diff options
Diffstat (limited to 'vendor/rustc-rayon/src/iter/take_any.rs')
-rw-r--r-- | vendor/rustc-rayon/src/iter/take_any.rs | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/vendor/rustc-rayon/src/iter/take_any.rs b/vendor/rustc-rayon/src/iter/take_any.rs new file mode 100644 index 000000000..e3992b383 --- /dev/null +++ b/vendor/rustc-rayon/src/iter/take_any.rs @@ -0,0 +1,144 @@ +use super::plumbing::*; +use super::*; +use std::sync::atomic::{AtomicUsize, Ordering}; + +/// `TakeAny` is an iterator that iterates over `n` elements from anywhere in `I`. +/// This struct is created by the [`take_any()`] method on [`ParallelIterator`] +/// +/// [`take_any()`]: trait.ParallelIterator.html#method.take_any +/// [`ParallelIterator`]: trait.ParallelIterator.html +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +#[derive(Clone, Debug)] +pub struct TakeAny<I: ParallelIterator> { + base: I, + count: usize, +} + +impl<I> TakeAny<I> +where + I: ParallelIterator, +{ + /// Creates a new `TakeAny` iterator. + pub(super) fn new(base: I, count: usize) -> Self { + TakeAny { base, count } + } +} + +impl<I> ParallelIterator for TakeAny<I> +where + I: ParallelIterator, +{ + type Item = I::Item; + + fn drive_unindexed<C>(self, consumer: C) -> C::Result + where + C: UnindexedConsumer<Self::Item>, + { + let consumer1 = TakeAnyConsumer { + base: consumer, + count: &AtomicUsize::new(self.count), + }; + self.base.drive_unindexed(consumer1) + } +} + +/// //////////////////////////////////////////////////////////////////////// +/// Consumer implementation + +struct TakeAnyConsumer<'f, C> { + base: C, + count: &'f AtomicUsize, +} + +impl<'f, T, C> Consumer<T> for TakeAnyConsumer<'f, C> +where + C: Consumer<T>, + T: Send, +{ + type Folder = TakeAnyFolder<'f, C::Folder>; + type Reducer = C::Reducer; + type Result = C::Result; + + fn split_at(self, index: usize) -> (Self, Self, Self::Reducer) { + let (left, right, reducer) = self.base.split_at(index); + ( + TakeAnyConsumer { base: left, ..self }, + TakeAnyConsumer { + base: right, + ..self + }, + reducer, + ) + } + + fn into_folder(self) -> Self::Folder { + TakeAnyFolder { + base: self.base.into_folder(), + count: self.count, + } + } + + fn full(&self) -> bool { + self.count.load(Ordering::Relaxed) == 0 || self.base.full() + } +} + +impl<'f, T, C> UnindexedConsumer<T> for TakeAnyConsumer<'f, C> +where + C: UnindexedConsumer<T>, + T: Send, +{ + fn split_off_left(&self) -> Self { + TakeAnyConsumer { + base: self.base.split_off_left(), + ..*self + } + } + + fn to_reducer(&self) -> Self::Reducer { + self.base.to_reducer() + } +} + +struct TakeAnyFolder<'f, C> { + base: C, + count: &'f AtomicUsize, +} + +fn checked_decrement(u: &AtomicUsize) -> bool { + u.fetch_update(Ordering::Relaxed, Ordering::Relaxed, |u| u.checked_sub(1)) + .is_ok() +} + +impl<'f, T, C> Folder<T> for TakeAnyFolder<'f, C> +where + C: Folder<T>, +{ + type Result = C::Result; + + fn consume(mut self, item: T) -> Self { + if checked_decrement(self.count) { + self.base = self.base.consume(item); + } + self + } + + fn consume_iter<I>(mut self, iter: I) -> Self + where + I: IntoIterator<Item = T>, + { + self.base = self.base.consume_iter( + iter.into_iter() + .take_while(move |_| checked_decrement(self.count)), + ); + self + } + + fn complete(self) -> C::Result { + self.base.complete() + } + + fn full(&self) -> bool { + self.count.load(Ordering::Relaxed) == 0 || self.base.full() + } +} |