diff options
Diffstat (limited to 'vendor/rayon/src/iter/flat_map.rs')
-rw-r--r-- | vendor/rayon/src/iter/flat_map.rs | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/vendor/rayon/src/iter/flat_map.rs b/vendor/rayon/src/iter/flat_map.rs new file mode 100644 index 0000000..f264e1e --- /dev/null +++ b/vendor/rayon/src/iter/flat_map.rs @@ -0,0 +1,154 @@ +use super::plumbing::*; +use super::*; + +use std::fmt::{self, Debug}; + +/// `FlatMap` maps each element to a parallel iterator, then flattens these iterators together. +/// This struct is created by the [`flat_map()`] method on [`ParallelIterator`] +/// +/// [`flat_map()`]: trait.ParallelIterator.html#method.flat_map +/// [`ParallelIterator`]: trait.ParallelIterator.html +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +#[derive(Clone)] +pub struct FlatMap<I: ParallelIterator, F> { + base: I, + map_op: F, +} + +impl<I: ParallelIterator + Debug, F> Debug for FlatMap<I, F> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("FlatMap").field("base", &self.base).finish() + } +} + +impl<I: ParallelIterator, F> FlatMap<I, F> { + /// Creates a new `FlatMap` iterator. + pub(super) fn new(base: I, map_op: F) -> Self { + FlatMap { base, map_op } + } +} + +impl<I, F, PI> ParallelIterator for FlatMap<I, F> +where + I: ParallelIterator, + F: Fn(I::Item) -> PI + Sync + Send, + PI: IntoParallelIterator, +{ + type Item = PI::Item; + + fn drive_unindexed<C>(self, consumer: C) -> C::Result + where + C: UnindexedConsumer<Self::Item>, + { + let consumer = FlatMapConsumer::new(consumer, &self.map_op); + self.base.drive_unindexed(consumer) + } +} + +/// //////////////////////////////////////////////////////////////////////// +/// Consumer implementation + +struct FlatMapConsumer<'f, C, F> { + base: C, + map_op: &'f F, +} + +impl<'f, C, F> FlatMapConsumer<'f, C, F> { + fn new(base: C, map_op: &'f F) -> Self { + FlatMapConsumer { base, map_op } + } +} + +impl<'f, T, U, C, F> Consumer<T> for FlatMapConsumer<'f, C, F> +where + C: UnindexedConsumer<U::Item>, + F: Fn(T) -> U + Sync, + U: IntoParallelIterator, +{ + type Folder = FlatMapFolder<'f, C, F, C::Result>; + type Reducer = C::Reducer; + type Result = C::Result; + + fn split_at(self, index: usize) -> (Self, Self, C::Reducer) { + let (left, right, reducer) = self.base.split_at(index); + ( + FlatMapConsumer::new(left, self.map_op), + FlatMapConsumer::new(right, self.map_op), + reducer, + ) + } + + fn into_folder(self) -> Self::Folder { + FlatMapFolder { + base: self.base, + map_op: self.map_op, + previous: None, + } + } + + fn full(&self) -> bool { + self.base.full() + } +} + +impl<'f, T, U, C, F> UnindexedConsumer<T> for FlatMapConsumer<'f, C, F> +where + C: UnindexedConsumer<U::Item>, + F: Fn(T) -> U + Sync, + U: IntoParallelIterator, +{ + fn split_off_left(&self) -> Self { + FlatMapConsumer::new(self.base.split_off_left(), self.map_op) + } + + fn to_reducer(&self) -> Self::Reducer { + self.base.to_reducer() + } +} + +struct FlatMapFolder<'f, C, F, R> { + base: C, + map_op: &'f F, + previous: Option<R>, +} + +impl<'f, T, U, C, F> Folder<T> for FlatMapFolder<'f, C, F, C::Result> +where + C: UnindexedConsumer<U::Item>, + F: Fn(T) -> U + Sync, + U: IntoParallelIterator, +{ + type Result = C::Result; + + fn consume(self, item: T) -> Self { + let map_op = self.map_op; + let par_iter = map_op(item).into_par_iter(); + let consumer = self.base.split_off_left(); + let result = par_iter.drive_unindexed(consumer); + + let previous = match self.previous { + None => Some(result), + Some(previous) => { + let reducer = self.base.to_reducer(); + Some(reducer.reduce(previous, result)) + } + }; + + FlatMapFolder { + base: self.base, + map_op, + previous, + } + } + + fn complete(self) -> Self::Result { + match self.previous { + Some(previous) => previous, + None => self.base.into_folder().complete(), + } + } + + fn full(&self) -> bool { + self.base.full() + } +} |