rayon/iter/
reduce.rs

1use super::plumbing::*;
2use super::ParallelIterator;
3
4pub(super) fn reduce<PI, R, ID, T>(pi: PI, identity: ID, reduce_op: R) -> T
5where
6    PI: ParallelIterator<Item = T>,
7    R: Fn(T, T) -> T + Sync,
8    ID: Fn() -> T + Sync,
9    T: Send,
10{
11    let consumer = ReduceConsumer {
12        identity: &identity,
13        reduce_op: &reduce_op,
14    };
15    pi.drive_unindexed(consumer)
16}
17
18struct ReduceConsumer<'r, R, ID> {
19    identity: &'r ID,
20    reduce_op: &'r R,
21}
22
23impl<'r, R, ID> Copy for ReduceConsumer<'r, R, ID> {}
24
25impl<'r, R, ID> Clone for ReduceConsumer<'r, R, ID> {
26    fn clone(&self) -> Self {
27        *self
28    }
29}
30
31impl<'r, R, ID, T> Consumer<T> for ReduceConsumer<'r, R, ID>
32where
33    R: Fn(T, T) -> T + Sync,
34    ID: Fn() -> T + Sync,
35    T: Send,
36{
37    type Folder = ReduceFolder<'r, R, T>;
38    type Reducer = Self;
39    type Result = T;
40
41    fn split_at(self, _index: usize) -> (Self, Self, Self) {
42        (self, self, self)
43    }
44
45    fn into_folder(self) -> Self::Folder {
46        ReduceFolder {
47            reduce_op: self.reduce_op,
48            item: (self.identity)(),
49        }
50    }
51
52    fn full(&self) -> bool {
53        false
54    }
55}
56
57impl<'r, R, ID, T> UnindexedConsumer<T> for ReduceConsumer<'r, R, ID>
58where
59    R: Fn(T, T) -> T + Sync,
60    ID: Fn() -> T + Sync,
61    T: Send,
62{
63    fn split_off_left(&self) -> Self {
64        *self
65    }
66
67    fn to_reducer(&self) -> Self::Reducer {
68        *self
69    }
70}
71
72impl<'r, R, ID, T> Reducer<T> for ReduceConsumer<'r, R, ID>
73where
74    R: Fn(T, T) -> T + Sync,
75{
76    fn reduce(self, left: T, right: T) -> T {
77        (self.reduce_op)(left, right)
78    }
79}
80
81struct ReduceFolder<'r, R, T> {
82    reduce_op: &'r R,
83    item: T,
84}
85
86impl<'r, R, T> Folder<T> for ReduceFolder<'r, R, T>
87where
88    R: Fn(T, T) -> T,
89{
90    type Result = T;
91
92    fn consume(self, item: T) -> Self {
93        ReduceFolder {
94            reduce_op: self.reduce_op,
95            item: (self.reduce_op)(self.item, item),
96        }
97    }
98
99    fn consume_iter<I>(self, iter: I) -> Self
100    where
101        I: IntoIterator<Item = T>,
102    {
103        ReduceFolder {
104            reduce_op: self.reduce_op,
105            item: iter.into_iter().fold(self.item, self.reduce_op),
106        }
107    }
108
109    fn complete(self) -> T {
110        self.item
111    }
112
113    fn full(&self) -> bool {
114        false
115    }
116}
rayon/iter/reduce.rs

rayon/iter/
reduce.rs
