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Diffstat (limited to 'vendor/rayon/src/iter/skip.rs')
-rw-r--r-- | vendor/rayon/src/iter/skip.rs | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/vendor/rayon/src/iter/skip.rs b/vendor/rayon/src/iter/skip.rs new file mode 100644 index 0000000..2d0f947 --- /dev/null +++ b/vendor/rayon/src/iter/skip.rs @@ -0,0 +1,95 @@ +use super::noop::NoopConsumer; +use super::plumbing::*; +use super::*; +use std::cmp::min; + +/// `Skip` is an iterator that skips over the first `n` elements. +/// This struct is created by the [`skip()`] method on [`IndexedParallelIterator`] +/// +/// [`skip()`]: trait.IndexedParallelIterator.html#method.skip +/// [`IndexedParallelIterator`]: trait.IndexedParallelIterator.html +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +#[derive(Debug, Clone)] +pub struct Skip<I> { + base: I, + n: usize, +} + +impl<I> Skip<I> +where + I: IndexedParallelIterator, +{ + /// Creates a new `Skip` iterator. + pub(super) fn new(base: I, n: usize) -> Self { + let n = min(base.len(), n); + Skip { base, n } + } +} + +impl<I> ParallelIterator for Skip<I> +where + I: IndexedParallelIterator, +{ + type Item = I::Item; + + fn drive_unindexed<C>(self, consumer: C) -> C::Result + where + C: UnindexedConsumer<Self::Item>, + { + bridge(self, consumer) + } + + fn opt_len(&self) -> Option<usize> { + Some(self.len()) + } +} + +impl<I> IndexedParallelIterator for Skip<I> +where + I: IndexedParallelIterator, +{ + fn len(&self) -> usize { + self.base.len() - self.n + } + + fn drive<C: Consumer<Self::Item>>(self, consumer: C) -> C::Result { + bridge(self, consumer) + } + + fn with_producer<CB>(self, callback: CB) -> CB::Output + where + CB: ProducerCallback<Self::Item>, + { + return self.base.with_producer(Callback { + callback, + n: self.n, + }); + + struct Callback<CB> { + callback: CB, + n: usize, + } + + impl<T, CB> ProducerCallback<T> for Callback<CB> + where + CB: ProducerCallback<T>, + { + type Output = CB::Output; + fn callback<P>(self, base: P) -> CB::Output + where + P: Producer<Item = T>, + { + crate::in_place_scope(|scope| { + let Self { callback, n } = self; + let (before_skip, after_skip) = base.split_at(n); + + // Run the skipped part separately for side effects. + // We'll still get any panics propagated back by the scope. + scope.spawn(move |_| bridge_producer_consumer(n, before_skip, NoopConsumer)); + + callback.callback(after_skip) + }) + } + } + } +} |