par_iter/iter/
skip_any_while.rs

1use std::{
2    fmt,
3    sync::atomic::{AtomicBool, Ordering},
4};
5
6use super::{plumbing::*, *};
7
8/// `SkipAnyWhile` is an iterator that skips over elements from anywhere in `I`
9/// until the callback returns `false`.
10/// This struct is created by the [`skip_any_while()`] method on
11/// [`ParallelIterator`]
12///
13/// [`skip_any_while()`]: trait.ParallelIterator.html#method.skip_any_while
14/// [`ParallelIterator`]: trait.ParallelIterator.html
15#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
16#[derive(Clone)]
17pub struct SkipAnyWhile<I: ParallelIterator, P> {
18    base: I,
19    predicate: P,
20}
21
22impl<I: ParallelIterator + fmt::Debug, P> fmt::Debug for SkipAnyWhile<I, P> {
23    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
24        f.debug_struct("SkipAnyWhile")
25            .field("base", &self.base)
26            .finish()
27    }
28}
29
30impl<I, P> SkipAnyWhile<I, P>
31where
32    I: ParallelIterator,
33{
34    /// Creates a new `SkipAnyWhile` iterator.
35    pub(super) fn new(base: I, predicate: P) -> Self {
36        SkipAnyWhile { base, predicate }
37    }
38}
39
40impl<I, P> ParallelIterator for SkipAnyWhile<I, P>
41where
42    I: ParallelIterator,
43    P: Fn(&I::Item) -> bool + Sync + Send,
44{
45    type Item = I::Item;
46
47    fn drive_unindexed<C>(self, consumer: C) -> C::Result
48    where
49        C: UnindexedConsumer<Self::Item>,
50    {
51        let consumer1 = SkipAnyWhileConsumer {
52            base: consumer,
53            predicate: &self.predicate,
54            skipping: &AtomicBool::new(true),
55        };
56        self.base.drive_unindexed(consumer1)
57    }
58}
59
60/// ////////////////////////////////////////////////////////////////////////
61/// Consumer implementation
62
63struct SkipAnyWhileConsumer<'p, C, P> {
64    base: C,
65    predicate: &'p P,
66    skipping: &'p AtomicBool,
67}
68
69impl<'p, T, C, P> Consumer<T> for SkipAnyWhileConsumer<'p, C, P>
70where
71    C: Consumer<T>,
72    P: Fn(&T) -> bool + Sync,
73{
74    type Folder = SkipAnyWhileFolder<'p, C::Folder, P>;
75    type Reducer = C::Reducer;
76    type Result = C::Result;
77
78    fn split_at(self, index: usize) -> (Self, Self, Self::Reducer) {
79        let (left, right, reducer) = self.base.split_at(index);
80        (
81            SkipAnyWhileConsumer { base: left, ..self },
82            SkipAnyWhileConsumer {
83                base: right,
84                ..self
85            },
86            reducer,
87        )
88    }
89
90    fn into_folder(self) -> Self::Folder {
91        SkipAnyWhileFolder {
92            base: self.base.into_folder(),
93            predicate: self.predicate,
94            skipping: self.skipping,
95        }
96    }
97
98    fn full(&self) -> bool {
99        self.base.full()
100    }
101}
102
103impl<'p, T, C, P> UnindexedConsumer<T> for SkipAnyWhileConsumer<'p, C, P>
104where
105    C: UnindexedConsumer<T>,
106    P: Fn(&T) -> bool + Sync,
107{
108    fn split_off_left(&self) -> Self {
109        SkipAnyWhileConsumer {
110            base: self.base.split_off_left(),
111            ..*self
112        }
113    }
114
115    fn to_reducer(&self) -> Self::Reducer {
116        self.base.to_reducer()
117    }
118}
119
120struct SkipAnyWhileFolder<'p, C, P> {
121    base: C,
122    predicate: &'p P,
123    skipping: &'p AtomicBool,
124}
125
126fn skip<T>(item: &T, skipping: &AtomicBool, predicate: &impl Fn(&T) -> bool) -> bool {
127    if !skipping.load(Ordering::Relaxed) {
128        return false;
129    }
130    if predicate(item) {
131        return true;
132    }
133    skipping.store(false, Ordering::Relaxed);
134    false
135}
136
137impl<'p, T, C, P> Folder<T> for SkipAnyWhileFolder<'p, C, P>
138where
139    C: Folder<T>,
140    P: Fn(&T) -> bool + 'p,
141{
142    type Result = C::Result;
143
144    fn consume(mut self, item: T) -> Self {
145        if !skip(&item, self.skipping, self.predicate) {
146            self.base = self.base.consume(item);
147        }
148        self
149    }
150
151    fn consume_iter<I>(mut self, iter: I) -> Self
152    where
153        I: IntoIterator<Item = T>,
154    {
155        self.base = self.base.consume_iter(
156            iter.into_iter()
157                .skip_while(move |x| skip(x, self.skipping, self.predicate)),
158        );
159        self
160    }
161
162    fn complete(self) -> C::Result {
163        self.base.complete()
164    }
165
166    fn full(&self) -> bool {
167        self.base.full()
168    }
169}
par_iter/iter/skip_any_while.rs

par_iter/iter/
skip_any_while.rs
