rayon/iter/
flat_map_iter.rs

1use super::plumbing::*;
2use super::*;
3
4use std::fmt::{self, Debug};
5
6/// `FlatMapIter` maps each element to a serial iterator, then flattens these iterators together.
7/// This struct is created by the [`flat_map_iter()`] method on [`ParallelIterator`]
8///
9/// [`flat_map_iter()`]: ParallelIterator::flat_map_iter()
10#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
11#[derive(Clone)]
12pub struct FlatMapIter<I, F> {
13    base: I,
14    map_op: F,
15}
16
17impl<I: Debug, F> Debug for FlatMapIter<I, F> {
18    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
19        f.debug_struct("FlatMapIter")
20            .field("base", &self.base)
21            .finish()
22    }
23}
24
25impl<I, F> FlatMapIter<I, F> {
26    /// Creates a new `FlatMapIter` iterator.
27    pub(super) fn new(base: I, map_op: F) -> Self {
28        FlatMapIter { base, map_op }
29    }
30}
31
32impl<I, F, SI> ParallelIterator for FlatMapIter<I, F>
33where
34    I: ParallelIterator,
35    F: Fn(I::Item) -> SI + Sync + Send,
36    SI: IntoIterator<Item: Send>,
37{
38    type Item = SI::Item;
39
40    fn drive_unindexed<C>(self, consumer: C) -> C::Result
41    where
42        C: UnindexedConsumer<Self::Item>,
43    {
44        let consumer = FlatMapIterConsumer::new(consumer, &self.map_op);
45        self.base.drive_unindexed(consumer)
46    }
47}
48
49// ////////////////////////////////////////////////////////////////////////
50// Consumer implementation
51
52struct FlatMapIterConsumer<'f, C, F> {
53    base: C,
54    map_op: &'f F,
55}
56
57impl<'f, C, F> FlatMapIterConsumer<'f, C, F> {
58    fn new(base: C, map_op: &'f F) -> Self {
59        FlatMapIterConsumer { base, map_op }
60    }
61}
62
63impl<'f, T, U, C, F> Consumer<T> for FlatMapIterConsumer<'f, C, F>
64where
65    C: UnindexedConsumer<U::Item>,
66    F: Fn(T) -> U + Sync,
67    U: IntoIterator,
68{
69    type Folder = FlatMapIterFolder<'f, C::Folder, F>;
70    type Reducer = C::Reducer;
71    type Result = C::Result;
72
73    fn split_at(self, index: usize) -> (Self, Self, C::Reducer) {
74        let (left, right, reducer) = self.base.split_at(index);
75        (
76            FlatMapIterConsumer::new(left, self.map_op),
77            FlatMapIterConsumer::new(right, self.map_op),
78            reducer,
79        )
80    }
81
82    fn into_folder(self) -> Self::Folder {
83        FlatMapIterFolder {
84            base: self.base.into_folder(),
85            map_op: self.map_op,
86        }
87    }
88
89    fn full(&self) -> bool {
90        self.base.full()
91    }
92}
93
94impl<'f, T, U, C, F> UnindexedConsumer<T> for FlatMapIterConsumer<'f, C, F>
95where
96    C: UnindexedConsumer<U::Item>,
97    F: Fn(T) -> U + Sync,
98    U: IntoIterator,
99{
100    fn split_off_left(&self) -> Self {
101        FlatMapIterConsumer::new(self.base.split_off_left(), self.map_op)
102    }
103
104    fn to_reducer(&self) -> Self::Reducer {
105        self.base.to_reducer()
106    }
107}
108
109struct FlatMapIterFolder<'f, C, F> {
110    base: C,
111    map_op: &'f F,
112}
113
114impl<'f, T, U, C, F> Folder<T> for FlatMapIterFolder<'f, C, F>
115where
116    C: Folder<U::Item>,
117    F: Fn(T) -> U,
118    U: IntoIterator,
119{
120    type Result = C::Result;
121
122    fn consume(self, item: T) -> Self {
123        let map_op = self.map_op;
124        let base = self.base.consume_iter(map_op(item));
125        FlatMapIterFolder { base, map_op }
126    }
127
128    fn consume_iter<I>(self, iter: I) -> Self
129    where
130        I: IntoIterator<Item = T>,
131    {
132        let map_op = self.map_op;
133        let iter = iter.into_iter().flat_map(map_op);
134        let base = self.base.consume_iter(iter);
135        FlatMapIterFolder { base, map_op }
136    }
137
138    fn complete(self) -> Self::Result {
139        self.base.complete()
140    }
141
142    fn full(&self) -> bool {
143        self.base.full()
144    }
145}
rayon/iter/flat_map_iter.rs

rayon/iter/
flat_map_iter.rs
