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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 19:33:14 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 19:33:14 +0000
commit36d22d82aa202bb199967e9512281e9a53db42c9 (patch)
tree105e8c98ddea1c1e4784a60a5a6410fa416be2de /third_party/rust/rayon/src/iter/chain.rs
parentInitial commit. (diff)
downloadfirefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.tar.xz
firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.zip
Adding upstream version 115.7.0esr.upstream/115.7.0esr
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'third_party/rust/rayon/src/iter/chain.rs')
-rw-r--r--third_party/rust/rayon/src/iter/chain.rs268
1 files changed, 268 insertions, 0 deletions
diff --git a/third_party/rust/rayon/src/iter/chain.rs b/third_party/rust/rayon/src/iter/chain.rs
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+use super::plumbing::*;
+use super::*;
+use rayon_core::join;
+use std::cmp;
+use std::iter;
+
+/// `Chain` is an iterator that joins `b` after `a` in one continuous iterator.
+/// This struct is created by the [`chain()`] method on [`ParallelIterator`]
+///
+/// [`chain()`]: trait.ParallelIterator.html#method.chain
+/// [`ParallelIterator`]: trait.ParallelIterator.html
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[derive(Debug, Clone)]
+pub struct Chain<A, B>
+where
+ A: ParallelIterator,
+ B: ParallelIterator<Item = A::Item>,
+{
+ a: A,
+ b: B,
+}
+
+impl<A, B> Chain<A, B>
+where
+ A: ParallelIterator,
+ B: ParallelIterator<Item = A::Item>,
+{
+ /// Creates a new `Chain` iterator.
+ pub(super) fn new(a: A, b: B) -> Self {
+ Chain { a, b }
+ }
+}
+
+impl<A, B> ParallelIterator for Chain<A, B>
+where
+ A: ParallelIterator,
+ B: ParallelIterator<Item = A::Item>,
+{
+ type Item = A::Item;
+
+ fn drive_unindexed<C>(self, consumer: C) -> C::Result
+ where
+ C: UnindexedConsumer<Self::Item>,
+ {
+ let Chain { a, b } = self;
+
+ // If we returned a value from our own `opt_len`, then the collect consumer in particular
+ // will balk at being treated like an actual `UnindexedConsumer`. But when we do know the
+ // length, we can use `Consumer::split_at` instead, and this is still harmless for other
+ // truly-unindexed consumers too.
+ let (left, right, reducer) = if let Some(len) = a.opt_len() {
+ consumer.split_at(len)
+ } else {
+ let reducer = consumer.to_reducer();
+ (consumer.split_off_left(), consumer, reducer)
+ };
+
+ let (a, b) = join(|| a.drive_unindexed(left), || b.drive_unindexed(right));
+ reducer.reduce(a, b)
+ }
+
+ fn opt_len(&self) -> Option<usize> {
+ self.a.opt_len()?.checked_add(self.b.opt_len()?)
+ }
+}
+
+impl<A, B> IndexedParallelIterator for Chain<A, B>
+where
+ A: IndexedParallelIterator,
+ B: IndexedParallelIterator<Item = A::Item>,
+{
+ fn drive<C>(self, consumer: C) -> C::Result
+ where
+ C: Consumer<Self::Item>,
+ {
+ let Chain { a, b } = self;
+ let (left, right, reducer) = consumer.split_at(a.len());
+ let (a, b) = join(|| a.drive(left), || b.drive(right));
+ reducer.reduce(a, b)
+ }
+
+ fn len(&self) -> usize {
+ self.a.len().checked_add(self.b.len()).expect("overflow")
+ }
+
+ fn with_producer<CB>(self, callback: CB) -> CB::Output
+ where
+ CB: ProducerCallback<Self::Item>,
+ {
+ let a_len = self.a.len();
+ return self.a.with_producer(CallbackA {
+ callback,
+ a_len,
+ b: self.b,
+ });
+
+ struct CallbackA<CB, B> {
+ callback: CB,
+ a_len: usize,
+ b: B,
+ }
+
+ impl<CB, B> ProducerCallback<B::Item> for CallbackA<CB, B>
+ where
+ B: IndexedParallelIterator,
+ CB: ProducerCallback<B::Item>,
+ {
+ type Output = CB::Output;
+
+ fn callback<A>(self, a_producer: A) -> Self::Output
+ where
+ A: Producer<Item = B::Item>,
+ {
+ self.b.with_producer(CallbackB {
+ callback: self.callback,
+ a_len: self.a_len,
+ a_producer,
+ })
+ }
+ }
+
+ struct CallbackB<CB, A> {
+ callback: CB,
+ a_len: usize,
+ a_producer: A,
+ }
+
+ impl<CB, A> ProducerCallback<A::Item> for CallbackB<CB, A>
+ where
+ A: Producer,
+ CB: ProducerCallback<A::Item>,
+ {
+ type Output = CB::Output;
+
+ fn callback<B>(self, b_producer: B) -> Self::Output
+ where
+ B: Producer<Item = A::Item>,
+ {
+ let producer = ChainProducer::new(self.a_len, self.a_producer, b_producer);
+ self.callback.callback(producer)
+ }
+ }
+ }
+}
+
+/// ////////////////////////////////////////////////////////////////////////
+
+struct ChainProducer<A, B>
+where
+ A: Producer,
+ B: Producer<Item = A::Item>,
+{
+ a_len: usize,
+ a: A,
+ b: B,
+}
+
+impl<A, B> ChainProducer<A, B>
+where
+ A: Producer,
+ B: Producer<Item = A::Item>,
+{
+ fn new(a_len: usize, a: A, b: B) -> Self {
+ ChainProducer { a_len, a, b }
+ }
+}
+
+impl<A, B> Producer for ChainProducer<A, B>
+where
+ A: Producer,
+ B: Producer<Item = A::Item>,
+{
+ type Item = A::Item;
+ type IntoIter = ChainSeq<A::IntoIter, B::IntoIter>;
+
+ fn into_iter(self) -> Self::IntoIter {
+ ChainSeq::new(self.a.into_iter(), self.b.into_iter())
+ }
+
+ fn min_len(&self) -> usize {
+ cmp::max(self.a.min_len(), self.b.min_len())
+ }
+
+ fn max_len(&self) -> usize {
+ cmp::min(self.a.max_len(), self.b.max_len())
+ }
+
+ fn split_at(self, index: usize) -> (Self, Self) {
+ if index <= self.a_len {
+ let a_rem = self.a_len - index;
+ let (a_left, a_right) = self.a.split_at(index);
+ let (b_left, b_right) = self.b.split_at(0);
+ (
+ ChainProducer::new(index, a_left, b_left),
+ ChainProducer::new(a_rem, a_right, b_right),
+ )
+ } else {
+ let (a_left, a_right) = self.a.split_at(self.a_len);
+ let (b_left, b_right) = self.b.split_at(index - self.a_len);
+ (
+ ChainProducer::new(self.a_len, a_left, b_left),
+ ChainProducer::new(0, a_right, b_right),
+ )
+ }
+ }
+
+ fn fold_with<F>(self, mut folder: F) -> F
+ where
+ F: Folder<A::Item>,
+ {
+ folder = self.a.fold_with(folder);
+ if folder.full() {
+ folder
+ } else {
+ self.b.fold_with(folder)
+ }
+ }
+}
+
+/// ////////////////////////////////////////////////////////////////////////
+/// Wrapper for Chain to implement ExactSizeIterator
+
+struct ChainSeq<A, B> {
+ chain: iter::Chain<A, B>,
+}
+
+impl<A, B> ChainSeq<A, B> {
+ fn new(a: A, b: B) -> ChainSeq<A, B>
+ where
+ A: ExactSizeIterator,
+ B: ExactSizeIterator<Item = A::Item>,
+ {
+ ChainSeq { chain: a.chain(b) }
+ }
+}
+
+impl<A, B> Iterator for ChainSeq<A, B>
+where
+ A: Iterator,
+ B: Iterator<Item = A::Item>,
+{
+ type Item = A::Item;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ self.chain.next()
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ self.chain.size_hint()
+ }
+}
+
+impl<A, B> ExactSizeIterator for ChainSeq<A, B>
+where
+ A: ExactSizeIterator,
+ B: ExactSizeIterator<Item = A::Item>,
+{
+}
+
+impl<A, B> DoubleEndedIterator for ChainSeq<A, B>
+where
+ A: DoubleEndedIterator,
+ B: DoubleEndedIterator<Item = A::Item>,
+{
+ fn next_back(&mut self) -> Option<Self::Item> {
+ self.chain.next_back()
+ }
+}