src/group_map.rs b/third_party/rust/itertools/src/group_map.rs new file mode 100644 index 0000000000..a2d0ebb2ab --- /dev/null +++ b/third_party/rust/itertools/src/group_map.rs @@ -0,0 +1,32 @@ +#![cfg(feature = "use_std")] + +use std::collections::HashMap; +use std::hash::Hash; +use std::iter::Iterator; + +/// Return a `HashMap` of keys mapped to a list of their corresponding values. +/// +/// See [`.into_group_map()`](crate::Itertools::into_group_map) +/// for more information. +pub fn into_group_map<I, K, V>(iter: I) -> HashMap<K, Vec<V>> + where I: Iterator<Item=(K, V)>, + K: Hash + Eq, +{ + let mut lookup = HashMap::new(); + + iter.for_each(|(key, val)| { + lookup.entry(key).or_insert_with(Vec::new).push(val); + }); + + lookup +} + +pub fn into_group_map_by<I, K, V>(iter: I, f: impl Fn(&V) -> K) -> HashMap<K, Vec<V>> + where + I: Iterator<Item=V>, + K: Hash + Eq, +{ + into_group_map( + iter.map(|v| (f(&v), v)) + ) +} diff --git a/third_party/rust/itertools/src/groupbylazy.rs b/third_party/rust/itertools/src/groupbylazy.rs new file mode 100644 index 0000000000..a5a321df45 --- /dev/null +++ b/third_party/rust/itertools/src/groupbylazy.rs @@ -0,0 +1,571 @@ +use std::cell::{Cell, RefCell}; +use alloc::vec::{self, Vec}; + +/// A trait to unify `FnMut` for `GroupBy` with the chunk key in `IntoChunks` +trait KeyFunction<A> { + type Key; + fn call_mut(&mut self, arg: A) -> Self::Key; +} + +impl<A, K, F: ?Sized> KeyFunction<A> for F + where F: FnMut(A) -> K +{ + type Key = K; + #[inline] + fn call_mut(&mut self, arg: A) -> Self::Key { + (*self)(arg) + } +} + + +/// `ChunkIndex` acts like the grouping key function for `IntoChunks` +#[derive(Debug)] +struct ChunkIndex { + size: usize, + index: usize, + key: usize, +} + +impl ChunkIndex { + #[inline(always)] + fn new(size: usize) -> Self { + ChunkIndex { + size, + index: 0, + key: 0, + } + } +} + +impl<A> KeyFunction<A> for ChunkIndex { + type Key = usize; + #[inline(always)] + fn call_mut(&mut self, _arg: A) -> Self::Key { + if self.index == self.size { + self.key += 1; + self.index = 0; + } + self.index += 1; + self.key + } +} + + +struct GroupInner<K, I, F> + where I: Iterator +{ + key: F, + iter: I, + current_key: Option<K>, + current_elt: Option<I::Item>, + /// flag set if iterator is exhausted + done: bool, + /// Index of group we are currently buffering or visiting + top_group: usize, + /// Least index for which we still have elements buffered + oldest_buffered_group: usize, + /// Group index for `buffer[0]` -- the slots + /// bottom_group..oldest_buffered_group are unused and will be erased when + /// that range is large enough. + bottom_group: usize, + /// Buffered groups, from `bottom_group` (index 0) to `top_group`. + buffer: Vec<vec::IntoIter<I::Item>>, + /// index of last group iter that was dropped, usize::MAX == none + dropped_group: usize, +} + +impl<K, I, F> GroupInner<K, I, F> + where I: Iterator, + F: for<'a> KeyFunction<&'a I::Item, Key=K>, + K: PartialEq, +{ + /// `client`: Index of group that requests next element + #[inline(always)] + fn step(&mut self, client: usize) -> Option<I::Item> { + /* + println!("client={}, bottom_group={}, oldest_buffered_group={}, top_group={}, buffers=[{}]", + client, self.bottom_group, self.oldest_buffered_group, + self.top_group, + self.buffer.iter().map(|elt| elt.len()).format(", ")); + */ + if client < self.oldest_buffered_group { + None + } else if client < self.top_group || + (client == self.top_group && + self.buffer.len() > self.top_group - self.bottom_group) + { + self.lookup_buffer(client) + } else if self.done { + None + } else if self.top_group == client { + self.step_current() + } else { + self.step_buffering(client) + } + } + + #[inline(never)] + fn lookup_buffer(&mut self, client: usize) -> Option<I::Item> { + // if `bufidx` doesn't exist in self.buffer, it might be empty + let bufidx = client - self.bottom_group; + if client < self.oldest_buffered_group { + return None; + } + let elt = self.buffer.get_mut(bufidx).and_then(|queue| queue.next()); + if elt.is_none() && client == self.oldest_buffered_group { + // FIXME: VecDeque is unfortunately not zero allocation when empty, + // so we do this job manually. + // `bottom_group..oldest_buffered_group` is unused, and if it's large enough, erase it. + self.oldest_buffered_group += 1; + // skip forward further empty queues too + while self.buffer.get(self.oldest_buffered_group - self.bottom_group) + .map_or(false, |buf| buf.len() == 0) + { + self.oldest_buffered_group += 1; + } + + let nclear = self.oldest_buffered_group - self.bottom_group; + if nclear > 0 && nclear >= self.buffer.len() / 2 { + let mut i = 0; + self.buffer.retain(|buf| { + i += 1; + debug_assert!(buf.len() == 0 || i > nclear); + i > nclear + }); + self.bottom_group = self.oldest_buffered_group; + } + } + elt + } + + /// Take the next element from the iterator, and set the done + /// flag if exhausted. Must not be called after done. + #[inline(always)] + fn next_element(&mut self) -> Option<I::Item> { + debug_assert!(!self.done); + match self.iter.next() { + None => { self.done = true; None } + otherwise => otherwise, + } + } + + + #[inline(never)] + fn step_buffering(&mut self, client: usize) -> Option<I::Item> { + // requested a later group -- walk through the current group up to + // the requested group index, and buffer the elements (unless + // the group is marked as dropped). + // Because the `Groups` iterator is always the first to request + // each group index, client is the next index efter top_group. + debug_assert!(self.top_group + 1 == client); + let mut group = Vec::new(); + + if let Some(elt) = self.current_elt.take() { + if self.top_group != self.dropped_group { + group.push(elt); + } + } + let mut first_elt = None; // first element of the next group + + while let Some(elt) = self.next_element() { + let key = self.key.call_mut(&elt); + match self.current_key.take() { + None => {} + Some(old_key) => if old_key != key { + self.current_key = Some(key); + first_elt = Some(elt); + break; + }, + } + self.current_key = Some(key); + if self.top_group != self.dropped_group { + group.push(elt); + } + } + + if self.top_group != self.dropped_group { + self.push_next_group(group); + } + if first_elt.is_some() { + self.top_group += 1; + debug_assert!(self.top_group == client); + } + first_elt + } + + fn push_next_group(&mut self, group: Vec<I::Item>) { + // When we add a new buffered group, fill up slots between oldest_buffered_group and top_group + while self.top_group - self.bottom_group > self.buffer.len() { + if self.buffer.is_empty() { + self.bottom_group += 1; + self.oldest_buffered_group += 1; + } else { + self.buffer.push(Vec::new().into_iter()); + } + } + self.buffer.push(group.into_iter()); + debug_assert!(self.top_group + 1 - self.bottom_group == self.buffer.len()); + } + + /// This is the immediate case, where we use no buffering + #[inline] + fn step_current(&mut self) -> Option<I::Item> { + debug_assert!(!self.done); + if let elt @ Some(..) = self.current_elt.take() { + return elt; + } + match self.next_element() { + None => None, + Some(elt) => { + let key = self.key.call_mut(&elt); + match self.current_key.take() { + None => {} + Some(old_key) => if old_key != key { + self.current_key = Some(key); + self.current_elt = Some(elt); + self.top_group += 1; + return None; + }, + } + self.current_key = Some(key); + Some(elt) + } + } + } + + /// Request the just started groups' key. + /// + /// `client`: Index of group + /// + /// **Panics** if no group key is available. + fn group_key(&mut self, client: usize) -> K { + // This can only be called after we have just returned the first + // element of a group. + // Perform this by simply buffering one more element, grabbing the + // next key. + debug_assert!(!self.done); + debug_assert!(client == self.top_group); + debug_assert!(self.current_key.is_some()); + debug_assert!(self.current_elt.is_none()); + let old_key = self.current_key.take().unwrap(); + if let Some(elt) = self.next_element() { + let key = self.key.call_mut(&elt); + if old_key != key { + self.top_group += 1; + } + self.current_key = Some(key); + self.current_elt = Some(elt); + } + old_key + } +} + +impl<K, I, F> GroupInner<K, I, F> + where I: Iterator, +{ + /// Called when a group is dropped + fn drop_group(&mut self, client: usize) { + // It's only useful to track the maximal index + if self.dropped_group == !0 || client > self.dropped_group { + self.dropped_group = client; + } + } +} + +/// `GroupBy` is the storage for the lazy grouping operation. +/// +/// If the groups are consumed in their original order, or if each +/// group is dropped without keeping it around, then `GroupBy` uses +/// no allocations. It needs allocations only if several group iterators +/// are alive at the same time. +/// +/// This type implements [`IntoIterator`] (it is **not** an iterator +/// itself), because the group iterators need to borrow from this +/// value. It should be stored in a local variable or temporary and +/// iterated. +/// +/// See [`.group_by()`](crate::Itertools::group_by) for more information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct GroupBy<K, I, F> + where I: Iterator, +{ + inner: RefCell<GroupInner<K, I, F>>, + // the group iterator's current index. Keep this in the main value + // so that simultaneous iterators all use the same state. + index: Cell<usize>, +} + +/// Create a new +pub fn new<K, J, F>(iter: J, f: F) -> GroupBy<K, J::IntoIter, F> + where J: IntoIterator, + F: FnMut(&J::Item) -> K, +{ + GroupBy { + inner: RefCell::new(GroupInner { + key: f, + iter: iter.into_iter(), + current_key: None, + current_elt: None, + done: false, + top_group: 0, + oldest_buffered_group: 0, + bottom_group: 0, + buffer: Vec::new(), + dropped_group: !0, + }), + index: Cell::new(0), + } +} + +impl<K, I, F> GroupBy<K, I, F> + where I: Iterator, +{ + /// `client`: Index of group that requests next element + fn step(&self, client: usize) -> Option<I::Item> + where F: FnMut(&I::Item) -> K, + K: PartialEq, + { + self.inner.borrow_mut().step(client) + } + + /// `client`: Index of group + fn drop_group(&self, client: usize) { + self.inner.borrow_mut().drop_group(client); + } +} + +impl<'a, K, I, F> IntoIterator for &'a GroupBy<K, I, F> + where I: Iterator, + I::Item: 'a, + F: FnMut(&I::Item) -> K, + K: PartialEq +{ + type Item = (K, Group<'a, K, I, F>); + type IntoIter = Groups<'a, K, I, F>; + + fn into_iter(self) -> Self::IntoIter { + Groups { parent: self } + } +} + + +/// An iterator that yields the Group iterators. +/// +/// Iterator element type is `(K, Group)`: +/// the group's key `K` and the group's iterator. +/// +/// See [`.group_by()`](crate::Itertools::group_by) for more information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct Groups<'a, K: 'a, I: 'a, F: 'a> + where I: Iterator, + I::Item: 'a +{ + parent: &'a GroupBy<K, I, F>, +} + +impl<'a, K, I, F> Iterator for Groups<'a, K, I, F> + where I: Iterator, + I::Item: 'a, + F: FnMut(&I::Item) -> K, + K: PartialEq +{ + type Item = (K, Group<'a, K, I, F>); + + #[inline] + fn next(&mut self) -> Option<Self::Item> { + let index = self.parent.index.get(); + self.parent.index.set(index + 1); + let inner = &mut *self.parent.inner.borrow_mut(); + inner.step(index).map(|elt| { + let key = inner.group_key(index); + (key, Group { + parent: self.parent, + index, + first: Some(elt), + }) + }) + } +} + +/// An iterator for the elements in a single group. +/// +/// Iterator element type is `I::Item`. +pub struct Group<'a, K: 'a, I: 'a, F: 'a> + where I: Iterator, + I::Item: 'a, +{ + parent: &'a GroupBy<K, I, F>, + index: usize, + first: Option<I::Item>, +} + +impl<'a, K, I, F> Drop for Group<'a, K, I, F> + where I: Iterator, + I::Item: 'a, +{ + fn drop(&mut self) { + self.parent.drop_group(self.index); + } +} + +impl<'a, K, I, F> Iterator for Group<'a, K, I, F> + where I: Iterator, + I::Item: 'a, + F: FnMut(&I::Item) -> K, + K: PartialEq, +{ + type Item = I::Item; + #[inline] + fn next(&mut self) -> Option<Self::Item> { + if let elt @ Some(..) = self.first.take() { + return elt; + } + self.parent.step(self.index) + } +} + +///// IntoChunks ///// + +/// Create a new +pub fn new_chunks<J>(iter: J, size: usize) -> IntoChunks<J::IntoIter> + where J: IntoIterator, +{ + IntoChunks { + inner: RefCell::new(GroupInner { + key: ChunkIndex::new(size), + iter: iter.into_iter(), + current_key: None, + current_elt: None, + done: false, + top_group: 0, + oldest_buffered_group: 0, + bottom_group: 0, + buffer: Vec::new(), + dropped_group: !0, + }), + index: Cell::new(0), + } +} + + +/// `ChunkLazy` is the storage for a lazy chunking operation. +/// +/// `IntoChunks` behaves just like `GroupBy`: it is iterable, and +/// it only buffers if several chunk iterators are alive at the same time. +/// +/// This type implements [`IntoIterator`] (it is **not** an iterator +/// itself), because the chunk iterators need to borrow from this +/// value. It should be stored in a local variable or temporary and +/// iterated. +/// +/// Iterator element type is `Chunk`, each chunk's iterator. +/// +/// See [`.chunks()`](crate::Itertools::chunks) for more information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct IntoChunks<I> + where I: Iterator, +{ + inner: RefCell<GroupInner<usize, I, ChunkIndex>>, + // the chunk iterator's current index. Keep this in the main value + // so that simultaneous iterators all use the same state. + index: Cell<usize>, +} + + +impl<I> IntoChunks<I> + where I: Iterator, +{ + /// `client`: Index of chunk that requests next element + fn step(&self, client: usize) -> Option<I::Item> { + self.inner.borrow_mut().step(client) + } + + /// `client`: Index of chunk + fn drop_group(&self, client: usize) { + self.inner.borrow_mut().drop_group(client); + } +} + +impl<'a, I> IntoIterator for &'a IntoChunks<I> + where I: Iterator, + I::Item: 'a, +{ + type Item = Chunk<'a, I>; + type IntoIter = Chunks<'a, I>; + + fn into_iter(self) -> Self::IntoIter { + Chunks { + parent: self, + } + } +} + + +/// An iterator that yields the Chunk iterators. +/// +/// Iterator element type is `Chunk`. +/// +/// See [`.chunks()`](crate::Itertools::chunks) for more information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct Chunks<'a, I: 'a> + where I: Iterator, + I::Item: 'a, +{ + parent: &'a IntoChunks<I>, +} + +impl<'a, I> Iterator for Chunks<'a, I> + where I: Iterator, + I::Item: 'a, +{ + type Item = Chunk<'a, I>; + + #[inline] + fn next(&mut self) -> Option<Self::Item> { + let index = self.parent.index.get(); + self.parent.index.set(index + 1); + let inner = &mut *self.parent.inner.borrow_mut(); + inner.step(index).map(|elt| { + Chunk { + parent: self.parent, + index, + first: Some(elt), + } + }) + } +} + +/// An iterator for the elements in a single chunk. +/// +/// Iterator element type is `I::Item`. +pub struct Chunk<'a, I: 'a> + where I: Iterator, + I::Item: 'a, +{ + parent: &'a IntoChunks<I>, + index: usize, + first: Option<I::Item>, +} + +impl<'a, I> Drop for Chunk<'a, I> + where I: Iterator, + I::Item: 'a, +{ + fn drop(&mut self) { + self.parent.drop_group(self.index); + } +} + +impl<'a, I> Iterator for Chunk<'a, I> + where I: Iterator, + I::Item: 'a, +{ + type Item = I::Item; + #[inline] + fn next(&mut self) -> Option<Self::Item> { + if let elt @ Some(..) = self.first.take() { + return elt; + } + self.parent.step(self.index) + } +} diff --git a/third_party/rust/itertools/src/grouping_map.rs b/third_party/rust/itertools/src/grouping_map.rs new file mode 100644 index 0000000000..bb5b582c92 --- /dev/null +++ b/third_party/rust/itertools/src/grouping_map.rs @@ -0,0 +1,535 @@ +#![cfg(feature = "use_std")] + +use crate::MinMaxResult; +use std::collections::HashMap; +use std::cmp::Ordering; +use std::hash::Hash; +use std::iter::Iterator; +use std::ops::{Add, Mul}; + +/// A wrapper to allow for an easy [`into_grouping_map_by`](crate::Itertools::into_grouping_map_by) +#[derive(Clone, Debug)] +pub struct MapForGrouping<I, F>(I, F); + +impl<I, F> MapForGrouping<I, F> { + pub(crate) fn new(iter: I, key_mapper: F) -> Self { + Self(iter, key_mapper) + } +} + +impl<K, V, I, F> Iterator for MapForGrouping<I, F> + where I: Iterator<Item = V>, + K: Hash + Eq, + F: FnMut(&V) -> K, +{ + type Item = (K, V); + fn next(&mut self) -> Option<Self::Item> { + self.0.next().map(|val| ((self.1)(&val), val)) + } +} + +/// Creates a new `GroupingMap` from `iter` +pub fn new<I, K, V>(iter: I) -> GroupingMap<I> + where I: Iterator<Item = (K, V)>, + K: Hash + Eq, +{ + GroupingMap { iter } +} + +/// `GroupingMapBy` is an intermediate struct for efficient group-and-fold operations. +/// +/// See [`GroupingMap`] for more informations. +pub type GroupingMapBy<I, F> = GroupingMap<MapForGrouping<I, F>>; + +/// `GroupingMap` is an intermediate struct for efficient group-and-fold operations. +/// It groups elements by their key and at the same time fold each group +/// using some aggregating operation. +/// +/// No method on this struct performs temporary allocations. +#[derive(Clone, Debug)] +#[must_use = "GroupingMap is lazy and do nothing unless consumed"] +pub struct GroupingMap<I> { + iter: I, +} + +impl<I, K, V> GroupingMap<I> + where I: Iterator<Item = (K, V)>, + K: Hash + Eq, +{ + /// This is the generic way to perform any operation on a `GroupingMap`. + /// It's suggested to use this method only to implement custom operations + /// when the already provided ones are not enough. + /// + /// Groups elements from the `GroupingMap` source by key and applies `operation` to the elements + /// of each group sequentially, passing the previously accumulated value, a reference to the key + /// and the current element as arguments, and stores the results in an `HashMap`. + /// + /// The `operation` function is invoked on each element with the following parameters: + /// - the current value of the accumulator of the group if there is currently one; + /// - a reference to the key of the group this element belongs to; + /// - the element from the source being aggregated; + /// + /// If `operation` returns `Some(element)` then the accumulator is updated with `element`, + /// otherwise the previous accumulation is discarded. + /// + /// Return a `HashMap` associating the key of each group with the result of aggregation of + /// that group's elements. If the aggregation of the last element of a group discards the + /// accumulator then there won't be an entry associated to that group's key. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let data = vec![2, 8, 5, 7, 9, 0, 4, 10]; + /// let lookup = data.into_iter() + /// .into_grouping_map_by(|&n| n % 4) + /// .aggregate(|acc, _key, val| { + /// if val == 0 || val == 10 { + /// None + /// } else { + /// Some(acc.unwrap_or(0) + val) + /// } + /// }); + /// + /// assert_eq!(lookup[&0], 4); // 0 resets the accumulator so only 4 is summed + /// assert_eq!(lookup[&1], 5 + 9); + /// assert_eq!(lookup.get(&2), None); // 10 resets the accumulator and nothing is summed afterward + /// assert_eq!(lookup[&3], 7); + /// assert_eq!(lookup.len(), 3); // The final keys are only 0, 1 and 2 + /// ``` + pub fn aggregate<FO, R>(self, mut operation: FO) -> HashMap<K, R> + where FO: FnMut(Option<R>, &K, V) -> Option<R>, + { + let mut destination_map = HashMap::new(); + + self.iter.for_each(|(key, val)| { + let acc = destination_map.remove(&key); + if let Some(op_res) = operation(acc, &key, val) { + destination_map.insert(key, op_res); + } + }); + + destination_map + } + + /// Groups elements from the `GroupingMap` source by key and applies `operation` to the elements + /// of each group sequentially, passing the previously accumulated value, a reference to the key + /// and the current element as arguments, and stores the results in a new map. + /// + /// `init` is the value from which will be cloned the initial value of each accumulator. + /// + /// `operation` is a function that is invoked on each element with the following parameters: + /// - the current value of the accumulator of the group; + /// - a reference to the key of the group this element belongs to; + /// - the element from the source being accumulated. + /// + /// Return a `HashMap` associating the key of each group with the result of folding that group's elements. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let lookup = (1..=7) + /// .into_grouping_map_by(|&n| n % 3) + /// .fold(0, |acc, _key, val| acc + val); + /// + /// assert_eq!(lookup[&0], 3 + 6); + /// assert_eq!(lookup[&1], 1 + 4 + 7); + /// assert_eq!(lookup[&2], 2 + 5); + /// assert_eq!(lookup.len(), 3); + /// ``` + pub fn fold<FO, R>(self, init: R, mut operation: FO) -> HashMap<K, R> + where R: Clone, + FO: FnMut(R, &K, V) -> R, + { + self.aggregate(|acc, key, val| { + let acc = acc.unwrap_or_else(|| init.clone()); + Some(operation(acc, key, val)) + }) + } + + /// Groups elements from the `GroupingMap` source by key and applies `operation` to the elements + /// of each group sequentially, passing the previously accumulated value, a reference to the key + /// and the current element as arguments, and stores the results in a new map. + /// + /// This is similar to [`fold`] but the initial value of the accumulator is the first element of the group. + /// + /// `operation` is a function that is invoked on each element with the following parameters: + /// - the current value of the accumulator of the group; + /// - a reference to the key of the group this element belongs to; + /// - the element from the source being accumulated. + /// + /// Return a `HashMap` associating the key of each group with the result of folding that group's elements. + /// + /// [`fold`]: GroupingMap::fold + /// + /// ``` + /// use itertools::Itertools; + /// + /// let lookup = (1..=7) + /// .into_grouping_map_by(|&n| n % 3) + /// .fold_first(|acc, _key, val| acc + val); + /// + /// assert_eq!(lookup[&0], 3 + 6); + /// assert_eq!(lookup[&1], 1 + 4 + 7); + /// assert_eq!(lookup[&2], 2 + 5); + /// assert_eq!(lookup.len(), 3); + /// ``` + pub fn fold_first<FO>(self, mut operation: FO) -> HashMap<K, V> + where FO: FnMut(V, &K, V) -> V, + { + self.aggregate(|acc, key, val| { + Some(match acc { + Some(acc) => operation(acc, key, val), + None => val, + }) + }) + } + + /// Groups elements from the `GroupingMap` source by key and collects the elements of each group in + /// an instance of `C`. The iteration order is preserved when inserting elements. + /// + /// Return a `HashMap` associating the key of each group with the collection containing that group's elements. + /// + /// ``` + /// use itertools::Itertools; + /// use std::collections::HashSet; + /// + /// let lookup = vec![0, 1, 2, 3, 4, 5, 6, 2, 3, 6].into_iter() + /// .into_grouping_map_by(|&n| n % 3) + /// .collect::<HashSet<_>>(); + /// + /// assert_eq!(lookup[&0], vec![0, 3, 6].into_iter().collect::<HashSet<_>>()); + /// assert_eq!(lookup[&1], vec![1, 4].into_iter().collect::<HashSet<_>>()); + /// assert_eq!(lookup[&2], vec![2, 5].into_iter().collect::<HashSet<_>>()); + /// assert_eq!(lookup.len(), 3); + /// ``` + pub fn collect<C>(self) -> HashMap<K, C> + where C: Default + Extend<V>, + { + let mut destination_map = HashMap::new(); + + self.iter.for_each(|(key, val)| { + destination_map.entry(key).or_insert_with(C::default).extend(Some(val)); + }); + + destination_map + } + + /// Groups elements from the `GroupingMap` source by key and finds the maximum of each group. + /// + /// If several elements are equally maximum, the last element is picked. + /// + /// Returns a `HashMap` associating the key of each group with the maximum of that group's elements. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let lookup = vec![1, 3, 4, 5, 7, 8, 9, 12].into_iter() + /// .into_grouping_map_by(|&n| n % 3) + /// .max(); + /// + /// assert_eq!(lookup[&0], 12); + /// assert_eq!(lookup[&1], 7); + /// assert_eq!(lookup[&2], 8); + /// assert_eq!(lookup.len(), 3); + /// ``` + pub fn max(self) -> HashMap<K, V> + where V: Ord, + { + self.max_by(|_, v1, v2| V::cmp(v1, v2)) + } + + /// Groups elements from the `GroupingMap` source by key and finds the maximum of each group + /// with respect to the specified comparison function. + /// + /// If several elements are equally maximum, the last element is picked. + /// + /// Returns a `HashMap` associating the key of each group with the maximum of that group's elements. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let lookup = vec![1, 3, 4, 5, 7, 8, 9, 12].into_iter() + /// .into_grouping_map_by(|&n| n % 3) + /// .max_by(|_key, x, y| y.cmp(x)); + /// + /// assert_eq!(lookup[&0], 3); + /// assert_eq!(lookup[&1], 1); + /// assert_eq!(lookup[&2], 5); + /// assert_eq!(lookup.len(), 3); + /// ``` + pub fn max_by<F>(self, mut compare: F) -> HashMap<K, V> + where F: FnMut(&K, &V, &V) -> Ordering, + { + self.fold_first(|acc, key, val| match compare(key, &acc, &val) { + Ordering::Less | Ordering::Equal => val, + Ordering::Greater => acc + }) + } + + /// Groups elements from the `GroupingMap` source by key and finds the element of each group + /// that gives the maximum from the specified function. + /// + /// If several elements are equally maximum, the last element is picked. + /// + /// Returns a `HashMap` associating the key of each group with the maximum of that group's elements. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let lookup = vec![1, 3, 4, 5, 7, 8, 9, 12].into_iter() + /// .into_grouping_map_by(|&n| n % 3) + /// .max_by_key(|_key, &val| val % 4); + /// + /// assert_eq!(lookup[&0], 3); + /// assert_eq!(lookup[&1], 7); + /// assert_eq!(lookup[&2], 5); + /// assert_eq!(lookup.len(), 3); + /// ``` + pub fn max_by_key<F, CK>(self, mut f: F) -> HashMap<K, V> + where F: FnMut(&K, &V) -> CK, + CK: Ord, + { + self.max_by(|key, v1, v2| f(key, v1).cmp(&f(key, v2))) + } + + /// Groups elements from the `GroupingMap` source by key and finds the minimum of each group. + /// + /// If several elements are equally minimum, the first element is picked. + /// + /// Returns a `HashMap` associating the key of each group with the minimum of that group's elements. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let lookup = vec![1, 3, 4, 5, 7, 8, 9, 12].into_iter() + /// .into_grouping_map_by(|&n| n % 3) + /// .min(); + /// + /// assert_eq!(lookup[&0], 3); + /// assert_eq!(lookup[&1], 1); + /// assert_eq!(lookup[&2], 5); + /// assert_eq!(lookup.len(), 3); + /// ``` + pub fn min(self) -> HashMap<K, V> + where V: Ord, + { + self.min_by(|_, v1, v2| V::cmp(v1, v2)) + } + + /// Groups elements from the `GroupingMap` source by key and finds the minimum of each group + /// with respect to the specified comparison function. + /// + /// If several elements are equally minimum, the first element is picked. + /// + /// Returns a `HashMap` associating the key of each group with the minimum of that group's elements. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let lookup = vec![1, 3, 4, 5, 7, 8, 9, 12].into_iter() + /// .into_grouping_map_by(|&n| n % 3) + /// .min_by(|_key, x, y| y.cmp(x)); + /// + /// assert_eq!(lookup[&0], 12); + /// assert_eq!(lookup[&1], 7); + /// assert_eq!(lookup[&2], 8); + /// assert_eq!(lookup.len(), 3); + /// ``` + pub fn min_by<F>(self, mut compare: F) -> HashMap<K, V> + where F: FnMut(&K, &V, &V) -> Ordering, + { + self.fold_first(|acc, key, val| match compare(key, &acc, &val) { + Ordering::Less | Ordering::Equal => acc, + Ordering::Greater => val + }) + } + + /// Groups elements from the `GroupingMap` source by key and finds the element of each group + /// that gives the minimum from the specified function. + /// + /// If several elements are equally minimum, the first element is picked. + /// + /// Returns a `HashMap` associating the key of each group with the minimum of that group's elements. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let lookup = vec![1, 3, 4, 5, 7, 8, 9, 12].into_iter() + /// .into_grouping_map_by(|&n| n % 3) + /// .min_by_key(|_key, &val| val % 4); + /// + /// assert_eq!(lookup[&0], 12); + /// assert_eq!(lookup[&1], 4); + /// assert_eq!(lookup[&2], 8); + /// assert_eq!(lookup.len(), 3); + /// ``` + pub fn min_by_key<F, CK>(self, mut f: F) -> HashMap<K, V> + where F: FnMut(&K, &V) -> CK, + CK: Ord, + { + self.min_by(|key, v1, v2| f(key, v1).cmp(&f(key, v2))) + } + + /// Groups elements from the `GroupingMap` source by key and find the maximum and minimum of + /// each group. + /// + /// If several elements are equally maximum, the last element is picked. + /// If several elements are equally minimum, the first element is picked. + /// + /// See [.minmax()](crate::Itertools::minmax) for the non-grouping version. + /// + /// Differences from the non grouping version: + /// - It never produces a `MinMaxResult::NoElements` + /// - It doesn't have any speedup + /// + /// Returns a `HashMap` associating the key of each group with the minimum and maximum of that group's elements. + /// + /// ``` + /// use itertools::Itertools; + /// use itertools::MinMaxResult::{OneElement, MinMax}; + /// + /// let lookup = vec![1, 3, 4, 5, 7, 9, 12].into_iter() + /// .into_grouping_map_by(|&n| n % 3) + /// .minmax(); + /// + /// assert_eq!(lookup[&0], MinMax(3, 12)); + /// assert_eq!(lookup[&1], MinMax(1, 7)); + /// assert_eq!(lookup[&2], OneElement(5)); + /// assert_eq!(lookup.len(), 3); + /// ``` + pub fn minmax(self) -> HashMap<K, MinMaxResult<V>> + where V: Ord, + { + self.minmax_by(|_, v1, v2| V::cmp(v1, v2)) + } + + /// Groups elements from the `GroupingMap` source by key and find the maximum and minimum of + /// each group with respect to the specified comparison function. + /// + /// If several elements are equally maximum, the last element is picked. + /// If several elements are equally minimum, the first element is picked. + /// + /// It has the same differences from the non-grouping version as `minmax`. + /// + /// Returns a `HashMap` associating the key of each group with the minimum and maximum of that group's elements. + /// + /// ``` + /// use itertools::Itertools; + /// use itertools::MinMaxResult::{OneElement, MinMax}; + /// + /// let lookup = vec![1, 3, 4, 5, 7, 9, 12].into_iter() + /// .into_grouping_map_by(|&n| n % 3) + /// .minmax_by(|_key, x, y| y.cmp(x)); + /// + /// assert_eq!(lookup[&0], MinMax(12, 3)); + /// assert_eq!(lookup[&1], MinMax(7, 1)); + /// assert_eq!(lookup[&2], OneElement(5)); + /// assert_eq!(lookup.len(), 3); + /// ``` + pub fn minmax_by<F>(self, mut compare: F) -> HashMap<K, MinMaxResult<V>> + where F: FnMut(&K, &V, &V) -> Ordering, + { + self.aggregate(|acc, key, val| { + Some(match acc { + Some(MinMaxResult::OneElement(e)) => { + if compare(key, &val, &e) == Ordering::Less { + MinMaxResult::MinMax(val, e) + } else { + MinMaxResult::MinMax(e, val) + } + } + Some(MinMaxResult::MinMax(min, max)) => { + if compare(key, &val, &min) == Ordering::Less { + MinMaxResult::MinMax(val, max) + } else if compare(key, &val, &max) != Ordering::Less { + MinMaxResult::MinMax(min, val) + } else { + MinMaxResult::MinMax(min, max) + } + } + None => MinMaxResult::OneElement(val), + Some(MinMaxResult::NoElements) => unreachable!(), + }) + }) + } + + /// Groups elements from the `GroupingMap` source by key and find the elements of each group + /// that gives the minimum and maximum from the specified function. + /// + /// If several elements are equally maximum, the last element is picked. + /// If several elements are equally minimum, the first element is picked. + /// + /// It has the same differences from the non-grouping version as `minmax`. + /// + /// Returns a `HashMap` associating the key of each group with the minimum and maximum of that group's elements. + /// + /// ``` + /// use itertools::Itertools; + /// use itertools::MinMaxResult::{OneElement, MinMax}; + /// + /// let lookup = vec![1, 3, 4, 5, 7, 9, 12].into_iter() + /// .into_grouping_map_by(|&n| n % 3) + /// .minmax_by_key(|_key, &val| val % 4); + /// + /// assert_eq!(lookup[&0], MinMax(12, 3)); + /// assert_eq!(lookup[&1], MinMax(4, 7)); + /// assert_eq!(lookup[&2], OneElement(5)); + /// assert_eq!(lookup.len(), 3); + /// ``` + pub fn minmax_by_key<F, CK>(self, mut f: F) -> HashMap<K, MinMaxResult<V>> + where F: FnMut(&K, &V) -> CK, + CK: Ord, + { + self.minmax_by(|key, v1, v2| f(key, v1).cmp(&f(key, v2))) + } + + /// Groups elements from the `GroupingMap` source by key and sums them. + /// + /// This is just a shorthand for `self.fold_first(|acc, _, val| acc + val)`. + /// It is more limited than `Iterator::sum` since it doesn't use the `Sum` trait. + /// + /// Returns a `HashMap` associating the key of each group with the sum of that group's elements. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let lookup = vec![1, 3, 4, 5, 7, 8, 9, 12].into_iter() + /// .into_grouping_map_by(|&n| n % 3) + /// .sum(); + /// + /// assert_eq!(lookup[&0], 3 + 9 + 12); + /// assert_eq!(lookup[&1], 1 + 4 + 7); + /// assert_eq!(lookup[&2], 5 + 8); + /// assert_eq!(lookup.len(), 3); + /// ``` + pub fn sum(self) -> HashMap<K, V> + where V: Add<V, Output = V> + { + self.fold_first(|acc, _, val| acc + val) + } + + /// Groups elements from the `GroupingMap` source by key and multiply them. + /// + /// This is just a shorthand for `self.fold_first(|acc, _, val| acc * val)`. + /// It is more limited than `Iterator::product` since it doesn't use the `Product` trait. + /// + /// Returns a `HashMap` associating the key of each group with the product of that group's elements. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let lookup = vec![1, 3, 4, 5, 7, 8, 9, 12].into_iter() + /// .into_grouping_map_by(|&n| n % 3) + /// .product(); + /// + /// assert_eq!(lookup[&0], 3 * 9 * 12); + /// assert_eq!(lookup[&1], 1 * 4 * 7); + /// assert_eq!(lookup[&2], 5 * 8); + /// assert_eq!(lookup.len(), 3); + /// ``` + pub fn product(self) -> HashMap<K, V> + where V: Mul<V, Output = V>, + { + self.fold_first(|acc, _, val| acc * val) + } +} diff --git a/third_party/rust/itertools/src/impl_macros.rs b/third_party/rust/itertools/src/impl_macros.rs new file mode 100644 index 0000000000..a029843b05 --- /dev/null +++ b/third_party/rust/itertools/src/impl_macros.rs @@ -0,0 +1,29 @@ +//! +//! Implementation's internal macros + +macro_rules! debug_fmt_fields { + ($tyname:ident, $($($field:tt/*TODO ideally we would accept ident or tuple element here*/).+),*) => { + fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result { + f.debug_struct(stringify!($tyname)) + $( + .field(stringify!($($field).+), &self.$($field).+) + )* + .finish() + } + } +} + +macro_rules! clone_fields { + ($($field:ident),*) => { + #[inline] // TODO is this sensible? + fn clone(&self) -> Self { + Self { + $($field: self.$field.clone(),)* + } + } + } +} + +macro_rules! ignore_ident{ + ($id:ident, $($t:tt)*) => {$($t)*}; +} diff --git a/third_party/rust/itertools/src/intersperse.rs b/third_party/rust/itertools/src/intersperse.rs new file mode 100644 index 0000000000..10a3a5389c --- /dev/null +++ b/third_party/rust/itertools/src/intersperse.rs @@ -0,0 +1,118 @@ +use std::iter::{Fuse, FusedIterator}; +use super::size_hint; + +pub trait IntersperseElement<Item> { + fn generate(&mut self) -> Item; +} + +#[derive(Debug, Clone)] +pub struct IntersperseElementSimple<Item>(Item); + +impl<Item: Clone> IntersperseElement<Item> for IntersperseElementSimple<Item> { + fn generate(&mut self) -> Item { + self.0.clone() + } +} + +/// An iterator adaptor to insert a particular value +/// between each element of the adapted iterator. +/// +/// Iterator element type is `I::Item` +/// +/// This iterator is *fused*. +/// +/// See [`.intersperse()`](crate::Itertools::intersperse) for more information. +pub type Intersperse<I> = IntersperseWith<I, IntersperseElementSimple<<I as Iterator>::Item>>; + +/// Create a new Intersperse iterator +pub fn intersperse<I>(iter: I, elt: I::Item) -> Intersperse<I> + where I: Iterator, +{ + intersperse_with(iter, IntersperseElementSimple(elt)) +} + +impl<Item, F: FnMut()->Item> IntersperseElement<Item> for F { + fn generate(&mut self) -> Item { + self() + } +} + +/// An iterator adaptor to insert a particular value created by a function +/// between each element of the adapted iterator. +/// +/// Iterator element type is `I::Item` +/// +/// This iterator is *fused*. +/// +/// See [`.intersperse_with()`](crate::Itertools::intersperse_with) for more information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +#[derive(Clone, Debug)] +pub struct IntersperseWith<I, ElemF> + where I: Iterator, +{ + element: ElemF, + iter: Fuse<I>, + peek: Option<I::Item>, +} + +/// Create a new `IntersperseWith` iterator +pub fn intersperse_with<I, ElemF>(iter: I, elt: ElemF) -> IntersperseWith<I, ElemF> + where I: Iterator, +{ + let mut iter = iter.fuse(); + IntersperseWith { + peek: iter.next(), + iter, + element: elt, + } +} + +impl<I, ElemF> Iterator for IntersperseWith<I, ElemF> + where I: Iterator, + ElemF: IntersperseElement<I::Item> +{ + type Item = I::Item; + #[inline] + fn next(&mut self) -> Option<Self::Item> { + if self.peek.is_some() { + self.peek.take() + } else { + self.peek = self.iter.next(); + if self.peek.is_some() { + Some(self.element.generate()) + } else { + None + } + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + // 2 * SH + { 1 or 0 } + let has_peek = self.peek.is_some() as usize; + let sh = self.iter.size_hint(); + size_hint::add_scalar(size_hint::add(sh, sh), has_peek) + } + + fn fold<B, F>(mut self, init: B, mut f: F) -> B where + Self: Sized, F: FnMut(B, Self::Item) -> B, + { + let mut accum = init; + + if let Some(x) = self.peek.take() { + accum = f(accum, x); + } + + let element = &mut self.element; + + self.iter.fold(accum, + |accum, x| { + let accum = f(accum, element.generate()); + f(accum, x) + }) + } +} + +impl<I, ElemF> FusedIterator for IntersperseWith<I, ElemF> + where I: Iterator, + ElemF: IntersperseElement<I::Item> +{} diff --git a/third_party/rust/itertools/src/k_smallest.rs b/third_party/rust/itertools/src/k_smallest.rs new file mode 100644 index 0000000000..acaea5941c --- /dev/null +++ b/third_party/rust/itertools/src/k_smallest.rs @@ -0,0 +1,20 @@ +use alloc::collections::BinaryHeap; +use core::cmp::Ord; + +pub(crate) fn k_smallest<T: Ord, I: Iterator<Item = T>>(mut iter: I, k: usize) -> BinaryHeap<T> { + if k == 0 { return BinaryHeap::new(); } + + let mut heap = iter.by_ref().take(k).collect::<BinaryHeap<_>>(); + + iter.for_each(|i| { + debug_assert_eq!(heap.len(), k); + // Equivalent to heap.push(min(i, heap.pop())) but more efficient. + // This should be done with a single `.peek_mut().unwrap()` but + // `PeekMut` sifts-down unconditionally on Rust 1.46.0 and prior. + if *heap.peek().unwrap() > i { + *heap.peek_mut().unwrap() = i; + } + }); + + heap +} diff --git a/third_party/rust/itertools/src/kmerge_impl.rs b/third_party/rust/itertools/src/kmerge_impl.rs new file mode 100644 index 0000000000..509d5fc6a3 --- /dev/null +++ b/third_party/rust/itertools/src/kmerge_impl.rs @@ -0,0 +1,227 @@ +use crate::size_hint; +use crate::Itertools; + +use alloc::vec::Vec; +use std::iter::FusedIterator; +use std::mem::replace; +use std::fmt; + +/// Head element and Tail iterator pair +/// +/// `PartialEq`, `Eq`, `PartialOrd` and `Ord` are implemented by comparing sequences based on +/// first items (which are guaranteed to exist). +/// +/// The meanings of `PartialOrd` and `Ord` are reversed so as to turn the heap used in +/// `KMerge` into a min-heap. +#[derive(Debug)] +struct HeadTail<I> + where I: Iterator +{ + head: I::Item, + tail: I, +} + +impl<I> HeadTail<I> + where I: Iterator +{ + /// Constructs a `HeadTail` from an `Iterator`. Returns `None` if the `Iterator` is empty. + fn new(mut it: I) -> Option<HeadTail<I>> { + let head = it.next(); + head.map(|h| { + HeadTail { + head: h, + tail: it, + } + }) + } + + /// Get the next element and update `head`, returning the old head in `Some`. + /// + /// Returns `None` when the tail is exhausted (only `head` then remains). + fn next(&mut self) -> Option<I::Item> { + if let Some(next) = self.tail.next() { + Some(replace(&mut self.head, next)) + } else { + None + } + } + + /// Hints at the size of the sequence, same as the `Iterator` method. + fn size_hint(&self) -> (usize, Option<usize>) { + size_hint::add_scalar(self.tail.size_hint(), 1) + } +} + +impl<I> Clone for HeadTail<I> + where I: Iterator + Clone, + I::Item: Clone +{ + clone_fields!(head, tail); +} + +/// Make `data` a heap (min-heap w.r.t the sorting). +fn heapify<T, S>(data: &mut [T], mut less_than: S) + where S: FnMut(&T, &T) -> bool +{ + for i in (0..data.len() / 2).rev() { + sift_down(data, i, &mut less_than); + } +} + +/// Sift down element at `index` (`heap` is a min-heap wrt the ordering) +fn sift_down<T, S>(heap: &mut [T], index: usize, mut less_than: S) + where S: FnMut(&T, &T) -> bool +{ + debug_assert!(index <= heap.len()); + let mut pos = index; + let mut child = 2 * pos + 1; + // Require the right child to be present + // This allows to find the index of the smallest child without a branch + // that wouldn't be predicted if present + while child + 1 < heap.len() { + // pick the smaller of the two children + // use arithmetic to avoid an unpredictable branch + child += less_than(&heap[child+1], &heap[child]) as usize; + + // sift down is done if we are already in order + if !less_than(&heap[child], &heap[pos]) { + return; + } + heap.swap(pos, child); + pos = child; + child = 2 * pos + 1; + } + // Check if the last (left) child was an only child + // if it is then it has to be compared with the parent + if child + 1 == heap.len() && less_than(&heap[child], &heap[pos]) { + heap.swap(pos, child); + } +} + +/// An iterator adaptor that merges an abitrary number of base iterators in ascending order. +/// If all base iterators are sorted (ascending), the result is sorted. +/// +/// Iterator element type is `I::Item`. +/// +/// See [`.kmerge()`](crate::Itertools::kmerge) for more information. +pub type KMerge<I> = KMergeBy<I, KMergeByLt>; + +pub trait KMergePredicate<T> { + fn kmerge_pred(&mut self, a: &T, b: &T) -> bool; +} + +#[derive(Clone, Debug)] +pub struct KMergeByLt; + +impl<T: PartialOrd> KMergePredicate<T> for KMergeByLt { + fn kmerge_pred(&mut self, a: &T, b: &T) -> bool { + a < b + } +} + +impl<T, F: FnMut(&T, &T)->bool> KMergePredicate<T> for F { + fn kmerge_pred(&mut self, a: &T, b: &T) -> bool { + self(a, b) + } +} + +/// Create an iterator that merges elements of the contained iterators using +/// the ordering function. +/// +/// [`IntoIterator`] enabled version of [`Itertools::kmerge`]. +/// +/// ``` +/// use itertools::kmerge; +/// +/// for elt in kmerge(vec![vec![0, 2, 4], vec![1, 3, 5], vec![6, 7]]) { +/// /* loop body */ +/// } +/// ``` +pub fn kmerge<I>(iterable: I) -> KMerge<<I::Item as IntoIterator>::IntoIter> + where I: IntoIterator, + I::Item: IntoIterator, + <<I as IntoIterator>::Item as IntoIterator>::Item: PartialOrd +{ + kmerge_by(iterable, KMergeByLt) +} + +/// An iterator adaptor that merges an abitrary number of base iterators +/// according to an ordering function. +/// +/// Iterator element type is `I::Item`. +/// +/// See [`.kmerge_by()`](crate::Itertools::kmerge_by) for more +/// information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct KMergeBy<I, F> + where I: Iterator, +{ + heap: Vec<HeadTail<I>>, + less_than: F, +} + +impl<I, F> fmt::Debug for KMergeBy<I, F> + where I: Iterator + fmt::Debug, + I::Item: fmt::Debug, +{ + debug_fmt_fields!(KMergeBy, heap); +} + +/// Create an iterator that merges elements of the contained iterators. +/// +/// [`IntoIterator`] enabled version of [`Itertools::kmerge_by`]. +pub fn kmerge_by<I, F>(iterable: I, mut less_than: F) + -> KMergeBy<<I::Item as IntoIterator>::IntoIter, F> + where I: IntoIterator, + I::Item: IntoIterator, + F: KMergePredicate<<<I as IntoIterator>::Item as IntoIterator>::Item>, +{ + let iter = iterable.into_iter(); + let (lower, _) = iter.size_hint(); + let mut heap: Vec<_> = Vec::with_capacity(lower); + heap.extend(iter.filter_map(|it| HeadTail::new(it.into_iter()))); + heapify(&mut heap, |a, b| less_than.kmerge_pred(&a.head, &b.head)); + KMergeBy { heap, less_than } +} + +impl<I, F> Clone for KMergeBy<I, F> + where I: Iterator + Clone, + I::Item: Clone, + F: Clone, +{ + clone_fields!(heap, less_than); +} + +impl<I, F> Iterator for KMergeBy<I, F> + where I: Iterator, + F: KMergePredicate<I::Item> +{ + type Item = I::Item; + + fn next(&mut self) -> Option<Self::Item> { + if self.heap.is_empty() { + return None; + } + let result = if let Some(next) = self.heap[0].next() { + next + } else { + self.heap.swap_remove(0).head + }; + let less_than = &mut self.less_than; + sift_down(&mut self.heap, 0, |a, b| less_than.kmerge_pred(&a.head, &b.head)); + Some(result) + } + + fn size_hint(&self) -> (usize, Option<usize>) { + #[allow(deprecated)] //TODO: once msrv hits 1.51. replace `fold1` with `reduce` + self.heap.iter() + .map(|i| i.size_hint()) + .fold1(size_hint::add) + .unwrap_or((0, Some(0))) + } +} + +impl<I, F> FusedIterator for KMergeBy<I, F> + where I: Iterator, + F: KMergePredicate<I::Item> +{} diff --git a/third_party/rust/itertools/src/lazy_buffer.rs b/third_party/rust/itertools/src/lazy_buffer.rs new file mode 100644 index 0000000000..ca24062aab --- /dev/null +++ b/third_party/rust/itertools/src/lazy_buffer.rs @@ -0,0 +1,63 @@ +use std::ops::Index; +use alloc::vec::Vec; + +#[derive(Debug, Clone)] +pub struct LazyBuffer<I: Iterator> { + pub it: I, + done: bool, + buffer: Vec<I::Item>, +} + +impl<I> LazyBuffer<I> +where + I: Iterator, +{ + pub fn new(it: I) -> LazyBuffer<I> { + LazyBuffer { + it, + done: false, + buffer: Vec::new(), + } + } + + pub fn len(&self) -> usize { + self.buffer.len() + } + + pub fn get_next(&mut self) -> bool { + if self.done { + return false; + } + if let Some(x) = self.it.next() { + self.buffer.push(x); + true + } else { + self.done = true; + false + } + } + + pub fn prefill(&mut self, len: usize) { + let buffer_len = self.buffer.len(); + + if !self.done && len > buffer_len { + let delta = len - buffer_len; + + self.buffer.extend(self.it.by_ref().take(delta)); + self.done = self.buffer.len() < len; + } + } +} + +impl<I, J> Index<J> for LazyBuffer<I> +where + I: Iterator, + I::Item: Sized, + Vec<I::Item>: Index<J> +{ + type Output = <Vec<I::Item> as Index<J>>::Output; + + fn index(&self, index: J) -> &Self::Output { + self.buffer.index(index) + } +} diff --git a/third_party/rust/itertools/src/lib.rs b/third_party/rust/itertools/src/lib.rs new file mode 100644 index 0000000000..f91968870f --- /dev/null +++ b/third_party/rust/itertools/src/lib.rs @@ -0,0 +1,3784 @@ +#![warn(missing_docs)] +#![crate_name="itertools"] +#![cfg_attr(not(feature = "use_std"), no_std)] + +//! Extra iterator adaptors, functions and macros. +//! +//! To extend [`Iterator`] with methods in this crate, import +//! the [`Itertools`] trait: +//! +//! ``` +//! use itertools::Itertools; +//! ``` +//! +//! Now, new methods like [`interleave`](Itertools::interleave) +//! are available on all iterators: +//! +//! ``` +//! use itertools::Itertools; +//! +//! let it = (1..3).interleave(vec![-1, -2]); +//! itertools::assert_equal(it, vec![1, -1, 2, -2]); +//! ``` +//! +//! Most iterator methods are also provided as functions (with the benefit +//! that they convert parameters using [`IntoIterator`]): +//! +//! ``` +//! use itertools::interleave; +//! +//! for elt in interleave(&[1, 2, 3], &[2, 3, 4]) { +//! /* loop body */ +//! } +//! ``` +//! +//! ## Crate Features +//! +//! - `use_std` +//! - Enabled by default. +//! - Disable to compile itertools using `#![no_std]`. This disables +//! any items that depend on collections (like `group_by`, `unique`, +//! `kmerge`, `join` and many more). +//! +//! ## Rust Version +//! +//! This version of itertools requires Rust 1.32 or later. +#![doc(html_root_url="https://docs.rs/itertools/0.8/")] + +#[cfg(not(feature = "use_std"))] +extern crate core as std; + +#[cfg(feature = "use_alloc")] +extern crate alloc; + +#[cfg(feature = "use_alloc")] +use alloc::{ + string::String, + vec::Vec, +}; + +pub use either::Either; + +use core::borrow::Borrow; +#[cfg(feature = "use_std")] +use std::collections::HashMap; +use std::iter::{IntoIterator, once}; +use std::cmp::Ordering; +use std::fmt; +#[cfg(feature = "use_std")] +use std::collections::HashSet; +#[cfg(feature = "use_std")] +use std::hash::Hash; +#[cfg(feature = "use_alloc")] +use std::fmt::Write; +#[cfg(feature = "use_alloc")] +type VecIntoIter<T> = alloc::vec::IntoIter<T>; +#[cfg(feature = "use_alloc")] +use std::iter::FromIterator; + +#[macro_use] +mod impl_macros; + +// for compatibility with no std and macros +#[doc(hidden)] +pub use std::iter as __std_iter; + +/// The concrete iterator types. +pub mod structs { + pub use crate::adaptors::{ + Dedup, + DedupBy, + DedupWithCount, + DedupByWithCount, + Interleave, + InterleaveShortest, + FilterMapOk, + FilterOk, + Product, + PutBack, + Batching, + MapInto, + MapOk, + Merge, + MergeBy, + TakeWhileRef, + WhileSome, + Coalesce, + TupleCombinations, + Positions, + Update, + }; + #[allow(deprecated)] + pub use crate::adaptors::{MapResults, Step}; + #[cfg(feature = "use_alloc")] + pub use crate::adaptors::MultiProduct; + #[cfg(feature = "use_alloc")] + pub use crate::combinations::Combinations; + #[cfg(feature = "use_alloc")] + pub use crate::combinations_with_replacement::CombinationsWithReplacement; + pub use crate::cons_tuples_impl::ConsTuples; + pub use crate::exactly_one_err::ExactlyOneError; + pub use crate::format::{Format, FormatWith}; + pub use crate::flatten_ok::FlattenOk; + #[cfg(feature = "use_std")] + pub use crate::grouping_map::{GroupingMap, GroupingMapBy}; + #[cfg(feature = "use_alloc")] + pub use crate::groupbylazy::{IntoChunks, Chunk, Chunks, GroupBy, Group, Groups}; + pub use crate::intersperse::{Intersperse, IntersperseWith}; + #[cfg(feature = "use_alloc")] + pub use crate::kmerge_impl::{KMerge, KMergeBy}; + pub use crate::merge_join::MergeJoinBy; + #[cfg(feature = "use_alloc")] + pub use crate::multipeek_impl::MultiPeek; + #[cfg(feature = "use_alloc")] + pub use crate::peek_nth::PeekNth; + pub use crate::pad_tail::PadUsing; + pub use crate::peeking_take_while::PeekingTakeWhile; + #[cfg(feature = "use_alloc")] + pub use crate::permutations::Permutations; + pub use crate::process_results_impl::ProcessResults; + #[cfg(feature = "use_alloc")] + pub use crate::powerset::Powerset; + #[cfg(feature = "use_alloc")] + pub use crate::put_back_n_impl::PutBackN; + #[cfg(feature = "use_alloc")] + pub use crate::rciter_impl::RcIter; + pub use crate::repeatn::RepeatN; + #[allow(deprecated)] + pub use crate::sources::{RepeatCall, Unfold, Iterate}; + #[cfg(feature = "use_alloc")] + pub use crate::tee::Tee; + pub use crate::tuple_impl::{TupleBuffer, TupleWindows, CircularTupleWindows, Tuples}; + #[cfg(feature = "use_std")] + pub use crate::duplicates_impl::{Duplicates, DuplicatesBy}; + #[cfg(feature = "use_std")] + pub use crate::unique_impl::{Unique, UniqueBy}; + pub use crate::with_position::WithPosition; + pub use crate::zip_eq_impl::ZipEq; + pub use crate::zip_longest::ZipLongest; + pub use crate::ziptuple::Zip; +} + +/// Traits helpful for using certain `Itertools` methods in generic contexts. +pub mod traits { + pub use crate::tuple_impl::HomogeneousTuple; +} + +#[allow(deprecated)] +pub use crate::structs::*; +pub use crate::concat_impl::concat; +pub use crate::cons_tuples_impl::cons_tuples; +pub use crate::diff::diff_with; +pub use crate::diff::Diff; +#[cfg(feature = "use_alloc")] +pub use crate::kmerge_impl::{kmerge_by}; +pub use crate::minmax::MinMaxResult; +pub use crate::peeking_take_while::PeekingNext; +pub use crate::process_results_impl::process_results; +pub use crate::repeatn::repeat_n; +#[allow(deprecated)] +pub use crate::sources::{repeat_call, unfold, iterate}; +pub use crate::with_position::Position; +pub use crate::unziptuple::{multiunzip, MultiUnzip}; +pub use crate::ziptuple::multizip; +mod adaptors; +mod either_or_both; +pub use crate::either_or_both::EitherOrBoth; +#[doc(hidden)] +pub mod free; +#[doc(inline)] +pub use crate::free::*; +mod concat_impl; +mod cons_tuples_impl; +#[cfg(feature = "use_alloc")] +mod combinations; +#[cfg(feature = "use_alloc")] +mod combinations_with_replacement; +mod exactly_one_err; +mod diff; +mod flatten_ok; +#[cfg(feature = "use_std")] +mod extrema_set; +mod format; +#[cfg(feature = "use_std")] +mod grouping_map; +#[cfg(feature = "use_alloc")] +mod group_map; +#[cfg(feature = "use_alloc")] +mod groupbylazy; +mod intersperse; +#[cfg(feature = "use_alloc")] +mod k_smallest; +#[cfg(feature = "use_alloc")] +mod kmerge_impl; +#[cfg(feature = "use_alloc")] +mod lazy_buffer; +mod merge_join; +mod minmax; +#[cfg(feature = "use_alloc")] +mod multipeek_impl; +mod pad_tail; +#[cfg(feature = "use_alloc")] +mod peek_nth; +mod peeking_take_while; +#[cfg(feature = "use_alloc")] +mod permutations; +#[cfg(feature = "use_alloc")] +mod powerset; +mod process_results_impl; +#[cfg(feature = "use_alloc")] +mod put_back_n_impl; +#[cfg(feature = "use_alloc")] +mod rciter_impl; +mod repeatn; +mod size_hint; +mod sources; +#[cfg(feature = "use_alloc")] +mod tee; +mod tuple_impl; +#[cfg(feature = "use_std")] +mod duplicates_impl; +#[cfg(feature = "use_std")] +mod unique_impl; +mod unziptuple; +mod with_position; +mod zip_eq_impl; +mod zip_longest; +mod ziptuple; + +#[macro_export] +/// Create an iterator over the “cartesian product” of iterators. +/// +/// Iterator element type is like `(A, B, ..., E)` if formed +/// from iterators `(I, J, ..., M)` with element types `I::Item = A`, `J::Item = B`, etc. +/// +/// ``` +/// # use itertools::iproduct; +/// # +/// # fn main() { +/// // Iterate over the coordinates of a 4 x 4 x 4 grid +/// // from (0, 0, 0), (0, 0, 1), .., (0, 1, 0), (0, 1, 1), .. etc until (3, 3, 3) +/// for (i, j, k) in iproduct!(0..4, 0..4, 0..4) { +/// // .. +/// } +/// # } +/// ``` +macro_rules! iproduct { + (@flatten $I:expr,) => ( + $I + ); + (@flatten $I:expr, $J:expr, $($K:expr,)*) => ( + $crate::iproduct!(@flatten $crate::cons_tuples($crate::iproduct!($I, $J)), $($K,)*) + ); + ($I:expr) => ( + $crate::__std_iter::IntoIterator::into_iter($I) + ); + ($I:expr, $J:expr) => ( + $crate::Itertools::cartesian_product($crate::iproduct!($I), $crate::iproduct!($J)) + ); + ($I:expr, $J:expr, $($K:expr),+) => ( + $crate::iproduct!(@flatten $crate::iproduct!($I, $J), $($K,)+) + ); +} + +#[macro_export] +/// Create an iterator running multiple iterators in lockstep. +/// +/// The `izip!` iterator yields elements until any subiterator +/// returns `None`. +/// +/// This is a version of the standard ``.zip()`` that's supporting more than +/// two iterators. The iterator element type is a tuple with one element +/// from each of the input iterators. Just like ``.zip()``, the iteration stops +/// when the shortest of the inputs reaches its end. +/// +/// **Note:** The result of this macro is in the general case an iterator +/// composed of repeated `.zip()` and a `.map()`; it has an anonymous type. +/// The special cases of one and two arguments produce the equivalent of +/// `$a.into_iter()` and `$a.into_iter().zip($b)` respectively. +/// +/// Prefer this macro `izip!()` over [`multizip`] for the performance benefits +/// of using the standard library `.zip()`. +/// +/// ``` +/// # use itertools::izip; +/// # +/// # fn main() { +/// +/// // iterate over three sequences side-by-side +/// let mut results = [0, 0, 0, 0]; +/// let inputs = [3, 7, 9, 6]; +/// +/// for (r, index, input) in izip!(&mut results, 0..10, &inputs) { +/// *r = index * 10 + input; +/// } +/// +/// assert_eq!(results, [0 + 3, 10 + 7, 29, 36]); +/// # } +/// ``` +macro_rules! izip { + // @closure creates a tuple-flattening closure for .map() call. usage: + // @closure partial_pattern => partial_tuple , rest , of , iterators + // eg. izip!( @closure ((a, b), c) => (a, b, c) , dd , ee ) + ( @closure $p:pat => $tup:expr ) => { + |$p| $tup + }; + + // The "b" identifier is a different identifier on each recursion level thanks to hygiene. + ( @closure $p:pat => ( $($tup:tt)* ) , $_iter:expr $( , $tail:expr )* ) => { + $crate::izip!(@closure ($p, b) => ( $($tup)*, b ) $( , $tail )*) + }; + + // unary + ($first:expr $(,)*) => { + $crate::__std_iter::IntoIterator::into_iter($first) + }; + + // binary + ($first:expr, $second:expr $(,)*) => { + $crate::izip!($first) + .zip($second) + }; + + // n-ary where n > 2 + ( $first:expr $( , $rest:expr )* $(,)* ) => { + $crate::izip!($first) + $( + .zip($rest) + )* + .map( + $crate::izip!(@closure a => (a) $( , $rest )*) + ) + }; +} + +#[macro_export] +/// [Chain][`chain`] zero or more iterators together into one sequence. +/// +/// The comma-separated arguments must implement [`IntoIterator`]. +/// The final argument may be followed by a trailing comma. +/// +/// [`chain`]: Iterator::chain +/// +/// # Examples +/// +/// Empty invocations of `chain!` expand to an invocation of [`std::iter::empty`]: +/// ``` +/// use std::iter; +/// use itertools::chain; +/// +/// let _: iter::Empty<()> = chain!(); +/// let _: iter::Empty<i8> = chain!(); +/// ``` +/// +/// Invocations of `chain!` with one argument expand to [`arg.into_iter()`](IntoIterator): +/// ``` +/// use std::{ops::Range, slice}; +/// use itertools::chain; +/// let _: <Range<_> as IntoIterator>::IntoIter = chain!((2..6),); // trailing comma optional! +/// let _: <&[_] as IntoIterator>::IntoIter = chain!(&[2, 3, 4]); +/// ``` +/// +/// Invocations of `chain!` with multiple arguments [`.into_iter()`](IntoIterator) each +/// argument, and then [`chain`] them together: +/// ``` +/// use std::{iter::*, ops::Range, slice}; +/// use itertools::{assert_equal, chain}; +/// +/// // e.g., this: +/// let with_macro: Chain<Chain<Once<_>, Take<Repeat<_>>>, slice::Iter<_>> = +/// chain![once(&0), repeat(&1).take(2), &[2, 3, 5],]; +/// +/// // ...is equivalent to this: +/// let with_method: Chain<Chain<Once<_>, Take<Repeat<_>>>, slice::Iter<_>> = +/// once(&0) +/// .chain(repeat(&1).take(2)) +/// .chain(&[2, 3, 5]); +/// +/// assert_equal(with_macro, with_method); +/// ``` +macro_rules! chain { + () => { + core::iter::empty() + }; + ($first:expr $(, $rest:expr )* $(,)?) => { + { + let iter = core::iter::IntoIterator::into_iter($first); + $( + let iter = + core::iter::Iterator::chain( + iter, + core::iter::IntoIterator::into_iter($rest)); + )* + iter + } + }; +} + +/// An [`Iterator`] blanket implementation that provides extra adaptors and +/// methods. +/// +/// This trait defines a number of methods. They are divided into two groups: +/// +/// * *Adaptors* take an iterator and parameter as input, and return +/// a new iterator value. These are listed first in the trait. An example +/// of an adaptor is [`.interleave()`](Itertools::interleave) +/// +/// * *Regular methods* are those that don't return iterators and instead +/// return a regular value of some other kind. +/// [`.next_tuple()`](Itertools::next_tuple) is an example and the first regular +/// method in the list. +pub trait Itertools : Iterator { + // adaptors + + /// Alternate elements from two iterators until both have run out. + /// + /// Iterator element type is `Self::Item`. + /// + /// This iterator is *fused*. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let it = (1..7).interleave(vec![-1, -2]); + /// itertools::assert_equal(it, vec![1, -1, 2, -2, 3, 4, 5, 6]); + /// ``` + fn interleave<J>(self, other: J) -> Interleave<Self, J::IntoIter> + where J: IntoIterator<Item = Self::Item>, + Self: Sized + { + interleave(self, other) + } + + /// Alternate elements from two iterators until at least one of them has run + /// out. + /// + /// Iterator element type is `Self::Item`. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let it = (1..7).interleave_shortest(vec![-1, -2]); + /// itertools::assert_equal(it, vec![1, -1, 2, -2, 3]); + /// ``` + fn interleave_shortest<J>(self, other: J) -> InterleaveShortest<Self, J::IntoIter> + where J: IntoIterator<Item = Self::Item>, + Self: Sized + { + adaptors::interleave_shortest(self, other.into_iter()) + } + + /// An iterator adaptor to insert a particular value + /// between each element of the adapted iterator. + /// + /// Iterator element type is `Self::Item`. + /// + /// This iterator is *fused*. + /// + /// ``` + /// use itertools::Itertools; + /// + /// itertools::assert_equal((0..3).intersperse(8), vec![0, 8, 1, 8, 2]); + /// ``` + fn intersperse(self, element: Self::Item) -> Intersperse<Self> + where Self: Sized, + Self::Item: Clone + { + intersperse::intersperse(self, element) + } + + /// An iterator adaptor to insert a particular value created by a function + /// between each element of the adapted iterator. + /// + /// Iterator element type is `Self::Item`. + /// + /// This iterator is *fused*. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let mut i = 10; + /// itertools::assert_equal((0..3).intersperse_with(|| { i -= 1; i }), vec![0, 9, 1, 8, 2]); + /// assert_eq!(i, 8); + /// ``` + fn intersperse_with<F>(self, element: F) -> IntersperseWith<Self, F> + where Self: Sized, + F: FnMut() -> Self::Item + { + intersperse::intersperse_with(self, element) + } + + /// Create an iterator which iterates over both this and the specified + /// iterator simultaneously, yielding pairs of two optional elements. + /// + /// This iterator is *fused*. + /// + /// As long as neither input iterator is exhausted yet, it yields two values + /// via `EitherOrBoth::Both`. + /// + /// When the parameter iterator is exhausted, it only yields a value from the + /// `self` iterator via `EitherOrBoth::Left`. + /// + /// When the `self` iterator is exhausted, it only yields a value from the + /// parameter iterator via `EitherOrBoth::Right`. + /// + /// When both iterators return `None`, all further invocations of `.next()` + /// will return `None`. + /// + /// Iterator element type is + /// [`EitherOrBoth<Self::Item, J::Item>`](EitherOrBoth). + /// + /// ```rust + /// use itertools::EitherOrBoth::{Both, Right}; + /// use itertools::Itertools; + /// let it = (0..1).zip_longest(1..3); + /// itertools::assert_equal(it, vec![Both(0, 1), Right(2)]); + /// ``` + #[inline] + fn zip_longest<J>(self, other: J) -> ZipLongest<Self, J::IntoIter> + where J: IntoIterator, + Self: Sized + { + zip_longest::zip_longest(self, other.into_iter()) + } + + /// Create an iterator which iterates over both this and the specified + /// iterator simultaneously, yielding pairs of elements. + /// + /// **Panics** if the iterators reach an end and they are not of equal + /// lengths. + #[inline] + fn zip_eq<J>(self, other: J) -> ZipEq<Self, J::IntoIter> + where J: IntoIterator, + Self: Sized + { + zip_eq(self, other) + } + + /// A “meta iterator adaptor”. Its closure receives a reference to the + /// iterator and may pick off as many elements as it likes, to produce the + /// next iterator element. + /// + /// Iterator element type is `B`. + /// + /// ``` + /// use itertools::Itertools; + /// + /// // An adaptor that gathers elements in pairs + /// let pit = (0..4).batching(|it| { + /// match it.next() { + /// None => None, + /// Some(x) => match it.next() { + /// None => None, + /// Some(y) => Some((x, y)), + /// } + /// } + /// }); + /// + /// itertools::assert_equal(pit, vec![(0, 1), (2, 3)]); + /// ``` + /// + fn batching<B, F>(self, f: F) -> Batching<Self, F> + where F: FnMut(&mut Self) -> Option<B>, + Self: Sized + { + adaptors::batching(self, f) + } + + /// Return an *iterable* that can group iterator elements. + /// Consecutive elements that map to the same key (“runs”), are assigned + /// to the same group. + /// + /// `GroupBy` is the storage for the lazy grouping operation. + /// + /// If the groups are consumed in order, or if each group's iterator is + /// dropped without keeping it around, then `GroupBy` uses no + /// allocations. It needs allocations only if several group iterators + /// are alive at the same time. + /// + /// This type implements [`IntoIterator`] (it is **not** an iterator + /// itself), because the group iterators need to borrow from this + /// value. It should be stored in a local variable or temporary and + /// iterated. + /// + /// Iterator element type is `(K, Group)`: the group's key and the + /// group iterator. + /// + /// ``` + /// use itertools::Itertools; + /// + /// // group data into runs of larger than zero or not. + /// let data = vec![1, 3, -2, -2, 1, 0, 1, 2]; + /// // groups: |---->|------>|--------->| + /// + /// // Note: The `&` is significant here, `GroupBy` is iterable + /// // only by reference. You can also call `.into_iter()` explicitly. + /// let mut data_grouped = Vec::new(); + /// for (key, group) in &data.into_iter().group_by(|elt| *elt >= 0) { + /// data_grouped.push((key, group.collect())); + /// } + /// assert_eq!(data_grouped, vec![(true, vec![1, 3]), (false, vec![-2, -2]), (true, vec![1, 0, 1, 2])]); + /// ``` + #[cfg(feature = "use_alloc")] + fn group_by<K, F>(self, key: F) -> GroupBy<K, Self, F> + where Self: Sized, + F: FnMut(&Self::Item) -> K, + K: PartialEq, + { + groupbylazy::new(self, key) + } + + /// Return an *iterable* that can chunk the iterator. + /// + /// Yield subiterators (chunks) that each yield a fixed number elements, + /// determined by `size`. The last chunk will be shorter if there aren't + /// enough elements. + /// + /// `IntoChunks` is based on `GroupBy`: it is iterable (implements + /// `IntoIterator`, **not** `Iterator`), and it only buffers if several + /// chunk iterators are alive at the same time. + /// + /// Iterator element type is `Chunk`, each chunk's iterator. + /// + /// **Panics** if `size` is 0. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let data = vec![1, 1, 2, -2, 6, 0, 3, 1]; + /// //chunk size=3 |------->|-------->|--->| + /// + /// // Note: The `&` is significant here, `IntoChunks` is iterable + /// // only by reference. You can also call `.into_iter()` explicitly. + /// for chunk in &data.into_iter().chunks(3) { + /// // Check that the sum of each chunk is 4. + /// assert_eq!(4, chunk.sum()); + /// } + /// ``` + #[cfg(feature = "use_alloc")] + fn chunks(self, size: usize) -> IntoChunks<Self> + where Self: Sized, + { + assert!(size != 0); + groupbylazy::new_chunks(self, size) + } + + /// Return an iterator over all contiguous windows producing tuples of + /// a specific size (up to 12). + /// + /// `tuple_windows` clones the iterator elements so that they can be + /// part of successive windows, this makes it most suited for iterators + /// of references and other values that are cheap to copy. + /// + /// ``` + /// use itertools::Itertools; + /// let mut v = Vec::new(); + /// + /// // pairwise iteration + /// for (a, b) in (1..5).tuple_windows() { + /// v.push((a, b)); + /// } + /// assert_eq!(v, vec![(1, 2), (2, 3), (3, 4)]); + /// + /// let mut it = (1..5).tuple_windows(); + /// assert_eq!(Some((1, 2, 3)), it.next()); + /// assert_eq!(Some((2, 3, 4)), it.next()); + /// assert_eq!(None, it.next()); + /// + /// // this requires a type hint + /// let it = (1..5).tuple_windows::<(_, _, _)>(); + /// itertools::assert_equal(it, vec![(1, 2, 3), (2, 3, 4)]); + /// + /// // you can also specify the complete type + /// use itertools::TupleWindows; + /// use std::ops::Range; + /// + /// let it: TupleWindows<Range<u32>, (u32, u32, u32)> = (1..5).tuple_windows(); + /// itertools::assert_equal(it, vec![(1, 2, 3), (2, 3, 4)]); + /// ``` + fn tuple_windows<T>(self) -> TupleWindows<Self, T> + where Self: Sized + Iterator<Item = T::Item>, + T: traits::HomogeneousTuple, + T::Item: Clone + { + tuple_impl::tuple_windows(self) + } + + /// Return an iterator over all windows, wrapping back to the first + /// elements when the window would otherwise exceed the length of the + /// iterator, producing tuples of a specific size (up to 12). + /// + /// `circular_tuple_windows` clones the iterator elements so that they can be + /// part of successive windows, this makes it most suited for iterators + /// of references and other values that are cheap to copy. + /// + /// ``` + /// use itertools::Itertools; + /// let mut v = Vec::new(); + /// for (a, b) in (1..5).circular_tuple_windows() { + /// v.push((a, b)); + /// } + /// assert_eq!(v, vec![(1, 2), (2, 3), (3, 4), (4, 1)]); + /// + /// let mut it = (1..5).circular_tuple_windows(); + /// assert_eq!(Some((1, 2, 3)), it.next()); + /// assert_eq!(Some((2, 3, 4)), it.next()); + /// assert_eq!(Some((3, 4, 1)), it.next()); + /// assert_eq!(Some((4, 1, 2)), it.next()); + /// assert_eq!(None, it.next()); + /// + /// // this requires a type hint + /// let it = (1..5).circular_tuple_windows::<(_, _, _)>(); + /// itertools::assert_equal(it, vec![(1, 2, 3), (2, 3, 4), (3, 4, 1), (4, 1, 2)]); + /// ``` + fn circular_tuple_windows<T>(self) -> CircularTupleWindows<Self, T> + where Self: Sized + Clone + Iterator<Item = T::Item> + ExactSizeIterator, + T: tuple_impl::TupleCollect + Clone, + T::Item: Clone + { + tuple_impl::circular_tuple_windows(self) + } + /// Return an iterator that groups the items in tuples of a specific size + /// (up to 12). + /// + /// See also the method [`.next_tuple()`](Itertools::next_tuple). + /// + /// ``` + /// use itertools::Itertools; + /// let mut v = Vec::new(); + /// for (a, b) in (1..5).tuples() { + /// v.push((a, b)); + /// } + /// assert_eq!(v, vec![(1, 2), (3, 4)]); + /// + /// let mut it = (1..7).tuples(); + /// assert_eq!(Some((1, 2, 3)), it.next()); + /// assert_eq!(Some((4, 5, 6)), it.next()); + /// assert_eq!(None, it.next()); + /// + /// // this requires a type hint + /// let it = (1..7).tuples::<(_, _, _)>(); + /// itertools::assert_equal(it, vec![(1, 2, 3), (4, 5, 6)]); + /// + /// // you can also specify the complete type + /// use itertools::Tuples; + /// use std::ops::Range; + /// + /// let it: Tuples<Range<u32>, (u32, u32, u32)> = (1..7).tuples(); + /// itertools::assert_equal(it, vec![(1, 2, 3), (4, 5, 6)]); + /// ``` + /// + /// See also [`Tuples::into_buffer`]. + fn tuples<T>(self) -> Tuples<Self, T> + where Self: Sized + Iterator<Item = T::Item>, + T: traits::HomogeneousTuple + { + tuple_impl::tuples(self) + } + + /// Split into an iterator pair that both yield all elements from + /// the original iterator. + /// + /// **Note:** If the iterator is clonable, prefer using that instead + /// of using this method. Cloning is likely to be more efficient. + /// + /// Iterator element type is `Self::Item`. + /// + /// ``` + /// use itertools::Itertools; + /// let xs = vec![0, 1, 2, 3]; + /// + /// let (mut t1, t2) = xs.into_iter().tee(); + /// itertools::assert_equal(t1.next(), Some(0)); + /// itertools::assert_equal(t2, 0..4); + /// itertools::assert_equal(t1, 1..4); + /// ``` + #[cfg(feature = "use_alloc")] + fn tee(self) -> (Tee<Self>, Tee<Self>) + where Self: Sized, + Self::Item: Clone + { + tee::new(self) + } + + /// Return an iterator adaptor that steps `n` elements in the base iterator + /// for each iteration. + /// + /// The iterator steps by yielding the next element from the base iterator, + /// then skipping forward `n - 1` elements. + /// + /// Iterator element type is `Self::Item`. + /// + /// **Panics** if the step is 0. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let it = (0..8).step(3); + /// itertools::assert_equal(it, vec![0, 3, 6]); + /// ``` + #[deprecated(note="Use std .step_by() instead", since="0.8.0")] + #[allow(deprecated)] + fn step(self, n: usize) -> Step<Self> + where Self: Sized + { + adaptors::step(self, n) + } + + /// Convert each item of the iterator using the [`Into`] trait. + /// + /// ```rust + /// use itertools::Itertools; + /// + /// (1i32..42i32).map_into::<f64>().collect_vec(); + /// ``` + fn map_into<R>(self) -> MapInto<Self, R> + where Self: Sized, + Self::Item: Into<R>, + { + adaptors::map_into(self) + } + + /// See [`.map_ok()`](Itertools::map_ok). + #[deprecated(note="Use .map_ok() instead", since="0.10.0")] + fn map_results<F, T, U, E>(self, f: F) -> MapOk<Self, F> + where Self: Iterator<Item = Result<T, E>> + Sized, + F: FnMut(T) -> U, + { + self.map_ok(f) + } + + /// Return an iterator adaptor that applies the provided closure + /// to every `Result::Ok` value. `Result::Err` values are + /// unchanged. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let input = vec![Ok(41), Err(false), Ok(11)]; + /// let it = input.into_iter().map_ok(|i| i + 1); + /// itertools::assert_equal(it, vec![Ok(42), Err(false), Ok(12)]); + /// ``` + fn map_ok<F, T, U, E>(self, f: F) -> MapOk<Self, F> + where Self: Iterator<Item = Result<T, E>> + Sized, + F: FnMut(T) -> U, + { + adaptors::map_ok(self, f) + } + + /// Return an iterator adaptor that filters every `Result::Ok` + /// value with the provided closure. `Result::Err` values are + /// unchanged. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let input = vec![Ok(22), Err(false), Ok(11)]; + /// let it = input.into_iter().filter_ok(|&i| i > 20); + /// itertools::assert_equal(it, vec![Ok(22), Err(false)]); + /// ``` + fn filter_ok<F, T, E>(self, f: F) -> FilterOk<Self, F> + where Self: Iterator<Item = Result<T, E>> + Sized, + F: FnMut(&T) -> bool, + { + adaptors::filter_ok(self, f) + } + + /// Return an iterator adaptor that filters and transforms every + /// `Result::Ok` value with the provided closure. `Result::Err` + /// values are unchanged. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let input = vec![Ok(22), Err(false), Ok(11)]; + /// let it = input.into_iter().filter_map_ok(|i| if i > 20 { Some(i * 2) } else { None }); + /// itertools::assert_equal(it, vec![Ok(44), Err(false)]); + /// ``` + fn filter_map_ok<F, T, U, E>(self, f: F) -> FilterMapOk<Self, F> + where Self: Iterator<Item = Result<T, E>> + Sized, + F: FnMut(T) -> Option<U>, + { + adaptors::filter_map_ok(self, f) + } + + /// Return an iterator adaptor that flattens every `Result::Ok` value into + /// a series of `Result::Ok` values. `Result::Err` values are unchanged. + /// + /// This is useful when you have some common error type for your crate and + /// need to propagate it upwards, but the `Result::Ok` case needs to be flattened. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let input = vec![Ok(0..2), Err(false), Ok(2..4)]; + /// let it = input.iter().cloned().flatten_ok(); + /// itertools::assert_equal(it.clone(), vec![Ok(0), Ok(1), Err(false), Ok(2), Ok(3)]); + /// + /// // This can also be used to propagate errors when collecting. + /// let output_result: Result<Vec<i32>, bool> = it.collect(); + /// assert_eq!(output_result, Err(false)); + /// ``` + fn flatten_ok<T, E>(self) -> FlattenOk<Self, T, E> + where Self: Iterator<Item = Result<T, E>> + Sized, + T: IntoIterator + { + flatten_ok::flatten_ok(self) + } + + /// Return an iterator adaptor that merges the two base iterators in + /// ascending order. If both base iterators are sorted (ascending), the + /// result is sorted. + /// + /// Iterator element type is `Self::Item`. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let a = (0..11).step(3); + /// let b = (0..11).step(5); + /// let it = a.merge(b); + /// itertools::assert_equal(it, vec![0, 0, 3, 5, 6, 9, 10]); + /// ``` + fn merge<J>(self, other: J) -> Merge<Self, J::IntoIter> + where Self: Sized, + Self::Item: PartialOrd, + J: IntoIterator<Item = Self::Item> + { + merge(self, other) + } + + /// Return an iterator adaptor that merges the two base iterators in order. + /// This is much like [`.merge()`](Itertools::merge) but allows for a custom ordering. + /// + /// This can be especially useful for sequences of tuples. + /// + /// Iterator element type is `Self::Item`. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let a = (0..).zip("bc".chars()); + /// let b = (0..).zip("ad".chars()); + /// let it = a.merge_by(b, |x, y| x.1 <= y.1); + /// itertools::assert_equal(it, vec![(0, 'a'), (0, 'b'), (1, 'c'), (1, 'd')]); + /// ``` + + fn merge_by<J, F>(self, other: J, is_first: F) -> MergeBy<Self, J::IntoIter, F> + where Self: Sized, + J: IntoIterator<Item = Self::Item>, + F: FnMut(&Self::Item, &Self::Item) -> bool + { + adaptors::merge_by_new(self, other.into_iter(), is_first) + } + + /// Create an iterator that merges items from both this and the specified + /// iterator in ascending order. + /// + /// It chooses whether to pair elements based on the `Ordering` returned by the + /// specified compare function. At any point, inspecting the tip of the + /// iterators `I` and `J` as items `i` of type `I::Item` and `j` of type + /// `J::Item` respectively, the resulting iterator will: + /// + /// - Emit `EitherOrBoth::Left(i)` when `i < j`, + /// and remove `i` from its source iterator + /// - Emit `EitherOrBoth::Right(j)` when `i > j`, + /// and remove `j` from its source iterator + /// - Emit `EitherOrBoth::Both(i, j)` when `i == j`, + /// and remove both `i` and `j` from their respective source iterators + /// + /// ``` + /// use itertools::Itertools; + /// use itertools::EitherOrBoth::{Left, Right, Both}; + /// + /// let multiples_of_2 = (0..10).step(2); + /// let multiples_of_3 = (0..10).step(3); + /// + /// itertools::assert_equal( + /// multiples_of_2.merge_join_by(multiples_of_3, |i, j| i.cmp(j)), + /// vec![Both(0, 0), Left(2), Right(3), Left(4), Both(6, 6), Left(8), Right(9)] + /// ); + /// ``` + #[inline] + fn merge_join_by<J, F>(self, other: J, cmp_fn: F) -> MergeJoinBy<Self, J::IntoIter, F> + where J: IntoIterator, + F: FnMut(&Self::Item, &J::Item) -> std::cmp::Ordering, + Self: Sized + { + merge_join_by(self, other, cmp_fn) + } + + /// Return an iterator adaptor that flattens an iterator of iterators by + /// merging them in ascending order. + /// + /// If all base iterators are sorted (ascending), the result is sorted. + /// + /// Iterator element type is `Self::Item`. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let a = (0..6).step(3); + /// let b = (1..6).step(3); + /// let c = (2..6).step(3); + /// let it = vec![a, b, c].into_iter().kmerge(); + /// itertools::assert_equal(it, vec![0, 1, 2, 3, 4, 5]); + /// ``` + #[cfg(feature = "use_alloc")] + fn kmerge(self) -> KMerge<<Self::Item as IntoIterator>::IntoIter> + where Self: Sized, + Self::Item: IntoIterator, + <Self::Item as IntoIterator>::Item: PartialOrd, + { + kmerge(self) + } + + /// Return an iterator adaptor that flattens an iterator of iterators by + /// merging them according to the given closure. + /// + /// The closure `first` is called with two elements *a*, *b* and should + /// return `true` if *a* is ordered before *b*. + /// + /// If all base iterators are sorted according to `first`, the result is + /// sorted. + /// + /// Iterator element type is `Self::Item`. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let a = vec![-1f64, 2., 3., -5., 6., -7.]; + /// let b = vec![0., 2., -4.]; + /// let mut it = vec![a, b].into_iter().kmerge_by(|a, b| a.abs() < b.abs()); + /// assert_eq!(it.next(), Some(0.)); + /// assert_eq!(it.last(), Some(-7.)); + /// ``` + #[cfg(feature = "use_alloc")] + fn kmerge_by<F>(self, first: F) + -> KMergeBy<<Self::Item as IntoIterator>::IntoIter, F> + where Self: Sized, + Self::Item: IntoIterator, + F: FnMut(&<Self::Item as IntoIterator>::Item, + &<Self::Item as IntoIterator>::Item) -> bool + { + kmerge_by(self, first) + } + + /// Return an iterator adaptor that iterates over the cartesian product of + /// the element sets of two iterators `self` and `J`. + /// + /// Iterator element type is `(Self::Item, J::Item)`. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let it = (0..2).cartesian_product("αβ".chars()); + /// itertools::assert_equal(it, vec![(0, 'α'), (0, 'β'), (1, 'α'), (1, 'β')]); + /// ``` + fn cartesian_product<J>(self, other: J) -> Product<Self, J::IntoIter> + where Self: Sized, + Self::Item: Clone, + J: IntoIterator, + J::IntoIter: Clone + { + adaptors::cartesian_product(self, other.into_iter()) + } + + /// Return an iterator adaptor that iterates over the cartesian product of + /// all subiterators returned by meta-iterator `self`. + /// + /// All provided iterators must yield the same `Item` type. To generate + /// the product of iterators yielding multiple types, use the + /// [`iproduct`] macro instead. + /// + /// + /// The iterator element type is `Vec<T>`, where `T` is the iterator element + /// of the subiterators. + /// + /// ``` + /// use itertools::Itertools; + /// let mut multi_prod = (0..3).map(|i| (i * 2)..(i * 2 + 2)) + /// .multi_cartesian_product(); + /// assert_eq!(multi_prod.next(), Some(vec![0, 2, 4])); + /// assert_eq!(multi_prod.next(), Some(vec![0, 2, 5])); + /// assert_eq!(multi_prod.next(), Some(vec![0, 3, 4])); + /// assert_eq!(multi_prod.next(), Some(vec![0, 3, 5])); + /// assert_eq!(multi_prod.next(), Some(vec![1, 2, 4])); + /// assert_eq!(multi_prod.next(), Some(vec![1, 2, 5])); + /// assert_eq!(multi_prod.next(), Some(vec![1, 3, 4])); + /// assert_eq!(multi_prod.next(), Some(vec![1, 3, 5])); + /// assert_eq!(multi_prod.next(), None); + /// ``` + #[cfg(feature = "use_alloc")] + fn multi_cartesian_product(self) -> MultiProduct<<Self::Item as IntoIterator>::IntoIter> + where Self: Sized, + Self::Item: IntoIterator, + <Self::Item as IntoIterator>::IntoIter: Clone, + <Self::Item as IntoIterator>::Item: Clone + { + adaptors::multi_cartesian_product(self) + } + + /// Return an iterator adaptor that uses the passed-in closure to + /// optionally merge together consecutive elements. + /// + /// The closure `f` is passed two elements, `previous` and `current` and may + /// return either (1) `Ok(combined)` to merge the two values or + /// (2) `Err((previous', current'))` to indicate they can't be merged. + /// In (2), the value `previous'` is emitted by the iterator. + /// Either (1) `combined` or (2) `current'` becomes the previous value + /// when coalesce continues with the next pair of elements to merge. The + /// value that remains at the end is also emitted by the iterator. + /// + /// Iterator element type is `Self::Item`. + /// + /// This iterator is *fused*. + /// + /// ``` + /// use itertools::Itertools; + /// + /// // sum same-sign runs together + /// let data = vec![-1., -2., -3., 3., 1., 0., -1.]; + /// itertools::assert_equal(data.into_iter().coalesce(|x, y| + /// if (x >= 0.) == (y >= 0.) { + /// Ok(x + y) + /// } else { + /// Err((x, y)) + /// }), + /// vec![-6., 4., -1.]); + /// ``` + fn coalesce<F>(self, f: F) -> Coalesce<Self, F> + where Self: Sized, + F: FnMut(Self::Item, Self::Item) + -> Result<Self::Item, (Self::Item, Self::Item)> + { + adaptors::coalesce(self, f) + } + + /// Remove duplicates from sections of consecutive identical elements. + /// If the iterator is sorted, all elements will be unique. + /// + /// Iterator element type is `Self::Item`. + /// + /// This iterator is *fused*. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let data = vec![1., 1., 2., 3., 3., 2., 2.]; + /// itertools::assert_equal(data.into_iter().dedup(), + /// vec![1., 2., 3., 2.]); + /// ``` + fn dedup(self) -> Dedup<Self> + where Self: Sized, + Self::Item: PartialEq, + { + adaptors::dedup(self) + } + + /// Remove duplicates from sections of consecutive identical elements, + /// determining equality using a comparison function. + /// If the iterator is sorted, all elements will be unique. + /// + /// Iterator element type is `Self::Item`. + /// + /// This iterator is *fused*. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let data = vec![(0, 1.), (1, 1.), (0, 2.), (0, 3.), (1, 3.), (1, 2.), (2, 2.)]; + /// itertools::assert_equal(data.into_iter().dedup_by(|x, y| x.1 == y.1), + /// vec![(0, 1.), (0, 2.), (0, 3.), (1, 2.)]); + /// ``` + fn dedup_by<Cmp>(self, cmp: Cmp) -> DedupBy<Self, Cmp> + where Self: Sized, + Cmp: FnMut(&Self::Item, &Self::Item)->bool, + { + adaptors::dedup_by(self, cmp) + } + + /// Remove duplicates from sections of consecutive identical elements, while keeping a count of + /// how many repeated elements were present. + /// If the iterator is sorted, all elements will be unique. + /// + /// Iterator element type is `(usize, Self::Item)`. + /// + /// This iterator is *fused*. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let data = vec!['a', 'a', 'b', 'c', 'c', 'b', 'b']; + /// itertools::assert_equal(data.into_iter().dedup_with_count(), + /// vec![(2, 'a'), (1, 'b'), (2, 'c'), (2, 'b')]); + /// ``` + fn dedup_with_count(self) -> DedupWithCount<Self> + where + Self: Sized, + { + adaptors::dedup_with_count(self) + } + + /// Remove duplicates from sections of consecutive identical elements, while keeping a count of + /// how many repeated elements were present. + /// This will determine equality using a comparison function. + /// If the iterator is sorted, all elements will be unique. + /// + /// Iterator element type is `(usize, Self::Item)`. + /// + /// This iterator is *fused*. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let data = vec![(0, 'a'), (1, 'a'), (0, 'b'), (0, 'c'), (1, 'c'), (1, 'b'), (2, 'b')]; + /// itertools::assert_equal(data.into_iter().dedup_by_with_count(|x, y| x.1 == y.1), + /// vec![(2, (0, 'a')), (1, (0, 'b')), (2, (0, 'c')), (2, (1, 'b'))]); + /// ``` + fn dedup_by_with_count<Cmp>(self, cmp: Cmp) -> DedupByWithCount<Self, Cmp> + where + Self: Sized, + Cmp: FnMut(&Self::Item, &Self::Item) -> bool, + { + adaptors::dedup_by_with_count(self, cmp) + } + + /// Return an iterator adaptor that produces elements that appear more than once during the + /// iteration. Duplicates are detected using hash and equality. + /// + /// The iterator is stable, returning the duplicate items in the order in which they occur in + /// the adapted iterator. Each duplicate item is returned exactly once. If an item appears more + /// than twice, the second item is the item retained and the rest are discarded. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let data = vec![10, 20, 30, 20, 40, 10, 50]; + /// itertools::assert_equal(data.into_iter().duplicates(), + /// vec![20, 10]); + /// ``` + #[cfg(feature = "use_std")] + fn duplicates(self) -> Duplicates<Self> + where Self: Sized, + Self::Item: Eq + Hash + { + duplicates_impl::duplicates(self) + } + + /// Return an iterator adaptor that produces elements that appear more than once during the + /// iteration. Duplicates are detected using hash and equality. + /// + /// Duplicates are detected by comparing the key they map to with the keying function `f` by + /// hash and equality. The keys are stored in a hash map in the iterator. + /// + /// The iterator is stable, returning the duplicate items in the order in which they occur in + /// the adapted iterator. Each duplicate item is returned exactly once. If an item appears more + /// than twice, the second item is the item retained and the rest are discarded. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let data = vec!["a", "bb", "aa", "c", "ccc"]; + /// itertools::assert_equal(data.into_iter().duplicates_by(|s| s.len()), + /// vec!["aa", "c"]); + /// ``` + #[cfg(feature = "use_std")] + fn duplicates_by<V, F>(self, f: F) -> DuplicatesBy<Self, V, F> + where Self: Sized, + V: Eq + Hash, + F: FnMut(&Self::Item) -> V + { + duplicates_impl::duplicates_by(self, f) + } + + /// Return an iterator adaptor that filters out elements that have + /// already been produced once during the iteration. Duplicates + /// are detected using hash and equality. + /// + /// Clones of visited elements are stored in a hash set in the + /// iterator. + /// + /// The iterator is stable, returning the non-duplicate items in the order + /// in which they occur in the adapted iterator. In a set of duplicate + /// items, the first item encountered is the item retained. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let data = vec![10, 20, 30, 20, 40, 10, 50]; + /// itertools::assert_equal(data.into_iter().unique(), + /// vec![10, 20, 30, 40, 50]); + /// ``` + #[cfg(feature = "use_std")] + fn unique(self) -> Unique<Self> + where Self: Sized, + Self::Item: Clone + Eq + Hash + { + unique_impl::unique(self) + } + + /// Return an iterator adaptor that filters out elements that have + /// already been produced once during the iteration. + /// + /// Duplicates are detected by comparing the key they map to + /// with the keying function `f` by hash and equality. + /// The keys are stored in a hash set in the iterator. + /// + /// The iterator is stable, returning the non-duplicate items in the order + /// in which they occur in the adapted iterator. In a set of duplicate + /// items, the first item encountered is the item retained. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let data = vec!["a", "bb", "aa", "c", "ccc"]; + /// itertools::assert_equal(data.into_iter().unique_by(|s| s.len()), + /// vec!["a", "bb", "ccc"]); + /// ``` + #[cfg(feature = "use_std")] + fn unique_by<V, F>(self, f: F) -> UniqueBy<Self, V, F> + where Self: Sized, + V: Eq + Hash, + F: FnMut(&Self::Item) -> V + { + unique_impl::unique_by(self, f) + } + + /// Return an iterator adaptor that borrows from this iterator and + /// takes items while the closure `accept` returns `true`. + /// + /// This adaptor can only be used on iterators that implement `PeekingNext` + /// like `.peekable()`, `put_back` and a few other collection iterators. + /// + /// The last and rejected element (first `false`) is still available when + /// `peeking_take_while` is done. + /// + /// + /// See also [`.take_while_ref()`](Itertools::take_while_ref) + /// which is a similar adaptor. + fn peeking_take_while<F>(&mut self, accept: F) -> PeekingTakeWhile<Self, F> + where Self: Sized + PeekingNext, + F: FnMut(&Self::Item) -> bool, + { + peeking_take_while::peeking_take_while(self, accept) + } + + /// Return an iterator adaptor that borrows from a `Clone`-able iterator + /// to only pick off elements while the predicate `accept` returns `true`. + /// + /// It uses the `Clone` trait to restore the original iterator so that the + /// last and rejected element (first `false`) is still available when + /// `take_while_ref` is done. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let mut hexadecimals = "0123456789abcdef".chars(); + /// + /// let decimals = hexadecimals.take_while_ref(|c| c.is_numeric()) + /// .collect::<String>(); + /// assert_eq!(decimals, "0123456789"); + /// assert_eq!(hexadecimals.next(), Some('a')); + /// + /// ``` + fn take_while_ref<F>(&mut self, accept: F) -> TakeWhileRef<Self, F> + where Self: Clone, + F: FnMut(&Self::Item) -> bool + { + adaptors::take_while_ref(self, accept) + } + + /// Return an iterator adaptor that filters `Option<A>` iterator elements + /// and produces `A`. Stops on the first `None` encountered. + /// + /// Iterator element type is `A`, the unwrapped element. + /// + /// ``` + /// use itertools::Itertools; + /// + /// // List all hexadecimal digits + /// itertools::assert_equal( + /// (0..).map(|i| std::char::from_digit(i, 16)).while_some(), + /// "0123456789abcdef".chars()); + /// + /// ``` + fn while_some<A>(self) -> WhileSome<Self> + where Self: Sized + Iterator<Item = Option<A>> + { + adaptors::while_some(self) + } + + /// Return an iterator adaptor that iterates over the combinations of the + /// elements from an iterator. + /// + /// Iterator element can be any homogeneous tuple of type `Self::Item` with + /// size up to 12. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let mut v = Vec::new(); + /// for (a, b) in (1..5).tuple_combinations() { + /// v.push((a, b)); + /// } + /// assert_eq!(v, vec![(1, 2), (1, 3), (1, 4), (2, 3), (2, 4), (3, 4)]); + /// + /// let mut it = (1..5).tuple_combinations(); + /// assert_eq!(Some((1, 2, 3)), it.next()); + /// assert_eq!(Some((1, 2, 4)), it.next()); + /// assert_eq!(Some((1, 3, 4)), it.next()); + /// assert_eq!(Some((2, 3, 4)), it.next()); + /// assert_eq!(None, it.next()); + /// + /// // this requires a type hint + /// let it = (1..5).tuple_combinations::<(_, _, _)>(); + /// itertools::assert_equal(it, vec![(1, 2, 3), (1, 2, 4), (1, 3, 4), (2, 3, 4)]); + /// + /// // you can also specify the complete type + /// use itertools::TupleCombinations; + /// use std::ops::Range; + /// + /// let it: TupleCombinations<Range<u32>, (u32, u32, u32)> = (1..5).tuple_combinations(); + /// itertools::assert_equal(it, vec![(1, 2, 3), (1, 2, 4), (1, 3, 4), (2, 3, 4)]); + /// ``` + fn tuple_combinations<T>(self) -> TupleCombinations<Self, T> + where Self: Sized + Clone, + Self::Item: Clone, + T: adaptors::HasCombination<Self>, + { + adaptors::tuple_combinations(self) + } + + /// Return an iterator adaptor that iterates over the `k`-length combinations of + /// the elements from an iterator. + /// + /// Iterator element type is `Vec<Self::Item>`. The iterator produces a new Vec per iteration, + /// and clones the iterator elements. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let it = (1..5).combinations(3); + /// itertools::assert_equal(it, vec![ + /// vec![1, 2, 3], + /// vec![1, 2, 4], + /// vec![1, 3, 4], + /// vec![2, 3, 4], + /// ]); + /// ``` + /// + /// Note: Combinations does not take into account the equality of the iterated values. + /// ``` + /// use itertools::Itertools; + /// + /// let it = vec![1, 2, 2].into_iter().combinations(2); + /// itertools::assert_equal(it, vec![ + /// vec![1, 2], // Note: these are the same + /// vec![1, 2], // Note: these are the same + /// vec![2, 2], + /// ]); + /// ``` + #[cfg(feature = "use_alloc")] + fn combinations(self, k: usize) -> Combinations<Self> + where Self: Sized, + Self::Item: Clone + { + combinations::combinations(self, k) + } + + /// Return an iterator that iterates over the `k`-length combinations of + /// the elements from an iterator, with replacement. + /// + /// Iterator element type is `Vec<Self::Item>`. The iterator produces a new Vec per iteration, + /// and clones the iterator elements. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let it = (1..4).combinations_with_replacement(2); + /// itertools::assert_equal(it, vec![ + /// vec![1, 1], + /// vec![1, 2], + /// vec![1, 3], + /// vec![2, 2], + /// vec![2, 3], + /// vec![3, 3], + /// ]); + /// ``` + #[cfg(feature = "use_alloc")] + fn combinations_with_replacement(self, k: usize) -> CombinationsWithReplacement<Self> + where + Self: Sized, + Self::Item: Clone, + { + combinations_with_replacement::combinations_with_replacement(self, k) + } + + /// Return an iterator adaptor that iterates over all k-permutations of the + /// elements from an iterator. + /// + /// Iterator element type is `Vec<Self::Item>` with length `k`. The iterator + /// produces a new Vec per iteration, and clones the iterator elements. + /// + /// If `k` is greater than the length of the input iterator, the resultant + /// iterator adaptor will be empty. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let perms = (5..8).permutations(2); + /// itertools::assert_equal(perms, vec![ + /// vec![5, 6], + /// vec![5, 7], + /// vec![6, 5], + /// vec![6, 7], + /// vec![7, 5], + /// vec![7, 6], + /// ]); + /// ``` + /// + /// Note: Permutations does not take into account the equality of the iterated values. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let it = vec![2, 2].into_iter().permutations(2); + /// itertools::assert_equal(it, vec![ + /// vec![2, 2], // Note: these are the same + /// vec![2, 2], // Note: these are the same + /// ]); + /// ``` + /// + /// Note: The source iterator is collected lazily, and will not be + /// re-iterated if the permutations adaptor is completed and re-iterated. + #[cfg(feature = "use_alloc")] + fn permutations(self, k: usize) -> Permutations<Self> + where Self: Sized, + Self::Item: Clone + { + permutations::permutations(self, k) + } + + /// Return an iterator that iterates through the powerset of the elements from an + /// iterator. + /// + /// Iterator element type is `Vec<Self::Item>`. The iterator produces a new `Vec` + /// per iteration, and clones the iterator elements. + /// + /// The powerset of a set contains all subsets including the empty set and the full + /// input set. A powerset has length _2^n_ where _n_ is the length of the input + /// set. + /// + /// Each `Vec` produced by this iterator represents a subset of the elements + /// produced by the source iterator. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let sets = (1..4).powerset().collect::<Vec<_>>(); + /// itertools::assert_equal(sets, vec![ + /// vec![], + /// vec![1], + /// vec![2], + /// vec![3], + /// vec![1, 2], + /// vec![1, 3], + /// vec![2, 3], + /// vec![1, 2, 3], + /// ]); + /// ``` + #[cfg(feature = "use_alloc")] + fn powerset(self) -> Powerset<Self> + where Self: Sized, + Self::Item: Clone, + { + powerset::powerset(self) + } + + /// Return an iterator adaptor that pads the sequence to a minimum length of + /// `min` by filling missing elements using a closure `f`. + /// + /// Iterator element type is `Self::Item`. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let it = (0..5).pad_using(10, |i| 2*i); + /// itertools::assert_equal(it, vec![0, 1, 2, 3, 4, 10, 12, 14, 16, 18]); + /// + /// let it = (0..10).pad_using(5, |i| 2*i); + /// itertools::assert_equal(it, vec![0, 1, 2, 3, 4, 5, 6, 7, 8, 9]); + /// + /// let it = (0..5).pad_using(10, |i| 2*i).rev(); + /// itertools::assert_equal(it, vec![18, 16, 14, 12, 10, 4, 3, 2, 1, 0]); + /// ``` + fn pad_using<F>(self, min: usize, f: F) -> PadUsing<Self, F> + where Self: Sized, + F: FnMut(usize) -> Self::Item + { + pad_tail::pad_using(self, min, f) + } + + /// Return an iterator adaptor that wraps each element in a `Position` to + /// ease special-case handling of the first or last elements. + /// + /// Iterator element type is + /// [`Position<Self::Item>`](Position) + /// + /// ``` + /// use itertools::{Itertools, Position}; + /// + /// let it = (0..4).with_position(); + /// itertools::assert_equal(it, + /// vec![Position::First(0), + /// Position::Middle(1), + /// Position::Middle(2), + /// Position::Last(3)]); + /// + /// let it = (0..1).with_position(); + /// itertools::assert_equal(it, vec![Position::Only(0)]); + /// ``` + fn with_position(self) -> WithPosition<Self> + where Self: Sized, + { + with_position::with_position(self) + } + + /// Return an iterator adaptor that yields the indices of all elements + /// satisfying a predicate, counted from the start of the iterator. + /// + /// Equivalent to `iter.enumerate().filter(|(_, v)| predicate(v)).map(|(i, _)| i)`. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let data = vec![1, 2, 3, 3, 4, 6, 7, 9]; + /// itertools::assert_equal(data.iter().positions(|v| v % 2 == 0), vec![1, 4, 5]); + /// + /// itertools::assert_equal(data.iter().positions(|v| v % 2 == 1).rev(), vec![7, 6, 3, 2, 0]); + /// ``` + fn positions<P>(self, predicate: P) -> Positions<Self, P> + where Self: Sized, + P: FnMut(Self::Item) -> bool, + { + adaptors::positions(self, predicate) + } + + /// Return an iterator adaptor that applies a mutating function + /// to each element before yielding it. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let input = vec![vec![1], vec![3, 2, 1]]; + /// let it = input.into_iter().update(|mut v| v.push(0)); + /// itertools::assert_equal(it, vec![vec![1, 0], vec![3, 2, 1, 0]]); + /// ``` + fn update<F>(self, updater: F) -> Update<Self, F> + where Self: Sized, + F: FnMut(&mut Self::Item), + { + adaptors::update(self, updater) + } + + // non-adaptor methods + /// Advances the iterator and returns the next items grouped in a tuple of + /// a specific size (up to 12). + /// + /// If there are enough elements to be grouped in a tuple, then the tuple is + /// returned inside `Some`, otherwise `None` is returned. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let mut iter = 1..5; + /// + /// assert_eq!(Some((1, 2)), iter.next_tuple()); + /// ``` + fn next_tuple<T>(&mut self) -> Option<T> + where Self: Sized + Iterator<Item = T::Item>, + T: traits::HomogeneousTuple + { + T::collect_from_iter_no_buf(self) + } + + /// Collects all items from the iterator into a tuple of a specific size + /// (up to 12). + /// + /// If the number of elements inside the iterator is **exactly** equal to + /// the tuple size, then the tuple is returned inside `Some`, otherwise + /// `None` is returned. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let iter = 1..3; + /// + /// if let Some((x, y)) = iter.collect_tuple() { + /// assert_eq!((x, y), (1, 2)) + /// } else { + /// panic!("Expected two elements") + /// } + /// ``` + fn collect_tuple<T>(mut self) -> Option<T> + where Self: Sized + Iterator<Item = T::Item>, + T: traits::HomogeneousTuple + { + match self.next_tuple() { + elt @ Some(_) => match self.next() { + Some(_) => None, + None => elt, + }, + _ => None + } + } + + + /// Find the position and value of the first element satisfying a predicate. + /// + /// The iterator is not advanced past the first element found. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let text = "Hα"; + /// assert_eq!(text.chars().find_position(|ch| ch.is_lowercase()), Some((1, 'α'))); + /// ``` + fn find_position<P>(&mut self, mut pred: P) -> Option<(usize, Self::Item)> + where P: FnMut(&Self::Item) -> bool + { + for (index, elt) in self.enumerate() { + if pred(&elt) { + return Some((index, elt)); + } + } + None + } + /// Find the value of the first element satisfying a predicate or return the last element, if any. + /// + /// The iterator is not advanced past the first element found. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let numbers = [1, 2, 3, 4]; + /// assert_eq!(numbers.iter().find_or_last(|&&x| x > 5), Some(&4)); + /// assert_eq!(numbers.iter().find_or_last(|&&x| x > 2), Some(&3)); + /// assert_eq!(std::iter::empty::<i32>().find_or_last(|&x| x > 5), None); + /// ``` + fn find_or_last<P>(mut self, mut predicate: P) -> Option<Self::Item> + where Self: Sized, + P: FnMut(&Self::Item) -> bool, + { + let mut prev = None; + self.find_map(|x| if predicate(&x) { Some(x) } else { prev = Some(x); None }) + .or(prev) + } + /// Find the value of the first element satisfying a predicate or return the first element, if any. + /// + /// The iterator is not advanced past the first element found. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let numbers = [1, 2, 3, 4]; + /// assert_eq!(numbers.iter().find_or_first(|&&x| x > 5), Some(&1)); + /// assert_eq!(numbers.iter().find_or_first(|&&x| x > 2), Some(&3)); + /// assert_eq!(std::iter::empty::<i32>().find_or_first(|&x| x > 5), None); + /// ``` + fn find_or_first<P>(mut self, mut predicate: P) -> Option<Self::Item> + where Self: Sized, + P: FnMut(&Self::Item) -> bool, + { + let first = self.next()?; + Some(if predicate(&first) { + first + } else { + self.find(|x| predicate(x)).unwrap_or(first) + }) + } + /// Returns `true` if the given item is present in this iterator. + /// + /// This method is short-circuiting. If the given item is present in this + /// iterator, this method will consume the iterator up-to-and-including + /// the item. If the given item is not present in this iterator, the + /// iterator will be exhausted. + /// + /// ``` + /// use itertools::Itertools; + /// + /// #[derive(PartialEq, Debug)] + /// enum Enum { A, B, C, D, E, } + /// + /// let mut iter = vec![Enum::A, Enum::B, Enum::C, Enum::D].into_iter(); + /// + /// // search `iter` for `B` + /// assert_eq!(iter.contains(&Enum::B), true); + /// // `B` was found, so the iterator now rests at the item after `B` (i.e, `C`). + /// assert_eq!(iter.next(), Some(Enum::C)); + /// + /// // search `iter` for `E` + /// assert_eq!(iter.contains(&Enum::E), false); + /// // `E` wasn't found, so `iter` is now exhausted + /// assert_eq!(iter.next(), None); + /// ``` + fn contains<Q>(&mut self, query: &Q) -> bool + where + Self: Sized, + Self::Item: Borrow<Q>, + Q: PartialEq, + { + self.any(|x| x.borrow() == query) + } + + /// Check whether all elements compare equal. + /// + /// Empty iterators are considered to have equal elements: + /// + /// ``` + /// use itertools::Itertools; + /// + /// let data = vec![1, 1, 1, 2, 2, 3, 3, 3, 4, 5, 5]; + /// assert!(!data.iter().all_equal()); + /// assert!(data[0..3].iter().all_equal()); + /// assert!(data[3..5].iter().all_equal()); + /// assert!(data[5..8].iter().all_equal()); + /// + /// let data : Option<usize> = None; + /// assert!(data.into_iter().all_equal()); + /// ``` + fn all_equal(&mut self) -> bool + where Self: Sized, + Self::Item: PartialEq, + { + match self.next() { + None => true, + Some(a) => self.all(|x| a == x), + } + } + + /// Check whether all elements are unique (non equal). + /// + /// Empty iterators are considered to have unique elements: + /// + /// ``` + /// use itertools::Itertools; + /// + /// let data = vec![1, 2, 3, 4, 1, 5]; + /// assert!(!data.iter().all_unique()); + /// assert!(data[0..4].iter().all_unique()); + /// assert!(data[1..6].iter().all_unique()); + /// + /// let data : Option<usize> = None; + /// assert!(data.into_iter().all_unique()); + /// ``` + #[cfg(feature = "use_std")] + fn all_unique(&mut self) -> bool + where Self: Sized, + Self::Item: Eq + Hash + { + let mut used = HashSet::new(); + self.all(move |elt| used.insert(elt)) + } + + /// Consume the first `n` elements from the iterator eagerly, + /// and return the same iterator again. + /// + /// It works similarly to *.skip(* `n` *)* except it is eager and + /// preserves the iterator type. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let mut iter = "αβγ".chars().dropping(2); + /// itertools::assert_equal(iter, "γ".chars()); + /// ``` + /// + /// *Fusing notes: if the iterator is exhausted by dropping, + /// the result of calling `.next()` again depends on the iterator implementation.* + fn dropping(mut self, n: usize) -> Self + where Self: Sized + { + if n > 0 { + self.nth(n - 1); + } + self + } + + /// Consume the last `n` elements from the iterator eagerly, + /// and return the same iterator again. + /// + /// This is only possible on double ended iterators. `n` may be + /// larger than the number of elements. + /// + /// Note: This method is eager, dropping the back elements immediately and + /// preserves the iterator type. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let init = vec![0, 3, 6, 9].into_iter().dropping_back(1); + /// itertools::assert_equal(init, vec![0, 3, 6]); + /// ``` + fn dropping_back(mut self, n: usize) -> Self + where Self: Sized, + Self: DoubleEndedIterator + { + if n > 0 { + (&mut self).rev().nth(n - 1); + } + self + } + + /// Run the closure `f` eagerly on each element of the iterator. + /// + /// Consumes the iterator until its end. + /// + /// ``` + /// use std::sync::mpsc::channel; + /// use itertools::Itertools; + /// + /// let (tx, rx) = channel(); + /// + /// // use .foreach() to apply a function to each value -- sending it + /// (0..5).map(|x| x * 2 + 1).foreach(|x| { tx.send(x).unwrap(); } ); + /// + /// drop(tx); + /// + /// itertools::assert_equal(rx.iter(), vec![1, 3, 5, 7, 9]); + /// ``` + #[deprecated(note="Use .for_each() instead", since="0.8.0")] + fn foreach<F>(self, f: F) + where F: FnMut(Self::Item), + Self: Sized, + { + self.for_each(f); + } + + /// Combine all an iterator's elements into one element by using [`Extend`]. + /// + /// This combinator will extend the first item with each of the rest of the + /// items of the iterator. If the iterator is empty, the default value of + /// `I::Item` is returned. + /// + /// ```rust + /// use itertools::Itertools; + /// + /// let input = vec![vec![1], vec![2, 3], vec![4, 5, 6]]; + /// assert_eq!(input.into_iter().concat(), + /// vec![1, 2, 3, 4, 5, 6]); + /// ``` + fn concat(self) -> Self::Item + where Self: Sized, + Self::Item: Extend<<<Self as Iterator>::Item as IntoIterator>::Item> + IntoIterator + Default + { + concat(self) + } + + /// `.collect_vec()` is simply a type specialization of [`Iterator::collect`], + /// for convenience. + #[cfg(feature = "use_alloc")] + fn collect_vec(self) -> Vec<Self::Item> + where Self: Sized + { + self.collect() + } + + /// `.try_collect()` is more convenient way of writing + /// `.collect::<Result<_, _>>()` + /// + /// # Example + /// + /// ``` + /// use std::{fs, io}; + /// use itertools::Itertools; + /// + /// fn process_dir_entries(entries: &[fs::DirEntry]) { + /// // ... + /// } + /// + /// fn do_stuff() -> std::io::Result<()> { + /// let entries: Vec<_> = fs::read_dir(".")?.try_collect()?; + /// process_dir_entries(&entries); + /// + /// Ok(()) + /// } + /// ``` + #[cfg(feature = "use_alloc")] + fn try_collect<T, U, E>(self) -> Result<U, E> + where + Self: Sized + Iterator<Item = Result<T, E>>, + Result<U, E>: FromIterator<Result<T, E>>, + { + self.collect() + } + + /// Assign to each reference in `self` from the `from` iterator, + /// stopping at the shortest of the two iterators. + /// + /// The `from` iterator is queried for its next element before the `self` + /// iterator, and if either is exhausted the method is done. + /// + /// Return the number of elements written. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let mut xs = [0; 4]; + /// xs.iter_mut().set_from(1..); + /// assert_eq!(xs, [1, 2, 3, 4]); + /// ``` + #[inline] + fn set_from<'a, A: 'a, J>(&mut self, from: J) -> usize + where Self: Iterator<Item = &'a mut A>, + J: IntoIterator<Item = A> + { + let mut count = 0; + for elt in from { + match self.next() { + None => break, + Some(ptr) => *ptr = elt, + } + count += 1; + } + count + } + + /// Combine all iterator elements into one String, separated by `sep`. + /// + /// Use the `Display` implementation of each element. + /// + /// ``` + /// use itertools::Itertools; + /// + /// assert_eq!(["a", "b", "c"].iter().join(", "), "a, b, c"); + /// assert_eq!([1, 2, 3].iter().join(", "), "1, 2, 3"); + /// ``` + #[cfg(feature = "use_alloc")] + fn join(&mut self, sep: &str) -> String + where Self::Item: std::fmt::Display + { + match self.next() { + None => String::new(), + Some(first_elt) => { + // estimate lower bound of capacity needed + let (lower, _) = self.size_hint(); + let mut result = String::with_capacity(sep.len() * lower); + write!(&mut result, "{}", first_elt).unwrap(); + self.for_each(|elt| { + result.push_str(sep); + write!(&mut result, "{}", elt).unwrap(); + }); + result + } + } + } + + /// Format all iterator elements, separated by `sep`. + /// + /// All elements are formatted (any formatting trait) + /// with `sep` inserted between each element. + /// + /// **Panics** if the formatter helper is formatted more than once. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let data = [1.1, 2.71828, -3.]; + /// assert_eq!( + /// format!("{:.2}", data.iter().format(", ")), + /// "1.10, 2.72, -3.00"); + /// ``` + fn format(self, sep: &str) -> Format<Self> + where Self: Sized, + { + format::new_format_default(self, sep) + } + + /// Format all iterator elements, separated by `sep`. + /// + /// This is a customizable version of [`.format()`](Itertools::format). + /// + /// The supplied closure `format` is called once per iterator element, + /// with two arguments: the element and a callback that takes a + /// `&Display` value, i.e. any reference to type that implements `Display`. + /// + /// Using `&format_args!(...)` is the most versatile way to apply custom + /// element formatting. The callback can be called multiple times if needed. + /// + /// **Panics** if the formatter helper is formatted more than once. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let data = [1.1, 2.71828, -3.]; + /// let data_formatter = data.iter().format_with(", ", |elt, f| f(&format_args!("{:.2}", elt))); + /// assert_eq!(format!("{}", data_formatter), + /// "1.10, 2.72, -3.00"); + /// + /// // .format_with() is recursively composable + /// let matrix = [[1., 2., 3.], + /// [4., 5., 6.]]; + /// let matrix_formatter = matrix.iter().format_with("\n", |row, f| { + /// f(&row.iter().format_with(", ", |elt, g| g(&elt))) + /// }); + /// assert_eq!(format!("{}", matrix_formatter), + /// "1, 2, 3\n4, 5, 6"); + /// + /// + /// ``` + fn format_with<F>(self, sep: &str, format: F) -> FormatWith<Self, F> + where Self: Sized, + F: FnMut(Self::Item, &mut dyn FnMut(&dyn fmt::Display) -> fmt::Result) -> fmt::Result, + { + format::new_format(self, sep, format) + } + + /// See [`.fold_ok()`](Itertools::fold_ok). + #[deprecated(note="Use .fold_ok() instead", since="0.10.0")] + fn fold_results<A, E, B, F>(&mut self, start: B, f: F) -> Result<B, E> + where Self: Iterator<Item = Result<A, E>>, + F: FnMut(B, A) -> B + { + self.fold_ok(start, f) + } + + /// Fold `Result` values from an iterator. + /// + /// Only `Ok` values are folded. If no error is encountered, the folded + /// value is returned inside `Ok`. Otherwise, the operation terminates + /// and returns the first `Err` value it encounters. No iterator elements are + /// consumed after the first error. + /// + /// The first accumulator value is the `start` parameter. + /// Each iteration passes the accumulator value and the next value inside `Ok` + /// to the fold function `f` and its return value becomes the new accumulator value. + /// + /// For example the sequence *Ok(1), Ok(2), Ok(3)* will result in a + /// computation like this: + /// + /// ```ignore + /// let mut accum = start; + /// accum = f(accum, 1); + /// accum = f(accum, 2); + /// accum = f(accum, 3); + /// ``` + /// + /// With a `start` value of 0 and an addition as folding function, + /// this effectively results in *((0 + 1) + 2) + 3* + /// + /// ``` + /// use std::ops::Add; + /// use itertools::Itertools; + /// + /// let values = [1, 2, -2, -1, 2, 1]; + /// assert_eq!( + /// values.iter() + /// .map(Ok::<_, ()>) + /// .fold_ok(0, Add::add), + /// Ok(3) + /// ); + /// assert!( + /// values.iter() + /// .map(|&x| if x >= 0 { Ok(x) } else { Err("Negative number") }) + /// .fold_ok(0, Add::add) + /// .is_err() + /// ); + /// ``` + fn fold_ok<A, E, B, F>(&mut self, mut start: B, mut f: F) -> Result<B, E> + where Self: Iterator<Item = Result<A, E>>, + F: FnMut(B, A) -> B + { + for elt in self { + match elt { + Ok(v) => start = f(start, v), + Err(u) => return Err(u), + } + } + Ok(start) + } + + /// Fold `Option` values from an iterator. + /// + /// Only `Some` values are folded. If no `None` is encountered, the folded + /// value is returned inside `Some`. Otherwise, the operation terminates + /// and returns `None`. No iterator elements are consumed after the `None`. + /// + /// This is the `Option` equivalent to [`fold_ok`](Itertools::fold_ok). + /// + /// ``` + /// use std::ops::Add; + /// use itertools::Itertools; + /// + /// let mut values = vec![Some(1), Some(2), Some(-2)].into_iter(); + /// assert_eq!(values.fold_options(5, Add::add), Some(5 + 1 + 2 - 2)); + /// + /// let mut more_values = vec![Some(2), None, Some(0)].into_iter(); + /// assert!(more_values.fold_options(0, Add::add).is_none()); + /// assert_eq!(more_values.next().unwrap(), Some(0)); + /// ``` + fn fold_options<A, B, F>(&mut self, mut start: B, mut f: F) -> Option<B> + where Self: Iterator<Item = Option<A>>, + F: FnMut(B, A) -> B + { + for elt in self { + match elt { + Some(v) => start = f(start, v), + None => return None, + } + } + Some(start) + } + + /// Accumulator of the elements in the iterator. + /// + /// Like `.fold()`, without a base case. If the iterator is + /// empty, return `None`. With just one element, return it. + /// Otherwise elements are accumulated in sequence using the closure `f`. + /// + /// ``` + /// use itertools::Itertools; + /// + /// assert_eq!((0..10).fold1(|x, y| x + y).unwrap_or(0), 45); + /// assert_eq!((0..0).fold1(|x, y| x * y), None); + /// ``` + #[deprecated(since = "0.10.2", note = "Use `Iterator::reduce` instead")] + fn fold1<F>(mut self, f: F) -> Option<Self::Item> + where F: FnMut(Self::Item, Self::Item) -> Self::Item, + Self: Sized, + { + self.next().map(move |x| self.fold(x, f)) + } + + /// Accumulate the elements in the iterator in a tree-like manner. + /// + /// You can think of it as, while there's more than one item, repeatedly + /// combining adjacent items. It does so in bottom-up-merge-sort order, + /// however, so that it needs only logarithmic stack space. + /// + /// This produces a call tree like the following (where the calls under + /// an item are done after reading that item): + /// + /// ```text + /// 1 2 3 4 5 6 7 + /// │ │ │ │ │ │ │ + /// └─f └─f └─f │ + /// │ │ │ │ + /// └───f └─f + /// │ │ + /// └─────f + /// ``` + /// + /// Which, for non-associative functions, will typically produce a different + /// result than the linear call tree used by [`Iterator::reduce`]: + /// + /// ```text + /// 1 2 3 4 5 6 7 + /// │ │ │ │ │ │ │ + /// └─f─f─f─f─f─f + /// ``` + /// + /// If `f` is associative, prefer the normal [`Iterator::reduce`] instead. + /// + /// ``` + /// use itertools::Itertools; + /// + /// // The same tree as above + /// let num_strings = (1..8).map(|x| x.to_string()); + /// assert_eq!(num_strings.tree_fold1(|x, y| format!("f({}, {})", x, y)), + /// Some(String::from("f(f(f(1, 2), f(3, 4)), f(f(5, 6), 7))"))); + /// + /// // Like fold1, an empty iterator produces None + /// assert_eq!((0..0).tree_fold1(|x, y| x * y), None); + /// + /// // tree_fold1 matches fold1 for associative operations... + /// assert_eq!((0..10).tree_fold1(|x, y| x + y), + /// (0..10).fold1(|x, y| x + y)); + /// // ...but not for non-associative ones + /// assert_ne!((0..10).tree_fold1(|x, y| x - y), + /// (0..10).fold1(|x, y| x - y)); + /// ``` + fn tree_fold1<F>(mut self, mut f: F) -> Option<Self::Item> + where F: FnMut(Self::Item, Self::Item) -> Self::Item, + Self: Sized, + { + type State<T> = Result<T, Option<T>>; + + fn inner0<T, II, FF>(it: &mut II, f: &mut FF) -> State<T> + where + II: Iterator<Item = T>, + FF: FnMut(T, T) -> T + { + // This function could be replaced with `it.next().ok_or(None)`, + // but half the useful tree_fold1 work is combining adjacent items, + // so put that in a form that LLVM is more likely to optimize well. + + let a = + if let Some(v) = it.next() { v } + else { return Err(None) }; + let b = + if let Some(v) = it.next() { v } + else { return Err(Some(a)) }; + Ok(f(a, b)) + } + + fn inner<T, II, FF>(stop: usize, it: &mut II, f: &mut FF) -> State<T> + where + II: Iterator<Item = T>, + FF: FnMut(T, T) -> T + { + let mut x = inner0(it, f)?; + for height in 0..stop { + // Try to get another tree the same size with which to combine it, + // creating a new tree that's twice as big for next time around. + let next = + if height == 0 { + inner0(it, f) + } else { + inner(height, it, f) + }; + match next { + Ok(y) => x = f(x, y), + + // If we ran out of items, combine whatever we did manage + // to get. It's better combined with the current value + // than something in a parent frame, because the tree in + // the parent is always as least as big as this one. + Err(None) => return Err(Some(x)), + Err(Some(y)) => return Err(Some(f(x, y))), + } + } + Ok(x) + } + + match inner(usize::max_value(), &mut self, &mut f) { + Err(x) => x, + _ => unreachable!(), + } + } + + /// An iterator method that applies a function, producing a single, final value. + /// + /// `fold_while()` is basically equivalent to [`Iterator::fold`] but with additional support for + /// early exit via short-circuiting. + /// + /// ``` + /// use itertools::Itertools; + /// use itertools::FoldWhile::{Continue, Done}; + /// + /// let numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; + /// + /// let mut result = 0; + /// + /// // for loop: + /// for i in &numbers { + /// if *i > 5 { + /// break; + /// } + /// result = result + i; + /// } + /// + /// // fold: + /// let result2 = numbers.iter().fold(0, |acc, x| { + /// if *x > 5 { acc } else { acc + x } + /// }); + /// + /// // fold_while: + /// let result3 = numbers.iter().fold_while(0, |acc, x| { + /// if *x > 5 { Done(acc) } else { Continue(acc + x) } + /// }).into_inner(); + /// + /// // they're the same + /// assert_eq!(result, result2); + /// assert_eq!(result2, result3); + /// ``` + /// + /// The big difference between the computations of `result2` and `result3` is that while + /// `fold()` called the provided closure for every item of the callee iterator, + /// `fold_while()` actually stopped iterating as soon as it encountered `Fold::Done(_)`. + fn fold_while<B, F>(&mut self, init: B, mut f: F) -> FoldWhile<B> + where Self: Sized, + F: FnMut(B, Self::Item) -> FoldWhile<B> + { + use Result::{ + Ok as Continue, + Err as Break, + }; + + let result = self.try_fold(init, #[inline(always)] |acc, v| + match f(acc, v) { + FoldWhile::Continue(acc) => Continue(acc), + FoldWhile::Done(acc) => Break(acc), + } + ); + + match result { + Continue(acc) => FoldWhile::Continue(acc), + Break(acc) => FoldWhile::Done(acc), + } + } + + /// Iterate over the entire iterator and add all the elements. + /// + /// An empty iterator returns `None`, otherwise `Some(sum)`. + /// + /// # Panics + /// + /// When calling `sum1()` and a primitive integer type is being returned, this + /// method will panic if the computation overflows and debug assertions are + /// enabled. + /// + /// # Examples + /// + /// ``` + /// use itertools::Itertools; + /// + /// let empty_sum = (1..1).sum1::<i32>(); + /// assert_eq!(empty_sum, None); + /// + /// let nonempty_sum = (1..11).sum1::<i32>(); + /// assert_eq!(nonempty_sum, Some(55)); + /// ``` + fn sum1<S>(mut self) -> Option<S> + where Self: Sized, + S: std::iter::Sum<Self::Item>, + { + self.next() + .map(|first| once(first).chain(self).sum()) + } + + /// Iterate over the entire iterator and multiply all the elements. + /// + /// An empty iterator returns `None`, otherwise `Some(product)`. + /// + /// # Panics + /// + /// When calling `product1()` and a primitive integer type is being returned, + /// method will panic if the computation overflows and debug assertions are + /// enabled. + /// + /// # Examples + /// ``` + /// use itertools::Itertools; + /// + /// let empty_product = (1..1).product1::<i32>(); + /// assert_eq!(empty_product, None); + /// + /// let nonempty_product = (1..11).product1::<i32>(); + /// assert_eq!(nonempty_product, Some(3628800)); + /// ``` + fn product1<P>(mut self) -> Option<P> + where Self: Sized, + P: std::iter::Product<Self::Item>, + { + self.next() + .map(|first| once(first).chain(self).product()) + } + + /// Sort all iterator elements into a new iterator in ascending order. + /// + /// **Note:** This consumes the entire iterator, uses the + /// [`slice::sort_unstable`] method and returns the result as a new + /// iterator that owns its elements. + /// + /// The sorted iterator, if directly collected to a `Vec`, is converted + /// without any extra copying or allocation cost. + /// + /// ``` + /// use itertools::Itertools; + /// + /// // sort the letters of the text in ascending order + /// let text = "bdacfe"; + /// itertools::assert_equal(text.chars().sorted_unstable(), + /// "abcdef".chars()); + /// ``` + #[cfg(feature = "use_alloc")] + fn sorted_unstable(self) -> VecIntoIter<Self::Item> + where Self: Sized, + Self::Item: Ord + { + // Use .sort_unstable() directly since it is not quite identical with + // .sort_by(Ord::cmp) + let mut v = Vec::from_iter(self); + v.sort_unstable(); + v.into_iter() + } + + /// Sort all iterator elements into a new iterator in ascending order. + /// + /// **Note:** This consumes the entire iterator, uses the + /// [`slice::sort_unstable_by`] method and returns the result as a new + /// iterator that owns its elements. + /// + /// The sorted iterator, if directly collected to a `Vec`, is converted + /// without any extra copying or allocation cost. + /// + /// ``` + /// use itertools::Itertools; + /// + /// // sort people in descending order by age + /// let people = vec![("Jane", 20), ("John", 18), ("Jill", 30), ("Jack", 27)]; + /// + /// let oldest_people_first = people + /// .into_iter() + /// .sorted_unstable_by(|a, b| Ord::cmp(&b.1, &a.1)) + /// .map(|(person, _age)| person); + /// + /// itertools::assert_equal(oldest_people_first, + /// vec!["Jill", "Jack", "Jane", "John"]); + /// ``` + #[cfg(feature = "use_alloc")] + fn sorted_unstable_by<F>(self, cmp: F) -> VecIntoIter<Self::Item> + where Self: Sized, + F: FnMut(&Self::Item, &Self::Item) -> Ordering, + { + let mut v = Vec::from_iter(self); + v.sort_unstable_by(cmp); + v.into_iter() + } + + /// Sort all iterator elements into a new iterator in ascending order. + /// + /// **Note:** This consumes the entire iterator, uses the + /// [`slice::sort_unstable_by_key`] method and returns the result as a new + /// iterator that owns its elements. + /// + /// The sorted iterator, if directly collected to a `Vec`, is converted + /// without any extra copying or allocation cost. + /// + /// ``` + /// use itertools::Itertools; + /// + /// // sort people in descending order by age + /// let people = vec![("Jane", 20), ("John", 18), ("Jill", 30), ("Jack", 27)]; + /// + /// let oldest_people_first = people + /// .into_iter() + /// .sorted_unstable_by_key(|x| -x.1) + /// .map(|(person, _age)| person); + /// + /// itertools::assert_equal(oldest_people_first, + /// vec!["Jill", "Jack", "Jane", "John"]); + /// ``` + #[cfg(feature = "use_alloc")] + fn sorted_unstable_by_key<K, F>(self, f: F) -> VecIntoIter<Self::Item> + where Self: Sized, + K: Ord, + F: FnMut(&Self::Item) -> K, + { + let mut v = Vec::from_iter(self); + v.sort_unstable_by_key(f); + v.into_iter() + } + + /// Sort all iterator elements into a new iterator in ascending order. + /// + /// **Note:** This consumes the entire iterator, uses the + /// [`slice::sort`] method and returns the result as a new + /// iterator that owns its elements. + /// + /// The sorted iterator, if directly collected to a `Vec`, is converted + /// without any extra copying or allocation cost. + /// + /// ``` + /// use itertools::Itertools; + /// + /// // sort the letters of the text in ascending order + /// let text = "bdacfe"; + /// itertools::assert_equal(text.chars().sorted(), + /// "abcdef".chars()); + /// ``` + #[cfg(feature = "use_alloc")] + fn sorted(self) -> VecIntoIter<Self::Item> + where Self: Sized, + Self::Item: Ord + { + // Use .sort() directly since it is not quite identical with + // .sort_by(Ord::cmp) + let mut v = Vec::from_iter(self); + v.sort(); + v.into_iter() + } + + /// Sort all iterator elements into a new iterator in ascending order. + /// + /// **Note:** This consumes the entire iterator, uses the + /// [`slice::sort_by`] method and returns the result as a new + /// iterator that owns its elements. + /// + /// The sorted iterator, if directly collected to a `Vec`, is converted + /// without any extra copying or allocation cost. + /// + /// ``` + /// use itertools::Itertools; + /// + /// // sort people in descending order by age + /// let people = vec![("Jane", 20), ("John", 18), ("Jill", 30), ("Jack", 27)]; + /// + /// let oldest_people_first = people + /// .into_iter() + /// .sorted_by(|a, b| Ord::cmp(&b.1, &a.1)) + /// .map(|(person, _age)| person); + /// + /// itertools::assert_equal(oldest_people_first, + /// vec!["Jill", "Jack", "Jane", "John"]); + /// ``` + #[cfg(feature = "use_alloc")] + fn sorted_by<F>(self, cmp: F) -> VecIntoIter<Self::Item> + where Self: Sized, + F: FnMut(&Self::Item, &Self::Item) -> Ordering, + { + let mut v = Vec::from_iter(self); + v.sort_by(cmp); + v.into_iter() + } + + /// Sort all iterator elements into a new iterator in ascending order. + /// + /// **Note:** This consumes the entire iterator, uses the + /// [`slice::sort_by_key`] method and returns the result as a new + /// iterator that owns its elements. + /// + /// The sorted iterator, if directly collected to a `Vec`, is converted + /// without any extra copying or allocation cost. + /// + /// ``` + /// use itertools::Itertools; + /// + /// // sort people in descending order by age + /// let people = vec![("Jane", 20), ("John", 18), ("Jill", 30), ("Jack", 27)]; + /// + /// let oldest_people_first = people + /// .into_iter() + /// .sorted_by_key(|x| -x.1) + /// .map(|(person, _age)| person); + /// + /// itertools::assert_equal(oldest_people_first, + /// vec!["Jill", "Jack", "Jane", "John"]); + /// ``` + #[cfg(feature = "use_alloc")] + fn sorted_by_key<K, F>(self, f: F) -> VecIntoIter<Self::Item> + where Self: Sized, + K: Ord, + F: FnMut(&Self::Item) -> K, + { + let mut v = Vec::from_iter(self); + v.sort_by_key(f); + v.into_iter() + } + + /// Sort all iterator elements into a new iterator in ascending order. The key function is + /// called exactly once per key. + /// + /// **Note:** This consumes the entire iterator, uses the + /// [`slice::sort_by_cached_key`] method and returns the result as a new + /// iterator that owns its elements. + /// + /// The sorted iterator, if directly collected to a `Vec`, is converted + /// without any extra copying or allocation cost. + /// + /// ``` + /// use itertools::Itertools; + /// + /// // sort people in descending order by age + /// let people = vec![("Jane", 20), ("John", 18), ("Jill", 30), ("Jack", 27)]; + /// + /// let oldest_people_first = people + /// .into_iter() + /// .sorted_by_cached_key(|x| -x.1) + /// .map(|(person, _age)| person); + /// + /// itertools::assert_equal(oldest_people_first, + /// vec!["Jill", "Jack", "Jane", "John"]); + /// ``` + #[cfg(feature = "use_alloc")] + fn sorted_by_cached_key<K, F>(self, f: F) -> VecIntoIter<Self::Item> + where + Self: Sized, + K: Ord, + F: FnMut(&Self::Item) -> K, + { + let mut v = Vec::from_iter(self); + v.sort_by_cached_key(f); + v.into_iter() + } + + /// Sort the k smallest elements into a new iterator, in ascending order. + /// + /// **Note:** This consumes the entire iterator, and returns the result + /// as a new iterator that owns its elements. If the input contains + /// less than k elements, the result is equivalent to `self.sorted()`. + /// + /// This is guaranteed to use `k * sizeof(Self::Item) + O(1)` memory + /// and `O(n log k)` time, with `n` the number of elements in the input. + /// + /// The sorted iterator, if directly collected to a `Vec`, is converted + /// without any extra copying or allocation cost. + /// + /// **Note:** This is functionally-equivalent to `self.sorted().take(k)` + /// but much more efficient. + /// + /// ``` + /// use itertools::Itertools; + /// + /// // A random permutation of 0..15 + /// let numbers = vec![6, 9, 1, 14, 0, 4, 8, 7, 11, 2, 10, 3, 13, 12, 5]; + /// + /// let five_smallest = numbers + /// .into_iter() + /// .k_smallest(5); + /// + /// itertools::assert_equal(five_smallest, 0..5); + /// ``` + #[cfg(feature = "use_alloc")] + fn k_smallest(self, k: usize) -> VecIntoIter<Self::Item> + where Self: Sized, + Self::Item: Ord + { + crate::k_smallest::k_smallest(self, k) + .into_sorted_vec() + .into_iter() + } + + /// Collect all iterator elements into one of two + /// partitions. Unlike [`Iterator::partition`], each partition may + /// have a distinct type. + /// + /// ``` + /// use itertools::{Itertools, Either}; + /// + /// let successes_and_failures = vec![Ok(1), Err(false), Err(true), Ok(2)]; + /// + /// let (successes, failures): (Vec<_>, Vec<_>) = successes_and_failures + /// .into_iter() + /// .partition_map(|r| { + /// match r { + /// Ok(v) => Either::Left(v), + /// Err(v) => Either::Right(v), + /// } + /// }); + /// + /// assert_eq!(successes, [1, 2]); + /// assert_eq!(failures, [false, true]); + /// ``` + fn partition_map<A, B, F, L, R>(self, mut predicate: F) -> (A, B) + where Self: Sized, + F: FnMut(Self::Item) -> Either<L, R>, + A: Default + Extend<L>, + B: Default + Extend<R>, + { + let mut left = A::default(); + let mut right = B::default(); + + self.for_each(|val| match predicate(val) { + Either::Left(v) => left.extend(Some(v)), + Either::Right(v) => right.extend(Some(v)), + }); + + (left, right) + } + + /// Partition a sequence of `Result`s into one list of all the `Ok` elements + /// and another list of all the `Err` elements. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let successes_and_failures = vec![Ok(1), Err(false), Err(true), Ok(2)]; + /// + /// let (successes, failures): (Vec<_>, Vec<_>) = successes_and_failures + /// .into_iter() + /// .partition_result(); + /// + /// assert_eq!(successes, [1, 2]); + /// assert_eq!(failures, [false, true]); + /// ``` + fn partition_result<A, B, T, E>(self) -> (A, B) + where + Self: Iterator<Item = Result<T, E>> + Sized, + A: Default + Extend<T>, + B: Default + Extend<E>, + { + self.partition_map(|r| match r { + Ok(v) => Either::Left(v), + Err(v) => Either::Right(v), + }) + } + + /// Return a `HashMap` of keys mapped to `Vec`s of values. Keys and values + /// are taken from `(Key, Value)` tuple pairs yielded by the input iterator. + /// + /// Essentially a shorthand for `.into_grouping_map().collect::<Vec<_>>()`. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let data = vec![(0, 10), (2, 12), (3, 13), (0, 20), (3, 33), (2, 42)]; + /// let lookup = data.into_iter().into_group_map(); + /// + /// assert_eq!(lookup[&0], vec![10, 20]); + /// assert_eq!(lookup.get(&1), None); + /// assert_eq!(lookup[&2], vec![12, 42]); + /// assert_eq!(lookup[&3], vec![13, 33]); + /// ``` + #[cfg(feature = "use_std")] + fn into_group_map<K, V>(self) -> HashMap<K, Vec<V>> + where Self: Iterator<Item=(K, V)> + Sized, + K: Hash + Eq, + { + group_map::into_group_map(self) + } + + /// Return an `Iterator` on a `HashMap`. Keys mapped to `Vec`s of values. The key is specified + /// in the closure. + /// + /// Essentially a shorthand for `.into_grouping_map_by(f).collect::<Vec<_>>()`. + /// + /// ``` + /// use itertools::Itertools; + /// use std::collections::HashMap; + /// + /// let data = vec![(0, 10), (2, 12), (3, 13), (0, 20), (3, 33), (2, 42)]; + /// let lookup: HashMap<u32,Vec<(u32, u32)>> = + /// data.clone().into_iter().into_group_map_by(|a| a.0); + /// + /// assert_eq!(lookup[&0], vec![(0,10),(0,20)]); + /// assert_eq!(lookup.get(&1), None); + /// assert_eq!(lookup[&2], vec![(2,12), (2,42)]); + /// assert_eq!(lookup[&3], vec![(3,13), (3,33)]); + /// + /// assert_eq!( + /// data.into_iter() + /// .into_group_map_by(|x| x.0) + /// .into_iter() + /// .map(|(key, values)| (key, values.into_iter().fold(0,|acc, (_,v)| acc + v ))) + /// .collect::<HashMap<u32,u32>>()[&0], + /// 30, + /// ); + /// ``` + #[cfg(feature = "use_std")] + fn into_group_map_by<K, V, F>(self, f: F) -> HashMap<K, Vec<V>> + where + Self: Iterator<Item=V> + Sized, + K: Hash + Eq, + F: Fn(&V) -> K, + { + group_map::into_group_map_by(self, f) + } + + /// Constructs a `GroupingMap` to be used later with one of the efficient + /// group-and-fold operations it allows to perform. + /// + /// The input iterator must yield item in the form of `(K, V)` where the + /// value of type `K` will be used as key to identify the groups and the + /// value of type `V` as value for the folding operation. + /// + /// See [`GroupingMap`] for more informations + /// on what operations are available. + #[cfg(feature = "use_std")] + fn into_grouping_map<K, V>(self) -> GroupingMap<Self> + where Self: Iterator<Item=(K, V)> + Sized, + K: Hash + Eq, + { + grouping_map::new(self) + } + + /// Constructs a `GroupingMap` to be used later with one of the efficient + /// group-and-fold operations it allows to perform. + /// + /// The values from this iterator will be used as values for the folding operation + /// while the keys will be obtained from the values by calling `key_mapper`. + /// + /// See [`GroupingMap`] for more informations + /// on what operations are available. + #[cfg(feature = "use_std")] + fn into_grouping_map_by<K, V, F>(self, key_mapper: F) -> GroupingMapBy<Self, F> + where Self: Iterator<Item=V> + Sized, + K: Hash + Eq, + F: FnMut(&V) -> K + { + grouping_map::new(grouping_map::MapForGrouping::new(self, key_mapper)) + } + + /// Return all minimum elements of an iterator. + /// + /// # Examples + /// + /// ``` + /// use itertools::Itertools; + /// + /// let a: [i32; 0] = []; + /// assert_eq!(a.iter().min_set(), Vec::<&i32>::new()); + /// + /// let a = [1]; + /// assert_eq!(a.iter().min_set(), vec![&1]); + /// + /// let a = [1, 2, 3, 4, 5]; + /// assert_eq!(a.iter().min_set(), vec![&1]); + /// + /// let a = [1, 1, 1, 1]; + /// assert_eq!(a.iter().min_set(), vec![&1, &1, &1, &1]); + /// ``` + /// + /// The elements can be floats but no particular result is guaranteed + /// if an element is NaN. + #[cfg(feature = "use_std")] + fn min_set(self) -> Vec<Self::Item> + where Self: Sized, Self::Item: Ord + { + extrema_set::min_set_impl(self, |_| (), |x, y, _, _| x.cmp(y)) + } + + /// Return all minimum elements of an iterator, as determined by + /// the specified function. + /// + /// # Examples + /// + /// ``` + /// # use std::cmp::Ordering; + /// use itertools::Itertools; + /// + /// let a: [(i32, i32); 0] = []; + /// assert_eq!(a.iter().min_set_by(|_, _| Ordering::Equal), Vec::<&(i32, i32)>::new()); + /// + /// let a = [(1, 2)]; + /// assert_eq!(a.iter().min_set_by(|&&(k1,_), &&(k2, _)| k1.cmp(&k2)), vec![&(1, 2)]); + /// + /// let a = [(1, 2), (2, 2), (3, 9), (4, 8), (5, 9)]; + /// assert_eq!(a.iter().min_set_by(|&&(_,k1), &&(_,k2)| k1.cmp(&k2)), vec![&(1, 2), &(2, 2)]); + /// + /// let a = [(1, 2), (1, 3), (1, 4), (1, 5)]; + /// assert_eq!(a.iter().min_set_by(|&&(k1,_), &&(k2, _)| k1.cmp(&k2)), vec![&(1, 2), &(1, 3), &(1, 4), &(1, 5)]); + /// ``` + /// + /// The elements can be floats but no particular result is guaranteed + /// if an element is NaN. + #[cfg(feature = "use_std")] + fn min_set_by<F>(self, mut compare: F) -> Vec<Self::Item> + where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> Ordering + { + extrema_set::min_set_impl( + self, + |_| (), + |x, y, _, _| compare(x, y) + ) + } + + /// Return all minimum elements of an iterator, as determined by + /// the specified function. + /// + /// # Examples + /// + /// ``` + /// use itertools::Itertools; + /// + /// let a: [(i32, i32); 0] = []; + /// assert_eq!(a.iter().min_set_by_key(|_| ()), Vec::<&(i32, i32)>::new()); + /// + /// let a = [(1, 2)]; + /// assert_eq!(a.iter().min_set_by_key(|&&(k,_)| k), vec![&(1, 2)]); + /// + /// let a = [(1, 2), (2, 2), (3, 9), (4, 8), (5, 9)]; + /// assert_eq!(a.iter().min_set_by_key(|&&(_, k)| k), vec![&(1, 2), &(2, 2)]); + /// + /// let a = [(1, 2), (1, 3), (1, 4), (1, 5)]; + /// assert_eq!(a.iter().min_set_by_key(|&&(k, _)| k), vec![&(1, 2), &(1, 3), &(1, 4), &(1, 5)]); + /// ``` + /// + /// The elements can be floats but no particular result is guaranteed + /// if an element is NaN. + #[cfg(feature = "use_std")] + fn min_set_by_key<K, F>(self, key: F) -> Vec<Self::Item> + where Self: Sized, K: Ord, F: FnMut(&Self::Item) -> K + { + extrema_set::min_set_impl(self, key, |_, _, kx, ky| kx.cmp(ky)) + } + + /// Return all maximum elements of an iterator. + /// + /// # Examples + /// + /// ``` + /// use itertools::Itertools; + /// + /// let a: [i32; 0] = []; + /// assert_eq!(a.iter().max_set(), Vec::<&i32>::new()); + /// + /// let a = [1]; + /// assert_eq!(a.iter().max_set(), vec![&1]); + /// + /// let a = [1, 2, 3, 4, 5]; + /// assert_eq!(a.iter().max_set(), vec![&5]); + /// + /// let a = [1, 1, 1, 1]; + /// assert_eq!(a.iter().max_set(), vec![&1, &1, &1, &1]); + /// ``` + /// + /// The elements can be floats but no particular result is guaranteed + /// if an element is NaN. + #[cfg(feature = "use_std")] + fn max_set(self) -> Vec<Self::Item> + where Self: Sized, Self::Item: Ord + { + extrema_set::max_set_impl(self, |_| (), |x, y, _, _| x.cmp(y)) + } + + /// Return all maximum elements of an iterator, as determined by + /// the specified function. + /// + /// # Examples + /// + /// ``` + /// # use std::cmp::Ordering; + /// use itertools::Itertools; + /// + /// let a: [(i32, i32); 0] = []; + /// assert_eq!(a.iter().max_set_by(|_, _| Ordering::Equal), Vec::<&(i32, i32)>::new()); + /// + /// let a = [(1, 2)]; + /// assert_eq!(a.iter().max_set_by(|&&(k1,_), &&(k2, _)| k1.cmp(&k2)), vec![&(1, 2)]); + /// + /// let a = [(1, 2), (2, 2), (3, 9), (4, 8), (5, 9)]; + /// assert_eq!(a.iter().max_set_by(|&&(_,k1), &&(_,k2)| k1.cmp(&k2)), vec![&(3, 9), &(5, 9)]); + /// + /// let a = [(1, 2), (1, 3), (1, 4), (1, 5)]; + /// assert_eq!(a.iter().max_set_by(|&&(k1,_), &&(k2, _)| k1.cmp(&k2)), vec![&(1, 2), &(1, 3), &(1, 4), &(1, 5)]); + /// ``` + /// + /// The elements can be floats but no particular result is guaranteed + /// if an element is NaN. + #[cfg(feature = "use_std")] + fn max_set_by<F>(self, mut compare: F) -> Vec<Self::Item> + where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> Ordering + { + extrema_set::max_set_impl( + self, + |_| (), + |x, y, _, _| compare(x, y) + ) + } + + /// Return all minimum elements of an iterator, as determined by + /// the specified function. + /// + /// # Examples + /// + /// ``` + /// use itertools::Itertools; + /// + /// let a: [(i32, i32); 0] = []; + /// assert_eq!(a.iter().max_set_by_key(|_| ()), Vec::<&(i32, i32)>::new()); + /// + /// let a = [(1, 2)]; + /// assert_eq!(a.iter().max_set_by_key(|&&(k,_)| k), vec![&(1, 2)]); + /// + /// let a = [(1, 2), (2, 2), (3, 9), (4, 8), (5, 9)]; + /// assert_eq!(a.iter().max_set_by_key(|&&(_, k)| k), vec![&(3, 9), &(5, 9)]); + /// + /// let a = [(1, 2), (1, 3), (1, 4), (1, 5)]; + /// assert_eq!(a.iter().max_set_by_key(|&&(k, _)| k), vec![&(1, 2), &(1, 3), &(1, 4), &(1, 5)]); + /// ``` + /// + /// The elements can be floats but no particular result is guaranteed + /// if an element is NaN. + #[cfg(feature = "use_std")] + fn max_set_by_key<K, F>(self, key: F) -> Vec<Self::Item> + where Self: Sized, K: Ord, F: FnMut(&Self::Item) -> K + { + extrema_set::max_set_impl(self, key, |_, _, kx, ky| kx.cmp(ky)) + } + + /// Return the minimum and maximum elements in the iterator. + /// + /// The return type `MinMaxResult` is an enum of three variants: + /// + /// - `NoElements` if the iterator is empty. + /// - `OneElement(x)` if the iterator has exactly one element. + /// - `MinMax(x, y)` is returned otherwise, where `x <= y`. Two + /// values are equal if and only if there is more than one + /// element in the iterator and all elements are equal. + /// + /// On an iterator of length `n`, `minmax` does `1.5 * n` comparisons, + /// and so is faster than calling `min` and `max` separately which does + /// `2 * n` comparisons. + /// + /// # Examples + /// + /// ``` + /// use itertools::Itertools; + /// use itertools::MinMaxResult::{NoElements, OneElement, MinMax}; + /// + /// let a: [i32; 0] = []; + /// assert_eq!(a.iter().minmax(), NoElements); + /// + /// let a = [1]; + /// assert_eq!(a.iter().minmax(), OneElement(&1)); + /// + /// let a = [1, 2, 3, 4, 5]; + /// assert_eq!(a.iter().minmax(), MinMax(&1, &5)); + /// + /// let a = [1, 1, 1, 1]; + /// assert_eq!(a.iter().minmax(), MinMax(&1, &1)); + /// ``` + /// + /// The elements can be floats but no particular result is guaranteed + /// if an element is NaN. + fn minmax(self) -> MinMaxResult<Self::Item> + where Self: Sized, Self::Item: PartialOrd + { + minmax::minmax_impl(self, |_| (), |x, y, _, _| x < y) + } + + /// Return the minimum and maximum element of an iterator, as determined by + /// the specified function. + /// + /// The return value is a variant of [`MinMaxResult`] like for [`.minmax()`](Itertools::minmax). + /// + /// For the minimum, the first minimal element is returned. For the maximum, + /// the last maximal element wins. This matches the behavior of the standard + /// [`Iterator::min`] and [`Iterator::max`] methods. + /// + /// The keys can be floats but no particular result is guaranteed + /// if a key is NaN. + fn minmax_by_key<K, F>(self, key: F) -> MinMaxResult<Self::Item> + where Self: Sized, K: PartialOrd, F: FnMut(&Self::Item) -> K + { + minmax::minmax_impl(self, key, |_, _, xk, yk| xk < yk) + } + + /// Return the minimum and maximum element of an iterator, as determined by + /// the specified comparison function. + /// + /// The return value is a variant of [`MinMaxResult`] like for [`.minmax()`](Itertools::minmax). + /// + /// For the minimum, the first minimal element is returned. For the maximum, + /// the last maximal element wins. This matches the behavior of the standard + /// [`Iterator::min`] and [`Iterator::max`] methods. + fn minmax_by<F>(self, mut compare: F) -> MinMaxResult<Self::Item> + where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> Ordering + { + minmax::minmax_impl( + self, + |_| (), + |x, y, _, _| Ordering::Less == compare(x, y) + ) + } + + /// Return the position of the maximum element in the iterator. + /// + /// If several elements are equally maximum, the position of the + /// last of them is returned. + /// + /// # Examples + /// + /// ``` + /// use itertools::Itertools; + /// + /// let a: [i32; 0] = []; + /// assert_eq!(a.iter().position_max(), None); + /// + /// let a = [-3, 0, 1, 5, -10]; + /// assert_eq!(a.iter().position_max(), Some(3)); + /// + /// let a = [1, 1, -1, -1]; + /// assert_eq!(a.iter().position_max(), Some(1)); + /// ``` + fn position_max(self) -> Option<usize> + where Self: Sized, Self::Item: Ord + { + self.enumerate() + .max_by(|x, y| Ord::cmp(&x.1, &y.1)) + .map(|x| x.0) + } + + /// Return the position of the maximum element in the iterator, as + /// determined by the specified function. + /// + /// If several elements are equally maximum, the position of the + /// last of them is returned. + /// + /// # Examples + /// + /// ``` + /// use itertools::Itertools; + /// + /// let a: [i32; 0] = []; + /// assert_eq!(a.iter().position_max_by_key(|x| x.abs()), None); + /// + /// let a = [-3_i32, 0, 1, 5, -10]; + /// assert_eq!(a.iter().position_max_by_key(|x| x.abs()), Some(4)); + /// + /// let a = [1_i32, 1, -1, -1]; + /// assert_eq!(a.iter().position_max_by_key(|x| x.abs()), Some(3)); + /// ``` + fn position_max_by_key<K, F>(self, mut key: F) -> Option<usize> + where Self: Sized, K: Ord, F: FnMut(&Self::Item) -> K + { + self.enumerate() + .max_by(|x, y| Ord::cmp(&key(&x.1), &key(&y.1))) + .map(|x| x.0) + } + + /// Return the position of the maximum element in the iterator, as + /// determined by the specified comparison function. + /// + /// If several elements are equally maximum, the position of the + /// last of them is returned. + /// + /// # Examples + /// + /// ``` + /// use itertools::Itertools; + /// + /// let a: [i32; 0] = []; + /// assert_eq!(a.iter().position_max_by(|x, y| x.cmp(y)), None); + /// + /// let a = [-3_i32, 0, 1, 5, -10]; + /// assert_eq!(a.iter().position_max_by(|x, y| x.cmp(y)), Some(3)); + /// + /// let a = [1_i32, 1, -1, -1]; + /// assert_eq!(a.iter().position_max_by(|x, y| x.cmp(y)), Some(1)); + /// ``` + fn position_max_by<F>(self, mut compare: F) -> Option<usize> + where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> Ordering + { + self.enumerate() + .max_by(|x, y| compare(&x.1, &y.1)) + .map(|x| x.0) + } + + /// Return the position of the minimum element in the iterator. + /// + /// If several elements are equally minimum, the position of the + /// first of them is returned. + /// + /// # Examples + /// + /// ``` + /// use itertools::Itertools; + /// + /// let a: [i32; 0] = []; + /// assert_eq!(a.iter().position_min(), None); + /// + /// let a = [-3, 0, 1, 5, -10]; + /// assert_eq!(a.iter().position_min(), Some(4)); + /// + /// let a = [1, 1, -1, -1]; + /// assert_eq!(a.iter().position_min(), Some(2)); + /// ``` + fn position_min(self) -> Option<usize> + where Self: Sized, Self::Item: Ord + { + self.enumerate() + .min_by(|x, y| Ord::cmp(&x.1, &y.1)) + .map(|x| x.0) + } + + /// Return the position of the minimum element in the iterator, as + /// determined by the specified function. + /// + /// If several elements are equally minimum, the position of the + /// first of them is returned. + /// + /// # Examples + /// + /// ``` + /// use itertools::Itertools; + /// + /// let a: [i32; 0] = []; + /// assert_eq!(a.iter().position_min_by_key(|x| x.abs()), None); + /// + /// let a = [-3_i32, 0, 1, 5, -10]; + /// assert_eq!(a.iter().position_min_by_key(|x| x.abs()), Some(1)); + /// + /// let a = [1_i32, 1, -1, -1]; + /// assert_eq!(a.iter().position_min_by_key(|x| x.abs()), Some(0)); + /// ``` + fn position_min_by_key<K, F>(self, mut key: F) -> Option<usize> + where Self: Sized, K: Ord, F: FnMut(&Self::Item) -> K + { + self.enumerate() + .min_by(|x, y| Ord::cmp(&key(&x.1), &key(&y.1))) + .map(|x| x.0) + } + + /// Return the position of the minimum element in the iterator, as + /// determined by the specified comparison function. + /// + /// If several elements are equally minimum, the position of the + /// first of them is returned. + /// + /// # Examples + /// + /// ``` + /// use itertools::Itertools; + /// + /// let a: [i32; 0] = []; + /// assert_eq!(a.iter().position_min_by(|x, y| x.cmp(y)), None); + /// + /// let a = [-3_i32, 0, 1, 5, -10]; + /// assert_eq!(a.iter().position_min_by(|x, y| x.cmp(y)), Some(4)); + /// + /// let a = [1_i32, 1, -1, -1]; + /// assert_eq!(a.iter().position_min_by(|x, y| x.cmp(y)), Some(2)); + /// ``` + fn position_min_by<F>(self, mut compare: F) -> Option<usize> + where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> Ordering + { + self.enumerate() + .min_by(|x, y| compare(&x.1, &y.1)) + .map(|x| x.0) + } + + /// Return the positions of the minimum and maximum elements in + /// the iterator. + /// + /// The return type [`MinMaxResult`] is an enum of three variants: + /// + /// - `NoElements` if the iterator is empty. + /// - `OneElement(xpos)` if the iterator has exactly one element. + /// - `MinMax(xpos, ypos)` is returned otherwise, where the + /// element at `xpos` ≤ the element at `ypos`. While the + /// referenced elements themselves may be equal, `xpos` cannot + /// be equal to `ypos`. + /// + /// On an iterator of length `n`, `position_minmax` does `1.5 * n` + /// comparisons, and so is faster than calling `position_min` and + /// `position_max` separately which does `2 * n` comparisons. + /// + /// For the minimum, if several elements are equally minimum, the + /// position of the first of them is returned. For the maximum, if + /// several elements are equally maximum, the position of the last + /// of them is returned. + /// + /// The elements can be floats but no particular result is + /// guaranteed if an element is NaN. + /// + /// # Examples + /// + /// ``` + /// use itertools::Itertools; + /// use itertools::MinMaxResult::{NoElements, OneElement, MinMax}; + /// + /// let a: [i32; 0] = []; + /// assert_eq!(a.iter().position_minmax(), NoElements); + /// + /// let a = [10]; + /// assert_eq!(a.iter().position_minmax(), OneElement(0)); + /// + /// let a = [-3, 0, 1, 5, -10]; + /// assert_eq!(a.iter().position_minmax(), MinMax(4, 3)); + /// + /// let a = [1, 1, -1, -1]; + /// assert_eq!(a.iter().position_minmax(), MinMax(2, 1)); + /// ``` + fn position_minmax(self) -> MinMaxResult<usize> + where Self: Sized, Self::Item: PartialOrd + { + use crate::MinMaxResult::{NoElements, OneElement, MinMax}; + match minmax::minmax_impl(self.enumerate(), |_| (), |x, y, _, _| x.1 < y.1) { + NoElements => NoElements, + OneElement(x) => OneElement(x.0), + MinMax(x, y) => MinMax(x.0, y.0), + } + } + + /// Return the postions of the minimum and maximum elements of an + /// iterator, as determined by the specified function. + /// + /// The return value is a variant of [`MinMaxResult`] like for + /// [`position_minmax`]. + /// + /// For the minimum, if several elements are equally minimum, the + /// position of the first of them is returned. For the maximum, if + /// several elements are equally maximum, the position of the last + /// of them is returned. + /// + /// The keys can be floats but no particular result is guaranteed + /// if a key is NaN. + /// + /// # Examples + /// + /// ``` + /// use itertools::Itertools; + /// use itertools::MinMaxResult::{NoElements, OneElement, MinMax}; + /// + /// let a: [i32; 0] = []; + /// assert_eq!(a.iter().position_minmax_by_key(|x| x.abs()), NoElements); + /// + /// let a = [10_i32]; + /// assert_eq!(a.iter().position_minmax_by_key(|x| x.abs()), OneElement(0)); + /// + /// let a = [-3_i32, 0, 1, 5, -10]; + /// assert_eq!(a.iter().position_minmax_by_key(|x| x.abs()), MinMax(1, 4)); + /// + /// let a = [1_i32, 1, -1, -1]; + /// assert_eq!(a.iter().position_minmax_by_key(|x| x.abs()), MinMax(0, 3)); + /// ``` + /// + /// [`position_minmax`]: Self::position_minmax + fn position_minmax_by_key<K, F>(self, mut key: F) -> MinMaxResult<usize> + where Self: Sized, K: PartialOrd, F: FnMut(&Self::Item) -> K + { + use crate::MinMaxResult::{NoElements, OneElement, MinMax}; + match self.enumerate().minmax_by_key(|e| key(&e.1)) { + NoElements => NoElements, + OneElement(x) => OneElement(x.0), + MinMax(x, y) => MinMax(x.0, y.0), + } + } + + /// Return the postions of the minimum and maximum elements of an + /// iterator, as determined by the specified comparison function. + /// + /// The return value is a variant of [`MinMaxResult`] like for + /// [`position_minmax`]. + /// + /// For the minimum, if several elements are equally minimum, the + /// position of the first of them is returned. For the maximum, if + /// several elements are equally maximum, the position of the last + /// of them is returned. + /// + /// # Examples + /// + /// ``` + /// use itertools::Itertools; + /// use itertools::MinMaxResult::{NoElements, OneElement, MinMax}; + /// + /// let a: [i32; 0] = []; + /// assert_eq!(a.iter().position_minmax_by(|x, y| x.cmp(y)), NoElements); + /// + /// let a = [10_i32]; + /// assert_eq!(a.iter().position_minmax_by(|x, y| x.cmp(y)), OneElement(0)); + /// + /// let a = [-3_i32, 0, 1, 5, -10]; + /// assert_eq!(a.iter().position_minmax_by(|x, y| x.cmp(y)), MinMax(4, 3)); + /// + /// let a = [1_i32, 1, -1, -1]; + /// assert_eq!(a.iter().position_minmax_by(|x, y| x.cmp(y)), MinMax(2, 1)); + /// ``` + /// + /// [`position_minmax`]: Self::position_minmax + fn position_minmax_by<F>(self, mut compare: F) -> MinMaxResult<usize> + where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> Ordering + { + use crate::MinMaxResult::{NoElements, OneElement, MinMax}; + match self.enumerate().minmax_by(|x, y| compare(&x.1, &y.1)) { + NoElements => NoElements, + OneElement(x) => OneElement(x.0), + MinMax(x, y) => MinMax(x.0, y.0), + } + } + + /// If the iterator yields exactly one element, that element will be returned, otherwise + /// an error will be returned containing an iterator that has the same output as the input + /// iterator. + /// + /// This provides an additional layer of validation over just calling `Iterator::next()`. + /// If your assumption that there should only be one element yielded is false this provides + /// the opportunity to detect and handle that, preventing errors at a distance. + /// + /// # Examples + /// ``` + /// use itertools::Itertools; + /// + /// assert_eq!((0..10).filter(|&x| x == 2).exactly_one().unwrap(), 2); + /// assert!((0..10).filter(|&x| x > 1 && x < 4).exactly_one().unwrap_err().eq(2..4)); + /// assert!((0..10).filter(|&x| x > 1 && x < 5).exactly_one().unwrap_err().eq(2..5)); + /// assert!((0..10).filter(|&_| false).exactly_one().unwrap_err().eq(0..0)); + /// ``` + fn exactly_one(mut self) -> Result<Self::Item, ExactlyOneError<Self>> + where + Self: Sized, + { + match self.next() { + Some(first) => { + match self.next() { + Some(second) => { + Err(ExactlyOneError::new(Some(Either::Left([first, second])), self)) + } + None => { + Ok(first) + } + } + } + None => Err(ExactlyOneError::new(None, self)), + } + } + + /// If the iterator yields no elements, Ok(None) will be returned. If the iterator yields + /// exactly one element, that element will be returned, otherwise an error will be returned + /// containing an iterator that has the same output as the input iterator. + /// + /// This provides an additional layer of validation over just calling `Iterator::next()`. + /// If your assumption that there should be at most one element yielded is false this provides + /// the opportunity to detect and handle that, preventing errors at a distance. + /// + /// # Examples + /// ``` + /// use itertools::Itertools; + /// + /// assert_eq!((0..10).filter(|&x| x == 2).at_most_one().unwrap(), Some(2)); + /// assert!((0..10).filter(|&x| x > 1 && x < 4).at_most_one().unwrap_err().eq(2..4)); + /// assert!((0..10).filter(|&x| x > 1 && x < 5).at_most_one().unwrap_err().eq(2..5)); + /// assert_eq!((0..10).filter(|&_| false).at_most_one().unwrap(), None); + /// ``` + fn at_most_one(mut self) -> Result<Option<Self::Item>, ExactlyOneError<Self>> + where + Self: Sized, + { + match self.next() { + Some(first) => { + match self.next() { + Some(second) => { + Err(ExactlyOneError::new(Some(Either::Left([first, second])), self)) + } + None => { + Ok(Some(first)) + } + } + } + None => Ok(None), + } + } + + /// An iterator adaptor that allows the user to peek at multiple `.next()` + /// values without advancing the base iterator. + /// + /// # Examples + /// ``` + /// use itertools::Itertools; + /// + /// let mut iter = (0..10).multipeek(); + /// assert_eq!(iter.peek(), Some(&0)); + /// assert_eq!(iter.peek(), Some(&1)); + /// assert_eq!(iter.peek(), Some(&2)); + /// assert_eq!(iter.next(), Some(0)); + /// assert_eq!(iter.peek(), Some(&1)); + /// ``` + #[cfg(feature = "use_alloc")] + fn multipeek(self) -> MultiPeek<Self> + where + Self: Sized, + { + multipeek_impl::multipeek(self) + } + + /// Collect the items in this iterator and return a `HashMap` which + /// contains each item that appears in the iterator and the number + /// of times it appears. + /// + /// # Examples + /// ``` + /// # use itertools::Itertools; + /// let counts = [1, 1, 1, 3, 3, 5].into_iter().counts(); + /// assert_eq!(counts[&1], 3); + /// assert_eq!(counts[&3], 2); + /// assert_eq!(counts[&5], 1); + /// assert_eq!(counts.get(&0), None); + /// ``` + #[cfg(feature = "use_std")] + fn counts(self) -> HashMap<Self::Item, usize> + where + Self: Sized, + Self::Item: Eq + Hash, + { + let mut counts = HashMap::new(); + self.for_each(|item| *counts.entry(item).or_default() += 1); + counts + } + + /// Collect the items in this iterator and return a `HashMap` which + /// contains each item that appears in the iterator and the number + /// of times it appears, + /// determining identity using a keying function. + /// + /// ``` + /// # use itertools::Itertools; + /// struct Character { + /// first_name: &'static str, + /// last_name: &'static str, + /// } + /// + /// let characters = + /// vec![ + /// Character { first_name: "Amy", last_name: "Pond" }, + /// Character { first_name: "Amy", last_name: "Wong" }, + /// Character { first_name: "Amy", last_name: "Santiago" }, + /// Character { first_name: "James", last_name: "Bond" }, + /// Character { first_name: "James", last_name: "Sullivan" }, + /// Character { first_name: "James", last_name: "Norington" }, + /// Character { first_name: "James", last_name: "Kirk" }, + /// ]; + /// + /// let first_name_frequency = + /// characters + /// .into_iter() + /// .counts_by(|c| c.first_name); + /// + /// assert_eq!(first_name_frequency["Amy"], 3); + /// assert_eq!(first_name_frequency["James"], 4); + /// assert_eq!(first_name_frequency.contains_key("Asha"), false); + /// ``` + #[cfg(feature = "use_std")] + fn counts_by<K, F>(self, f: F) -> HashMap<K, usize> + where + Self: Sized, + K: Eq + Hash, + F: FnMut(Self::Item) -> K, + { + self.map(f).counts() + } + + /// Converts an iterator of tuples into a tuple of containers. + /// + /// `unzip()` consumes an entire iterator of n-ary tuples, producing `n` collections, one for each + /// column. + /// + /// This function is, in some sense, the opposite of [`multizip`]. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let inputs = vec![(1, 2, 3), (4, 5, 6), (7, 8, 9)]; + /// + /// let (a, b, c): (Vec<_>, Vec<_>, Vec<_>) = inputs + /// .into_iter() + /// .multiunzip(); + /// + /// assert_eq!(a, vec![1, 4, 7]); + /// assert_eq!(b, vec![2, 5, 8]); + /// assert_eq!(c, vec![3, 6, 9]); + /// ``` + fn multiunzip<FromI>(self) -> FromI + where + Self: Sized + MultiUnzip<FromI>, + { + MultiUnzip::multiunzip(self) + } +} + +impl<T: ?Sized> Itertools for T where T: Iterator { } + +/// Return `true` if both iterables produce equal sequences +/// (elements pairwise equal and sequences of the same length), +/// `false` otherwise. +/// +/// [`IntoIterator`] enabled version of [`Iterator::eq`]. +/// +/// ``` +/// assert!(itertools::equal(vec![1, 2, 3], 1..4)); +/// assert!(!itertools::equal(&[0, 0], &[0, 0, 0])); +/// ``` +pub fn equal<I, J>(a: I, b: J) -> bool + where I: IntoIterator, + J: IntoIterator, + I::Item: PartialEq<J::Item> +{ + a.into_iter().eq(b) +} + +/// Assert that two iterables produce equal sequences, with the same +/// semantics as [`equal(a, b)`](equal). +/// +/// **Panics** on assertion failure with a message that shows the +/// two iteration elements. +/// +/// ```ignore +/// assert_equal("exceed".split('c'), "excess".split('c')); +/// // ^PANIC: panicked at 'Failed assertion Some("eed") == Some("ess") for iteration 1', +/// ``` +pub fn assert_equal<I, J>(a: I, b: J) + where I: IntoIterator, + J: IntoIterator, + I::Item: fmt::Debug + PartialEq<J::Item>, + J::Item: fmt::Debug, +{ + let mut ia = a.into_iter(); + let mut ib = b.into_iter(); + let mut i = 0; + loop { + match (ia.next(), ib.next()) { + (None, None) => return, + (a, b) => { + let equal = match (&a, &b) { + (&Some(ref a), &Some(ref b)) => a == b, + _ => false, + }; + assert!(equal, "Failed assertion {a:?} == {b:?} for iteration {i}", + i=i, a=a, b=b); + i += 1; + } + } + } +} + +/// Partition a sequence using predicate `pred` so that elements +/// that map to `true` are placed before elements which map to `false`. +/// +/// The order within the partitions is arbitrary. +/// +/// Return the index of the split point. +/// +/// ``` +/// use itertools::partition; +/// +/// # // use repeated numbers to not promise any ordering +/// let mut data = [7, 1, 1, 7, 1, 1, 7]; +/// let split_index = partition(&mut data, |elt| *elt >= 3); +/// +/// assert_eq!(data, [7, 7, 7, 1, 1, 1, 1]); +/// assert_eq!(split_index, 3); +/// ``` +pub fn partition<'a, A: 'a, I, F>(iter: I, mut pred: F) -> usize + where I: IntoIterator<Item = &'a mut A>, + I::IntoIter: DoubleEndedIterator, + F: FnMut(&A) -> bool +{ + let mut split_index = 0; + let mut iter = iter.into_iter(); + 'main: while let Some(front) = iter.next() { + if !pred(front) { + loop { + match iter.next_back() { + Some(back) => if pred(back) { + std::mem::swap(front, back); + break; + }, + None => break 'main, + } + } + } + split_index += 1; + } + split_index +} + +/// An enum used for controlling the execution of `fold_while`. +/// +/// See [`.fold_while()`](Itertools::fold_while) for more information. +#[derive(Copy, Clone, Debug, Eq, PartialEq)] +pub enum FoldWhile<T> { + /// Continue folding with this value + Continue(T), + /// Fold is complete and will return this value + Done(T), +} + +impl<T> FoldWhile<T> { + /// Return the value in the continue or done. + pub fn into_inner(self) -> T { + match self { + FoldWhile::Continue(x) | FoldWhile::Done(x) => x, + } + } + + /// Return true if `self` is `Done`, false if it is `Continue`. + pub fn is_done(&self) -> bool { + match *self { + FoldWhile::Continue(_) => false, + FoldWhile::Done(_) => true, + } + } +} diff --git a/third_party/rust/itertools/src/merge_join.rs b/third_party/rust/itertools/src/merge_join.rs new file mode 100644 index 0000000000..f2fbdea2c4 --- /dev/null +++ b/third_party/rust/itertools/src/merge_join.rs @@ -0,0 +1,169 @@ +use std::cmp::Ordering; +use std::iter::Fuse; +use std::fmt; + +use super::adaptors::{PutBack, put_back}; +use crate::either_or_both::EitherOrBoth; +#[cfg(doc)] +use crate::Itertools; + +/// Return an iterator adaptor that merge-joins items from the two base iterators in ascending order. +/// +/// [`IntoIterator`] enabled version of [`Itertools::merge_join_by`]. +pub fn merge_join_by<I, J, F>(left: I, right: J, cmp_fn: F) + -> MergeJoinBy<I::IntoIter, J::IntoIter, F> + where I: IntoIterator, + J: IntoIterator, + F: FnMut(&I::Item, &J::Item) -> Ordering +{ + MergeJoinBy { + left: put_back(left.into_iter().fuse()), + right: put_back(right.into_iter().fuse()), + cmp_fn, + } +} + +/// An iterator adaptor that merge-joins items from the two base iterators in ascending order. +/// +/// See [`.merge_join_by()`](crate::Itertools::merge_join_by) for more information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct MergeJoinBy<I: Iterator, J: Iterator, F> { + left: PutBack<Fuse<I>>, + right: PutBack<Fuse<J>>, + cmp_fn: F +} + +impl<I, J, F> Clone for MergeJoinBy<I, J, F> + where I: Iterator, + J: Iterator, + PutBack<Fuse<I>>: Clone, + PutBack<Fuse<J>>: Clone, + F: Clone, +{ + clone_fields!(left, right, cmp_fn); +} + +impl<I, J, F> fmt::Debug for MergeJoinBy<I, J, F> + where I: Iterator + fmt::Debug, + I::Item: fmt::Debug, + J: Iterator + fmt::Debug, + J::Item: fmt::Debug, +{ + debug_fmt_fields!(MergeJoinBy, left, right); +} + +impl<I, J, F> Iterator for MergeJoinBy<I, J, F> + where I: Iterator, + J: Iterator, + F: FnMut(&I::Item, &J::Item) -> Ordering +{ + type Item = EitherOrBoth<I::Item, J::Item>; + + fn next(&mut self) -> Option<Self::Item> { + match (self.left.next(), self.right.next()) { + (None, None) => None, + (Some(left), None) => + Some(EitherOrBoth::Left(left)), + (None, Some(right)) => + Some(EitherOrBoth::Right(right)), + (Some(left), Some(right)) => { + match (self.cmp_fn)(&left, &right) { + Ordering::Equal => + Some(EitherOrBoth::Both(left, right)), + Ordering::Less => { + self.right.put_back(right); + Some(EitherOrBoth::Left(left)) + }, + Ordering::Greater => { + self.left.put_back(left); + Some(EitherOrBoth::Right(right)) + } + } + } + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + let (a_lower, a_upper) = self.left.size_hint(); + let (b_lower, b_upper) = self.right.size_hint(); + + let lower = ::std::cmp::max(a_lower, b_lower); + + let upper = match (a_upper, b_upper) { + (Some(x), Some(y)) => x.checked_add(y), + _ => None, + }; + + (lower, upper) + } + + fn count(mut self) -> usize { + let mut count = 0; + loop { + match (self.left.next(), self.right.next()) { + (None, None) => break count, + (Some(_left), None) => break count + 1 + self.left.into_parts().1.count(), + (None, Some(_right)) => break count + 1 + self.right.into_parts().1.count(), + (Some(left), Some(right)) => { + count += 1; + match (self.cmp_fn)(&left, &right) { + Ordering::Equal => {} + Ordering::Less => self.right.put_back(right), + Ordering::Greater => self.left.put_back(left), + } + } + } + } + } + + fn last(mut self) -> Option<Self::Item> { + let mut previous_element = None; + loop { + match (self.left.next(), self.right.next()) { + (None, None) => break previous_element, + (Some(left), None) => { + break Some(EitherOrBoth::Left( + self.left.into_parts().1.last().unwrap_or(left), + )) + } + (None, Some(right)) => { + break Some(EitherOrBoth::Right( + self.right.into_parts().1.last().unwrap_or(right), + )) + } + (Some(left), Some(right)) => { + previous_element = match (self.cmp_fn)(&left, &right) { + Ordering::Equal => Some(EitherOrBoth::Both(left, right)), + Ordering::Less => { + self.right.put_back(right); + Some(EitherOrBoth::Left(left)) + } + Ordering::Greater => { + self.left.put_back(left); + Some(EitherOrBoth::Right(right)) + } + } + } + } + } + } + + fn nth(&mut self, mut n: usize) -> Option<Self::Item> { + loop { + if n == 0 { + break self.next(); + } + n -= 1; + match (self.left.next(), self.right.next()) { + (None, None) => break None, + (Some(_left), None) => break self.left.nth(n).map(EitherOrBoth::Left), + (None, Some(_right)) => break self.right.nth(n).map(EitherOrBoth::Right), + (Some(left), Some(right)) => match (self.cmp_fn)(&left, &right) { + Ordering::Equal => {} + Ordering::Less => self.right.put_back(right), + Ordering::Greater => self.left.put_back(left), + }, + } + } + } +} diff --git a/third_party/rust/itertools/src/minmax.rs b/third_party/rust/itertools/src/minmax.rs new file mode 100644 index 0000000000..52b2f115dd --- /dev/null +++ b/third_party/rust/itertools/src/minmax.rs @@ -0,0 +1,115 @@ + +/// `MinMaxResult` is an enum returned by `minmax`. +/// +/// See [`.minmax()`](crate::Itertools::minmax) for more detail. +#[derive(Copy, Clone, PartialEq, Debug)] +pub enum MinMaxResult<T> { + /// Empty iterator + NoElements, + + /// Iterator with one element, so the minimum and maximum are the same + OneElement(T), + + /// More than one element in the iterator, the first element is not larger + /// than the second + MinMax(T, T) +} + +impl<T: Clone> MinMaxResult<T> { + /// `into_option` creates an `Option` of type `(T, T)`. The returned `Option` + /// has variant `None` if and only if the `MinMaxResult` has variant + /// `NoElements`. Otherwise `Some((x, y))` is returned where `x <= y`. + /// If the `MinMaxResult` has variant `OneElement(x)`, performing this + /// operation will make one clone of `x`. + /// + /// # Examples + /// + /// ``` + /// use itertools::MinMaxResult::{self, NoElements, OneElement, MinMax}; + /// + /// let r: MinMaxResult<i32> = NoElements; + /// assert_eq!(r.into_option(), None); + /// + /// let r = OneElement(1); + /// assert_eq!(r.into_option(), Some((1, 1))); + /// + /// let r = MinMax(1, 2); + /// assert_eq!(r.into_option(), Some((1, 2))); + /// ``` + pub fn into_option(self) -> Option<(T,T)> { + match self { + MinMaxResult::NoElements => None, + MinMaxResult::OneElement(x) => Some((x.clone(), x)), + MinMaxResult::MinMax(x, y) => Some((x, y)) + } + } +} + +/// Implementation guts for `minmax` and `minmax_by_key`. +pub fn minmax_impl<I, K, F, L>(mut it: I, mut key_for: F, + mut lt: L) -> MinMaxResult<I::Item> + where I: Iterator, + F: FnMut(&I::Item) -> K, + L: FnMut(&I::Item, &I::Item, &K, &K) -> bool, +{ + let (mut min, mut max, mut min_key, mut max_key) = match it.next() { + None => return MinMaxResult::NoElements, + Some(x) => { + match it.next() { + None => return MinMaxResult::OneElement(x), + Some(y) => { + let xk = key_for(&x); + let yk = key_for(&y); + if !lt(&y, &x, &yk, &xk) {(x, y, xk, yk)} else {(y, x, yk, xk)} + } + } + } + }; + + loop { + // `first` and `second` are the two next elements we want to look + // at. We first compare `first` and `second` (#1). The smaller one + // is then compared to current minimum (#2). The larger one is + // compared to current maximum (#3). This way we do 3 comparisons + // for 2 elements. + let first = match it.next() { + None => break, + Some(x) => x + }; + let second = match it.next() { + None => { + let first_key = key_for(&first); + if lt(&first, &min, &first_key, &min_key) { + min = first; + } else if !lt(&first, &max, &first_key, &max_key) { + max = first; + } + break; + } + Some(x) => x + }; + let first_key = key_for(&first); + let second_key = key_for(&second); + if !lt(&second, &first, &second_key, &first_key) { + if lt(&first, &min, &first_key, &min_key) { + min = first; + min_key = first_key; + } + if !lt(&second, &max, &second_key, &max_key) { + max = second; + max_key = second_key; + } + } else { + if lt(&second, &min, &second_key, &min_key) { + min = second; + min_key = second_key; + } + if !lt(&first, &max, &first_key, &max_key) { + max = first; + max_key = first_key; + } + } + } + + MinMaxResult::MinMax(min, max) +} diff --git a/third_party/rust/itertools/src/multipeek_impl.rs b/third_party/rust/itertools/src/multipeek_impl.rs new file mode 100644 index 0000000000..8b49c695eb --- /dev/null +++ b/third_party/rust/itertools/src/multipeek_impl.rs @@ -0,0 +1,101 @@ +use std::iter::Fuse; +use alloc::collections::VecDeque; +use crate::size_hint; +use crate::PeekingNext; +#[cfg(doc)] +use crate::Itertools; + +/// See [`multipeek()`] for more information. +#[derive(Clone, Debug)] +pub struct MultiPeek<I> + where I: Iterator +{ + iter: Fuse<I>, + buf: VecDeque<I::Item>, + index: usize, +} + +/// An iterator adaptor that allows the user to peek at multiple `.next()` +/// values without advancing the base iterator. +/// +/// [`IntoIterator`] enabled version of [`Itertools::multipeek`]. +pub fn multipeek<I>(iterable: I) -> MultiPeek<I::IntoIter> + where I: IntoIterator +{ + MultiPeek { + iter: iterable.into_iter().fuse(), + buf: VecDeque::new(), + index: 0, + } +} + +impl<I> MultiPeek<I> + where I: Iterator +{ + /// Reset the peeking “cursor” + pub fn reset_peek(&mut self) { + self.index = 0; + } +} + +impl<I: Iterator> MultiPeek<I> { + /// Works exactly like `.next()` with the only difference that it doesn't + /// advance itself. `.peek()` can be called multiple times, to peek + /// further ahead. + /// When `.next()` is called, reset the peeking “cursor”. + pub fn peek(&mut self) -> Option<&I::Item> { + let ret = if self.index < self.buf.len() { + Some(&self.buf[self.index]) + } else { + match self.iter.next() { + Some(x) => { + self.buf.push_back(x); + Some(&self.buf[self.index]) + } + None => return None, + } + }; + + self.index += 1; + ret + } +} + +impl<I> PeekingNext for MultiPeek<I> + where I: Iterator, +{ + fn peeking_next<F>(&mut self, accept: F) -> Option<Self::Item> + where F: FnOnce(&Self::Item) -> bool + { + if self.buf.is_empty() { + if let Some(r) = self.peek() { + if !accept(r) { return None } + } + } else if let Some(r) = self.buf.get(0) { + if !accept(r) { return None } + } + self.next() + } +} + +impl<I> Iterator for MultiPeek<I> + where I: Iterator +{ + type Item = I::Item; + + fn next(&mut self) -> Option<Self::Item> { + self.index = 0; + self.buf.pop_front().or_else(|| self.iter.next()) + } + + fn size_hint(&self) -> (usize, Option<usize>) { + size_hint::add_scalar(self.iter.size_hint(), self.buf.len()) + } +} + +// Same size +impl<I> ExactSizeIterator for MultiPeek<I> + where I: ExactSizeIterator +{} + + diff --git a/third_party/rust/itertools/src/pad_tail.rs b/third_party/rust/itertools/src/pad_tail.rs new file mode 100644 index 0000000000..248a432436 --- /dev/null +++ b/third_party/rust/itertools/src/pad_tail.rs @@ -0,0 +1,96 @@ +use std::iter::{Fuse, FusedIterator}; +use crate::size_hint; + +/// An iterator adaptor that pads a sequence to a minimum length by filling +/// missing elements using a closure. +/// +/// Iterator element type is `I::Item`. +/// +/// See [`.pad_using()`](crate::Itertools::pad_using) for more information. +#[derive(Clone)] +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct PadUsing<I, F> { + iter: Fuse<I>, + min: usize, + pos: usize, + filler: F, +} + +impl<I, F> std::fmt::Debug for PadUsing<I, F> +where + I: std::fmt::Debug, +{ + debug_fmt_fields!(PadUsing, iter, min, pos); +} + +/// Create a new `PadUsing` iterator. +pub fn pad_using<I, F>(iter: I, min: usize, filler: F) -> PadUsing<I, F> + where I: Iterator, + F: FnMut(usize) -> I::Item +{ + PadUsing { + iter: iter.fuse(), + min, + pos: 0, + filler, + } +} + +impl<I, F> Iterator for PadUsing<I, F> + where I: Iterator, + F: FnMut(usize) -> I::Item +{ + type Item = I::Item; + + #[inline] + fn next(&mut self) -> Option<Self::Item> { + match self.iter.next() { + None => { + if self.pos < self.min { + let e = Some((self.filler)(self.pos)); + self.pos += 1; + e + } else { + None + } + }, + e => { + self.pos += 1; + e + } + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + let tail = self.min.saturating_sub(self.pos); + size_hint::max(self.iter.size_hint(), (tail, Some(tail))) + } +} + +impl<I, F> DoubleEndedIterator for PadUsing<I, F> + where I: DoubleEndedIterator + ExactSizeIterator, + F: FnMut(usize) -> I::Item +{ + fn next_back(&mut self) -> Option<Self::Item> { + if self.min == 0 { + self.iter.next_back() + } else if self.iter.len() >= self.min { + self.min -= 1; + self.iter.next_back() + } else { + self.min -= 1; + Some((self.filler)(self.min)) + } + } +} + +impl<I, F> ExactSizeIterator for PadUsing<I, F> + where I: ExactSizeIterator, + F: FnMut(usize) -> I::Item +{} + + +impl<I, F> FusedIterator for PadUsing<I, F> + where I: FusedIterator, + F: FnMut(usize) -> I::Item +{} diff --git a/third_party/rust/itertools/src/peek_nth.rs b/third_party/rust/itertools/src/peek_nth.rs new file mode 100644 index 0000000000..bcca45838e --- /dev/null +++ b/third_party/rust/itertools/src/peek_nth.rs @@ -0,0 +1,102 @@ +use crate::size_hint; +use crate::PeekingNext; +use alloc::collections::VecDeque; +use std::iter::Fuse; + +/// See [`peek_nth()`] for more information. +#[derive(Clone, Debug)] +pub struct PeekNth<I> +where + I: Iterator, +{ + iter: Fuse<I>, + buf: VecDeque<I::Item>, +} + +/// A drop-in replacement for [`std::iter::Peekable`] which adds a `peek_nth` +/// method allowing the user to `peek` at a value several iterations forward +/// without advancing the base iterator. +/// +/// This differs from `multipeek` in that subsequent calls to `peek` or +/// `peek_nth` will always return the same value until `next` is called +/// (making `reset_peek` unnecessary). +pub fn peek_nth<I>(iterable: I) -> PeekNth<I::IntoIter> +where + I: IntoIterator, +{ + PeekNth { + iter: iterable.into_iter().fuse(), + buf: VecDeque::new(), + } +} + +impl<I> PeekNth<I> +where + I: Iterator, +{ + /// Works exactly like the `peek` method in `std::iter::Peekable` + pub fn peek(&mut self) -> Option<&I::Item> { + self.peek_nth(0) + } + + /// Returns a reference to the `nth` value without advancing the iterator. + /// + /// # Examples + /// + /// Basic usage: + /// + /// ```rust + /// use itertools::peek_nth; + /// + /// let xs = vec![1,2,3]; + /// let mut iter = peek_nth(xs.iter()); + /// + /// assert_eq!(iter.peek_nth(0), Some(&&1)); + /// assert_eq!(iter.next(), Some(&1)); + /// + /// // The iterator does not advance even if we call `peek_nth` multiple times + /// assert_eq!(iter.peek_nth(0), Some(&&2)); + /// assert_eq!(iter.peek_nth(1), Some(&&3)); + /// assert_eq!(iter.next(), Some(&2)); + /// + /// // Calling `peek_nth` past the end of the iterator will return `None` + /// assert_eq!(iter.peek_nth(1), None); + /// ``` + pub fn peek_nth(&mut self, n: usize) -> Option<&I::Item> { + let unbuffered_items = (n + 1).saturating_sub(self.buf.len()); + + self.buf.extend(self.iter.by_ref().take(unbuffered_items)); + + self.buf.get(n) + } +} + +impl<I> Iterator for PeekNth<I> +where + I: Iterator, +{ + type Item = I::Item; + + fn next(&mut self) -> Option<Self::Item> { + self.buf.pop_front().or_else(|| self.iter.next()) + } + + fn size_hint(&self) -> (usize, Option<usize>) { + size_hint::add_scalar(self.iter.size_hint(), self.buf.len()) + } +} + +impl<I> ExactSizeIterator for PeekNth<I> where I: ExactSizeIterator {} + +impl<I> PeekingNext for PeekNth<I> +where + I: Iterator, +{ + fn peeking_next<F>(&mut self, accept: F) -> Option<Self::Item> + where + F: FnOnce(&Self::Item) -> bool, + { + self.peek().filter(|item| accept(item))?; + self.next() + } +} diff --git a/third_party/rust/itertools/src/peeking_take_while.rs b/third_party/rust/itertools/src/peeking_take_while.rs new file mode 100644 index 0000000000..b3a9c5ccb4 --- /dev/null +++ b/third_party/rust/itertools/src/peeking_take_while.rs @@ -0,0 +1,154 @@ +use std::iter::Peekable; +use crate::PutBack; +#[cfg(feature = "use_alloc")] +use crate::PutBackN; + +/// An iterator that allows peeking at an element before deciding to accept it. +/// +/// See [`.peeking_take_while()`](crate::Itertools::peeking_take_while) +/// for more information. +/// +/// This is implemented by peeking adaptors like peekable and put back, +/// but also by a few iterators that can be peeked natively, like the slice’s +/// by reference iterator (`std::slice::Iter`). +pub trait PeekingNext : Iterator { + /// Pass a reference to the next iterator element to the closure `accept`; + /// if `accept` returns true, return it as the next element, + /// else None. + fn peeking_next<F>(&mut self, accept: F) -> Option<Self::Item> + where F: FnOnce(&Self::Item) -> bool; +} + +impl<I> PeekingNext for Peekable<I> + where I: Iterator, +{ + fn peeking_next<F>(&mut self, accept: F) -> Option<Self::Item> + where F: FnOnce(&Self::Item) -> bool + { + if let Some(r) = self.peek() { + if !accept(r) { + return None; + } + } + self.next() + } +} + +impl<I> PeekingNext for PutBack<I> + where I: Iterator, +{ + fn peeking_next<F>(&mut self, accept: F) -> Option<Self::Item> + where F: FnOnce(&Self::Item) -> bool + { + if let Some(r) = self.next() { + if !accept(&r) { + self.put_back(r); + return None; + } + Some(r) + } else { + None + } + } +} + +#[cfg(feature = "use_alloc")] +impl<I> PeekingNext for PutBackN<I> + where I: Iterator, +{ + fn peeking_next<F>(&mut self, accept: F) -> Option<Self::Item> + where F: FnOnce(&Self::Item) -> bool + { + if let Some(r) = self.next() { + if !accept(&r) { + self.put_back(r); + return None; + } + Some(r) + } else { + None + } + } +} + +/// An iterator adaptor that takes items while a closure returns `true`. +/// +/// See [`.peeking_take_while()`](crate::Itertools::peeking_take_while) +/// for more information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct PeekingTakeWhile<'a, I: 'a, F> + where I: Iterator, +{ + iter: &'a mut I, + f: F, +} + +impl<'a, I: 'a, F> std::fmt::Debug for PeekingTakeWhile<'a, I, F> +where + I: Iterator + std::fmt::Debug, +{ + debug_fmt_fields!(PeekingTakeWhile, iter); +} + +/// Create a `PeekingTakeWhile` +pub fn peeking_take_while<I, F>(iter: &mut I, f: F) -> PeekingTakeWhile<I, F> + where I: Iterator, +{ + PeekingTakeWhile { + iter, + f, + } +} + +impl<'a, I, F> Iterator for PeekingTakeWhile<'a, I, F> + where I: PeekingNext, + F: FnMut(&I::Item) -> bool, + +{ + type Item = I::Item; + fn next(&mut self) -> Option<Self::Item> { + self.iter.peeking_next(&mut self.f) + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (0, self.iter.size_hint().1) + } +} + +// Some iterators are so lightweight we can simply clone them to save their +// state and use that for peeking. +macro_rules! peeking_next_by_clone { + ([$($typarm:tt)*] $type_:ty) => { + impl<$($typarm)*> PeekingNext for $type_ { + fn peeking_next<F>(&mut self, accept: F) -> Option<Self::Item> + where F: FnOnce(&Self::Item) -> bool + { + let saved_state = self.clone(); + if let Some(r) = self.next() { + if !accept(&r) { + *self = saved_state; + } else { + return Some(r) + } + } + None + } + } + } +} + +peeking_next_by_clone! { ['a, T] ::std::slice::Iter<'a, T> } +peeking_next_by_clone! { ['a] ::std::str::Chars<'a> } +peeking_next_by_clone! { ['a] ::std::str::CharIndices<'a> } +peeking_next_by_clone! { ['a] ::std::str::Bytes<'a> } +peeking_next_by_clone! { ['a, T] ::std::option::Iter<'a, T> } +peeking_next_by_clone! { ['a, T] ::std::result::Iter<'a, T> } +peeking_next_by_clone! { [T] ::std::iter::Empty<T> } +#[cfg(feature = "use_alloc")] +peeking_next_by_clone! { ['a, T] alloc::collections::linked_list::Iter<'a, T> } +#[cfg(feature = "use_alloc")] +peeking_next_by_clone! { ['a, T] alloc::collections::vec_deque::Iter<'a, T> } + +// cloning a Rev has no extra overhead; peekable and put backs are never DEI. +peeking_next_by_clone! { [I: Clone + PeekingNext + DoubleEndedIterator] + ::std::iter::Rev<I> } diff --git a/third_party/rust/itertools/src/permutations.rs b/third_party/rust/itertools/src/permutations.rs new file mode 100644 index 0000000000..d03b852626 --- /dev/null +++ b/third_party/rust/itertools/src/permutations.rs @@ -0,0 +1,277 @@ +use alloc::vec::Vec; +use std::fmt; +use std::iter::once; + +use super::lazy_buffer::LazyBuffer; + +/// An iterator adaptor that iterates through all the `k`-permutations of the +/// elements from an iterator. +/// +/// See [`.permutations()`](crate::Itertools::permutations) for +/// more information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct Permutations<I: Iterator> { + vals: LazyBuffer<I>, + state: PermutationState, +} + +impl<I> Clone for Permutations<I> + where I: Clone + Iterator, + I::Item: Clone, +{ + clone_fields!(vals, state); +} + +#[derive(Clone, Debug)] +enum PermutationState { + StartUnknownLen { + k: usize, + }, + OngoingUnknownLen { + k: usize, + min_n: usize, + }, + Complete(CompleteState), + Empty, +} + +#[derive(Clone, Debug)] +enum CompleteState { + Start { + n: usize, + k: usize, + }, + Ongoing { + indices: Vec<usize>, + cycles: Vec<usize>, + } +} + +enum CompleteStateRemaining { + Known(usize), + Overflow, +} + +impl<I> fmt::Debug for Permutations<I> + where I: Iterator + fmt::Debug, + I::Item: fmt::Debug, +{ + debug_fmt_fields!(Permutations, vals, state); +} + +pub fn permutations<I: Iterator>(iter: I, k: usize) -> Permutations<I> { + let mut vals = LazyBuffer::new(iter); + + if k == 0 { + // Special case, yields single empty vec; `n` is irrelevant + let state = PermutationState::Complete(CompleteState::Start { n: 0, k: 0 }); + + return Permutations { + vals, + state + }; + } + + let mut enough_vals = true; + + while vals.len() < k { + if !vals.get_next() { + enough_vals = false; + break; + } + } + + let state = if enough_vals { + PermutationState::StartUnknownLen { k } + } else { + PermutationState::Empty + }; + + Permutations { + vals, + state + } +} + +impl<I> Iterator for Permutations<I> +where + I: Iterator, + I::Item: Clone +{ + type Item = Vec<I::Item>; + + fn next(&mut self) -> Option<Self::Item> { + self.advance(); + + let &mut Permutations { ref vals, ref state } = self; + + match *state { + PermutationState::StartUnknownLen { .. } => panic!("unexpected iterator state"), + PermutationState::OngoingUnknownLen { k, min_n } => { + let latest_idx = min_n - 1; + let indices = (0..(k - 1)).chain(once(latest_idx)); + + Some(indices.map(|i| vals[i].clone()).collect()) + } + PermutationState::Complete(CompleteState::Ongoing { ref indices, ref cycles }) => { + let k = cycles.len(); + Some(indices[0..k].iter().map(|&i| vals[i].clone()).collect()) + }, + PermutationState::Complete(CompleteState::Start { .. }) | PermutationState::Empty => None + } + } + + fn count(self) -> usize { + fn from_complete(complete_state: CompleteState) -> usize { + match complete_state.remaining() { + CompleteStateRemaining::Known(count) => count, + CompleteStateRemaining::Overflow => { + panic!("Iterator count greater than usize::MAX"); + } + } + } + + let Permutations { vals, state } = self; + match state { + PermutationState::StartUnknownLen { k } => { + let n = vals.len() + vals.it.count(); + let complete_state = CompleteState::Start { n, k }; + + from_complete(complete_state) + } + PermutationState::OngoingUnknownLen { k, min_n } => { + let prev_iteration_count = min_n - k + 1; + let n = vals.len() + vals.it.count(); + let complete_state = CompleteState::Start { n, k }; + + from_complete(complete_state) - prev_iteration_count + }, + PermutationState::Complete(state) => from_complete(state), + PermutationState::Empty => 0 + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + match self.state { + PermutationState::StartUnknownLen { .. } | + PermutationState::OngoingUnknownLen { .. } => (0, None), // TODO can we improve this lower bound? + PermutationState::Complete(ref state) => match state.remaining() { + CompleteStateRemaining::Known(count) => (count, Some(count)), + CompleteStateRemaining::Overflow => (::std::usize::MAX, None) + } + PermutationState::Empty => (0, Some(0)) + } + } +} + +impl<I> Permutations<I> +where + I: Iterator, + I::Item: Clone +{ + fn advance(&mut self) { + let &mut Permutations { ref mut vals, ref mut state } = self; + + *state = match *state { + PermutationState::StartUnknownLen { k } => { + PermutationState::OngoingUnknownLen { k, min_n: k } + } + PermutationState::OngoingUnknownLen { k, min_n } => { + if vals.get_next() { + PermutationState::OngoingUnknownLen { k, min_n: min_n + 1 } + } else { + let n = min_n; + let prev_iteration_count = n - k + 1; + let mut complete_state = CompleteState::Start { n, k }; + + // Advance the complete-state iterator to the correct point + for _ in 0..(prev_iteration_count + 1) { + complete_state.advance(); + } + + PermutationState::Complete(complete_state) + } + } + PermutationState::Complete(ref mut state) => { + state.advance(); + + return; + } + PermutationState::Empty => { return; } + }; + } +} + +impl CompleteState { + fn advance(&mut self) { + *self = match *self { + CompleteState::Start { n, k } => { + let indices = (0..n).collect(); + let cycles = ((n - k)..n).rev().collect(); + + CompleteState::Ongoing { + cycles, + indices + } + }, + CompleteState::Ongoing { ref mut indices, ref mut cycles } => { + let n = indices.len(); + let k = cycles.len(); + + for i in (0..k).rev() { + if cycles[i] == 0 { + cycles[i] = n - i - 1; + + let to_push = indices.remove(i); + indices.push(to_push); + } else { + let swap_index = n - cycles[i]; + indices.swap(i, swap_index); + + cycles[i] -= 1; + return; + } + } + + CompleteState::Start { n, k } + } + } + } + + fn remaining(&self) -> CompleteStateRemaining { + use self::CompleteStateRemaining::{Known, Overflow}; + + match *self { + CompleteState::Start { n, k } => { + if n < k { + return Known(0); + } + + let count: Option<usize> = (n - k + 1..n + 1).fold(Some(1), |acc, i| { + acc.and_then(|acc| acc.checked_mul(i)) + }); + + match count { + Some(count) => Known(count), + None => Overflow + } + } + CompleteState::Ongoing { ref indices, ref cycles } => { + let mut count: usize = 0; + + for (i, &c) in cycles.iter().enumerate() { + let radix = indices.len() - i; + let next_count = count.checked_mul(radix) + .and_then(|count| count.checked_add(c)); + + count = match next_count { + Some(count) => count, + None => { return Overflow; } + }; + } + + Known(count) + } + } + } +} diff --git a/third_party/rust/itertools/src/powerset.rs b/third_party/rust/itertools/src/powerset.rs new file mode 100644 index 0000000000..4d7685b12a --- /dev/null +++ b/third_party/rust/itertools/src/powerset.rs @@ -0,0 +1,90 @@ +use std::fmt; +use std::iter::FusedIterator; +use std::usize; +use alloc::vec::Vec; + +use super::combinations::{Combinations, combinations}; +use super::size_hint; + +/// An iterator to iterate through the powerset of the elements from an iterator. +/// +/// See [`.powerset()`](crate::Itertools::powerset) for more +/// information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct Powerset<I: Iterator> { + combs: Combinations<I>, + // Iterator `position` (equal to count of yielded elements). + pos: usize, +} + +impl<I> Clone for Powerset<I> + where I: Clone + Iterator, + I::Item: Clone, +{ + clone_fields!(combs, pos); +} + +impl<I> fmt::Debug for Powerset<I> + where I: Iterator + fmt::Debug, + I::Item: fmt::Debug, +{ + debug_fmt_fields!(Powerset, combs, pos); +} + +/// Create a new `Powerset` from a clonable iterator. +pub fn powerset<I>(src: I) -> Powerset<I> + where I: Iterator, + I::Item: Clone, +{ + Powerset { + combs: combinations(src, 0), + pos: 0, + } +} + +impl<I> Iterator for Powerset<I> + where + I: Iterator, + I::Item: Clone, +{ + type Item = Vec<I::Item>; + + fn next(&mut self) -> Option<Self::Item> { + if let Some(elt) = self.combs.next() { + self.pos = self.pos.saturating_add(1); + Some(elt) + } else if self.combs.k() < self.combs.n() + || self.combs.k() == 0 + { + self.combs.reset(self.combs.k() + 1); + self.combs.next().map(|elt| { + self.pos = self.pos.saturating_add(1); + elt + }) + } else { + None + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + // Total bounds for source iterator. + let src_total = size_hint::add_scalar(self.combs.src().size_hint(), self.combs.n()); + + // Total bounds for self ( length(powerset(set) == 2 ^ length(set) ) + let self_total = size_hint::pow_scalar_base(2, src_total); + + if self.pos < usize::MAX { + // Subtract count of elements already yielded from total. + size_hint::sub_scalar(self_total, self.pos) + } else { + // Fallback: self.pos is saturated and no longer reliable. + (0, self_total.1) + } + } +} + +impl<I> FusedIterator for Powerset<I> + where + I: Iterator, + I::Item: Clone, +{} diff --git a/third_party/rust/itertools/src/process_results_impl.rs b/third_party/rust/itertools/src/process_results_impl.rs new file mode 100644 index 0000000000..44308f3780 --- /dev/null +++ b/third_party/rust/itertools/src/process_results_impl.rs @@ -0,0 +1,97 @@ + +/// An iterator that produces only the `T` values as long as the +/// inner iterator produces `Ok(T)`. +/// +/// Used by [`process_results`](crate::process_results), see its docs +/// for more information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +#[derive(Debug)] +pub struct ProcessResults<'a, I, E: 'a> { + error: &'a mut Result<(), E>, + iter: I, +} + +impl<'a, I, T, E> Iterator for ProcessResults<'a, I, E> + where I: Iterator<Item = Result<T, E>> +{ + type Item = T; + + fn next(&mut self) -> Option<Self::Item> { + match self.iter.next() { + Some(Ok(x)) => Some(x), + Some(Err(e)) => { + *self.error = Err(e); + None + } + None => None, + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (0, self.iter.size_hint().1) + } + + fn fold<B, F>(mut self, init: B, mut f: F) -> B + where + Self: Sized, + F: FnMut(B, Self::Item) -> B, + { + let error = self.error; + self.iter + .try_fold(init, |acc, opt| match opt { + Ok(x) => Ok(f(acc, x)), + Err(e) => { + *error = Err(e); + Err(acc) + } + }) + .unwrap_or_else(|e| e) + } +} + +/// “Lift” a function of the values of an iterator so that it can process +/// an iterator of `Result` values instead. +/// +/// `iterable` is an iterator or iterable with `Result<T, E>` elements, where +/// `T` is the value type and `E` the error type. +/// +/// `processor` is a closure that receives an adapted version of the iterable +/// as the only argument — the adapted iterator produces elements of type `T`, +/// as long as the original iterator produces `Ok` values. +/// +/// If the original iterable produces an error at any point, the adapted +/// iterator ends and the `process_results` function will return the +/// error iself. +/// +/// Otherwise, the return value from the closure is returned wrapped +/// inside `Ok`. +/// +/// # Example +/// +/// ``` +/// use itertools::process_results; +/// +/// type R = Result<i32, &'static str>; +/// +/// let first_values: Vec<R> = vec![Ok(1), Ok(0), Ok(3)]; +/// let second_values: Vec<R> = vec![Ok(2), Ok(1), Err("overflow")]; +/// +/// // “Lift” the iterator .max() method to work on the values in Results using process_results +/// +/// let first_max = process_results(first_values, |iter| iter.max().unwrap_or(0)); +/// let second_max = process_results(second_values, |iter| iter.max().unwrap_or(0)); +/// +/// assert_eq!(first_max, Ok(3)); +/// assert!(second_max.is_err()); +/// ``` +pub fn process_results<I, F, T, E, R>(iterable: I, processor: F) -> Result<R, E> + where I: IntoIterator<Item = Result<T, E>>, + F: FnOnce(ProcessResults<I::IntoIter, E>) -> R +{ + let iter = iterable.into_iter(); + let mut error = Ok(()); + + let result = processor(ProcessResults { error: &mut error, iter }); + + error.map(|_| result) +} diff --git a/third_party/rust/itertools/src/put_back_n_impl.rs b/third_party/rust/itertools/src/put_back_n_impl.rs new file mode 100644 index 0000000000..60ea8e6495 --- /dev/null +++ b/third_party/rust/itertools/src/put_back_n_impl.rs @@ -0,0 +1,61 @@ +use alloc::vec::Vec; + +use crate::size_hint; + +/// An iterator adaptor that allows putting multiple +/// items in front of the iterator. +/// +/// Iterator element type is `I::Item`. +#[derive(Debug, Clone)] +pub struct PutBackN<I: Iterator> { + top: Vec<I::Item>, + iter: I, +} + +/// Create an iterator where you can put back multiple values to the front +/// of the iteration. +/// +/// Iterator element type is `I::Item`. +pub fn put_back_n<I>(iterable: I) -> PutBackN<I::IntoIter> + where I: IntoIterator +{ + PutBackN { + top: Vec::new(), + iter: iterable.into_iter(), + } +} + +impl<I: Iterator> PutBackN<I> { + /// Puts x in front of the iterator. + /// The values are yielded in order of the most recently put back + /// values first. + /// + /// ```rust + /// use itertools::put_back_n; + /// + /// let mut it = put_back_n(1..5); + /// it.next(); + /// it.put_back(1); + /// it.put_back(0); + /// + /// assert!(itertools::equal(it, 0..5)); + /// ``` + #[inline] + pub fn put_back(&mut self, x: I::Item) { + self.top.push(x); + } +} + +impl<I: Iterator> Iterator for PutBackN<I> { + type Item = I::Item; + #[inline] + fn next(&mut self) -> Option<Self::Item> { + self.top.pop().or_else(|| self.iter.next()) + } + + #[inline] + fn size_hint(&self) -> (usize, Option<usize>) { + size_hint::add_scalar(self.iter.size_hint(), self.top.len()) + } +} + diff --git a/third_party/rust/itertools/src/rciter_impl.rs b/third_party/rust/itertools/src/rciter_impl.rs new file mode 100644 index 0000000000..7298350a88 --- /dev/null +++ b/third_party/rust/itertools/src/rciter_impl.rs @@ -0,0 +1,99 @@ + +use std::iter::{FusedIterator, IntoIterator}; +use alloc::rc::Rc; +use std::cell::RefCell; + +/// A wrapper for `Rc<RefCell<I>>`, that implements the `Iterator` trait. +#[derive(Debug)] +pub struct RcIter<I> { + /// The boxed iterator. + pub rciter: Rc<RefCell<I>>, +} + +/// Return an iterator inside a `Rc<RefCell<_>>` wrapper. +/// +/// The returned `RcIter` can be cloned, and each clone will refer back to the +/// same original iterator. +/// +/// `RcIter` allows doing interesting things like using `.zip()` on an iterator with +/// itself, at the cost of runtime borrow checking which may have a performance +/// penalty. +/// +/// Iterator element type is `Self::Item`. +/// +/// ``` +/// use itertools::rciter; +/// use itertools::zip; +/// +/// // In this example a range iterator is created and we iterate it using +/// // three separate handles (two of them given to zip). +/// // We also use the IntoIterator implementation for `&RcIter`. +/// +/// let mut iter = rciter(0..9); +/// let mut z = zip(&iter, &iter); +/// +/// assert_eq!(z.next(), Some((0, 1))); +/// assert_eq!(z.next(), Some((2, 3))); +/// assert_eq!(z.next(), Some((4, 5))); +/// assert_eq!(iter.next(), Some(6)); +/// assert_eq!(z.next(), Some((7, 8))); +/// assert_eq!(z.next(), None); +/// ``` +/// +/// **Panics** in iterator methods if a borrow error is encountered in the +/// iterator methods. It can only happen if the `RcIter` is reentered in +/// `.next()`, i.e. if it somehow participates in an “iterator knot” +/// where it is an adaptor of itself. +pub fn rciter<I>(iterable: I) -> RcIter<I::IntoIter> + where I: IntoIterator +{ + RcIter { rciter: Rc::new(RefCell::new(iterable.into_iter())) } +} + +impl<I> Clone for RcIter<I> { + clone_fields!(rciter); +} + +impl<A, I> Iterator for RcIter<I> + where I: Iterator<Item = A> +{ + type Item = A; + #[inline] + fn next(&mut self) -> Option<Self::Item> { + self.rciter.borrow_mut().next() + } + + #[inline] + fn size_hint(&self) -> (usize, Option<usize>) { + // To work sanely with other API that assume they own an iterator, + // so it can't change in other places, we can't guarantee as much + // in our size_hint. Other clones may drain values under our feet. + (0, self.rciter.borrow().size_hint().1) + } +} + +impl<I> DoubleEndedIterator for RcIter<I> + where I: DoubleEndedIterator +{ + #[inline] + fn next_back(&mut self) -> Option<Self::Item> { + self.rciter.borrow_mut().next_back() + } +} + +/// Return an iterator from `&RcIter<I>` (by simply cloning it). +impl<'a, I> IntoIterator for &'a RcIter<I> + where I: Iterator +{ + type Item = I::Item; + type IntoIter = RcIter<I>; + + fn into_iter(self) -> RcIter<I> { + self.clone() + } +} + + +impl<A, I> FusedIterator for RcIter<I> + where I: FusedIterator<Item = A> +{} diff --git a/third_party/rust/itertools/src/repeatn.rs b/third_party/rust/itertools/src/repeatn.rs new file mode 100644 index 0000000000..e025f6f6a5 --- /dev/null +++ b/third_party/rust/itertools/src/repeatn.rs @@ -0,0 +1,59 @@ +use std::iter::FusedIterator; + +/// An iterator that produces *n* repetitions of an element. +/// +/// See [`repeat_n()`](crate::repeat_n) for more information. +#[must_use = "iterators are lazy and do nothing unless consumed"] +#[derive(Clone, Debug)] +pub struct RepeatN<A> { + elt: Option<A>, + n: usize, +} + +/// Create an iterator that produces `n` repetitions of `element`. +pub fn repeat_n<A>(element: A, n: usize) -> RepeatN<A> + where A: Clone, +{ + if n == 0 { + RepeatN { elt: None, n, } + } else { + RepeatN { elt: Some(element), n, } + } +} + +impl<A> Iterator for RepeatN<A> + where A: Clone +{ + type Item = A; + + fn next(&mut self) -> Option<Self::Item> { + if self.n > 1 { + self.n -= 1; + self.elt.as_ref().cloned() + } else { + self.n = 0; + self.elt.take() + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (self.n, Some(self.n)) + } +} + +impl<A> DoubleEndedIterator for RepeatN<A> + where A: Clone +{ + #[inline] + fn next_back(&mut self) -> Option<Self::Item> { + self.next() + } +} + +impl<A> ExactSizeIterator for RepeatN<A> + where A: Clone +{} + +impl<A> FusedIterator for RepeatN<A> + where A: Clone +{} diff --git a/third_party/rust/itertools/src/size_hint.rs b/third_party/rust/itertools/src/size_hint.rs new file mode 100644 index 0000000000..71ea1412b5 --- /dev/null +++ b/third_party/rust/itertools/src/size_hint.rs @@ -0,0 +1,119 @@ +//! Arithmetic on `Iterator.size_hint()` values. +//! + +use std::usize; +use std::cmp; +use std::u32; + +/// `SizeHint` is the return type of `Iterator::size_hint()`. +pub type SizeHint = (usize, Option<usize>); + +/// Add `SizeHint` correctly. +#[inline] +pub fn add(a: SizeHint, b: SizeHint) -> SizeHint { + let min = a.0.saturating_add(b.0); + let max = match (a.1, b.1) { + (Some(x), Some(y)) => x.checked_add(y), + _ => None, + }; + + (min, max) +} + +/// Add `x` correctly to a `SizeHint`. +#[inline] +pub fn add_scalar(sh: SizeHint, x: usize) -> SizeHint { + let (mut low, mut hi) = sh; + low = low.saturating_add(x); + hi = hi.and_then(|elt| elt.checked_add(x)); + (low, hi) +} + +/// Subtract `x` correctly from a `SizeHint`. +#[inline] +#[allow(dead_code)] +pub fn sub_scalar(sh: SizeHint, x: usize) -> SizeHint { + let (mut low, mut hi) = sh; + low = low.saturating_sub(x); + hi = hi.map(|elt| elt.saturating_sub(x)); + (low, hi) +} + + +/// Multiply `SizeHint` correctly +/// +/// ```ignore +/// use std::usize; +/// use itertools::size_hint; +/// +/// assert_eq!(size_hint::mul((3, Some(4)), (3, Some(4))), +/// (9, Some(16))); +/// +/// assert_eq!(size_hint::mul((3, Some(4)), (usize::MAX, None)), +/// (usize::MAX, None)); +/// +/// assert_eq!(size_hint::mul((3, None), (0, Some(0))), +/// (0, Some(0))); +/// ``` +#[inline] +pub fn mul(a: SizeHint, b: SizeHint) -> SizeHint { + let low = a.0.saturating_mul(b.0); + let hi = match (a.1, b.1) { + (Some(x), Some(y)) => x.checked_mul(y), + (Some(0), None) | (None, Some(0)) => Some(0), + _ => None, + }; + (low, hi) +} + +/// Multiply `x` correctly with a `SizeHint`. +#[inline] +pub fn mul_scalar(sh: SizeHint, x: usize) -> SizeHint { + let (mut low, mut hi) = sh; + low = low.saturating_mul(x); + hi = hi.and_then(|elt| elt.checked_mul(x)); + (low, hi) +} + +/// Raise `base` correctly by a `SizeHint` exponent. +#[inline] +pub fn pow_scalar_base(base: usize, exp: SizeHint) -> SizeHint { + let exp_low = cmp::min(exp.0, u32::MAX as usize) as u32; + let low = base.saturating_pow(exp_low); + + let hi = exp.1.and_then(|exp| { + let exp_hi = cmp::min(exp, u32::MAX as usize) as u32; + base.checked_pow(exp_hi) + }); + + (low, hi) +} + +/// Return the maximum +#[inline] +pub fn max(a: SizeHint, b: SizeHint) -> SizeHint { + let (a_lower, a_upper) = a; + let (b_lower, b_upper) = b; + + let lower = cmp::max(a_lower, b_lower); + + let upper = match (a_upper, b_upper) { + (Some(x), Some(y)) => Some(cmp::max(x, y)), + _ => None, + }; + + (lower, upper) +} + +/// Return the minimum +#[inline] +pub fn min(a: SizeHint, b: SizeHint) -> SizeHint { + let (a_lower, a_upper) = a; + let (b_lower, b_upper) = b; + let lower = cmp::min(a_lower, b_lower); + let upper = match (a_upper, b_upper) { + (Some(u1), Some(u2)) => Some(cmp::min(u1, u2)), + _ => a_upper.or(b_upper), + }; + (lower, upper) +} diff --git a/third_party/rust/itertools/src/sources.rs b/third_party/rust/itertools/src/sources.rs new file mode 100644 index 0000000000..3877ce3c8b --- /dev/null +++ b/third_party/rust/itertools/src/sources.rs @@ -0,0 +1,183 @@ +//! Iterators that are sources (produce elements from parameters, +//! not from another iterator). +#![allow(deprecated)] + +use std::fmt; +use std::mem; + +/// See [`repeat_call`](crate::repeat_call) for more information. +#[derive(Clone)] +#[deprecated(note="Use std repeat_with() instead", since="0.8.0")] +pub struct RepeatCall<F> { + f: F, +} + +impl<F> fmt::Debug for RepeatCall<F> +{ + debug_fmt_fields!(RepeatCall, ); +} + +/// An iterator source that produces elements indefinitely by calling +/// a given closure. +/// +/// Iterator element type is the return type of the closure. +/// +/// ``` +/// use itertools::repeat_call; +/// use itertools::Itertools; +/// use std::collections::BinaryHeap; +/// +/// let mut heap = BinaryHeap::from(vec![2, 5, 3, 7, 8]); +/// +/// // extract each element in sorted order +/// for element in repeat_call(|| heap.pop()).while_some() { +/// print!("{}", element); +/// } +/// +/// itertools::assert_equal( +/// repeat_call(|| 1).take(5), +/// vec![1, 1, 1, 1, 1] +/// ); +/// ``` +#[deprecated(note="Use std repeat_with() instead", since="0.8.0")] +pub fn repeat_call<F, A>(function: F) -> RepeatCall<F> + where F: FnMut() -> A +{ + RepeatCall { f: function } +} + +impl<A, F> Iterator for RepeatCall<F> + where F: FnMut() -> A +{ + type Item = A; + + #[inline] + fn next(&mut self) -> Option<Self::Item> { + Some((self.f)()) + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (usize::max_value(), None) + } +} + +/// Creates a new unfold source with the specified closure as the "iterator +/// function" and an initial state to eventually pass to the closure +/// +/// `unfold` is a general iterator builder: it has a mutable state value, +/// and a closure with access to the state that produces the next value. +/// +/// This more or less equivalent to a regular struct with an [`Iterator`] +/// implementation, and is useful for one-off iterators. +/// +/// ``` +/// // an iterator that yields sequential Fibonacci numbers, +/// // and stops at the maximum representable value. +/// +/// use itertools::unfold; +/// +/// let mut fibonacci = unfold((1u32, 1u32), |(x1, x2)| { +/// // Attempt to get the next Fibonacci number +/// let next = x1.saturating_add(*x2); +/// +/// // Shift left: ret <- x1 <- x2 <- next +/// let ret = *x1; +/// *x1 = *x2; +/// *x2 = next; +/// +/// // If addition has saturated at the maximum, we are finished +/// if ret == *x1 && ret > 1 { +/// None +/// } else { +/// Some(ret) +/// } +/// }); +/// +/// itertools::assert_equal(fibonacci.by_ref().take(8), +/// vec![1, 1, 2, 3, 5, 8, 13, 21]); +/// assert_eq!(fibonacci.last(), Some(2_971_215_073)) +/// ``` +pub fn unfold<A, St, F>(initial_state: St, f: F) -> Unfold<St, F> + where F: FnMut(&mut St) -> Option<A> +{ + Unfold { + f, + state: initial_state, + } +} + +impl<St, F> fmt::Debug for Unfold<St, F> + where St: fmt::Debug, +{ + debug_fmt_fields!(Unfold, state); +} + +/// See [`unfold`](crate::unfold) for more information. +#[derive(Clone)] +#[must_use = "iterators are lazy and do nothing unless consumed"] +pub struct Unfold<St, F> { + f: F, + /// Internal state that will be passed to the closure on the next iteration + pub state: St, +} + +impl<A, St, F> Iterator for Unfold<St, F> + where F: FnMut(&mut St) -> Option<A> +{ + type Item = A; + + #[inline] + fn next(&mut self) -> Option<Self::Item> { + (self.f)(&mut self.state) + } +} + +/// An iterator that infinitely applies function to value and yields results. +/// +/// This `struct` is created by the [`iterate()`](crate::iterate) function. +/// See its documentation for more. +#[derive(Clone)] +#[must_use = "iterators are lazy and do nothing unless consumed"] +pub struct Iterate<St, F> { + state: St, + f: F, +} + +impl<St, F> fmt::Debug for Iterate<St, F> + where St: fmt::Debug, +{ + debug_fmt_fields!(Iterate, state); +} + +impl<St, F> Iterator for Iterate<St, F> + where F: FnMut(&St) -> St +{ + type Item = St; + + #[inline] + fn next(&mut self) -> Option<Self::Item> { + let next_state = (self.f)(&self.state); + Some(mem::replace(&mut self.state, next_state)) + } + + #[inline] + fn size_hint(&self) -> (usize, Option<usize>) { + (usize::max_value(), None) + } +} + +/// Creates a new iterator that infinitely applies function to value and yields results. +/// +/// ``` +/// use itertools::iterate; +/// +/// itertools::assert_equal(iterate(1, |&i| i * 3).take(5), vec![1, 3, 9, 27, 81]); +/// ``` +pub fn iterate<St, F>(initial_value: St, f: F) -> Iterate<St, F> + where F: FnMut(&St) -> St +{ + Iterate { + state: initial_value, + f, + } +} diff --git a/third_party/rust/itertools/src/tee.rs b/third_party/rust/itertools/src/tee.rs new file mode 100644 index 0000000000..ea4752906f --- /dev/null +++ b/third_party/rust/itertools/src/tee.rs @@ -0,0 +1,78 @@ +use super::size_hint; + +use std::cell::RefCell; +use alloc::collections::VecDeque; +use alloc::rc::Rc; + +/// Common buffer object for the two tee halves +#[derive(Debug)] +struct TeeBuffer<A, I> { + backlog: VecDeque<A>, + iter: I, + /// The owner field indicates which id should read from the backlog + owner: bool, +} + +/// One half of an iterator pair where both return the same elements. +/// +/// See [`.tee()`](crate::Itertools::tee) for more information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +#[derive(Debug)] +pub struct Tee<I> + where I: Iterator +{ + rcbuffer: Rc<RefCell<TeeBuffer<I::Item, I>>>, + id: bool, +} + +pub fn new<I>(iter: I) -> (Tee<I>, Tee<I>) + where I: Iterator +{ + let buffer = TeeBuffer{backlog: VecDeque::new(), iter, owner: false}; + let t1 = Tee{rcbuffer: Rc::new(RefCell::new(buffer)), id: true}; + let t2 = Tee{rcbuffer: t1.rcbuffer.clone(), id: false}; + (t1, t2) +} + +impl<I> Iterator for Tee<I> + where I: Iterator, + I::Item: Clone +{ + type Item = I::Item; + fn next(&mut self) -> Option<Self::Item> { + // .borrow_mut may fail here -- but only if the user has tied some kind of weird + // knot where the iterator refers back to itself. + let mut buffer = self.rcbuffer.borrow_mut(); + if buffer.owner == self.id { + match buffer.backlog.pop_front() { + None => {} + some_elt => return some_elt, + } + } + match buffer.iter.next() { + None => None, + Some(elt) => { + buffer.backlog.push_back(elt.clone()); + buffer.owner = !self.id; + Some(elt) + } + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + let buffer = self.rcbuffer.borrow(); + let sh = buffer.iter.size_hint(); + + if buffer.owner == self.id { + let log_len = buffer.backlog.len(); + size_hint::add_scalar(sh, log_len) + } else { + sh + } + } +} + +impl<I> ExactSizeIterator for Tee<I> + where I: ExactSizeIterator, + I::Item: Clone +{} diff --git a/third_party/rust/itertools/src/tuple_impl.rs b/third_party/rust/itertools/src/tuple_impl.rs new file mode 100644 index 0000000000..06b5c13cb3 --- /dev/null +++ b/third_party/rust/itertools/src/tuple_impl.rs @@ -0,0 +1,331 @@ +//! Some iterator that produces tuples + +use std::iter::Fuse; +use std::iter::FusedIterator; +use std::iter::Take; +use std::iter::Cycle; +use std::marker::PhantomData; + +// `HomogeneousTuple` is a public facade for `TupleCollect`, allowing +// tuple-related methods to be used by clients in generic contexts, while +// hiding the implementation details of `TupleCollect`. +// See https://github.com/rust-itertools/itertools/issues/387 + +/// Implemented for homogeneous tuples of size up to 12. +pub trait HomogeneousTuple + : TupleCollect +{} + +impl<T: TupleCollect> HomogeneousTuple for T {} + +/// An iterator over a incomplete tuple. +/// +/// See [`.tuples()`](crate::Itertools::tuples) and +/// [`Tuples::into_buffer()`]. +#[derive(Clone, Debug)] +pub struct TupleBuffer<T> + where T: HomogeneousTuple +{ + cur: usize, + buf: T::Buffer, +} + +impl<T> TupleBuffer<T> + where T: HomogeneousTuple +{ + fn new(buf: T::Buffer) -> Self { + TupleBuffer { + cur: 0, + buf, + } + } +} + +impl<T> Iterator for TupleBuffer<T> + where T: HomogeneousTuple +{ + type Item = T::Item; + + fn next(&mut self) -> Option<Self::Item> { + let s = self.buf.as_mut(); + if let Some(ref mut item) = s.get_mut(self.cur) { + self.cur += 1; + item.take() + } else { + None + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + let buffer = &self.buf.as_ref()[self.cur..]; + let len = if buffer.is_empty() { + 0 + } else { + buffer.iter() + .position(|x| x.is_none()) + .unwrap_or_else(|| buffer.len()) + }; + (len, Some(len)) + } +} + +impl<T> ExactSizeIterator for TupleBuffer<T> + where T: HomogeneousTuple +{ +} + +/// An iterator that groups the items in tuples of a specific size. +/// +/// See [`.tuples()`](crate::Itertools::tuples) for more information. +#[derive(Clone, Debug)] +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct Tuples<I, T> + where I: Iterator<Item = T::Item>, + T: HomogeneousTuple +{ + iter: Fuse<I>, + buf: T::Buffer, +} + +/// Create a new tuples iterator. +pub fn tuples<I, T>(iter: I) -> Tuples<I, T> + where I: Iterator<Item = T::Item>, + T: HomogeneousTuple +{ + Tuples { + iter: iter.fuse(), + buf: Default::default(), + } +} + +impl<I, T> Iterator for Tuples<I, T> + where I: Iterator<Item = T::Item>, + T: HomogeneousTuple +{ + type Item = T; + + fn next(&mut self) -> Option<Self::Item> { + T::collect_from_iter(&mut self.iter, &mut self.buf) + } +} + +impl<I, T> Tuples<I, T> + where I: Iterator<Item = T::Item>, + T: HomogeneousTuple +{ + /// Return a buffer with the produced items that was not enough to be grouped in a tuple. + /// + /// ``` + /// use itertools::Itertools; + /// + /// let mut iter = (0..5).tuples(); + /// assert_eq!(Some((0, 1, 2)), iter.next()); + /// assert_eq!(None, iter.next()); + /// itertools::assert_equal(vec![3, 4], iter.into_buffer()); + /// ``` + pub fn into_buffer(self) -> TupleBuffer<T> { + TupleBuffer::new(self.buf) + } +} + + +/// An iterator over all contiguous windows that produces tuples of a specific size. +/// +/// See [`.tuple_windows()`](crate::Itertools::tuple_windows) for more +/// information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +#[derive(Clone, Debug)] +pub struct TupleWindows<I, T> + where I: Iterator<Item = T::Item>, + T: HomogeneousTuple +{ + iter: I, + last: Option<T>, +} + +/// Create a new tuple windows iterator. +pub fn tuple_windows<I, T>(mut iter: I) -> TupleWindows<I, T> + where I: Iterator<Item = T::Item>, + T: HomogeneousTuple, + T::Item: Clone +{ + use std::iter::once; + + let mut last = None; + if T::num_items() != 1 { + // put in a duplicate item in front of the tuple; this simplifies + // .next() function. + if let Some(item) = iter.next() { + let iter = once(item.clone()).chain(once(item)).chain(&mut iter); + last = T::collect_from_iter_no_buf(iter); + } + } + + TupleWindows { + iter, + last, + } +} + +impl<I, T> Iterator for TupleWindows<I, T> + where I: Iterator<Item = T::Item>, + T: HomogeneousTuple + Clone, + T::Item: Clone +{ + type Item = T; + + fn next(&mut self) -> Option<Self::Item> { + if T::num_items() == 1 { + return T::collect_from_iter_no_buf(&mut self.iter) + } + if let Some(ref mut last) = self.last { + if let Some(new) = self.iter.next() { + last.left_shift_push(new); + return Some(last.clone()); + } + } + None + } +} + +impl<I, T> FusedIterator for TupleWindows<I, T> + where I: FusedIterator<Item = T::Item>, + T: HomogeneousTuple + Clone, + T::Item: Clone +{} + +/// An iterator over all windows,wrapping back to the first elements when the +/// window would otherwise exceed the length of the iterator, producing tuples +/// of a specific size. +/// +/// See [`.circular_tuple_windows()`](crate::Itertools::circular_tuple_windows) for more +/// information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +#[derive(Debug)] +pub struct CircularTupleWindows<I, T: Clone> + where I: Iterator<Item = T::Item> + Clone, + T: TupleCollect + Clone +{ + iter: Take<TupleWindows<Cycle<I>, T>>, + phantom_data: PhantomData<T> +} + +pub fn circular_tuple_windows<I, T>(iter: I) -> CircularTupleWindows<I, T> + where I: Iterator<Item = T::Item> + Clone + ExactSizeIterator, + T: TupleCollect + Clone, + T::Item: Clone +{ + let len = iter.len(); + let iter = tuple_windows(iter.cycle()).take(len); + + CircularTupleWindows { + iter, + phantom_data: PhantomData{} + } +} + +impl<I, T> Iterator for CircularTupleWindows<I, T> + where I: Iterator<Item = T::Item> + Clone, + T: TupleCollect + Clone, + T::Item: Clone +{ + type Item = T; + + fn next(&mut self) -> Option<Self::Item> { + self.iter.next() + } +} + +pub trait TupleCollect: Sized { + type Item; + type Buffer: Default + AsRef<[Option<Self::Item>]> + AsMut<[Option<Self::Item>]>; + + fn collect_from_iter<I>(iter: I, buf: &mut Self::Buffer) -> Option<Self> + where I: IntoIterator<Item = Self::Item>; + + fn collect_from_iter_no_buf<I>(iter: I) -> Option<Self> + where I: IntoIterator<Item = Self::Item>; + + fn num_items() -> usize; + + fn left_shift_push(&mut self, item: Self::Item); +} + +macro_rules! count_ident{ + () => {0}; + ($i0:ident, $($i:ident,)*) => {1 + count_ident!($($i,)*)}; +} +macro_rules! rev_for_each_ident{ + ($m:ident, ) => {}; + ($m:ident, $i0:ident, $($i:ident,)*) => { + rev_for_each_ident!($m, $($i,)*); + $m!($i0); + }; +} + +macro_rules! impl_tuple_collect { + ($dummy:ident,) => {}; // stop + ($dummy:ident, $($Y:ident,)*) => ( + impl_tuple_collect!($($Y,)*); + impl<A> TupleCollect for ($(ignore_ident!($Y, A),)*) { + type Item = A; + type Buffer = [Option<A>; count_ident!($($Y,)*) - 1]; + + #[allow(unused_assignments, unused_mut)] + fn collect_from_iter<I>(iter: I, buf: &mut Self::Buffer) -> Option<Self> + where I: IntoIterator<Item = A> + { + let mut iter = iter.into_iter(); + $( + let mut $Y = None; + )* + + loop { + $( + $Y = iter.next(); + if $Y.is_none() { + break + } + )* + return Some(($($Y.unwrap()),*,)) + } + + let mut i = 0; + let mut s = buf.as_mut(); + $( + if i < s.len() { + s[i] = $Y; + i += 1; + } + )* + return None; + } + + fn collect_from_iter_no_buf<I>(iter: I) -> Option<Self> + where I: IntoIterator<Item = A> + { + let mut iter = iter.into_iter(); + + Some(($( + { let $Y = iter.next()?; $Y }, + )*)) + } + + fn num_items() -> usize { + count_ident!($($Y,)*) + } + + fn left_shift_push(&mut self, mut item: A) { + use std::mem::replace; + + let &mut ($(ref mut $Y),*,) = self; + macro_rules! replace_item{($i:ident) => { + item = replace($i, item); + }} + rev_for_each_ident!(replace_item, $($Y,)*); + drop(item); + } + } + ) +} +impl_tuple_collect!(dummy, a, b, c, d, e, f, g, h, i, j, k, l,); diff --git a/third_party/rust/itertools/src/unique_impl.rs b/third_party/rust/itertools/src/unique_impl.rs new file mode 100644 index 0000000000..4e81e78ec0 --- /dev/null +++ b/third_party/rust/itertools/src/unique_impl.rs @@ -0,0 +1,179 @@ +use std::collections::HashMap; +use std::collections::hash_map::Entry; +use std::hash::Hash; +use std::fmt; +use std::iter::FusedIterator; + +/// An iterator adapter to filter out duplicate elements. +/// +/// See [`.unique_by()`](crate::Itertools::unique) for more information. +#[derive(Clone)] +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct UniqueBy<I: Iterator, V, F> { + iter: I, + // Use a Hashmap for the Entry API in order to prevent hashing twice. + // This can maybe be replaced with a HashSet once `get_or_insert_with` + // or a proper Entry API for Hashset is stable and meets this msrv + used: HashMap<V, ()>, + f: F, +} + +impl<I, V, F> fmt::Debug for UniqueBy<I, V, F> + where I: Iterator + fmt::Debug, + V: fmt::Debug + Hash + Eq, +{ + debug_fmt_fields!(UniqueBy, iter, used); +} + +/// Create a new `UniqueBy` iterator. +pub fn unique_by<I, V, F>(iter: I, f: F) -> UniqueBy<I, V, F> + where V: Eq + Hash, + F: FnMut(&I::Item) -> V, + I: Iterator, +{ + UniqueBy { + iter, + used: HashMap::new(), + f, + } +} + +// count the number of new unique keys in iterable (`used` is the set already seen) +fn count_new_keys<I, K>(mut used: HashMap<K, ()>, iterable: I) -> usize + where I: IntoIterator<Item=K>, + K: Hash + Eq, +{ + let iter = iterable.into_iter(); + let current_used = used.len(); + used.extend(iter.map(|key| (key, ()))); + used.len() - current_used +} + +impl<I, V, F> Iterator for UniqueBy<I, V, F> + where I: Iterator, + V: Eq + Hash, + F: FnMut(&I::Item) -> V +{ + type Item = I::Item; + + fn next(&mut self) -> Option<Self::Item> { + while let Some(v) = self.iter.next() { + let key = (self.f)(&v); + if self.used.insert(key, ()).is_none() { + return Some(v); + } + } + None + } + + #[inline] + fn size_hint(&self) -> (usize, Option<usize>) { + let (low, hi) = self.iter.size_hint(); + ((low > 0 && self.used.is_empty()) as usize, hi) + } + + fn count(self) -> usize { + let mut key_f = self.f; + count_new_keys(self.used, self.iter.map(move |elt| key_f(&elt))) + } +} + +impl<I, V, F> DoubleEndedIterator for UniqueBy<I, V, F> + where I: DoubleEndedIterator, + V: Eq + Hash, + F: FnMut(&I::Item) -> V +{ + fn next_back(&mut self) -> Option<Self::Item> { + while let Some(v) = self.iter.next_back() { + let key = (self.f)(&v); + if self.used.insert(key, ()).is_none() { + return Some(v); + } + } + None + } +} + +impl<I, V, F> FusedIterator for UniqueBy<I, V, F> + where I: FusedIterator, + V: Eq + Hash, + F: FnMut(&I::Item) -> V +{} + +impl<I> Iterator for Unique<I> + where I: Iterator, + I::Item: Eq + Hash + Clone +{ + type Item = I::Item; + + fn next(&mut self) -> Option<Self::Item> { + while let Some(v) = self.iter.iter.next() { + if let Entry::Vacant(entry) = self.iter.used.entry(v) { + let elt = entry.key().clone(); + entry.insert(()); + return Some(elt); + } + } + None + } + + #[inline] + fn size_hint(&self) -> (usize, Option<usize>) { + let (low, hi) = self.iter.iter.size_hint(); + ((low > 0 && self.iter.used.is_empty()) as usize, hi) + } + + fn count(self) -> usize { + count_new_keys(self.iter.used, self.iter.iter) + } +} + +impl<I> DoubleEndedIterator for Unique<I> + where I: DoubleEndedIterator, + I::Item: Eq + Hash + Clone +{ + fn next_back(&mut self) -> Option<Self::Item> { + while let Some(v) = self.iter.iter.next_back() { + if let Entry::Vacant(entry) = self.iter.used.entry(v) { + let elt = entry.key().clone(); + entry.insert(()); + return Some(elt); + } + } + None + } +} + +impl<I> FusedIterator for Unique<I> + where I: FusedIterator, + I::Item: Eq + Hash + Clone +{} + +/// An iterator adapter to filter out duplicate elements. +/// +/// See [`.unique()`](crate::Itertools::unique) for more information. +#[derive(Clone)] +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct Unique<I: Iterator> { + iter: UniqueBy<I, I::Item, ()>, +} + +impl<I> fmt::Debug for Unique<I> + where I: Iterator + fmt::Debug, + I::Item: Hash + Eq + fmt::Debug, +{ + debug_fmt_fields!(Unique, iter); +} + +pub fn unique<I>(iter: I) -> Unique<I> + where I: Iterator, + I::Item: Eq + Hash, +{ + Unique { + iter: UniqueBy { + iter, + used: HashMap::new(), + f: (), + } + } +} diff --git a/third_party/rust/itertools/src/unziptuple.rs b/third_party/rust/itertools/src/unziptuple.rs new file mode 100644 index 0000000000..7af29ec4ab --- /dev/null +++ b/third_party/rust/itertools/src/unziptuple.rs @@ -0,0 +1,80 @@ +/// Converts an iterator of tuples into a tuple of containers. +/// +/// `unzip()` consumes an entire iterator of n-ary tuples, producing `n` collections, one for each +/// column. +/// +/// This function is, in some sense, the opposite of [`multizip`]. +/// +/// ``` +/// use itertools::multiunzip; +/// +/// let inputs = vec![(1, 2, 3), (4, 5, 6), (7, 8, 9)]; +/// +/// let (a, b, c): (Vec<_>, Vec<_>, Vec<_>) = multiunzip(inputs); +/// +/// assert_eq!(a, vec![1, 4, 7]); +/// assert_eq!(b, vec![2, 5, 8]); +/// assert_eq!(c, vec![3, 6, 9]); +/// ``` +/// +/// [`multizip`]: crate::multizip +pub fn multiunzip<FromI, I>(i: I) -> FromI +where + I: IntoIterator, + I::IntoIter: MultiUnzip<FromI>, +{ + i.into_iter().multiunzip() +} + +/// An iterator that can be unzipped into multiple collections. +/// +/// See [`.multiunzip()`](crate::Itertools::multiunzip) for more information. +pub trait MultiUnzip<FromI>: Iterator { + /// Unzip this iterator into multiple collections. + fn multiunzip(self) -> FromI; +} + +macro_rules! impl_unzip_iter { + ($($T:ident => $FromT:ident),*) => ( + #[allow(non_snake_case)] + impl<IT: Iterator<Item = ($($T,)*)>, $($T, $FromT: Default + Extend<$T>),* > MultiUnzip<($($FromT,)*)> for IT { + fn multiunzip(self) -> ($($FromT,)*) { + // This implementation mirrors the logic of Iterator::unzip resp. Extend for (A, B) as close as possible. + // Unfortunately a lot of the used api there is still unstable (https://github.com/rust-lang/rust/issues/72631). + // + // Iterator::unzip: https://doc.rust-lang.org/src/core/iter/traits/iterator.rs.html#2825-2865 + // Extend for (A, B): https://doc.rust-lang.org/src/core/iter/traits/collect.rs.html#370-411 + + let mut res = ($($FromT::default(),)*); + let ($($FromT,)*) = &mut res; + + // Still unstable #72631 + // let (lower_bound, _) = self.size_hint(); + // if lower_bound > 0 { + // $($FromT.extend_reserve(lower_bound);)* + // } + + self.fold((), |(), ($($T,)*)| { + // Still unstable #72631 + // $( $FromT.extend_one($T); )* + $( $FromT.extend(std::iter::once($T)); )* + }); + res + } + } + ); +} + +impl_unzip_iter!(); +impl_unzip_iter!(A => FromA); +impl_unzip_iter!(A => FromA, B => FromB); +impl_unzip_iter!(A => FromA, B => FromB, C => FromC); +impl_unzip_iter!(A => FromA, B => FromB, C => FromC, D => FromD); +impl_unzip_iter!(A => FromA, B => FromB, C => FromC, D => FromD, E => FromE); +impl_unzip_iter!(A => FromA, B => FromB, C => FromC, D => FromD, E => FromE, F => FromF); +impl_unzip_iter!(A => FromA, B => FromB, C => FromC, D => FromD, E => FromE, F => FromF, G => FromG); +impl_unzip_iter!(A => FromA, B => FromB, C => FromC, D => FromD, E => FromE, F => FromF, G => FromG, H => FromH); +impl_unzip_iter!(A => FromA, B => FromB, C => FromC, D => FromD, E => FromE, F => FromF, G => FromG, H => FromH, I => FromI); +impl_unzip_iter!(A => FromA, B => FromB, C => FromC, D => FromD, E => FromE, F => FromF, G => FromG, H => FromH, I => FromI, J => FromJ); +impl_unzip_iter!(A => FromA, B => FromB, C => FromC, D => FromD, E => FromE, F => FromF, G => FromG, H => FromH, I => FromI, J => FromJ, K => FromK); +impl_unzip_iter!(A => FromA, B => FromB, C => FromC, D => FromD, E => FromE, F => FromF, G => FromG, H => FromH, I => FromI, J => FromJ, K => FromK, L => FromL); diff --git a/third_party/rust/itertools/src/with_position.rs b/third_party/rust/itertools/src/with_position.rs new file mode 100644 index 0000000000..1388503d1c --- /dev/null +++ b/third_party/rust/itertools/src/with_position.rs @@ -0,0 +1,100 @@ +use std::iter::{Fuse,Peekable, FusedIterator}; + +/// An iterator adaptor that wraps each element in an [`Position`]. +/// +/// Iterator element type is `Position<I::Item>`. +/// +/// See [`.with_position()`](crate::Itertools::with_position) for more information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct WithPosition<I> + where I: Iterator, +{ + handled_first: bool, + peekable: Peekable<Fuse<I>>, +} + +impl<I> Clone for WithPosition<I> + where I: Clone + Iterator, + I::Item: Clone, +{ + clone_fields!(handled_first, peekable); +} + +/// Create a new `WithPosition` iterator. +pub fn with_position<I>(iter: I) -> WithPosition<I> + where I: Iterator, +{ + WithPosition { + handled_first: false, + peekable: iter.fuse().peekable(), + } +} + +/// A value yielded by `WithPosition`. +/// Indicates the position of this element in the iterator results. +/// +/// See [`.with_position()`](crate::Itertools::with_position) for more information. +#[derive(Copy, Clone, Debug, PartialEq)] +pub enum Position<T> { + /// This is the first element. + First(T), + /// This is neither the first nor the last element. + Middle(T), + /// This is the last element. + Last(T), + /// This is the only element. + Only(T), +} + +impl<T> Position<T> { + /// Return the inner value. + pub fn into_inner(self) -> T { + match self { + Position::First(x) | + Position::Middle(x) | + Position::Last(x) | + Position::Only(x) => x, + } + } +} + +impl<I: Iterator> Iterator for WithPosition<I> { + type Item = Position<I::Item>; + + fn next(&mut self) -> Option<Self::Item> { + match self.peekable.next() { + Some(item) => { + if !self.handled_first { + // Haven't seen the first item yet, and there is one to give. + self.handled_first = true; + // Peek to see if this is also the last item, + // in which case tag it as `Only`. + match self.peekable.peek() { + Some(_) => Some(Position::First(item)), + None => Some(Position::Only(item)), + } + } else { + // Have seen the first item, and there's something left. + // Peek to see if this is the last item. + match self.peekable.peek() { + Some(_) => Some(Position::Middle(item)), + None => Some(Position::Last(item)), + } + } + } + // Iterator is finished. + None => None, + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + self.peekable.size_hint() + } +} + +impl<I> ExactSizeIterator for WithPosition<I> + where I: ExactSizeIterator, +{ } + +impl<I: Iterator> FusedIterator for WithPosition<I> +{} diff --git a/third_party/rust/itertools/src/zip_eq_impl.rs b/third_party/rust/itertools/src/zip_eq_impl.rs new file mode 100644 index 0000000000..a079b326a4 --- /dev/null +++ b/third_party/rust/itertools/src/zip_eq_impl.rs @@ -0,0 +1,60 @@ +use super::size_hint; + +/// An iterator which iterates two other iterators simultaneously +/// +/// See [`.zip_eq()`](crate::Itertools::zip_eq) for more information. +#[derive(Clone, Debug)] +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct ZipEq<I, J> { + a: I, + b: J, +} + +/// Iterate `i` and `j` in lock step. +/// +/// **Panics** if the iterators are not of the same length. +/// +/// [`IntoIterator`] enabled version of [`Itertools::zip_eq`](crate::Itertools::zip_eq). +/// +/// ``` +/// use itertools::zip_eq; +/// +/// let data = [1, 2, 3, 4, 5]; +/// for (a, b) in zip_eq(&data[..data.len() - 1], &data[1..]) { +/// /* loop body */ +/// } +/// ``` +pub fn zip_eq<I, J>(i: I, j: J) -> ZipEq<I::IntoIter, J::IntoIter> + where I: IntoIterator, + J: IntoIterator +{ + ZipEq { + a: i.into_iter(), + b: j.into_iter(), + } +} + +impl<I, J> Iterator for ZipEq<I, J> + where I: Iterator, + J: Iterator +{ + type Item = (I::Item, J::Item); + + fn next(&mut self) -> Option<Self::Item> { + match (self.a.next(), self.b.next()) { + (None, None) => None, + (Some(a), Some(b)) => Some((a, b)), + (None, Some(_)) | (Some(_), None) => + panic!("itertools: .zip_eq() reached end of one iterator before the other") + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + size_hint::min(self.a.size_hint(), self.b.size_hint()) + } +} + +impl<I, J> ExactSizeIterator for ZipEq<I, J> + where I: ExactSizeIterator, + J: ExactSizeIterator +{} diff --git a/third_party/rust/itertools/src/zip_longest.rs b/third_party/rust/itertools/src/zip_longest.rs new file mode 100644 index 0000000000..cb9a7bacb2 --- /dev/null +++ b/third_party/rust/itertools/src/zip_longest.rs @@ -0,0 +1,83 @@ +use std::cmp::Ordering::{Equal, Greater, Less}; +use super::size_hint; +use std::iter::{Fuse, FusedIterator}; + +use crate::either_or_both::EitherOrBoth; + +// ZipLongest originally written by SimonSapin, +// and dedicated to itertools https://github.com/rust-lang/rust/pull/19283 + +/// An iterator which iterates two other iterators simultaneously +/// +/// This iterator is *fused*. +/// +/// See [`.zip_longest()`](crate::Itertools::zip_longest) for more information. +#[derive(Clone, Debug)] +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct ZipLongest<T, U> { + a: Fuse<T>, + b: Fuse<U>, +} + +/// Create a new `ZipLongest` iterator. +pub fn zip_longest<T, U>(a: T, b: U) -> ZipLongest<T, U> + where T: Iterator, + U: Iterator +{ + ZipLongest { + a: a.fuse(), + b: b.fuse(), + } +} + +impl<T, U> Iterator for ZipLongest<T, U> + where T: Iterator, + U: Iterator +{ + type Item = EitherOrBoth<T::Item, U::Item>; + + #[inline] + fn next(&mut self) -> Option<Self::Item> { + match (self.a.next(), self.b.next()) { + (None, None) => None, + (Some(a), None) => Some(EitherOrBoth::Left(a)), + (None, Some(b)) => Some(EitherOrBoth::Right(b)), + (Some(a), Some(b)) => Some(EitherOrBoth::Both(a, b)), + } + } + + #[inline] + fn size_hint(&self) -> (usize, Option<usize>) { + size_hint::max(self.a.size_hint(), self.b.size_hint()) + } +} + +impl<T, U> DoubleEndedIterator for ZipLongest<T, U> + where T: DoubleEndedIterator + ExactSizeIterator, + U: DoubleEndedIterator + ExactSizeIterator +{ + #[inline] + fn next_back(&mut self) -> Option<Self::Item> { + match self.a.len().cmp(&self.b.len()) { + Equal => match (self.a.next_back(), self.b.next_back()) { + (None, None) => None, + (Some(a), Some(b)) => Some(EitherOrBoth::Both(a, b)), + // These can only happen if .len() is inconsistent with .next_back() + (Some(a), None) => Some(EitherOrBoth::Left(a)), + (None, Some(b)) => Some(EitherOrBoth::Right(b)), + }, + Greater => self.a.next_back().map(EitherOrBoth::Left), + Less => self.b.next_back().map(EitherOrBoth::Right), + } + } +} + +impl<T, U> ExactSizeIterator for ZipLongest<T, U> + where T: ExactSizeIterator, + U: ExactSizeIterator +{} + +impl<T, U> FusedIterator for ZipLongest<T, U> + where T: Iterator, + U: Iterator +{} diff --git a/third_party/rust/itertools/src/ziptuple.rs b/third_party/rust/itertools/src/ziptuple.rs new file mode 100644 index 0000000000..6d3a584c49 --- /dev/null +++ b/third_party/rust/itertools/src/ziptuple.rs @@ -0,0 +1,138 @@ +use super::size_hint; + +/// See [`multizip`] for more information. +#[derive(Clone, Debug)] +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +pub struct Zip<T> { + t: T, +} + +/// An iterator that generalizes *.zip()* and allows running multiple iterators in lockstep. +/// +/// The iterator `Zip<(I, J, ..., M)>` is formed from a tuple of iterators (or values that +/// implement [`IntoIterator`]) and yields elements +/// until any of the subiterators yields `None`. +/// +/// The iterator element type is a tuple like like `(A, B, ..., E)` where `A` to `E` are the +/// element types of the subiterator. +/// +/// **Note:** The result of this macro is a value of a named type (`Zip<(I, J, +/// ..)>` of each component iterator `I, J, ...`) if each component iterator is +/// nameable. +/// +/// Prefer [`izip!()`] over `multizip` for the performance benefits of using the +/// standard library `.zip()`. Prefer `multizip` if a nameable type is needed. +/// +/// ``` +/// use itertools::multizip; +/// +/// // iterate over three sequences side-by-side +/// let mut results = [0, 0, 0, 0]; +/// let inputs = [3, 7, 9, 6]; +/// +/// for (r, index, input) in multizip((&mut results, 0..10, &inputs)) { +/// *r = index * 10 + input; +/// } +/// +/// assert_eq!(results, [0 + 3, 10 + 7, 29, 36]); +/// ``` +/// [`izip!()`]: crate::izip +pub fn multizip<T, U>(t: U) -> Zip<T> + where Zip<T>: From<U>, + Zip<T>: Iterator, +{ + Zip::from(t) +} + +macro_rules! impl_zip_iter { + ($($B:ident),*) => ( + #[allow(non_snake_case)] + impl<$($B: IntoIterator),*> From<($($B,)*)> for Zip<($($B::IntoIter,)*)> { + fn from(t: ($($B,)*)) -> Self { + let ($($B,)*) = t; + Zip { t: ($($B.into_iter(),)*) } + } + } + + #[allow(non_snake_case)] + #[allow(unused_assignments)] + impl<$($B),*> Iterator for Zip<($($B,)*)> + where + $( + $B: Iterator, + )* + { + type Item = ($($B::Item,)*); + + fn next(&mut self) -> Option<Self::Item> + { + let ($(ref mut $B,)*) = self.t; + + // NOTE: Just like iter::Zip, we check the iterators + // for None in order. We may finish unevenly (some + // iterators gave n + 1 elements, some only n). + $( + let $B = match $B.next() { + None => return None, + Some(elt) => elt + }; + )* + Some(($($B,)*)) + } + + fn size_hint(&self) -> (usize, Option<usize>) + { + let sh = (::std::usize::MAX, None); + let ($(ref $B,)*) = self.t; + $( + let sh = size_hint::min($B.size_hint(), sh); + )* + sh + } + } + + #[allow(non_snake_case)] + impl<$($B),*> ExactSizeIterator for Zip<($($B,)*)> where + $( + $B: ExactSizeIterator, + )* + { } + + #[allow(non_snake_case)] + impl<$($B),*> DoubleEndedIterator for Zip<($($B,)*)> where + $( + $B: DoubleEndedIterator + ExactSizeIterator, + )* + { + #[inline] + fn next_back(&mut self) -> Option<Self::Item> { + let ($(ref mut $B,)*) = self.t; + let size = *[$( $B.len(), )*].iter().min().unwrap(); + + $( + if $B.len() != size { + for _ in 0..$B.len() - size { $B.next_back(); } + } + )* + + match ($($B.next_back(),)*) { + ($(Some($B),)*) => Some(($($B,)*)), + _ => None, + } + } + } + ); +} + +impl_zip_iter!(A); +impl_zip_iter!(A, B); +impl_zip_iter!(A, B, C); +impl_zip_iter!(A, B, C, D); +impl_zip_iter!(A, B, C, D, E); +impl_zip_iter!(A, B, C, D, E, F); +impl_zip_iter!(A, B, C, D, E, F, G); +impl_zip_iter!(A, B, C, D, E, F, G, H); +impl_zip_iter!(A, B, C, D, E, F, G, H, I); +impl_zip_iter!(A, B, C, D, E, F, G, H, I, J); +impl_zip_iter!(A, B, C, D, E, F, G, H, I, J, K); +impl_zip_iter!(A, B, C, D, E, F, G, H, I, J, K, L); |