New upstream version 1.63.0+dfsg1

[rustc.git] / vendor / rustc-rayon / src / iter / flatten.rs

diff --git a/vendor/rustc-rayon/src/iter/flatten.rs b/vendor/rustc-rayon/src/iter/flatten.rs
index 939ba163688281c3aa14cc133cdc95899ba76e43..29d88f99edaf7e9734771822e18b227120cc8fd3 100644 (file)
--- a/vendor/rustc-rayon/src/iter/flatten.rs
+++ b/vendor/rustc-rayon/src/iter/flatten.rs
@@ -1,9 +1,8 @@
 use super::plumbing::*;
 use super::*;
 
-/// `Flatten` turns each element to an iterator, then flattens these iterators
-/// together. This struct is created by the [`flatten()`] method on
-/// [`ParallelIterator`].
+/// `Flatten` turns each element to a parallel iterator, then flattens these iterators
+/// together. This struct is created by the [`flatten()`] method on [`ParallelIterator`].
 ///
 /// [`flatten()`]: trait.ParallelIterator.html#method.flatten
 /// [`ParallelIterator`]: trait.ParallelIterator.html
@@ -13,32 +12,129 @@ pub struct Flatten<I: ParallelIterator> {
     base: I,
 }
 
-impl<I, PI> Flatten<I>
+impl<I> Flatten<I>
 where
-    I: ParallelIterator<Item = PI>,
-    PI: IntoParallelIterator + Send,
+    I: ParallelIterator,
+    I::Item: IntoParallelIterator,
 {
-    /// Create a new `Flatten` iterator.
+    /// Creates a new `Flatten` iterator.
     pub(super) fn new(base: I) -> Self {
         Flatten { base }
     }
 }
 
-impl<I, PI> ParallelIterator for Flatten<I>
+impl<I> ParallelIterator for Flatten<I>
 where
-    I: ParallelIterator<Item = PI>,
-    PI: IntoParallelIterator + Send,
+    I: ParallelIterator,
+    I::Item: IntoParallelIterator,
 {
-    type Item = PI::Item;
+    type Item = <I::Item as IntoParallelIterator>::Item;
 
     fn drive_unindexed<C>(self, consumer: C) -> C::Result
     where
         C: UnindexedConsumer<Self::Item>,
     {
-        fn id<T>(x: T) -> T {
-            x
+        let consumer = FlattenConsumer::new(consumer);
+        self.base.drive_unindexed(consumer)
+    }
+}
+
+/// ////////////////////////////////////////////////////////////////////////
+/// Consumer implementation
+
+struct FlattenConsumer<C> {
+    base: C,
+}
+
+impl<C> FlattenConsumer<C> {
+    fn new(base: C) -> Self {
+        FlattenConsumer { base }
+    }
+}
+
+impl<T, C> Consumer<T> for FlattenConsumer<C>
+where
+    C: UnindexedConsumer<T::Item>,
+    T: IntoParallelIterator,
+{
+    type Folder = FlattenFolder<C, 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);
+        (
+            FlattenConsumer::new(left),
+            FlattenConsumer::new(right),
+            reducer,
+        )
+    }
+
+    fn into_folder(self) -> Self::Folder {
+        FlattenFolder {
+            base: self.base,
+            previous: None,
+        }
+    }
+
+    fn full(&self) -> bool {
+        self.base.full()
+    }
+}
+
+impl<T, C> UnindexedConsumer<T> for FlattenConsumer<C>
+where
+    C: UnindexedConsumer<T::Item>,
+    T: IntoParallelIterator,
+{
+    fn split_off_left(&self) -> Self {
+        FlattenConsumer::new(self.base.split_off_left())
+    }
+
+    fn to_reducer(&self) -> Self::Reducer {
+        self.base.to_reducer()
+    }
+}
+
+struct FlattenFolder<C, R> {
+    base: C,
+    previous: Option<R>,
+}
+
+impl<T, C> Folder<T> for FlattenFolder<C, C::Result>
+where
+    C: UnindexedConsumer<T::Item>,
+    T: IntoParallelIterator,
+{
+    type Result = C::Result;
+
+    fn consume(self, item: T) -> Self {
+        let par_iter = 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))
+            }
+        };
+
+        FlattenFolder {
+            base: self.base,
+            previous,
         }
+    }
+
+    fn complete(self) -> Self::Result {
+        match self.previous {
+            Some(previous) => previous,
+            None => self.base.into_folder().complete(),
+        }
+    }
 
-        self.base.flat_map(id).drive_unindexed(consumer)
+    fn full(&self) -> bool {
+        self.base.full()
     }
 }