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author | Jakub Kotur <qtr@google.com> | 2021-03-16 20:22:30 +0000 |
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committer | Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com> | 2021-03-16 20:22:30 +0000 |
commit | 4c0b8e0ef78bcd80a4facc34c6a2158d83f96802 (patch) | |
tree | 13641ab7afc7aa43b586606c18d53084dedf7ace /src/collections/mod.rs | |
parent | a679e9b8b7e4ae27a19b81f216e375ea8a9cdb8e (diff) | |
parent | 7522a9ba008ac88224e0990932bdd298a43a2336 (diff) | |
download | rayon-4c0b8e0ef78bcd80a4facc34c6a2158d83f96802.tar.gz |
Initial import of rayon-1.5.0. am: 041839ceab am: d836dd6404 am: 7522a9ba00
Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/rayon/+/1622436
Change-Id: I94b0e06d9da131d6f98db436ad1a178dfff2ec90
Diffstat (limited to 'src/collections/mod.rs')
-rw-r--r-- | src/collections/mod.rs | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/src/collections/mod.rs b/src/collections/mod.rs new file mode 100644 index 0000000..d9b7988 --- /dev/null +++ b/src/collections/mod.rs @@ -0,0 +1,84 @@ +//! Parallel iterator types for [standard collections][std::collections] +//! +//! You will rarely need to interact with this module directly unless you need +//! to name one of the iterator types. +//! +//! [std::collections]: https://doc.rust-lang.org/stable/std/collections/ + +/// Convert an iterable collection into a parallel iterator by first +/// collecting into a temporary `Vec`, then iterating that. +macro_rules! into_par_vec { + ($t:ty => $iter:ident<$($i:tt),*>, impl $($args:tt)*) => { + impl $($args)* IntoParallelIterator for $t { + type Item = <$t as IntoIterator>::Item; + type Iter = $iter<$($i),*>; + + fn into_par_iter(self) -> Self::Iter { + use std::iter::FromIterator; + $iter { inner: Vec::from_iter(self).into_par_iter() } + } + } + }; +} + +pub mod binary_heap; +pub mod btree_map; +pub mod btree_set; +pub mod hash_map; +pub mod hash_set; +pub mod linked_list; +pub mod vec_deque; + +use self::drain_guard::DrainGuard; + +mod drain_guard { + use crate::iter::ParallelDrainRange; + use std::mem; + use std::ops::RangeBounds; + + /// A proxy for draining a collection by converting to a `Vec` and back. + /// + /// This is used for draining `BinaryHeap` and `VecDeque`, which both have + /// zero-allocation conversions to/from `Vec`, though not zero-cost: + /// - `BinaryHeap` will heapify from `Vec`, but at least that will be empty. + /// - `VecDeque` has to shift items to offset 0 when converting to `Vec`. + #[allow(missing_debug_implementations)] + pub(super) struct DrainGuard<'a, T, C: From<Vec<T>>> { + collection: &'a mut C, + vec: Vec<T>, + } + + impl<'a, T, C> DrainGuard<'a, T, C> + where + C: Default + From<Vec<T>>, + Vec<T>: From<C>, + { + pub(super) fn new(collection: &'a mut C) -> Self { + Self { + // Temporarily steal the inner `Vec` so we can drain in place. + vec: Vec::from(mem::replace(collection, C::default())), + collection, + } + } + } + + impl<'a, T, C: From<Vec<T>>> Drop for DrainGuard<'a, T, C> { + fn drop(&mut self) { + // Restore the collection from the `Vec` with its original capacity. + *self.collection = C::from(mem::replace(&mut self.vec, Vec::new())); + } + } + + impl<'a, T, C> ParallelDrainRange<usize> for &'a mut DrainGuard<'_, T, C> + where + T: Send, + C: From<Vec<T>>, + { + type Iter = crate::vec::Drain<'a, T>; + type Item = T; + + fn par_drain<R: RangeBounds<usize>>(self, range: R) -> Self::Iter { + self.vec.par_drain(range) + } + } +} |