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()`]: trait.ParallelIterator.html#method.while_some
11/// [`ParallelIterator`]: trait.ParallelIterator.html
12#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
13#[derive(Debug, Clone)]
14pub struct WhileSome<I: ParallelIterator> {
15    base: I,
16}
17
18impl<I> WhileSome<I>
19where
20    I: ParallelIterator,
21{
22    /// Creates a new `WhileSome` iterator.
23    pub(super) fn new(base: I) -> Self {
24        WhileSome { base }
25    }
26}
27
28impl<I, T> ParallelIterator for WhileSome<I>
29where
30    I: ParallelIterator<Item = Option<T>>,
31    T: Send,
32{
33    type Item = T;
34
35    fn drive_unindexed<C>(self, consumer: C) -> C::Result
36    where
37        C: UnindexedConsumer<Self::Item>,
38    {
39        let full = AtomicBool::new(false);
40        let consumer1 = WhileSomeConsumer {
41            base: consumer,
42            full: &full,
43        };
44        self.base.drive_unindexed(consumer1)
45    }
46}
47
48/// ////////////////////////////////////////////////////////////////////////
49/// Consumer implementation
50
51struct WhileSomeConsumer<'f, C> {
52    base: C,
53    full: &'f AtomicBool,
54}
55
56impl<'f, T, C> Consumer<Option<T>> for WhileSomeConsumer<'f, C>
57where
58    C: Consumer<T>,
59    T: Send,
60{
61    type Folder = WhileSomeFolder<'f, C::Folder>;
62    type Reducer = C::Reducer;
63    type Result = C::Result;
64
65    fn split_at(self, index: usize) -> (Self, Self, Self::Reducer) {
66        let (left, right, reducer) = self.base.split_at(index);
67        (
68            WhileSomeConsumer { base: left, ..self },
69            WhileSomeConsumer {
70                base: right,
71                ..self
72            },
73            reducer,
74        )
75    }
76
77    fn into_folder(self) -> Self::Folder {
78        WhileSomeFolder {
79            base: self.base.into_folder(),
80            full: self.full,
81        }
82    }
83
84    fn full(&self) -> bool {
85        self.full.load(Ordering::Relaxed) || self.base.full()
86    }
87}
88
89impl<'f, T, C> UnindexedConsumer<Option<T>> for WhileSomeConsumer<'f, C>
90where
91    C: UnindexedConsumer<T>,
92    T: Send,
93{
94    fn split_off_left(&self) -> Self {
95        WhileSomeConsumer {
96            base: self.base.split_off_left(),
97            ..*self
98        }
99    }
100
101    fn to_reducer(&self) -> Self::Reducer {
102        self.base.to_reducer()
103    }
104}
105
106struct WhileSomeFolder<'f, C> {
107    base: C,
108    full: &'f AtomicBool,
109}
110
111impl<'f, T, C> Folder<Option<T>> for WhileSomeFolder<'f, C>
112where
113    C: Folder<T>,
114{
115    type Result = C::Result;
116
117    fn consume(mut self, item: Option<T>) -> Self {
118        match item {
119            Some(item) => self.base = self.base.consume(item),
120            None => self.full.store(true, Ordering::Relaxed),
121        }
122        self
123    }
124
125    fn consume_iter<I>(mut self, iter: I) -> Self
126    where
127        I: IntoIterator<Item = Option<T>>,
128    {
129        fn some<T>(full: &AtomicBool) -> impl Fn(&Option<T>) -> bool + '_ {
130            move |x| match *x {
131                Some(_) => !full.load(Ordering::Relaxed),
132                None => {
133                    full.store(true, Ordering::Relaxed);
134                    false
135                }
136            }
137        }
138
139        self.base = self.base.consume_iter(
140            iter.into_iter()
141                .take_while(some(self.full))
142                .map(Option::unwrap),
143        );
144        self
145    }
146
147    fn complete(self) -> C::Result {
148        self.base.complete()
149    }
150
151    fn full(&self) -> bool {
152        self.full.load(Ordering::Relaxed) || self.base.full()
153    }
154}
rayon/iter/while_some.rs

rayon/iter/
while_some.rs
