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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),
}
}
}