rayon/iter/
flatten_iter.rs

1use super::plumbing::*;
2use super::*;
3
4/// `FlattenIter` turns each element to a serial iterator, then flattens these iterators
5/// together. This struct is created by the [`flatten_iter()`] method on [`ParallelIterator`].
6///
7/// [`flatten_iter()`]: ParallelIterator::flatten_iter()
8#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
9#[derive(Debug, Clone)]
10pub struct FlattenIter<I> {
11    base: I,
12}
13
14impl<I> FlattenIter<I> {
15    /// Creates a new `FlattenIter` iterator.
16    pub(super) fn new(base: I) -> Self {
17        FlattenIter { base }
18    }
19}
20
21impl<I> ParallelIterator for FlattenIter<I>
22where
23    I: ParallelIterator<Item: IntoIterator<Item: Send>>,
24{
25    type Item = <I::Item as IntoIterator>::Item;
26
27    fn drive_unindexed<C>(self, consumer: C) -> C::Result
28    where
29        C: UnindexedConsumer<Self::Item>,
30    {
31        let consumer = FlattenIterConsumer::new(consumer);
32        self.base.drive_unindexed(consumer)
33    }
34}
35
36// ////////////////////////////////////////////////////////////////////////
37// Consumer implementation
38
39struct FlattenIterConsumer<C> {
40    base: C,
41}
42
43impl<C> FlattenIterConsumer<C> {
44    fn new(base: C) -> Self {
45        FlattenIterConsumer { base }
46    }
47}
48
49impl<T, C> Consumer<T> for FlattenIterConsumer<C>
50where
51    C: UnindexedConsumer<T::Item>,
52    T: IntoIterator,
53{
54    type Folder = FlattenIterFolder<C::Folder>;
55    type Reducer = C::Reducer;
56    type Result = C::Result;
57
58    fn split_at(self, index: usize) -> (Self, Self, C::Reducer) {
59        let (left, right, reducer) = self.base.split_at(index);
60        (
61            FlattenIterConsumer::new(left),
62            FlattenIterConsumer::new(right),
63            reducer,
64        )
65    }
66
67    fn into_folder(self) -> Self::Folder {
68        FlattenIterFolder {
69            base: self.base.into_folder(),
70        }
71    }
72
73    fn full(&self) -> bool {
74        self.base.full()
75    }
76}
77
78impl<T, C> UnindexedConsumer<T> for FlattenIterConsumer<C>
79where
80    C: UnindexedConsumer<T::Item>,
81    T: IntoIterator,
82{
83    fn split_off_left(&self) -> Self {
84        FlattenIterConsumer::new(self.base.split_off_left())
85    }
86
87    fn to_reducer(&self) -> Self::Reducer {
88        self.base.to_reducer()
89    }
90}
91
92struct FlattenIterFolder<C> {
93    base: C,
94}
95
96impl<T, C> Folder<T> for FlattenIterFolder<C>
97where
98    C: Folder<T::Item>,
99    T: IntoIterator,
100{
101    type Result = C::Result;
102
103    fn consume(self, item: T) -> Self {
104        let base = self.base.consume_iter(item);
105        FlattenIterFolder { base }
106    }
107
108    fn consume_iter<I>(self, iter: I) -> Self
109    where
110        I: IntoIterator<Item = T>,
111    {
112        let iter = iter.into_iter().flatten();
113        let base = self.base.consume_iter(iter);
114        FlattenIterFolder { base }
115    }
116
117    fn complete(self) -> Self::Result {
118        self.base.complete()
119    }
120
121    fn full(&self) -> bool {
122        self.base.full()
123    }
124}
rayon/iter/flatten_iter.rs

rayon/iter/
flatten_iter.rs
