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()`]: trait.ParallelIterator.html#method.flatten_iter
8/// [`ParallelIterator`]: trait.ParallelIterator.html
9#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
10#[derive(Debug, Clone)]
11pub struct FlattenIter<I: ParallelIterator> {
12    base: I,
13}
14
15impl<I> FlattenIter<I>
16where
17    I: ParallelIterator,
18    I::Item: IntoIterator,
19    <I::Item as IntoIterator>::Item: Send,
20{
21    /// Creates a new `FlattenIter` iterator.
22    pub(super) fn new(base: I) -> Self {
23        FlattenIter { base }
24    }
25}
26
27impl<I> ParallelIterator for FlattenIter<I>
28where
29    I: ParallelIterator,
30    I::Item: IntoIterator,
31    <I::Item as IntoIterator>::Item: Send,
32{
33    type Item = <I::Item as IntoIterator>::Item;
34
35    fn drive_unindexed<C>(self, consumer: C) -> C::Result
36    where
37        C: UnindexedConsumer<Self::Item>,
38    {
39        let consumer = FlattenIterConsumer::new(consumer);
40        self.base.drive_unindexed(consumer)
41    }
42}
43
44/// ////////////////////////////////////////////////////////////////////////
45/// Consumer implementation
46
47struct FlattenIterConsumer<C> {
48    base: C,
49}
50
51impl<C> FlattenIterConsumer<C> {
52    fn new(base: C) -> Self {
53        FlattenIterConsumer { base }
54    }
55}
56
57impl<T, C> Consumer<T> for FlattenIterConsumer<C>
58where
59    C: UnindexedConsumer<T::Item>,
60    T: IntoIterator,
61{
62    type Folder = FlattenIterFolder<C::Folder>;
63    type Reducer = C::Reducer;
64    type Result = C::Result;
65
66    fn split_at(self, index: usize) -> (Self, Self, C::Reducer) {
67        let (left, right, reducer) = self.base.split_at(index);
68        (
69            FlattenIterConsumer::new(left),
70            FlattenIterConsumer::new(right),
71            reducer,
72        )
73    }
74
75    fn into_folder(self) -> Self::Folder {
76        FlattenIterFolder {
77            base: self.base.into_folder(),
78        }
79    }
80
81    fn full(&self) -> bool {
82        self.base.full()
83    }
84}
85
86impl<T, C> UnindexedConsumer<T> for FlattenIterConsumer<C>
87where
88    C: UnindexedConsumer<T::Item>,
89    T: IntoIterator,
90{
91    fn split_off_left(&self) -> Self {
92        FlattenIterConsumer::new(self.base.split_off_left())
93    }
94
95    fn to_reducer(&self) -> Self::Reducer {
96        self.base.to_reducer()
97    }
98}
99
100struct FlattenIterFolder<C> {
101    base: C,
102}
103
104impl<T, C> Folder<T> for FlattenIterFolder<C>
105where
106    C: Folder<T::Item>,
107    T: IntoIterator,
108{
109    type Result = C::Result;
110
111    fn consume(self, item: T) -> Self {
112        let base = self.base.consume_iter(item);
113        FlattenIterFolder { base }
114    }
115
116    fn consume_iter<I>(self, iter: I) -> Self
117    where
118        I: IntoIterator<Item = T>,
119    {
120        let iter = iter.into_iter().flatten();
121        let base = self.base.consume_iter(iter);
122        FlattenIterFolder { base }
123    }
124
125    fn complete(self) -> Self::Result {
126        self.base.complete()
127    }
128
129    fn full(&self) -> bool {
130        self.base.full()
131    }
132}
rayon/iter/flatten_iter.rs

rayon/iter/
flatten_iter.rs
