rayon/iter/
skip_any_while.rs

1use super::plumbing::*;
2use super::*;
3use std::fmt;
4use std::sync::atomic::{AtomicBool, Ordering};
5
6/// `SkipAnyWhile` is an iterator that skips over elements from anywhere in `I`
7/// until the callback returns `false`.
8/// This struct is created by the [`skip_any_while()`] method on [`ParallelIterator`]
9///
10/// [`skip_any_while()`]: trait.ParallelIterator.html#method.skip_any_while
11/// [`ParallelIterator`]: trait.ParallelIterator.html
12#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
13#[derive(Clone)]
14pub struct SkipAnyWhile<I: ParallelIterator, P> {
15    base: I,
16    predicate: P,
17}
18
19impl<I: ParallelIterator + fmt::Debug, P> fmt::Debug for SkipAnyWhile<I, P> {
20    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
21        f.debug_struct("SkipAnyWhile")
22            .field("base", &self.base)
23            .finish()
24    }
25}
26
27impl<I, P> SkipAnyWhile<I, P>
28where
29    I: ParallelIterator,
30{
31    /// Creates a new `SkipAnyWhile` iterator.
32    pub(super) fn new(base: I, predicate: P) -> Self {
33        SkipAnyWhile { base, predicate }
34    }
35}
36
37impl<I, P> ParallelIterator for SkipAnyWhile<I, P>
38where
39    I: ParallelIterator,
40    P: Fn(&I::Item) -> bool + Sync + Send,
41{
42    type Item = I::Item;
43
44    fn drive_unindexed<C>(self, consumer: C) -> C::Result
45    where
46        C: UnindexedConsumer<Self::Item>,
47    {
48        let consumer1 = SkipAnyWhileConsumer {
49            base: consumer,
50            predicate: &self.predicate,
51            skipping: &AtomicBool::new(true),
52        };
53        self.base.drive_unindexed(consumer1)
54    }
55}
56
57/// ////////////////////////////////////////////////////////////////////////
58/// Consumer implementation
59
60struct SkipAnyWhileConsumer<'p, C, P> {
61    base: C,
62    predicate: &'p P,
63    skipping: &'p AtomicBool,
64}
65
66impl<'p, T, C, P> Consumer<T> for SkipAnyWhileConsumer<'p, C, P>
67where
68    C: Consumer<T>,
69    P: Fn(&T) -> bool + Sync,
70{
71    type Folder = SkipAnyWhileFolder<'p, C::Folder, P>;
72    type Reducer = C::Reducer;
73    type Result = C::Result;
74
75    fn split_at(self, index: usize) -> (Self, Self, Self::Reducer) {
76        let (left, right, reducer) = self.base.split_at(index);
77        (
78            SkipAnyWhileConsumer { base: left, ..self },
79            SkipAnyWhileConsumer {
80                base: right,
81                ..self
82            },
83            reducer,
84        )
85    }
86
87    fn into_folder(self) -> Self::Folder {
88        SkipAnyWhileFolder {
89            base: self.base.into_folder(),
90            predicate: self.predicate,
91            skipping: self.skipping,
92        }
93    }
94
95    fn full(&self) -> bool {
96        self.base.full()
97    }
98}
99
100impl<'p, T, C, P> UnindexedConsumer<T> for SkipAnyWhileConsumer<'p, C, P>
101where
102    C: UnindexedConsumer<T>,
103    P: Fn(&T) -> bool + Sync,
104{
105    fn split_off_left(&self) -> Self {
106        SkipAnyWhileConsumer {
107            base: self.base.split_off_left(),
108            ..*self
109        }
110    }
111
112    fn to_reducer(&self) -> Self::Reducer {
113        self.base.to_reducer()
114    }
115}
116
117struct SkipAnyWhileFolder<'p, C, P> {
118    base: C,
119    predicate: &'p P,
120    skipping: &'p AtomicBool,
121}
122
123fn skip<T>(item: &T, skipping: &AtomicBool, predicate: &impl Fn(&T) -> bool) -> bool {
124    if !skipping.load(Ordering::Relaxed) {
125        return false;
126    }
127    if predicate(item) {
128        return true;
129    }
130    skipping.store(false, Ordering::Relaxed);
131    false
132}
133
134impl<'p, T, C, P> Folder<T> for SkipAnyWhileFolder<'p, C, P>
135where
136    C: Folder<T>,
137    P: Fn(&T) -> bool + 'p,
138{
139    type Result = C::Result;
140
141    fn consume(mut self, item: T) -> Self {
142        if !skip(&item, self.skipping, self.predicate) {
143            self.base = self.base.consume(item);
144        }
145        self
146    }
147
148    fn consume_iter<I>(mut self, iter: I) -> Self
149    where
150        I: IntoIterator<Item = T>,
151    {
152        self.base = self.base.consume_iter(
153            iter.into_iter()
154                .skip_while(move |x| skip(x, self.skipping, self.predicate)),
155        );
156        self
157    }
158
159    fn complete(self) -> C::Result {
160        self.base.complete()
161    }
162
163    fn full(&self) -> bool {
164        self.base.full()
165    }
166}
rayon/iter/skip_any_while.rs

rayon/iter/
skip_any_while.rs
