1use super::plumbing::*;
2use super::ParallelIterator;
3use super::Try;
4
5use std::ops::ControlFlow::{self, Break, Continue};
6use std::sync::atomic::{AtomicBool, Ordering};
7
8pub(super) fn try_reduce_with<PI, R, T>(pi: PI, reduce_op: R) -> Option<T>
9where
10 PI: ParallelIterator<Item = T>,
11 R: Fn(T::Output, T::Output) -> T + Sync,
12 T: Try + Send,
13{
14 let full = AtomicBool::new(false);
15 let consumer = TryReduceWithConsumer {
16 reduce_op: &reduce_op,
17 full: &full,
18 };
19 pi.drive_unindexed(consumer)
20}
21
22struct TryReduceWithConsumer<'r, R> {
23 reduce_op: &'r R,
24 full: &'r AtomicBool,
25}
26
27impl<'r, R> Copy for TryReduceWithConsumer<'r, R> {}
28
29impl<'r, R> Clone for TryReduceWithConsumer<'r, R> {
30 fn clone(&self) -> Self {
31 *self
32 }
33}
34
35impl<'r, R, T> Consumer<T> for TryReduceWithConsumer<'r, R>
36where
37 R: Fn(T::Output, T::Output) -> T + Sync,
38 T: Try + Send,
39{
40 type Folder = TryReduceWithFolder<'r, R, T>;
41 type Reducer = Self;
42 type Result = Option<T>;
43
44 fn split_at(self, _index: usize) -> (Self, Self, Self) {
45 (self, self, self)
46 }
47
48 fn into_folder(self) -> Self::Folder {
49 TryReduceWithFolder {
50 reduce_op: self.reduce_op,
51 opt_control: None,
52 full: self.full,
53 }
54 }
55
56 fn full(&self) -> bool {
57 self.full.load(Ordering::Relaxed)
58 }
59}
60
61impl<'r, R, T> UnindexedConsumer<T> for TryReduceWithConsumer<'r, R>
62where
63 R: Fn(T::Output, T::Output) -> T + Sync,
64 T: Try + Send,
65{
66 fn split_off_left(&self) -> Self {
67 *self
68 }
69
70 fn to_reducer(&self) -> Self::Reducer {
71 *self
72 }
73}
74
75impl<'r, R, T> Reducer<Option<T>> for TryReduceWithConsumer<'r, R>
76where
77 R: Fn(T::Output, T::Output) -> T + Sync,
78 T: Try,
79{
80 fn reduce(self, left: Option<T>, right: Option<T>) -> Option<T> {
81 let reduce_op = self.reduce_op;
82 match (left, right) {
83 (Some(left), Some(right)) => match (left.branch(), right.branch()) {
84 (Continue(left), Continue(right)) => Some(reduce_op(left, right)),
85 (Break(r), _) | (_, Break(r)) => Some(T::from_residual(r)),
86 },
87 (None, x) | (x, None) => x,
88 }
89 }
90}
91
92struct TryReduceWithFolder<'r, R, T: Try> {
93 reduce_op: &'r R,
94 opt_control: Option<ControlFlow<T::Residual, T::Output>>,
95 full: &'r AtomicBool,
96}
97
98impl<'r, R, T> Folder<T> for TryReduceWithFolder<'r, R, T>
99where
100 R: Fn(T::Output, T::Output) -> T,
101 T: Try,
102{
103 type Result = Option<T>;
104
105 fn consume(mut self, item: T) -> Self {
106 let reduce_op = self.reduce_op;
107 let control = match (self.opt_control, item.branch()) {
108 (Some(Continue(left)), Continue(right)) => reduce_op(left, right).branch(),
109 (Some(control @ Break(_)), _) | (_, control) => control,
110 };
111 if let Break(_) = control {
112 self.full.store(true, Ordering::Relaxed)
113 }
114 self.opt_control = Some(control);
115 self
116 }
117
118 fn complete(self) -> Option<T> {
119 match self.opt_control {
120 Some(Continue(c)) => Some(T::from_output(c)),
121 Some(Break(r)) => Some(T::from_residual(r)),
122 None => None,
123 }
124 }
125
126 fn full(&self) -> bool {
127 match self.opt_control {
128 Some(Break(_)) => true,
129 _ => self.full.load(Ordering::Relaxed),
130 }
131 }
132}
133