rayon/iter/
filter_map.rs

1use super::plumbing::*;
2use super::*;
3
4use std::fmt::{self, Debug};
5
6/// `FilterMap` creates an iterator that uses `filter_op` to both filter and map elements.
7/// This struct is created by the [`filter_map()`] method on [`ParallelIterator`].
8///
9/// [`filter_map()`]: trait.ParallelIterator.html#method.filter_map
10/// [`ParallelIterator`]: trait.ParallelIterator.html
11#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
12#[derive(Clone)]
13pub struct FilterMap<I: ParallelIterator, P> {
14    base: I,
15    filter_op: P,
16}
17
18impl<I: ParallelIterator + Debug, P> Debug for FilterMap<I, P> {
19    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
20        f.debug_struct("FilterMap")
21            .field("base", &self.base)
22            .finish()
23    }
24}
25
26impl<I: ParallelIterator, P> FilterMap<I, P> {
27    /// Creates a new `FilterMap` iterator.
28    pub(super) fn new(base: I, filter_op: P) -> Self {
29        FilterMap { base, filter_op }
30    }
31}
32
33impl<I, P, R> ParallelIterator for FilterMap<I, P>
34where
35    I: ParallelIterator,
36    P: Fn(I::Item) -> Option<R> + Sync + Send,
37    R: Send,
38{
39    type Item = R;
40
41    fn drive_unindexed<C>(self, consumer: C) -> C::Result
42    where
43        C: UnindexedConsumer<Self::Item>,
44    {
45        let consumer = FilterMapConsumer::new(consumer, &self.filter_op);
46        self.base.drive_unindexed(consumer)
47    }
48}
49
50/// ////////////////////////////////////////////////////////////////////////
51/// Consumer implementation
52
53struct FilterMapConsumer<'p, C, P> {
54    base: C,
55    filter_op: &'p P,
56}
57
58impl<'p, C, P: 'p> FilterMapConsumer<'p, C, P> {
59    fn new(base: C, filter_op: &'p P) -> Self {
60        FilterMapConsumer { base, filter_op }
61    }
62}
63
64impl<'p, T, U, C, P> Consumer<T> for FilterMapConsumer<'p, C, P>
65where
66    C: Consumer<U>,
67    P: Fn(T) -> Option<U> + Sync + 'p,
68{
69    type Folder = FilterMapFolder<'p, C::Folder, P>;
70    type Reducer = C::Reducer;
71    type Result = C::Result;
72
73    fn split_at(self, index: usize) -> (Self, Self, Self::Reducer) {
74        let (left, right, reducer) = self.base.split_at(index);
75        (
76            FilterMapConsumer::new(left, self.filter_op),
77            FilterMapConsumer::new(right, self.filter_op),
78            reducer,
79        )
80    }
81
82    fn into_folder(self) -> Self::Folder {
83        let base = self.base.into_folder();
84        FilterMapFolder {
85            base,
86            filter_op: self.filter_op,
87        }
88    }
89
90    fn full(&self) -> bool {
91        self.base.full()
92    }
93}
94
95impl<'p, T, U, C, P> UnindexedConsumer<T> for FilterMapConsumer<'p, C, P>
96where
97    C: UnindexedConsumer<U>,
98    P: Fn(T) -> Option<U> + Sync + 'p,
99{
100    fn split_off_left(&self) -> Self {
101        FilterMapConsumer::new(self.base.split_off_left(), self.filter_op)
102    }
103
104    fn to_reducer(&self) -> Self::Reducer {
105        self.base.to_reducer()
106    }
107}
108
109struct FilterMapFolder<'p, C, P> {
110    base: C,
111    filter_op: &'p P,
112}
113
114impl<'p, T, U, C, P> Folder<T> for FilterMapFolder<'p, C, P>
115where
116    C: Folder<U>,
117    P: Fn(T) -> Option<U> + Sync + 'p,
118{
119    type Result = C::Result;
120
121    fn consume(self, item: T) -> Self {
122        let filter_op = self.filter_op;
123        if let Some(mapped_item) = filter_op(item) {
124            let base = self.base.consume(mapped_item);
125            FilterMapFolder { base, filter_op }
126        } else {
127            self
128        }
129    }
130
131    // This cannot easily specialize `consume_iter` to be better than
132    // the default, because that requires checking `self.base.full()`
133    // during a call to `self.base.consume_iter()`. (#632)
134
135    fn complete(self) -> C::Result {
136        self.base.complete()
137    }
138
139    fn full(&self) -> bool {
140        self.base.full()
141    }
142}
rayon/iter/filter_map.rs

rayon/iter/
filter_map.rs
