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}
167