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()`]: trait.ParallelIterator.html#method.flat_map_iter
10/// [`ParallelIterator`]: trait.ParallelIterator.html
11#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
12#[derive(Clone)]
13pub struct FlatMapIter<I: ParallelIterator, F> {
14    base: I,
15    map_op: F,
16}
17
18impl<I: ParallelIterator + Debug, F> Debug for FlatMapIter<I, F> {
19    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
20        f.debug_struct("FlatMapIter")
21            .field("base", &self.base)
22            .finish()
23    }
24}
25
26impl<I: ParallelIterator, F> FlatMapIter<I, F> {
27    /// Creates a new `FlatMapIter` iterator.
28    pub(super) fn new(base: I, map_op: F) -> Self {
29        FlatMapIter { base, map_op }
30    }
31}
32
33impl<I, F, SI> ParallelIterator for FlatMapIter<I, F>
34where
35    I: ParallelIterator,
36    F: Fn(I::Item) -> SI + Sync + Send,
37    SI: IntoIterator,
38    SI::Item: Send,
39{
40    type Item = SI::Item;
41
42    fn drive_unindexed<C>(self, consumer: C) -> C::Result
43    where
44        C: UnindexedConsumer<Self::Item>,
45    {
46        let consumer = FlatMapIterConsumer::new(consumer, &self.map_op);
47        self.base.drive_unindexed(consumer)
48    }
49}
50
51/// ////////////////////////////////////////////////////////////////////////
52/// Consumer implementation
53
54struct FlatMapIterConsumer<'f, C, F> {
55    base: C,
56    map_op: &'f F,
57}
58
59impl<'f, C, F> FlatMapIterConsumer<'f, C, F> {
60    fn new(base: C, map_op: &'f F) -> Self {
61        FlatMapIterConsumer { base, map_op }
62    }
63}
64
65impl<'f, T, U, C, F> Consumer<T> for FlatMapIterConsumer<'f, C, F>
66where
67    C: UnindexedConsumer<U::Item>,
68    F: Fn(T) -> U + Sync,
69    U: IntoIterator,
70{
71    type Folder = FlatMapIterFolder<'f, C::Folder, F>;
72    type Reducer = C::Reducer;
73    type Result = C::Result;
74
75    fn split_at(self, index: usize) -> (Self, Self, C::Reducer) {
76        let (left, right, reducer) = self.base.split_at(index);
77        (
78            FlatMapIterConsumer::new(left, self.map_op),
79            FlatMapIterConsumer::new(right, self.map_op),
80            reducer,
81        )
82    }
83
84    fn into_folder(self) -> Self::Folder {
85        FlatMapIterFolder {
86            base: self.base.into_folder(),
87            map_op: self.map_op,
88        }
89    }
90
91    fn full(&self) -> bool {
92        self.base.full()
93    }
94}
95
96impl<'f, T, U, C, F> UnindexedConsumer<T> for FlatMapIterConsumer<'f, C, F>
97where
98    C: UnindexedConsumer<U::Item>,
99    F: Fn(T) -> U + Sync,
100    U: IntoIterator,
101{
102    fn split_off_left(&self) -> Self {
103        FlatMapIterConsumer::new(self.base.split_off_left(), self.map_op)
104    }
105
106    fn to_reducer(&self) -> Self::Reducer {
107        self.base.to_reducer()
108    }
109}
110
111struct FlatMapIterFolder<'f, C, F> {
112    base: C,
113    map_op: &'f F,
114}
115
116impl<'f, T, U, C, F> Folder<T> for FlatMapIterFolder<'f, C, F>
117where
118    C: Folder<U::Item>,
119    F: Fn(T) -> U,
120    U: IntoIterator,
121{
122    type Result = C::Result;
123
124    fn consume(self, item: T) -> Self {
125        let map_op = self.map_op;
126        let base = self.base.consume_iter(map_op(item));
127        FlatMapIterFolder { base, map_op }
128    }
129
130    fn consume_iter<I>(self, iter: I) -> Self
131    where
132        I: IntoIterator<Item = T>,
133    {
134        let map_op = self.map_op;
135        let iter = iter.into_iter().flat_map(map_op);
136        let base = self.base.consume_iter(iter);
137        FlatMapIterFolder { base, map_op }
138    }
139
140    fn complete(self) -> Self::Result {
141        self.base.complete()
142    }
143
144    fn full(&self) -> bool {
145        self.base.full()
146    }
147}
rayon/iter/flat_map_iter.rs

rayon/iter/
flat_map_iter.rs
