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(name:"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<'_, C, P> = FilterConsumer::new(base:consumer, &self.filter_op);
46 self.base.drive_unindexed(consumer: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}
142