rayon/iter/
filter.rs

1use super::plumbing::*;
2use super::*;
3
4use std::fmt::{self, Debug};
5
6/// `Filter` takes a predicate `filter_op` and filters out elements that match.
7/// This struct is created by the [`filter()`] method on [`ParallelIterator`]
8///
9/// [`filter()`]: trait.ParallelIterator.html#method.filter
10/// [`ParallelIterator`]: trait.ParallelIterator.html
11#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
12#[derive(Clone)]
13pub struct Filter<I: ParallelIterator, P> {
14    base: I,
15    filter_op: P,
16}
17
18impl<I: ParallelIterator + Debug, P> Debug for Filter<I, P> {
19    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
20        f.debug_struct("Filter").field("base", &self.base).finish()
21    }
22}
23
24impl<I, P> Filter<I, P>
25where
26    I: ParallelIterator,
27{
28    /// Creates a new `Filter` iterator.
29    pub(super) fn new(base: I, filter_op: P) -> Self {
30        Filter { base, filter_op }
31    }
32}
33
34impl<I, P> ParallelIterator for Filter<I, P>
35where
36    I: ParallelIterator,
37    P: Fn(&I::Item) -> bool + Sync + Send,
38{
39    type Item = I::Item;
40
41    fn drive_unindexed<C>(self, consumer: C) -> C::Result
42    where
43        C: UnindexedConsumer<Self::Item>,
44    {
45        let consumer1 = FilterConsumer::new(consumer, &self.filter_op);
46        self.base.drive_unindexed(consumer1)
47    }
48}
49
50/// ////////////////////////////////////////////////////////////////////////
51/// Consumer implementation
52
53struct FilterConsumer<'p, C, P> {
54    base: C,
55    filter_op: &'p P,
56}
57
58impl<'p, C, P> FilterConsumer<'p, C, P> {
59    fn new(base: C, filter_op: &'p P) -> Self {
60        FilterConsumer { base, filter_op }
61    }
62}
63
64impl<'p, T, C, P: 'p> Consumer<T> for FilterConsumer<'p, C, P>
65where
66    C: Consumer<T>,
67    P: Fn(&T) -> bool + Sync,
68{
69    type Folder = FilterFolder<'p, C::Folder, P>;
70    type Reducer = C::Reducer;
71    type Result = C::Result;
72
73    fn split_at(self, index: usize) -> (Self, Self, C::Reducer) {
74        let (left, right, reducer) = self.base.split_at(index);
75        (
76            FilterConsumer::new(left, self.filter_op),
77            FilterConsumer::new(right, self.filter_op),
78            reducer,
79        )
80    }
81
82    fn into_folder(self) -> Self::Folder {
83        FilterFolder {
84            base: self.base.into_folder(),
85            filter_op: self.filter_op,
86        }
87    }
88
89    fn full(&self) -> bool {
90        self.base.full()
91    }
92}
93
94impl<'p, T, C, P: 'p> UnindexedConsumer<T> for FilterConsumer<'p, C, P>
95where
96    C: UnindexedConsumer<T>,
97    P: Fn(&T) -> bool + Sync,
98{
99    fn split_off_left(&self) -> Self {
100        FilterConsumer::new(self.base.split_off_left(), self.filter_op)
101    }
102
103    fn to_reducer(&self) -> Self::Reducer {
104        self.base.to_reducer()
105    }
106}
107
108struct FilterFolder<'p, C, P> {
109    base: C,
110    filter_op: &'p P,
111}
112
113impl<'p, C, P, T> Folder<T> for FilterFolder<'p, C, P>
114where
115    C: Folder<T>,
116    P: Fn(&T) -> bool + 'p,
117{
118    type Result = C::Result;
119
120    fn consume(self, item: T) -> Self {
121        let filter_op = self.filter_op;
122        if filter_op(&item) {
123            let base = self.base.consume(item);
124            FilterFolder { base, filter_op }
125        } else {
126            self
127        }
128    }
129
130    // This cannot easily specialize `consume_iter` to be better than
131    // the default, because that requires checking `self.base.full()`
132    // during a call to `self.base.consume_iter()`. (#632)
133
134    fn complete(self) -> Self::Result {
135        self.base.complete()
136    }
137
138    fn full(&self) -> bool {
139        self.base.full()
140    }
141}
rayon/iter/filter.rs

rayon/iter/
filter.rs
