rayon/iter/
map.rs

1use super::plumbing::*;
2use super::*;
3
4use std::fmt::{self, Debug};
5use std::iter;
6
7/// `Map` is an iterator that transforms the elements of an underlying iterator.
8///
9/// This struct is created by the [`map()`] method on [`ParallelIterator`]
10///
11/// [`map()`]: trait.ParallelIterator.html#method.map
12/// [`ParallelIterator`]: trait.ParallelIterator.html
13#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
14#[derive(Clone)]
15pub struct Map<I: ParallelIterator, F> {
16    base: I,
17    map_op: F,
18}
19
20impl<I: ParallelIterator + Debug, F> Debug for Map<I, F> {
21    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
22        f.debug_struct("Map").field("base", &self.base).finish()
23    }
24}
25
26impl<I, F> Map<I, F>
27where
28    I: ParallelIterator,
29{
30    /// Creates a new `Map` iterator.
31    pub(super) fn new(base: I, map_op: F) -> Self {
32        Map { base, map_op }
33    }
34}
35
36impl<I, F, R> ParallelIterator for Map<I, F>
37where
38    I: ParallelIterator,
39    F: Fn(I::Item) -> R + Sync + Send,
40    R: Send,
41{
42    type Item = F::Output;
43
44    fn drive_unindexed<C>(self, consumer: C) -> C::Result
45    where
46        C: UnindexedConsumer<Self::Item>,
47    {
48        let consumer1 = MapConsumer::new(consumer, &self.map_op);
49        self.base.drive_unindexed(consumer1)
50    }
51
52    fn opt_len(&self) -> Option<usize> {
53        self.base.opt_len()
54    }
55}
56
57impl<I, F, R> IndexedParallelIterator for Map<I, F>
58where
59    I: IndexedParallelIterator,
60    F: Fn(I::Item) -> R + Sync + Send,
61    R: Send,
62{
63    fn drive<C>(self, consumer: C) -> C::Result
64    where
65        C: Consumer<Self::Item>,
66    {
67        let consumer1 = MapConsumer::new(consumer, &self.map_op);
68        self.base.drive(consumer1)
69    }
70
71    fn len(&self) -> usize {
72        self.base.len()
73    }
74
75    fn with_producer<CB>(self, callback: CB) -> CB::Output
76    where
77        CB: ProducerCallback<Self::Item>,
78    {
79        return self.base.with_producer(Callback {
80            callback,
81            map_op: self.map_op,
82        });
83
84        struct Callback<CB, F> {
85            callback: CB,
86            map_op: F,
87        }
88
89        impl<T, F, R, CB> ProducerCallback<T> for Callback<CB, F>
90        where
91            CB: ProducerCallback<R>,
92            F: Fn(T) -> R + Sync,
93            R: Send,
94        {
95            type Output = CB::Output;
96
97            fn callback<P>(self, base: P) -> CB::Output
98            where
99                P: Producer<Item = T>,
100            {
101                let producer = MapProducer {
102                    base,
103                    map_op: &self.map_op,
104                };
105                self.callback.callback(producer)
106            }
107        }
108    }
109}
110
111/// ////////////////////////////////////////////////////////////////////////
112
113struct MapProducer<'f, P, F> {
114    base: P,
115    map_op: &'f F,
116}
117
118impl<'f, P, F, R> Producer for MapProducer<'f, P, F>
119where
120    P: Producer,
121    F: Fn(P::Item) -> R + Sync,
122    R: Send,
123{
124    type Item = F::Output;
125    type IntoIter = iter::Map<P::IntoIter, &'f F>;
126
127    fn into_iter(self) -> Self::IntoIter {
128        self.base.into_iter().map(self.map_op)
129    }
130
131    fn min_len(&self) -> usize {
132        self.base.min_len()
133    }
134    fn max_len(&self) -> usize {
135        self.base.max_len()
136    }
137
138    fn split_at(self, index: usize) -> (Self, Self) {
139        let (left, right) = self.base.split_at(index);
140        (
141            MapProducer {
142                base: left,
143                map_op: self.map_op,
144            },
145            MapProducer {
146                base: right,
147                map_op: self.map_op,
148            },
149        )
150    }
151
152    fn fold_with<G>(self, folder: G) -> G
153    where
154        G: Folder<Self::Item>,
155    {
156        let folder1 = MapFolder {
157            base: folder,
158            map_op: self.map_op,
159        };
160        self.base.fold_with(folder1).base
161    }
162}
163
164/// ////////////////////////////////////////////////////////////////////////
165/// Consumer implementation
166
167struct MapConsumer<'f, C, F> {
168    base: C,
169    map_op: &'f F,
170}
171
172impl<'f, C, F> MapConsumer<'f, C, F> {
173    fn new(base: C, map_op: &'f F) -> Self {
174        MapConsumer { base, map_op }
175    }
176}
177
178impl<'f, T, R, C, F> Consumer<T> for MapConsumer<'f, C, F>
179where
180    C: Consumer<F::Output>,
181    F: Fn(T) -> R + Sync,
182    R: Send,
183{
184    type Folder = MapFolder<'f, C::Folder, F>;
185    type Reducer = C::Reducer;
186    type Result = C::Result;
187
188    fn split_at(self, index: usize) -> (Self, Self, Self::Reducer) {
189        let (left, right, reducer) = self.base.split_at(index);
190        (
191            MapConsumer::new(left, self.map_op),
192            MapConsumer::new(right, self.map_op),
193            reducer,
194        )
195    }
196
197    fn into_folder(self) -> Self::Folder {
198        MapFolder {
199            base: self.base.into_folder(),
200            map_op: self.map_op,
201        }
202    }
203
204    fn full(&self) -> bool {
205        self.base.full()
206    }
207}
208
209impl<'f, T, R, C, F> UnindexedConsumer<T> for MapConsumer<'f, C, F>
210where
211    C: UnindexedConsumer<F::Output>,
212    F: Fn(T) -> R + Sync,
213    R: Send,
214{
215    fn split_off_left(&self) -> Self {
216        MapConsumer::new(self.base.split_off_left(), self.map_op)
217    }
218
219    fn to_reducer(&self) -> Self::Reducer {
220        self.base.to_reducer()
221    }
222}
223
224struct MapFolder<'f, C, F> {
225    base: C,
226    map_op: &'f F,
227}
228
229impl<'f, T, R, C, F> Folder<T> for MapFolder<'f, C, F>
230where
231    C: Folder<F::Output>,
232    F: Fn(T) -> R,
233{
234    type Result = C::Result;
235
236    fn consume(self, item: T) -> Self {
237        let mapped_item = (self.map_op)(item);
238        MapFolder {
239            base: self.base.consume(mapped_item),
240            map_op: self.map_op,
241        }
242    }
243
244    fn consume_iter<I>(mut self, iter: I) -> Self
245    where
246        I: IntoIterator<Item = T>,
247    {
248        self.base = self.base.consume_iter(iter.into_iter().map(self.map_op));
249        self
250    }
251
252    fn complete(self) -> C::Result {
253        self.base.complete()
254    }
255
256    fn full(&self) -> bool {
257        self.base.full()
258    }
259}
rayon/iter/map.rs

rayon/iter/
map.rs
