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-rw-r--r--src/iter/fold.rs302
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diff --git a/src/iter/fold.rs b/src/iter/fold.rs
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+use super::plumbing::*;
+use super::*;
+
+use std::fmt::{self, Debug};
+
+impl<U, I, ID, F> Fold<I, ID, F>
+where
+ I: ParallelIterator,
+ F: Fn(U, I::Item) -> U + Sync + Send,
+ ID: Fn() -> U + Sync + Send,
+ U: Send,
+{
+ pub(super) fn new(base: I, identity: ID, fold_op: F) -> Self {
+ Fold {
+ base,
+ identity,
+ fold_op,
+ }
+ }
+}
+
+/// `Fold` is an iterator that applies a function over an iterator producing a single value.
+/// This struct is created by the [`fold()`] method on [`ParallelIterator`]
+///
+/// [`fold()`]: trait.ParallelIterator.html#method.fold
+/// [`ParallelIterator`]: trait.ParallelIterator.html
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[derive(Clone)]
+pub struct Fold<I, ID, F> {
+ base: I,
+ identity: ID,
+ fold_op: F,
+}
+
+impl<I: ParallelIterator + Debug, ID, F> Debug for Fold<I, ID, F> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ f.debug_struct("Fold").field("base", &self.base).finish()
+ }
+}
+
+impl<U, I, ID, F> ParallelIterator for Fold<I, ID, F>
+where
+ I: ParallelIterator,
+ F: Fn(U, I::Item) -> U + Sync + Send,
+ ID: Fn() -> U + Sync + Send,
+ U: Send,
+{
+ type Item = U;
+
+ fn drive_unindexed<C>(self, consumer: C) -> C::Result
+ where
+ C: UnindexedConsumer<Self::Item>,
+ {
+ let consumer1 = FoldConsumer {
+ base: consumer,
+ fold_op: &self.fold_op,
+ identity: &self.identity,
+ };
+ self.base.drive_unindexed(consumer1)
+ }
+}
+
+struct FoldConsumer<'c, C, ID, F> {
+ base: C,
+ fold_op: &'c F,
+ identity: &'c ID,
+}
+
+impl<'r, U, T, C, ID, F> Consumer<T> for FoldConsumer<'r, C, ID, F>
+where
+ C: Consumer<U>,
+ F: Fn(U, T) -> U + Sync,
+ ID: Fn() -> U + Sync,
+ U: Send,
+{
+ type Folder = FoldFolder<'r, C::Folder, U, F>;
+ type Reducer = C::Reducer;
+ type Result = C::Result;
+
+ fn split_at(self, index: usize) -> (Self, Self, Self::Reducer) {
+ let (left, right, reducer) = self.base.split_at(index);
+ (
+ FoldConsumer { base: left, ..self },
+ FoldConsumer {
+ base: right,
+ ..self
+ },
+ reducer,
+ )
+ }
+
+ fn into_folder(self) -> Self::Folder {
+ FoldFolder {
+ base: self.base.into_folder(),
+ item: (self.identity)(),
+ fold_op: self.fold_op,
+ }
+ }
+
+ fn full(&self) -> bool {
+ self.base.full()
+ }
+}
+
+impl<'r, U, T, C, ID, F> UnindexedConsumer<T> for FoldConsumer<'r, C, ID, F>
+where
+ C: UnindexedConsumer<U>,
+ F: Fn(U, T) -> U + Sync,
+ ID: Fn() -> U + Sync,
+ U: Send,
+{
+ fn split_off_left(&self) -> Self {
+ FoldConsumer {
+ base: self.base.split_off_left(),
+ ..*self
+ }
+ }
+
+ fn to_reducer(&self) -> Self::Reducer {
+ self.base.to_reducer()
+ }
+}
+
+struct FoldFolder<'r, C, ID, F> {
+ base: C,
+ fold_op: &'r F,
+ item: ID,
+}
+
+impl<'r, C, ID, F, T> Folder<T> for FoldFolder<'r, C, ID, F>
+where
+ C: Folder<ID>,
+ F: Fn(ID, T) -> ID + Sync,
+{
+ type Result = C::Result;
+
+ fn consume(self, item: T) -> Self {
+ let item = (self.fold_op)(self.item, item);
+ FoldFolder {
+ base: self.base,
+ fold_op: self.fold_op,
+ item,
+ }
+ }
+
+ fn consume_iter<I>(self, iter: I) -> Self
+ where
+ I: IntoIterator<Item = T>,
+ {
+ fn not_full<C, ID, T>(base: &C) -> impl Fn(&T) -> bool + '_
+ where
+ C: Folder<ID>,
+ {
+ move |_| !base.full()
+ }
+
+ let base = self.base;
+ let item = iter
+ .into_iter()
+ // stop iterating if another thread has finished
+ .take_while(not_full(&base))
+ .fold(self.item, self.fold_op);
+
+ FoldFolder {
+ base,
+ item,
+ fold_op: self.fold_op,
+ }
+ }
+
+ fn complete(self) -> C::Result {
+ self.base.consume(self.item).complete()
+ }
+
+ fn full(&self) -> bool {
+ self.base.full()
+ }
+}
+
+// ///////////////////////////////////////////////////////////////////////////
+
+impl<U, I, F> FoldWith<I, U, F>
+where
+ I: ParallelIterator,
+ F: Fn(U, I::Item) -> U + Sync + Send,
+ U: Send + Clone,
+{
+ pub(super) fn new(base: I, item: U, fold_op: F) -> Self {
+ FoldWith {
+ base,
+ item,
+ fold_op,
+ }
+ }
+}
+
+/// `FoldWith` is an iterator that applies a function over an iterator producing a single value.
+/// This struct is created by the [`fold_with()`] method on [`ParallelIterator`]
+///
+/// [`fold_with()`]: trait.ParallelIterator.html#method.fold_with
+/// [`ParallelIterator`]: trait.ParallelIterator.html
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[derive(Clone)]
+pub struct FoldWith<I, U, F> {
+ base: I,
+ item: U,
+ fold_op: F,
+}
+
+impl<I: ParallelIterator + Debug, U: Debug, F> Debug for FoldWith<I, U, F> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ f.debug_struct("FoldWith")
+ .field("base", &self.base)
+ .field("item", &self.item)
+ .finish()
+ }
+}
+
+impl<U, I, F> ParallelIterator for FoldWith<I, U, F>
+where
+ I: ParallelIterator,
+ F: Fn(U, I::Item) -> U + Sync + Send,
+ U: Send + Clone,
+{
+ type Item = U;
+
+ fn drive_unindexed<C>(self, consumer: C) -> C::Result
+ where
+ C: UnindexedConsumer<Self::Item>,
+ {
+ let consumer1 = FoldWithConsumer {
+ base: consumer,
+ item: self.item,
+ fold_op: &self.fold_op,
+ };
+ self.base.drive_unindexed(consumer1)
+ }
+}
+
+struct FoldWithConsumer<'c, C, U, F> {
+ base: C,
+ item: U,
+ fold_op: &'c F,
+}
+
+impl<'r, U, T, C, F> Consumer<T> for FoldWithConsumer<'r, C, U, F>
+where
+ C: Consumer<U>,
+ F: Fn(U, T) -> U + Sync,
+ U: Send + Clone,
+{
+ type Folder = FoldFolder<'r, C::Folder, U, F>;
+ type Reducer = C::Reducer;
+ type Result = C::Result;
+
+ fn split_at(self, index: usize) -> (Self, Self, Self::Reducer) {
+ let (left, right, reducer) = self.base.split_at(index);
+ (
+ FoldWithConsumer {
+ base: left,
+ item: self.item.clone(),
+ ..self
+ },
+ FoldWithConsumer {
+ base: right,
+ ..self
+ },
+ reducer,
+ )
+ }
+
+ fn into_folder(self) -> Self::Folder {
+ FoldFolder {
+ base: self.base.into_folder(),
+ item: self.item,
+ fold_op: self.fold_op,
+ }
+ }
+
+ fn full(&self) -> bool {
+ self.base.full()
+ }
+}
+
+impl<'r, U, T, C, F> UnindexedConsumer<T> for FoldWithConsumer<'r, C, U, F>
+where
+ C: UnindexedConsumer<U>,
+ F: Fn(U, T) -> U + Sync,
+ U: Send + Clone,
+{
+ fn split_off_left(&self) -> Self {
+ FoldWithConsumer {
+ base: self.base.split_off_left(),
+ item: self.item.clone(),
+ ..*self
+ }
+ }
+
+ fn to_reducer(&self) -> Self::Reducer {
+ self.base.to_reducer()
+ }
+}
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