Initial import of rayon-1.5.0. am: 041839ceab am: d836dd6404 am: 7522a9ba00

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/rayon/+/1622436

Change-Id: I94b0e06d9da131d6f98db436ad1a178dfff2ec90

1 files changed, 114 insertions, 0 deletions

diff --git a/src/iter/product.rs b/src/iter/product.rs
new file mode 100644
index 0000000..a3d0727
--- /dev/null
+++ b/src/iter/product.rs
@@ -0,0 +1,114 @@
+use super::plumbing::*;
+use super::ParallelIterator;
+
+use std::iter::{self, Product};
+use std::marker::PhantomData;
+
+pub(super) fn product<PI, P>(pi: PI) -> P
+where
+    PI: ParallelIterator,
+    P: Send + Product<PI::Item> + Product,
+{
+    pi.drive_unindexed(ProductConsumer::new())
+}
+
+fn mul<T: Product>(left: T, right: T) -> T {
+    iter::once(left).chain(iter::once(right)).product()
+}
+
+struct ProductConsumer<P: Send> {
+    _marker: PhantomData<*const P>,
+}
+
+unsafe impl<P: Send> Send for ProductConsumer<P> {}
+
+impl<P: Send> ProductConsumer<P> {
+    fn new() -> ProductConsumer<P> {
+        ProductConsumer {
+            _marker: PhantomData,
+        }
+    }
+}
+
+impl<P, T> Consumer<T> for ProductConsumer<P>
+where
+    P: Send + Product<T> + Product,
+{
+    type Folder = ProductFolder<P>;
+    type Reducer = Self;
+    type Result = P;
+
+    fn split_at(self, _index: usize) -> (Self, Self, Self) {
+        (
+            ProductConsumer::new(),
+            ProductConsumer::new(),
+            ProductConsumer::new(),
+        )
+    }
+
+    fn into_folder(self) -> Self::Folder {
+        ProductFolder {
+            product: iter::empty::<T>().product(),
+        }
+    }
+
+    fn full(&self) -> bool {
+        false
+    }
+}
+
+impl<P, T> UnindexedConsumer<T> for ProductConsumer<P>
+where
+    P: Send + Product<T> + Product,
+{
+    fn split_off_left(&self) -> Self {
+        ProductConsumer::new()
+    }
+
+    fn to_reducer(&self) -> Self::Reducer {
+        ProductConsumer::new()
+    }
+}
+
+impl<P> Reducer<P> for ProductConsumer<P>
+where
+    P: Send + Product,
+{
+    fn reduce(self, left: P, right: P) -> P {
+        mul(left, right)
+    }
+}
+
+struct ProductFolder<P> {
+    product: P,
+}
+
+impl<P, T> Folder<T> for ProductFolder<P>
+where
+    P: Product<T> + Product,
+{
+    type Result = P;
+
+    fn consume(self, item: T) -> Self {
+        ProductFolder {
+            product: mul(self.product, iter::once(item).product()),
+        }
+    }
+
+    fn consume_iter<I>(self, iter: I) -> Self
+    where
+        I: IntoIterator<Item = T>,
+    {
+        ProductFolder {
+            product: mul(self.product, iter.into_iter().product()),
+        }
+    }
+
+    fn complete(self) -> P {
+        self.product
+    }
+
+    fn full(&self) -> bool {
+        false
+    }
+}