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Diffstat (limited to 'third_party/rust/rayon/src/range_inclusive.rs')
| -rw-r--r-- | third_party/rust/rayon/src/range_inclusive.rs | 288 |
1 files changed, 288 insertions, 0 deletions
diff --git a/third_party/rust/rayon/src/range_inclusive.rs b/third_party/rust/rayon/src/range_inclusive.rs new file mode 100644 index 0000000000..c802b6c61d --- /dev/null +++ b/third_party/rust/rayon/src/range_inclusive.rs @@ -0,0 +1,288 @@ +//! Parallel iterator types for [inclusive ranges][std::range], +//! the type for values created by `a..=b` expressions +//! +//! You will rarely need to interact with this module directly unless you have +//! need to name one of the iterator types. +//! +//! ``` +//! use rayon::prelude::*; +//! +//! let r = (0..=100u64).into_par_iter() +//! .sum(); +//! +//! // compare result with sequential calculation +//! assert_eq!((0..=100).sum::<u64>(), r); +//! ``` +//! +//! [std::range]: https://doc.rust-lang.org/core/ops/struct.RangeInclusive.html + +use crate::iter::plumbing::*; +use crate::iter::*; +use std::char; +use std::ops::RangeInclusive; + +/// Parallel iterator over an inclusive range, implemented for all integer types. +/// +/// **Note:** The `zip` operation requires `IndexedParallelIterator` +/// which is only implemented for `u8`, `i8`, `u16`, and `i16`. +/// +/// ``` +/// use rayon::prelude::*; +/// +/// let p = (0..=25u16).into_par_iter() +/// .zip(0..=25u16) +/// .filter(|&(x, y)| x % 5 == 0 || y % 5 == 0) +/// .map(|(x, y)| x * y) +/// .sum::<u16>(); +/// +/// let s = (0..=25u16).zip(0..=25u16) +/// .filter(|&(x, y)| x % 5 == 0 || y % 5 == 0) +/// .map(|(x, y)| x * y) +/// .sum(); +/// +/// assert_eq!(p, s); +/// ``` +#[derive(Debug, Clone)] +pub struct Iter<T> { + range: RangeInclusive<T>, +} + +impl<T> Iter<T> +where + RangeInclusive<T>: Eq, + T: Ord + Copy, +{ + /// Returns `Some((start, end))` for `start..=end`, or `None` if it is exhausted. + /// + /// Note that `RangeInclusive` does not specify the bounds of an exhausted iterator, + /// so this is a way for us to figure out what we've got. Thankfully, all of the + /// integer types we care about can be trivially cloned. + fn bounds(&self) -> Option<(T, T)> { + let start = *self.range.start(); + let end = *self.range.end(); + if start <= end && self.range == (start..=end) { + // If the range is still nonempty, this is obviously true + // If the range is exhausted, either start > end or + // the range does not equal start..=end. + Some((start, end)) + } else { + None + } + } +} + +impl<T> IntoParallelIterator for RangeInclusive<T> +where + Iter<T>: ParallelIterator, +{ + type Item = <Iter<T> as ParallelIterator>::Item; + type Iter = Iter<T>; + + fn into_par_iter(self) -> Self::Iter { + Iter { range: self } + } +} + +macro_rules! convert { + ( $self:ident . $method:ident ( $( $arg:expr ),* ) ) => { + if let Some((start, end)) = $self.bounds() { + if let Some(end) = end.checked_add(1) { + (start..end).into_par_iter().$method($( $arg ),*) + } else { + (start..end).into_par_iter().chain(once(end)).$method($( $arg ),*) + } + } else { + empty::<Self::Item>().$method($( $arg ),*) + } + }; +} + +macro_rules! parallel_range_impl { + ( $t:ty ) => { + impl ParallelIterator for Iter<$t> { + type Item = $t; + + fn drive_unindexed<C>(self, consumer: C) -> C::Result + where + C: UnindexedConsumer<Self::Item>, + { + convert!(self.drive_unindexed(consumer)) + } + + fn opt_len(&self) -> Option<usize> { + convert!(self.opt_len()) + } + } + }; +} + +macro_rules! indexed_range_impl { + ( $t:ty ) => { + parallel_range_impl! { $t } + + impl IndexedParallelIterator for Iter<$t> { + fn drive<C>(self, consumer: C) -> C::Result + where + C: Consumer<Self::Item>, + { + convert!(self.drive(consumer)) + } + + fn len(&self) -> usize { + self.range.len() + } + + fn with_producer<CB>(self, callback: CB) -> CB::Output + where + CB: ProducerCallback<Self::Item>, + { + convert!(self.with_producer(callback)) + } + } + }; +} + +// all RangeInclusive<T> with ExactSizeIterator +indexed_range_impl! {u8} +indexed_range_impl! {u16} +indexed_range_impl! {i8} +indexed_range_impl! {i16} + +// other RangeInclusive<T> with just Iterator +parallel_range_impl! {usize} +parallel_range_impl! {isize} +parallel_range_impl! {u32} +parallel_range_impl! {i32} +parallel_range_impl! {u64} +parallel_range_impl! {i64} +parallel_range_impl! {u128} +parallel_range_impl! {i128} + +// char is special +macro_rules! convert_char { + ( $self:ident . $method:ident ( $( $arg:expr ),* ) ) => { + if let Some((start, end)) = $self.bounds() { + let start = start as u32; + let end = end as u32; + if start < 0xD800 && 0xE000 <= end { + // chain the before and after surrogate range fragments + (start..0xD800) + .into_par_iter() + .chain(0xE000..end + 1) // cannot use RangeInclusive, so add one to end + .map(|codepoint| unsafe { char::from_u32_unchecked(codepoint) }) + .$method($( $arg ),*) + } else { + // no surrogate range to worry about + (start..end + 1) // cannot use RangeInclusive, so add one to end + .into_par_iter() + .map(|codepoint| unsafe { char::from_u32_unchecked(codepoint) }) + .$method($( $arg ),*) + } + } else { + empty().into_par_iter().$method($( $arg ),*) + } + }; +} + +impl ParallelIterator for Iter<char> { + type Item = char; + + fn drive_unindexed<C>(self, consumer: C) -> C::Result + where + C: UnindexedConsumer<Self::Item>, + { + convert_char!(self.drive(consumer)) + } + + fn opt_len(&self) -> Option<usize> { + Some(self.len()) + } +} + +// Range<u32> is broken on 16 bit platforms, may as well benefit from it +impl IndexedParallelIterator for Iter<char> { + // Split at the surrogate range first if we're allowed to + fn drive<C>(self, consumer: C) -> C::Result + where + C: Consumer<Self::Item>, + { + convert_char!(self.drive(consumer)) + } + + fn len(&self) -> usize { + if let Some((start, end)) = self.bounds() { + // Taken from <char as Step>::steps_between + let start = start as u32; + let end = end as u32; + let mut count = end - start; + if start < 0xD800 && 0xE000 <= end { + count -= 0x800 + } + (count + 1) as usize // add one for inclusive + } else { + 0 + } + } + + fn with_producer<CB>(self, callback: CB) -> CB::Output + where + CB: ProducerCallback<Self::Item>, + { + convert_char!(self.with_producer(callback)) + } +} + +#[test] +#[cfg(target_pointer_width = "64")] +fn test_u32_opt_len() { + use std::u32; + assert_eq!(Some(101), (0..=100u32).into_par_iter().opt_len()); + assert_eq!( + Some(u32::MAX as usize), + (0..=u32::MAX - 1).into_par_iter().opt_len() + ); + assert_eq!( + Some(u32::MAX as usize + 1), + (0..=u32::MAX).into_par_iter().opt_len() + ); +} + +#[test] +fn test_u64_opt_len() { + use std::{u64, usize}; + assert_eq!(Some(101), (0..=100u64).into_par_iter().opt_len()); + assert_eq!( + Some(usize::MAX), + (0..=usize::MAX as u64 - 1).into_par_iter().opt_len() + ); + assert_eq!(None, (0..=usize::MAX as u64).into_par_iter().opt_len()); + assert_eq!(None, (0..=u64::MAX).into_par_iter().opt_len()); +} + +#[test] +fn test_u128_opt_len() { + use std::{u128, usize}; + assert_eq!(Some(101), (0..=100u128).into_par_iter().opt_len()); + assert_eq!( + Some(usize::MAX), + (0..=usize::MAX as u128 - 1).into_par_iter().opt_len() + ); + assert_eq!(None, (0..=usize::MAX as u128).into_par_iter().opt_len()); + assert_eq!(None, (0..=u128::MAX).into_par_iter().opt_len()); +} + +// `usize as i64` can overflow, so make sure to wrap it appropriately +// when using the `opt_len` "indexed" mode. +#[test] +#[cfg(target_pointer_width = "64")] +fn test_usize_i64_overflow() { + use crate::ThreadPoolBuilder; + use std::i64; + + let iter = (-2..=i64::MAX).into_par_iter(); + assert_eq!(iter.opt_len(), Some(i64::MAX as usize + 3)); + + // always run with multiple threads to split into, or this will take forever... + let pool = ThreadPoolBuilder::new().num_threads(8).build().unwrap(); + pool.install(|| assert_eq!(iter.find_last(|_| true), Some(i64::MAX))); +} |