| //! 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::take(collection)), |
| 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::take(&mut self.vec)); |
| } |
| } |
| |
| 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) |
| } |
| } |
| } |