1 files changed, 129 insertions, 0 deletions
diff --git a/src/iter/try_reduce.rs b/src/iter/try_reduce.rs
new file mode 100644
index 0000000..76b3850
--- /dev/null
+++ b/src/iter/try_reduce.rs
@@ -0,0 +1,129 @@
+use super::plumbing::*;
+use super::ParallelIterator;
+
+use super::private::Try;
+use std::sync::atomic::{AtomicBool, Ordering};
+
+pub(super) fn try_reduce<PI, R, ID, T>(pi: PI, identity: ID, reduce_op: R) -> T
+where
+    PI: ParallelIterator<Item = T>,
+    R: Fn(T::Ok, T::Ok) -> T + Sync,
+    ID: Fn() -> T::Ok + Sync,
+    T: Try + Send,
+{
+    let full = AtomicBool::new(false);
+    let consumer = TryReduceConsumer {
+        identity: &identity,
+        reduce_op: &reduce_op,
+        full: &full,
+    };
+    pi.drive_unindexed(consumer)
+}
+
+struct TryReduceConsumer<'r, R, ID> {
+    identity: &'r ID,
+    reduce_op: &'r R,
+    full: &'r AtomicBool,
+}
+
+impl<'r, R, ID> Copy for TryReduceConsumer<'r, R, ID> {}
+
+impl<'r, R, ID> Clone for TryReduceConsumer<'r, R, ID> {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
+impl<'r, R, ID, T> Consumer<T> for TryReduceConsumer<'r, R, ID>
+where
+    R: Fn(T::Ok, T::Ok) -> T + Sync,
+    ID: Fn() -> T::Ok + Sync,
+    T: Try + Send,
+{
+    type Folder = TryReduceFolder<'r, R, T>;
+    type Reducer = Self;
+    type Result = T;
+
+    fn split_at(self, _index: usize) -> (Self, Self, Self) {
+        (self, self, self)
+    }
+
+    fn into_folder(self) -> Self::Folder {
+        TryReduceFolder {
+            reduce_op: self.reduce_op,
+            result: Ok((self.identity)()),
+            full: self.full,
+        }
+    }
+
+    fn full(&self) -> bool {
+        self.full.load(Ordering::Relaxed)
+    }
+}
+
+impl<'r, R, ID, T> UnindexedConsumer<T> for TryReduceConsumer<'r, R, ID>
+where
+    R: Fn(T::Ok, T::Ok) -> T + Sync,
+    ID: Fn() -> T::Ok + Sync,
+    T: Try + Send,
+{
+    fn split_off_left(&self) -> Self {
+        *self
+    }
+
+    fn to_reducer(&self) -> Self::Reducer {
+        *self
+    }
+}
+
+impl<'r, R, ID, T> Reducer<T> for TryReduceConsumer<'r, R, ID>
+where
+    R: Fn(T::Ok, T::Ok) -> T + Sync,
+    T: Try,
+{
+    fn reduce(self, left: T, right: T) -> T {
+        match (left.into_result(), right.into_result()) {
+            (Ok(left), Ok(right)) => (self.reduce_op)(left, right),
+            (Err(e), _) | (_, Err(e)) => T::from_error(e),
+        }
+    }
+}
+
+struct TryReduceFolder<'r, R, T: Try> {
+    reduce_op: &'r R,
+    result: Result<T::Ok, T::Error>,
+    full: &'r AtomicBool,
+}
+
+impl<'r, R, T> Folder<T> for TryReduceFolder<'r, R, T>
+where
+    R: Fn(T::Ok, T::Ok) -> T,
+    T: Try,
+{
+    type Result = T;
+
+    fn consume(mut self, item: T) -> Self {
+        let reduce_op = self.reduce_op;
+        if let Ok(left) = self.result {
+            self.result = match item.into_result() {
+                Ok(right) => reduce_op(left, right).into_result(),
+                Err(error) => Err(error),
+            };
+        }
+        if self.result.is_err() {
+            self.full.store(true, Ordering::Relaxed)
+        }
+        self
+    }
+
+    fn complete(self) -> T {
+        match self.result {
+            Ok(ok) => T::from_ok(ok),
+            Err(error) => T::from_error(error),
+        }
+    }
+
+    fn full(&self) -> bool {
+        self.full.load(Ordering::Relaxed)
+    }
+}