| 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() |
| } |
| } |