rayon/iter/
take_any_while.rs

1use super::plumbing::*;
2use super::*;
3use std::fmt;
4use std::sync::atomic::{AtomicBool, Ordering};
5
6/// `TakeAnyWhile` is an iterator that iterates over elements from anywhere in `I`
7/// until the callback returns `false`.
8/// This struct is created by the [`take_any_while()`] method on [`ParallelIterator`]
9///
10/// [`take_any_while()`]: ParallelIterator::take_any_while()
11#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
12#[derive(Clone)]
13pub struct TakeAnyWhile<I, P> {
14    base: I,
15    predicate: P,
16}
17
18impl<I: fmt::Debug, P> fmt::Debug for TakeAnyWhile<I, P> {
19    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
20        f.debug_struct("TakeAnyWhile")
21            .field("base", &self.base)
22            .finish()
23    }
24}
25
26impl<I, P> TakeAnyWhile<I, P> {
27    /// Creates a new `TakeAnyWhile` iterator.
28    pub(super) fn new(base: I, predicate: P) -> Self {
29        TakeAnyWhile { base, predicate }
30    }
31}
32
33impl<I, P> ParallelIterator for TakeAnyWhile<I, P>
34where
35    I: ParallelIterator,
36    P: Fn(&I::Item) -> bool + Sync + Send,
37{
38    type Item = I::Item;
39
40    fn drive_unindexed<C>(self, consumer: C) -> C::Result
41    where
42        C: UnindexedConsumer<Self::Item>,
43    {
44        let consumer1 = TakeAnyWhileConsumer {
45            base: consumer,
46            predicate: &self.predicate,
47            taking: &AtomicBool::new(true),
48        };
49        self.base.drive_unindexed(consumer1)
50    }
51}
52
53// ////////////////////////////////////////////////////////////////////////
54// Consumer implementation
55
56struct TakeAnyWhileConsumer<'p, C, P> {
57    base: C,
58    predicate: &'p P,
59    taking: &'p AtomicBool,
60}
61
62impl<'p, T, C, P> Consumer<T> for TakeAnyWhileConsumer<'p, C, P>
63where
64    C: Consumer<T>,
65    P: Fn(&T) -> bool + Sync,
66{
67    type Folder = TakeAnyWhileFolder<'p, C::Folder, P>;
68    type Reducer = C::Reducer;
69    type Result = C::Result;
70
71    fn split_at(self, index: usize) -> (Self, Self, Self::Reducer) {
72        let (left, right, reducer) = self.base.split_at(index);
73        (
74            TakeAnyWhileConsumer { base: left, ..self },
75            TakeAnyWhileConsumer {
76                base: right,
77                ..self
78            },
79            reducer,
80        )
81    }
82
83    fn into_folder(self) -> Self::Folder {
84        TakeAnyWhileFolder {
85            base: self.base.into_folder(),
86            predicate: self.predicate,
87            taking: self.taking,
88        }
89    }
90
91    fn full(&self) -> bool {
92        !self.taking.load(Ordering::Relaxed) || self.base.full()
93    }
94}
95
96impl<'p, T, C, P> UnindexedConsumer<T> for TakeAnyWhileConsumer<'p, C, P>
97where
98    C: UnindexedConsumer<T>,
99    P: Fn(&T) -> bool + Sync,
100{
101    fn split_off_left(&self) -> Self {
102        TakeAnyWhileConsumer {
103            base: self.base.split_off_left(),
104            ..*self
105        }
106    }
107
108    fn to_reducer(&self) -> Self::Reducer {
109        self.base.to_reducer()
110    }
111}
112
113struct TakeAnyWhileFolder<'p, C, P> {
114    base: C,
115    predicate: &'p P,
116    taking: &'p AtomicBool,
117}
118
119fn take<T>(item: &T, taking: &AtomicBool, predicate: &impl Fn(&T) -> bool) -> bool {
120    if !taking.load(Ordering::Relaxed) {
121        return false;
122    }
123    if predicate(item) {
124        return true;
125    }
126    taking.store(false, Ordering::Relaxed);
127    false
128}
129
130impl<'p, T, C, P> Folder<T> for TakeAnyWhileFolder<'p, C, P>
131where
132    C: Folder<T>,
133    P: Fn(&T) -> bool + 'p,
134{
135    type Result = C::Result;
136
137    fn consume(mut self, item: T) -> Self {
138        if take(&item, self.taking, self.predicate) {
139            self.base = self.base.consume(item);
140        }
141        self
142    }
143
144    fn consume_iter<I>(mut self, iter: I) -> Self
145    where
146        I: IntoIterator<Item = T>,
147    {
148        self.base = self.base.consume_iter(
149            iter.into_iter()
150                .take_while(move |x| take(x, self.taking, self.predicate)),
151        );
152        self
153    }
154
155    fn complete(self) -> C::Result {
156        self.base.complete()
157    }
158
159    fn full(&self) -> bool {
160        !self.taking.load(Ordering::Relaxed) || self.base.full()
161    }
162}
rayon/iter/take_any_while.rs

rayon/iter/
take_any_while.rs
