85 lines
2.6 KiB
Rust
85 lines
2.6 KiB
Rust
//! Parallel iterator types for [standard collections]
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//!
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//! You will rarely need to interact with this module directly unless you need
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//! to name one of the iterator types.
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//!
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//! [standard collections]: std::collections
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/// Convert an iterable collection into a parallel iterator by first
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/// collecting into a temporary `Vec`, then iterating that.
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macro_rules! into_par_vec {
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($t:ty => $iter:ident<$($i:tt),*>, impl $($args:tt)*) => {
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impl $($args)* IntoParallelIterator for $t {
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type Item = <$t as IntoIterator>::Item;
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type Iter = $iter<$($i),*>;
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fn into_par_iter(self) -> Self::Iter {
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use std::iter::FromIterator;
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$iter { inner: Vec::from_iter(self).into_par_iter() }
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}
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}
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};
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}
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pub mod binary_heap;
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pub mod btree_map;
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pub mod btree_set;
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pub mod hash_map;
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pub mod hash_set;
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pub mod linked_list;
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pub mod vec_deque;
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use self::drain_guard::DrainGuard;
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mod drain_guard {
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use crate::iter::ParallelDrainRange;
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use std::mem;
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use std::ops::RangeBounds;
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/// A proxy for draining a collection by converting to a `Vec` and back.
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///
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/// This is used for draining `BinaryHeap` and `VecDeque`, which both have
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/// zero-allocation conversions to/from `Vec`, though not zero-cost:
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/// - `BinaryHeap` will heapify from `Vec`, but at least that will be empty.
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/// - `VecDeque` has to shift items to offset 0 when converting to `Vec`.
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#[allow(missing_debug_implementations)]
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pub(super) struct DrainGuard<'a, T, C: From<Vec<T>>> {
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collection: &'a mut C,
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vec: Vec<T>,
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}
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impl<'a, T, C> DrainGuard<'a, T, C>
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where
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C: Default + From<Vec<T>>,
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Vec<T>: From<C>,
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{
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pub(super) fn new(collection: &'a mut C) -> Self {
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Self {
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// Temporarily steal the inner `Vec` so we can drain in place.
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vec: Vec::from(mem::take(collection)),
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collection,
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}
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}
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}
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impl<'a, T, C: From<Vec<T>>> Drop for DrainGuard<'a, T, C> {
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fn drop(&mut self) {
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// Restore the collection from the `Vec` with its original capacity.
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*self.collection = C::from(mem::take(&mut self.vec));
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}
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}
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impl<'a, T, C> ParallelDrainRange<usize> for &'a mut DrainGuard<'_, T, C>
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where
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T: Send,
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C: From<Vec<T>>,
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{
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type Iter = crate::vec::Drain<'a, T>;
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type Item = T;
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fn par_drain<R: RangeBounds<usize>>(self, range: R) -> Self::Iter {
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self.vec.par_drain(range)
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}
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}
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}
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