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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /vendor/rayon/src/iter/intersperse.rs | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'vendor/rayon/src/iter/intersperse.rs')
-rw-r--r-- | vendor/rayon/src/iter/intersperse.rs | 410 |
1 files changed, 410 insertions, 0 deletions
diff --git a/vendor/rayon/src/iter/intersperse.rs b/vendor/rayon/src/iter/intersperse.rs new file mode 100644 index 000000000..798bdc1d6 --- /dev/null +++ b/vendor/rayon/src/iter/intersperse.rs @@ -0,0 +1,410 @@ +use super::plumbing::*; +use super::*; +use std::cell::Cell; +use std::iter::{self, Fuse}; + +/// `Intersperse` is an iterator that inserts a particular item between each +/// item of the adapted iterator. This struct is created by the +/// [`intersperse()`] method on [`ParallelIterator`] +/// +/// [`intersperse()`]: trait.ParallelIterator.html#method.intersperse +/// [`ParallelIterator`]: trait.ParallelIterator.html +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +#[derive(Clone, Debug)] +pub struct Intersperse<I> +where + I: ParallelIterator, + I::Item: Clone, +{ + base: I, + item: I::Item, +} + +impl<I> Intersperse<I> +where + I: ParallelIterator, + I::Item: Clone, +{ + /// Creates a new `Intersperse` iterator + pub(super) fn new(base: I, item: I::Item) -> Self { + Intersperse { base, item } + } +} + +impl<I> ParallelIterator for Intersperse<I> +where + I: ParallelIterator, + I::Item: Clone + Send, +{ + type Item = I::Item; + + fn drive_unindexed<C>(self, consumer: C) -> C::Result + where + C: UnindexedConsumer<I::Item>, + { + let consumer1 = IntersperseConsumer::new(consumer, self.item); + self.base.drive_unindexed(consumer1) + } + + fn opt_len(&self) -> Option<usize> { + match self.base.opt_len()? { + 0 => Some(0), + len => len.checked_add(len - 1), + } + } +} + +impl<I> IndexedParallelIterator for Intersperse<I> +where + I: IndexedParallelIterator, + I::Item: Clone + Send, +{ + fn drive<C>(self, consumer: C) -> C::Result + where + C: Consumer<Self::Item>, + { + let consumer1 = IntersperseConsumer::new(consumer, self.item); + self.base.drive(consumer1) + } + + fn len(&self) -> usize { + let len = self.base.len(); + if len > 0 { + len.checked_add(len - 1).expect("overflow") + } else { + 0 + } + } + + fn with_producer<CB>(self, callback: CB) -> CB::Output + where + CB: ProducerCallback<Self::Item>, + { + let len = self.len(); + return self.base.with_producer(Callback { + callback, + item: self.item, + len, + }); + + struct Callback<CB, T> { + callback: CB, + item: T, + len: usize, + } + + impl<T, CB> ProducerCallback<T> for Callback<CB, T> + where + CB: ProducerCallback<T>, + T: Clone + Send, + { + type Output = CB::Output; + + fn callback<P>(self, base: P) -> CB::Output + where + P: Producer<Item = T>, + { + let producer = IntersperseProducer::new(base, self.item, self.len); + self.callback.callback(producer) + } + } + } +} + +struct IntersperseProducer<P> +where + P: Producer, +{ + base: P, + item: P::Item, + len: usize, + clone_first: bool, +} + +impl<P> IntersperseProducer<P> +where + P: Producer, +{ + fn new(base: P, item: P::Item, len: usize) -> Self { + IntersperseProducer { + base, + item, + len, + clone_first: false, + } + } +} + +impl<P> Producer for IntersperseProducer<P> +where + P: Producer, + P::Item: Clone + Send, +{ + type Item = P::Item; + type IntoIter = IntersperseIter<P::IntoIter>; + + fn into_iter(self) -> Self::IntoIter { + IntersperseIter { + base: self.base.into_iter().fuse(), + item: self.item, + clone_first: self.len > 0 && self.clone_first, + + // If there's more than one item, then even lengths end the opposite + // of how they started with respect to interspersed clones. + clone_last: self.len > 1 && ((self.len & 1 == 0) ^ self.clone_first), + } + } + + fn min_len(&self) -> usize { + self.base.min_len() + } + fn max_len(&self) -> usize { + self.base.max_len() + } + + fn split_at(self, index: usize) -> (Self, Self) { + debug_assert!(index <= self.len); + + // The left needs half of the items from the base producer, and the + // other half will be our interspersed item. If we're not leading with + // a cloned item, then we need to round up the base number of items, + // otherwise round down. + let base_index = (index + !self.clone_first as usize) / 2; + let (left_base, right_base) = self.base.split_at(base_index); + + let left = IntersperseProducer { + base: left_base, + item: self.item.clone(), + len: index, + clone_first: self.clone_first, + }; + + let right = IntersperseProducer { + base: right_base, + item: self.item, + len: self.len - index, + + // If the index is odd, the right side toggles `clone_first`. + clone_first: (index & 1 == 1) ^ self.clone_first, + }; + + (left, right) + } + + fn fold_with<F>(self, folder: F) -> F + where + F: Folder<Self::Item>, + { + let folder1 = IntersperseFolder { + base: folder, + item: self.item, + clone_first: self.clone_first, + }; + self.base.fold_with(folder1).base + } +} + +struct IntersperseIter<I> +where + I: Iterator, +{ + base: Fuse<I>, + item: I::Item, + clone_first: bool, + clone_last: bool, +} + +impl<I> Iterator for IntersperseIter<I> +where + I: DoubleEndedIterator + ExactSizeIterator, + I::Item: Clone, +{ + type Item = I::Item; + + fn next(&mut self) -> Option<Self::Item> { + if self.clone_first { + self.clone_first = false; + Some(self.item.clone()) + } else if let next @ Some(_) = self.base.next() { + // If there are any items left, we'll need another clone in front. + self.clone_first = self.base.len() != 0; + next + } else if self.clone_last { + self.clone_last = false; + Some(self.item.clone()) + } else { + None + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + let len = self.len(); + (len, Some(len)) + } +} + +impl<I> DoubleEndedIterator for IntersperseIter<I> +where + I: DoubleEndedIterator + ExactSizeIterator, + I::Item: Clone, +{ + fn next_back(&mut self) -> Option<Self::Item> { + if self.clone_last { + self.clone_last = false; + Some(self.item.clone()) + } else if let next_back @ Some(_) = self.base.next_back() { + // If there are any items left, we'll need another clone in back. + self.clone_last = self.base.len() != 0; + next_back + } else if self.clone_first { + self.clone_first = false; + Some(self.item.clone()) + } else { + None + } + } +} + +impl<I> ExactSizeIterator for IntersperseIter<I> +where + I: DoubleEndedIterator + ExactSizeIterator, + I::Item: Clone, +{ + fn len(&self) -> usize { + let len = self.base.len(); + len + len.saturating_sub(1) + self.clone_first as usize + self.clone_last as usize + } +} + +struct IntersperseConsumer<C, T> { + base: C, + item: T, + clone_first: Cell<bool>, +} + +impl<C, T> IntersperseConsumer<C, T> +where + C: Consumer<T>, +{ + fn new(base: C, item: T) -> Self { + IntersperseConsumer { + base, + item, + clone_first: false.into(), + } + } +} + +impl<C, T> Consumer<T> for IntersperseConsumer<C, T> +where + C: Consumer<T>, + T: Clone + Send, +{ + type Folder = IntersperseFolder<C::Folder, T>; + type Reducer = C::Reducer; + type Result = C::Result; + + fn split_at(mut self, index: usize) -> (Self, Self, Self::Reducer) { + // We'll feed twice as many items to the base consumer, except if we're + // not currently leading with a cloned item, then it's one less. + let base_index = index + index.saturating_sub(!self.clone_first.get() as usize); + let (left, right, reducer) = self.base.split_at(base_index); + + let right = IntersperseConsumer { + base: right, + item: self.item.clone(), + clone_first: true.into(), + }; + self.base = left; + (self, right, reducer) + } + + fn into_folder(self) -> Self::Folder { + IntersperseFolder { + base: self.base.into_folder(), + item: self.item, + clone_first: self.clone_first.get(), + } + } + + fn full(&self) -> bool { + self.base.full() + } +} + +impl<C, T> UnindexedConsumer<T> for IntersperseConsumer<C, T> +where + C: UnindexedConsumer<T>, + T: Clone + Send, +{ + fn split_off_left(&self) -> Self { + let left = IntersperseConsumer { + base: self.base.split_off_left(), + item: self.item.clone(), + clone_first: self.clone_first.clone(), + }; + self.clone_first.set(true); + left + } + + fn to_reducer(&self) -> Self::Reducer { + self.base.to_reducer() + } +} + +struct IntersperseFolder<C, T> { + base: C, + item: T, + clone_first: bool, +} + +impl<C, T> Folder<T> for IntersperseFolder<C, T> +where + C: Folder<T>, + T: Clone, +{ + type Result = C::Result; + + fn consume(mut self, item: T) -> Self { + if self.clone_first { + self.base = self.base.consume(self.item.clone()); + if self.base.full() { + return self; + } + } else { + self.clone_first = true; + } + self.base = self.base.consume(item); + self + } + + fn consume_iter<I>(self, iter: I) -> Self + where + I: IntoIterator<Item = T>, + { + let mut clone_first = self.clone_first; + let between_item = self.item; + let base = self.base.consume_iter(iter.into_iter().flat_map(|item| { + let first = if clone_first { + Some(between_item.clone()) + } else { + clone_first = true; + None + }; + first.into_iter().chain(iter::once(item)) + })); + IntersperseFolder { + base, + item: between_item, + clone_first, + } + } + + fn complete(self) -> C::Result { + self.base.complete() + } + + fn full(&self) -> bool { + self.base.full() + } +} |