rayon/iter/
try_fold.rs

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1use super::plumbing::*;
2use super::*;
3
4use super::private::Try;
5use std::fmt::{self, Debug};
6use std::marker::PhantomData;
7
8impl<U, I, ID, F> TryFold<I, U, ID, F>
9where
10    I: ParallelIterator,
11    F: Fn(U::Ok, I::Item) -> U + Sync + Send,
12    ID: Fn() -> U::Ok + Sync + Send,
13    U: Try + Send,
14{
15    pub(super) fn new(base: I, identity: ID, fold_op: F) -> Self {
16        TryFold {
17            base,
18            identity,
19            fold_op,
20            marker: PhantomData,
21        }
22    }
23}
24
25/// `TryFold` is an iterator that applies a function over an iterator producing a single value.
26/// This struct is created by the [`try_fold()`] method on [`ParallelIterator`]
27///
28/// [`try_fold()`]: trait.ParallelIterator.html#method.try_fold
29/// [`ParallelIterator`]: trait.ParallelIterator.html
30#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
31#[derive(Clone)]
32pub struct TryFold<I, U, ID, F> {
33    base: I,
34    identity: ID,
35    fold_op: F,
36    marker: PhantomData<U>,
37}
38
39impl<U, I: ParallelIterator + Debug, ID, F> Debug for TryFold<I, U, ID, F> {
40    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
41        f.debug_struct("TryFold").field("base", &self.base).finish()
42    }
43}
44
45impl<U, I, ID, F> ParallelIterator for TryFold<I, U, ID, F>
46where
47    I: ParallelIterator,
48    F: Fn(U::Ok, I::Item) -> U + Sync + Send,
49    ID: Fn() -> U::Ok + Sync + Send,
50    U: Try + Send,
51{
52    type Item = U;
53
54    fn drive_unindexed<C>(self, consumer: C) -> C::Result
55    where
56        C: UnindexedConsumer<Self::Item>,
57    {
58        let consumer1 = TryFoldConsumer {
59            base: consumer,
60            identity: &self.identity,
61            fold_op: &self.fold_op,
62            marker: PhantomData,
63        };
64        self.base.drive_unindexed(consumer1)
65    }
66}
67
68struct TryFoldConsumer<'c, U, C, ID, F> {
69    base: C,
70    identity: &'c ID,
71    fold_op: &'c F,
72    marker: PhantomData<U>,
73}
74
75impl<'r, U, T, C, ID, F> Consumer<T> for TryFoldConsumer<'r, U, C, ID, F>
76where
77    C: Consumer<U>,
78    F: Fn(U::Ok, T) -> U + Sync,
79    ID: Fn() -> U::Ok + Sync,
80    U: Try + Send,
81{
82    type Folder = TryFoldFolder<'r, C::Folder, U, F>;
83    type Reducer = C::Reducer;
84    type Result = C::Result;
85
86    fn split_at(self, index: usize) -> (Self, Self, Self::Reducer) {
87        let (left, right, reducer) = self.base.split_at(index);
88        (
89            TryFoldConsumer { base: left, ..self },
90            TryFoldConsumer {
91                base: right,
92                ..self
93            },
94            reducer,
95        )
96    }
97
98    fn into_folder(self) -> Self::Folder {
99        TryFoldFolder {
100            base: self.base.into_folder(),
101            result: Ok((self.identity)()),
102            fold_op: self.fold_op,
103        }
104    }
105
106    fn full(&self) -> bool {
107        self.base.full()
108    }
109}
110
111impl<'r, U, T, C, ID, F> UnindexedConsumer<T> for TryFoldConsumer<'r, U, C, ID, F>
112where
113    C: UnindexedConsumer<U>,
114    F: Fn(U::Ok, T) -> U + Sync,
115    ID: Fn() -> U::Ok + Sync,
116    U: Try + Send,
117{
118    fn split_off_left(&self) -> Self {
119        TryFoldConsumer {
120            base: self.base.split_off_left(),
121            ..*self
122        }
123    }
124
125    fn to_reducer(&self) -> Self::Reducer {
126        self.base.to_reducer()
127    }
128}
129
130struct TryFoldFolder<'r, C, U: Try, F> {
131    base: C,
132    fold_op: &'r F,
133    result: Result<U::Ok, U::Error>,
134}
135
136impl<'r, C, U, F, T> Folder<T> for TryFoldFolder<'r, C, U, F>
137where
138    C: Folder<U>,
139    F: Fn(U::Ok, T) -> U + Sync,
140    U: Try,
141{
142    type Result = C::Result;
143
144    fn consume(mut self, item: T) -> Self {
145        let fold_op = self.fold_op;
146        if let Ok(acc) = self.result {
147            self.result = fold_op(acc, item).into_result();
148        }
149        self
150    }
151
152    fn complete(self) -> C::Result {
153        let item = match self.result {
154            Ok(ok) => U::from_ok(ok),
155            Err(error) => U::from_error(error),
156        };
157        self.base.consume(item).complete()
158    }
159
160    fn full(&self) -> bool {
161        self.result.is_err() || self.base.full()
162    }
163}
164
165// ///////////////////////////////////////////////////////////////////////////
166
167impl<U, I, F> TryFoldWith<I, U, F>
168where
169    I: ParallelIterator,
170    F: Fn(U::Ok, I::Item) -> U + Sync,
171    U: Try + Send,
172    U::Ok: Clone + Send,
173{
174    pub(super) fn new(base: I, item: U::Ok, fold_op: F) -> Self {
175        TryFoldWith {
176            base,
177            item,
178            fold_op,
179        }
180    }
181}
182
183/// `TryFoldWith` is an iterator that applies a function over an iterator producing a single value.
184/// This struct is created by the [`try_fold_with()`] method on [`ParallelIterator`]
185///
186/// [`try_fold_with()`]: trait.ParallelIterator.html#method.try_fold_with
187/// [`ParallelIterator`]: trait.ParallelIterator.html
188#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
189#[derive(Clone)]
190pub struct TryFoldWith<I, U: Try, F> {
191    base: I,
192    item: U::Ok,
193    fold_op: F,
194}
195
196impl<I: ParallelIterator + Debug, U: Try, F> Debug for TryFoldWith<I, U, F>
197where
198    U::Ok: Debug,
199{
200    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
201        f.debug_struct("TryFoldWith")
202            .field("base", &self.base)
203            .field("item", &self.item)
204            .finish()
205    }
206}
207
208impl<U, I, F> ParallelIterator for TryFoldWith<I, U, F>
209where
210    I: ParallelIterator,
211    F: Fn(U::Ok, I::Item) -> U + Sync + Send,
212    U: Try + Send,
213    U::Ok: Clone + Send,
214{
215    type Item = U;
216
217    fn drive_unindexed<C>(self, consumer: C) -> C::Result
218    where
219        C: UnindexedConsumer<Self::Item>,
220    {
221        let consumer1 = TryFoldWithConsumer {
222            base: consumer,
223            item: self.item,
224            fold_op: &self.fold_op,
225        };
226        self.base.drive_unindexed(consumer1)
227    }
228}
229
230struct TryFoldWithConsumer<'c, C, U: Try, F> {
231    base: C,
232    item: U::Ok,
233    fold_op: &'c F,
234}
235
236impl<'r, U, T, C, F> Consumer<T> for TryFoldWithConsumer<'r, C, U, F>
237where
238    C: Consumer<U>,
239    F: Fn(U::Ok, T) -> U + Sync,
240    U: Try + Send,
241    U::Ok: Clone + Send,
242{
243    type Folder = TryFoldFolder<'r, C::Folder, U, F>;
244    type Reducer = C::Reducer;
245    type Result = C::Result;
246
247    fn split_at(self, index: usize) -> (Self, Self, Self::Reducer) {
248        let (left, right, reducer) = self.base.split_at(index);
249        (
250            TryFoldWithConsumer {
251                base: left,
252                item: self.item.clone(),
253                ..self
254            },
255            TryFoldWithConsumer {
256                base: right,
257                ..self
258            },
259            reducer,
260        )
261    }
262
263    fn into_folder(self) -> Self::Folder {
264        TryFoldFolder {
265            base: self.base.into_folder(),
266            result: Ok(self.item),
267            fold_op: self.fold_op,
268        }
269    }
270
271    fn full(&self) -> bool {
272        self.base.full()
273    }
274}
275
276impl<'r, U, T, C, F> UnindexedConsumer<T> for TryFoldWithConsumer<'r, C, U, F>
277where
278    C: UnindexedConsumer<U>,
279    F: Fn(U::Ok, T) -> U + Sync,
280    U: Try + Send,
281    U::Ok: Clone + Send,
282{
283    fn split_off_left(&self) -> Self {
284        TryFoldWithConsumer {
285            base: self.base.split_off_left(),
286            item: self.item.clone(),
287            ..*self
288        }
289    }
290
291    fn to_reducer(&self) -> Self::Reducer {
292        self.base.to_reducer()
293    }
294}
rayon/iter/try_fold.rs

rayon/iter/
try_fold.rs
