Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

vendor/rayon/src/iter/try_reduce_with.rs

@@ -0,0 +1,132 @@
+use super::plumbing::*;
+use super::ParallelIterator;
+use super::Try;
+
+use std::ops::ControlFlow::{self, Break, Continue};
+use std::sync::atomic::{AtomicBool, Ordering};
+
+pub(super) fn try_reduce_with<PI, R, T>(pi: PI, reduce_op: R) -> Option<T>
+where
+    PI: ParallelIterator<Item = T>,
+    R: Fn(T::Output, T::Output) -> T + Sync,
+    T: Try + Send,
+{
+    let full = AtomicBool::new(false);
+    let consumer = TryReduceWithConsumer {
+        reduce_op: &reduce_op,
+        full: &full,
+    };
+    pi.drive_unindexed(consumer)
+}
+
+struct TryReduceWithConsumer<'r, R> {
+    reduce_op: &'r R,
+    full: &'r AtomicBool,
+}
+
+impl<'r, R> Copy for TryReduceWithConsumer<'r, R> {}
+
+impl<'r, R> Clone for TryReduceWithConsumer<'r, R> {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
+impl<'r, R, T> Consumer<T> for TryReduceWithConsumer<'r, R>
+where
+    R: Fn(T::Output, T::Output) -> T + Sync,
+    T: Try + Send,
+{
+    type Folder = TryReduceWithFolder<'r, R, T>;
+    type Reducer = Self;
+    type Result = Option<T>;
+
+    fn split_at(self, _index: usize) -> (Self, Self, Self) {
+        (self, self, self)
+    }
+
+    fn into_folder(self) -> Self::Folder {
+        TryReduceWithFolder {
+            reduce_op: self.reduce_op,
+            opt_control: None,
+            full: self.full,
+        }
+    }
+
+    fn full(&self) -> bool {
+        self.full.load(Ordering::Relaxed)
+    }
+}
+
+impl<'r, R, T> UnindexedConsumer<T> for TryReduceWithConsumer<'r, R>
+where
+    R: Fn(T::Output, T::Output) -> T + Sync,
+    T: Try + Send,
+{
+    fn split_off_left(&self) -> Self {
+        *self
+    }
+
+    fn to_reducer(&self) -> Self::Reducer {
+        *self
+    }
+}
+
+impl<'r, R, T> Reducer<Option<T>> for TryReduceWithConsumer<'r, R>
+where
+    R: Fn(T::Output, T::Output) -> T + Sync,
+    T: Try,
+{
+    fn reduce(self, left: Option<T>, right: Option<T>) -> Option<T> {
+        let reduce_op = self.reduce_op;
+        match (left, right) {
+            (Some(left), Some(right)) => match (left.branch(), right.branch()) {
+                (Continue(left), Continue(right)) => Some(reduce_op(left, right)),
+                (Break(r), _) | (_, Break(r)) => Some(T::from_residual(r)),
+            },
+            (None, x) | (x, None) => x,
+        }
+    }
+}
+
+struct TryReduceWithFolder<'r, R, T: Try> {
+    reduce_op: &'r R,
+    opt_control: Option<ControlFlow<T::Residual, T::Output>>,
+    full: &'r AtomicBool,
+}
+
+impl<'r, R, T> Folder<T> for TryReduceWithFolder<'r, R, T>
+where
+    R: Fn(T::Output, T::Output) -> T,
+    T: Try,
+{
+    type Result = Option<T>;
+
+    fn consume(mut self, item: T) -> Self {
+        let reduce_op = self.reduce_op;
+        let control = match (self.opt_control, item.branch()) {
+            (Some(Continue(left)), Continue(right)) => reduce_op(left, right).branch(),
+            (Some(control @ Break(_)), _) | (_, control) => control,
+        };
+        if let Break(_) = control {
+            self.full.store(true, Ordering::Relaxed)
+        }
+        self.opt_control = Some(control);
+        self
+    }
+
+    fn complete(self) -> Option<T> {
+        match self.opt_control {
+            Some(Continue(c)) => Some(T::from_output(c)),
+            Some(Break(r)) => Some(T::from_residual(r)),
+            None => None,
+        }
+    }
+
+    fn full(&self) -> bool {
+        match self.opt_control {
+            Some(Break(_)) => true,
+            _ => self.full.load(Ordering::Relaxed),
+        }
+    }
+}