204 lines
5.3 KiB
Rust
204 lines
5.3 KiB
Rust
//! Parallel iterator types for [options][std::option]
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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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//! [std::option]: https://doc.rust-lang.org/stable/std/option/
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use crate::iter::plumbing::*;
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use crate::iter::*;
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use std::sync::atomic::{AtomicBool, Ordering};
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/// A parallel iterator over the value in [`Some`] variant of an [`Option`].
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///
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/// The iterator yields one value if the [`Option`] is a [`Some`], otherwise none.
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///
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/// This `struct` is created by the [`into_par_iter`] function.
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///
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/// [`Option`]: https://doc.rust-lang.org/std/option/enum.Option.html
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/// [`Some`]: https://doc.rust-lang.org/std/option/enum.Option.html#variant.Some
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/// [`into_par_iter`]: ../iter/trait.IntoParallelIterator.html#tymethod.into_par_iter
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#[derive(Debug, Clone)]
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pub struct IntoIter<T: Send> {
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opt: Option<T>,
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}
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impl<T: Send> IntoParallelIterator for Option<T> {
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type Item = T;
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type Iter = IntoIter<T>;
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fn into_par_iter(self) -> Self::Iter {
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IntoIter { opt: self }
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}
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}
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impl<T: Send> ParallelIterator for IntoIter<T> {
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type Item = T;
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fn drive_unindexed<C>(self, consumer: C) -> C::Result
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where
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C: UnindexedConsumer<Self::Item>,
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{
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self.drive(consumer)
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}
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fn opt_len(&self) -> Option<usize> {
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Some(self.len())
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}
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}
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impl<T: Send> IndexedParallelIterator for IntoIter<T> {
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fn drive<C>(self, consumer: C) -> C::Result
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where
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C: Consumer<Self::Item>,
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{
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let mut folder = consumer.into_folder();
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if let Some(item) = self.opt {
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folder = folder.consume(item);
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}
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folder.complete()
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}
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fn len(&self) -> usize {
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match self.opt {
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Some(_) => 1,
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None => 0,
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}
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}
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fn with_producer<CB>(self, callback: CB) -> CB::Output
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where
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CB: ProducerCallback<Self::Item>,
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{
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callback.callback(OptionProducer { opt: self.opt })
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}
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}
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/// A parallel iterator over a reference to the [`Some`] variant of an [`Option`].
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///
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/// The iterator yields one value if the [`Option`] is a [`Some`], otherwise none.
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///
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/// This `struct` is created by the [`par_iter`] function.
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///
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/// [`Option`]: https://doc.rust-lang.org/std/option/enum.Option.html
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/// [`Some`]: https://doc.rust-lang.org/std/option/enum.Option.html#variant.Some
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/// [`par_iter`]: ../iter/trait.IntoParallelRefIterator.html#tymethod.par_iter
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#[derive(Debug)]
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pub struct Iter<'a, T: Sync> {
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inner: IntoIter<&'a T>,
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}
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impl<'a, T: Sync> Clone for Iter<'a, T> {
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fn clone(&self) -> Self {
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Iter {
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inner: self.inner.clone(),
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}
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}
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}
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impl<'a, T: Sync> IntoParallelIterator for &'a Option<T> {
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type Item = &'a T;
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type Iter = Iter<'a, T>;
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fn into_par_iter(self) -> Self::Iter {
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Iter {
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inner: self.as_ref().into_par_iter(),
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}
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}
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}
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delegate_indexed_iterator! {
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Iter<'a, T> => &'a T,
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impl<'a, T: Sync + 'a>
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}
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/// A parallel iterator over a mutable reference to the [`Some`] variant of an [`Option`].
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///
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/// The iterator yields one value if the [`Option`] is a [`Some`], otherwise none.
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///
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/// This `struct` is created by the [`par_iter_mut`] function.
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///
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/// [`Option`]: https://doc.rust-lang.org/std/option/enum.Option.html
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/// [`Some`]: https://doc.rust-lang.org/std/option/enum.Option.html#variant.Some
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/// [`par_iter_mut`]: ../iter/trait.IntoParallelRefMutIterator.html#tymethod.par_iter_mut
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#[derive(Debug)]
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pub struct IterMut<'a, T: Send> {
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inner: IntoIter<&'a mut T>,
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}
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impl<'a, T: Send> IntoParallelIterator for &'a mut Option<T> {
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type Item = &'a mut T;
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type Iter = IterMut<'a, T>;
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fn into_par_iter(self) -> Self::Iter {
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IterMut {
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inner: self.as_mut().into_par_iter(),
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}
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}
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}
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delegate_indexed_iterator! {
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IterMut<'a, T> => &'a mut T,
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impl<'a, T: Send + 'a>
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}
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/// Private producer for an option
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struct OptionProducer<T: Send> {
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opt: Option<T>,
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}
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impl<T: Send> Producer for OptionProducer<T> {
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type Item = T;
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type IntoIter = std::option::IntoIter<T>;
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fn into_iter(self) -> Self::IntoIter {
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self.opt.into_iter()
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}
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fn split_at(self, index: usize) -> (Self, Self) {
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debug_assert!(index <= 1);
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let none = OptionProducer { opt: None };
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if index == 0 {
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(none, self)
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} else {
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(self, none)
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}
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}
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}
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/// Collect an arbitrary `Option`-wrapped collection.
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///
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/// If any item is `None`, then all previous items collected are discarded,
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/// and it returns only `None`.
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impl<C, T> FromParallelIterator<Option<T>> for Option<C>
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where
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C: FromParallelIterator<T>,
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T: Send,
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{
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fn from_par_iter<I>(par_iter: I) -> Self
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where
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I: IntoParallelIterator<Item = Option<T>>,
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{
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fn check<T>(found_none: &AtomicBool) -> impl Fn(&Option<T>) + '_ {
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move |item| {
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if item.is_none() {
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found_none.store(true, Ordering::Relaxed);
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}
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}
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}
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let found_none = AtomicBool::new(false);
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let collection = par_iter
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.into_par_iter()
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.inspect(check(&found_none))
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.while_some()
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.collect();
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if found_none.load(Ordering::Relaxed) {
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None
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} else {
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Some(collection)
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}
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}
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}
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