rayon/iter/
while_some.rs

1use super::plumbing::*;
2use super::*;
3use std::sync::atomic::{AtomicBool, Ordering};
4
5/// `WhileSome` is an iterator that yields the `Some` elements of an iterator,
6/// halting as soon as any `None` is produced.
7///
8/// This struct is created by the [`while_some()`] method on [`ParallelIterator`]
9///
10/// [`while_some()`]: ParallelIterator::while_some()
11#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
12#[derive(Debug, Clone)]
13pub struct WhileSome<I> {
14    base: I,
15}
16
17impl<I> WhileSome<I> {
18    /// Creates a new `WhileSome` iterator.
19    pub(super) fn new(base: I) -> Self {
20        WhileSome { base }
21    }
22}
23
24impl<I, T> ParallelIterator for WhileSome<I>
25where
26    I: ParallelIterator<Item = Option<T>>,
27    T: Send,
28{
29    type Item = T;
30
31    fn drive_unindexed<C>(self, consumer: C) -> C::Result
32    where
33        C: UnindexedConsumer<Self::Item>,
34    {
35        let full = AtomicBool::new(false);
36        let consumer1 = WhileSomeConsumer {
37            base: consumer,
38            full: &full,
39        };
40        self.base.drive_unindexed(consumer1)
41    }
42}
43
44// ////////////////////////////////////////////////////////////////////////
45// Consumer implementation
46
47struct WhileSomeConsumer<'f, C> {
48    base: C,
49    full: &'f AtomicBool,
50}
51
52impl<'f, T, C> Consumer<Option<T>> for WhileSomeConsumer<'f, C>
53where
54    C: Consumer<T>,
55    T: Send,
56{
57    type Folder = WhileSomeFolder<'f, C::Folder>;
58    type Reducer = C::Reducer;
59    type Result = C::Result;
60
61    fn split_at(self, index: usize) -> (Self, Self, Self::Reducer) {
62        let (left, right, reducer) = self.base.split_at(index);
63        (
64            WhileSomeConsumer { base: left, ..self },
65            WhileSomeConsumer {
66                base: right,
67                ..self
68            },
69            reducer,
70        )
71    }
72
73    fn into_folder(self) -> Self::Folder {
74        WhileSomeFolder {
75            base: self.base.into_folder(),
76            full: self.full,
77        }
78    }
79
80    fn full(&self) -> bool {
81        self.full.load(Ordering::Relaxed) || self.base.full()
82    }
83}
84
85impl<'f, T, C> UnindexedConsumer<Option<T>> for WhileSomeConsumer<'f, C>
86where
87    C: UnindexedConsumer<T>,
88    T: Send,
89{
90    fn split_off_left(&self) -> Self {
91        WhileSomeConsumer {
92            base: self.base.split_off_left(),
93            ..*self
94        }
95    }
96
97    fn to_reducer(&self) -> Self::Reducer {
98        self.base.to_reducer()
99    }
100}
101
102struct WhileSomeFolder<'f, C> {
103    base: C,
104    full: &'f AtomicBool,
105}
106
107impl<'f, T, C> Folder<Option<T>> for WhileSomeFolder<'f, C>
108where
109    C: Folder<T>,
110{
111    type Result = C::Result;
112
113    fn consume(mut self, item: Option<T>) -> Self {
114        match item {
115            Some(item) => self.base = self.base.consume(item),
116            None => self.full.store(true, Ordering::Relaxed),
117        }
118        self
119    }
120
121    fn consume_iter<I>(mut self, iter: I) -> Self
122    where
123        I: IntoIterator<Item = Option<T>>,
124    {
125        fn some<T>(full: &AtomicBool) -> impl Fn(&Option<T>) -> bool + '_ {
126            move |x| match *x {
127                Some(_) => !full.load(Ordering::Relaxed),
128                None => {
129                    full.store(true, Ordering::Relaxed);
130                    false
131                }
132            }
133        }
134
135        self.base = self.base.consume_iter(
136            iter.into_iter()
137                .take_while(some(self.full))
138                .map(Option::unwrap),
139        );
140        self
141    }
142
143    fn complete(self) -> C::Result {
144        self.base.complete()
145    }
146
147    fn full(&self) -> bool {
148        self.full.load(Ordering::Relaxed) || self.base.full()
149    }
150}
rayon/iter/while_some.rs

rayon/iter/
while_some.rs
