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//! This module contains the parallel iterator types for double-ended queues
//! (`VecDeque<T>`). You will rarely need to interact with it directly
//! unless you have need to name one of the iterator types.
use std::collections::VecDeque;
use std::ops::{Range, RangeBounds};
use crate::iter::plumbing::*;
use crate::iter::*;
use crate::math::simplify_range;
use crate::slice;
use crate::vec;
/// Parallel iterator over a double-ended queue
#[derive(Debug, Clone)]
pub struct IntoIter<T: Send> {
inner: vec::IntoIter<T>,
}
impl<T: Send> IntoParallelIterator for VecDeque<T> {
type Item = T;
type Iter = IntoIter<T>;
fn into_par_iter(self) -> Self::Iter {
// NOTE: requires data movement if the deque doesn't start at offset 0.
let inner = Vec::from(self).into_par_iter();
IntoIter { inner }
}
}
delegate_indexed_iterator! {
IntoIter<T> => T,
impl<T: Send>
}
/// Parallel iterator over an immutable reference to a double-ended queue
#[derive(Debug)]
pub struct Iter<'a, T: Sync> {
inner: Chain<slice::Iter<'a, T>, slice::Iter<'a, T>>,
}
impl<'a, T: Sync> Clone for Iter<'a, T> {
fn clone(&self) -> Self {
Iter {
inner: self.inner.clone(),
}
}
}
impl<'a, T: Sync> IntoParallelIterator for &'a VecDeque<T> {
type Item = &'a T;
type Iter = Iter<'a, T>;
fn into_par_iter(self) -> Self::Iter {
let (a, b) = self.as_slices();
Iter {
inner: a.into_par_iter().chain(b),
}
}
}
delegate_indexed_iterator! {
Iter<'a, T> => &'a T,
impl<'a, T: Sync + 'a>
}
/// Parallel iterator over a mutable reference to a double-ended queue
#[derive(Debug)]
pub struct IterMut<'a, T: Send> {
inner: Chain<slice::IterMut<'a, T>, slice::IterMut<'a, T>>,
}
impl<'a, T: Send> IntoParallelIterator for &'a mut VecDeque<T> {
type Item = &'a mut T;
type Iter = IterMut<'a, T>;
fn into_par_iter(self) -> Self::Iter {
let (a, b) = self.as_mut_slices();
IterMut {
inner: a.into_par_iter().chain(b),
}
}
}
delegate_indexed_iterator! {
IterMut<'a, T> => &'a mut T,
impl<'a, T: Send + 'a>
}
/// Draining parallel iterator that moves a range out of a double-ended queue,
/// but keeps the total capacity.
#[derive(Debug)]
pub struct Drain<'a, T: Send> {
deque: &'a mut VecDeque<T>,
range: Range<usize>,
orig_len: usize,
}
impl<'a, T: Send> ParallelDrainRange<usize> for &'a mut VecDeque<T> {
type Iter = Drain<'a, T>;
type Item = T;
fn par_drain<R: RangeBounds<usize>>(self, range: R) -> Self::Iter {
Drain {
orig_len: self.len(),
range: simplify_range(range, self.len()),
deque: self,
}
}
}
impl<'a, T: Send> ParallelIterator for Drain<'a, T> {
type Item = T;
fn drive_unindexed<C>(self, consumer: C) -> C::Result
where
C: UnindexedConsumer<Self::Item>,
{
bridge(self, consumer)
}
fn opt_len(&self) -> Option<usize> {
Some(self.len())
}
}
impl<'a, T: Send> IndexedParallelIterator for Drain<'a, T> {
fn drive<C>(self, consumer: C) -> C::Result
where
C: Consumer<Self::Item>,
{
bridge(self, consumer)
}
fn len(&self) -> usize {
self.range.len()
}
fn with_producer<CB>(self, callback: CB) -> CB::Output
where
CB: ProducerCallback<Self::Item>,
{
// NOTE: requires data movement if the deque doesn't start at offset 0.
super::DrainGuard::new(self.deque)
.par_drain(self.range.clone())
.with_producer(callback)
}
}
impl<'a, T: Send> Drop for Drain<'a, T> {
fn drop(&mut self) {
if self.deque.len() != self.orig_len - self.range.len() {
// We must not have produced, so just call a normal drain to remove the items.
assert_eq!(self.deque.len(), self.orig_len);
self.deque.drain(self.range.clone());
}
}
}
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