1 files changed, 134 insertions, 0 deletions
diff --git a/src/iter/try_reduce_with.rs b/src/iter/try_reduce_with.rs
new file mode 100644
index 0000000..6be3100
--- /dev/null
+++ b/src/iter/try_reduce_with.rs
@@ -0,0 +1,134 @@
+use super::plumbing::*;
+use super::ParallelIterator;
+
+use super::private::Try;
+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::Ok, T::Ok) -> 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::Ok, T::Ok) -> 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_result: 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::Ok, T::Ok) -> 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::Ok, T::Ok) -> T + Sync,
+    T: Try,
+{
+    fn reduce(self, left: Option<T>, right: Option<T>) -> Option<T> {
+        let reduce_op = self.reduce_op;
+        match (left, right) {
+            (None, x) | (x, None) => x,
+            (Some(a), Some(b)) => match (a.into_result(), b.into_result()) {
+                (Ok(a), Ok(b)) => Some(reduce_op(a, b)),
+                (Err(e), _) | (_, Err(e)) => Some(T::from_error(e)),
+            },
+        }
+    }
+}
+
+struct TryReduceWithFolder<'r, R, T: Try> {
+    reduce_op: &'r R,
+    opt_result: Option<Result<T::Ok, T::Error>>,
+    full: &'r AtomicBool,
+}
+
+impl<'r, R, T> Folder<T> for TryReduceWithFolder<'r, R, T>
+where
+    R: Fn(T::Ok, T::Ok) -> T,
+    T: Try,
+{
+    type Result = Option<T>;
+
+    fn consume(self, item: T) -> Self {
+        let reduce_op = self.reduce_op;
+        let result = match self.opt_result {
+            None => item.into_result(),
+            Some(Ok(a)) => match item.into_result() {
+                Ok(b) => reduce_op(a, b).into_result(),
+                Err(e) => Err(e),
+            },
+            Some(Err(e)) => Err(e),
+        };
+        if result.is_err() {
+            self.full.store(true, Ordering::Relaxed)
+        }
+        TryReduceWithFolder {
+            opt_result: Some(result),
+            ..self
+        }
+    }
+
+    fn complete(self) -> Option<T> {
+        let result = self.opt_result?;
+        Some(match result {
+            Ok(ok) => T::from_ok(ok),
+            Err(error) => T::from_error(error),
+        })
+    }
+
+    fn full(&self) -> bool {
+        self.full.load(Ordering::Relaxed)
+    }
+}