summaryrefslogtreecommitdiffstats
path: root/vendor/rayon/src/range_inclusive.rs
blob: b7bb0cac7339e79e4e7e4b67bc956aba0f641746 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
//! Parallel iterator types for [inclusive ranges][std::range],
//! the type for values created by `a..=b` expressions
//!
//! You will rarely need to interact with this module directly unless you have
//! need to name one of the iterator types.
//!
//! ```
//! use rayon::prelude::*;
//!
//! let r = (0..=100u64).into_par_iter()
//!                     .sum();
//!
//! // compare result with sequential calculation
//! assert_eq!((0..=100).sum::<u64>(), r);
//! ```
//!
//! [std::range]: https://doc.rust-lang.org/core/ops/struct.RangeInclusive.html

use crate::iter::plumbing::*;
use crate::iter::*;
use std::char;
use std::ops::RangeInclusive;

/// Parallel iterator over an inclusive range, implemented for all integer types and `char`.
///
/// **Note:** The `zip` operation requires `IndexedParallelIterator`
/// which is only implemented for `u8`, `i8`, `u16`, `i16`, and `char`.
///
/// ```
/// use rayon::prelude::*;
///
/// let p = (0..=25u16).into_par_iter()
///                   .zip(0..=25u16)
///                   .filter(|&(x, y)| x % 5 == 0 || y % 5 == 0)
///                   .map(|(x, y)| x * y)
///                   .sum::<u16>();
///
/// let s = (0..=25u16).zip(0..=25u16)
///                   .filter(|&(x, y)| x % 5 == 0 || y % 5 == 0)
///                   .map(|(x, y)| x * y)
///                   .sum();
///
/// assert_eq!(p, s);
/// ```
#[derive(Debug, Clone)]
pub struct Iter<T> {
    range: RangeInclusive<T>,
}

impl<T> Iter<T>
where
    RangeInclusive<T>: Eq,
    T: Ord + Copy,
{
    /// Returns `Some((start, end))` for `start..=end`, or `None` if it is exhausted.
    ///
    /// Note that `RangeInclusive` does not specify the bounds of an exhausted iterator,
    /// so this is a way for us to figure out what we've got.  Thankfully, all of the
    /// integer types we care about can be trivially cloned.
    fn bounds(&self) -> Option<(T, T)> {
        let start = *self.range.start();
        let end = *self.range.end();
        if start <= end && self.range == (start..=end) {
            // If the range is still nonempty, this is obviously true
            // If the range is exhausted, either start > end or
            // the range does not equal start..=end.
            Some((start, end))
        } else {
            None
        }
    }
}

/// Implemented for ranges of all primitive integer types and `char`.
impl<T> IntoParallelIterator for RangeInclusive<T>
where
    Iter<T>: ParallelIterator,
{
    type Item = <Iter<T> as ParallelIterator>::Item;
    type Iter = Iter<T>;

    fn into_par_iter(self) -> Self::Iter {
        Iter { range: self }
    }
}

/// These traits help drive integer type inference. Without them, an unknown `{integer}` type only
/// has constraints on `Iter<{integer}>`, which will probably give up and use `i32`. By adding
/// these traits on the item type, the compiler can see a more direct constraint to infer like
/// `{integer}: RangeInteger`, which works better. See `test_issue_833` for an example.
///
/// They have to be `pub` since they're seen in the public `impl ParallelIterator` constraints, but
/// we put them in a private modules so they're not actually reachable in our public API.
mod private {
    use super::*;

    /// Implementation details of `ParallelIterator for Iter<Self>`
    pub trait RangeInteger: Sized + Send {
        private_decl! {}

        fn drive_unindexed<C>(iter: Iter<Self>, consumer: C) -> C::Result
        where
            C: UnindexedConsumer<Self>;

        fn opt_len(iter: &Iter<Self>) -> Option<usize>;
    }

    /// Implementation details of `IndexedParallelIterator for Iter<Self>`
    pub trait IndexedRangeInteger: RangeInteger {
        private_decl! {}

        fn drive<C>(iter: Iter<Self>, consumer: C) -> C::Result
        where
            C: Consumer<Self>;

        fn len(iter: &Iter<Self>) -> usize;

        fn with_producer<CB>(iter: Iter<Self>, callback: CB) -> CB::Output
        where
            CB: ProducerCallback<Self>;
    }
}
use private::{IndexedRangeInteger, RangeInteger};

impl<T: RangeInteger> ParallelIterator for Iter<T> {
    type Item = T;

    fn drive_unindexed<C>(self, consumer: C) -> C::Result
    where
        C: UnindexedConsumer<T>,
    {
        T::drive_unindexed(self, consumer)
    }

    #[inline]
    fn opt_len(&self) -> Option<usize> {
        T::opt_len(self)
    }
}

impl<T: IndexedRangeInteger> IndexedParallelIterator for Iter<T> {
    fn drive<C>(self, consumer: C) -> C::Result
    where
        C: Consumer<T>,
    {
        T::drive(self, consumer)
    }

    #[inline]
    fn len(&self) -> usize {
        T::len(self)
    }

    fn with_producer<CB>(self, callback: CB) -> CB::Output
    where
        CB: ProducerCallback<T>,
    {
        T::with_producer(self, callback)
    }
}

macro_rules! convert {
    ( $iter:ident . $method:ident ( $( $arg:expr ),* ) ) => {
        if let Some((start, end)) = $iter.bounds() {
            if let Some(end) = end.checked_add(1) {
                (start..end).into_par_iter().$method($( $arg ),*)
            } else {
                (start..end).into_par_iter().chain(once(end)).$method($( $arg ),*)
            }
        } else {
            empty::<Self>().$method($( $arg ),*)
        }
    };
}

macro_rules! parallel_range_impl {
    ( $t:ty ) => {
        impl RangeInteger for $t {
            private_impl! {}

            fn drive_unindexed<C>(iter: Iter<$t>, consumer: C) -> C::Result
            where
                C: UnindexedConsumer<$t>,
            {
                convert!(iter.drive_unindexed(consumer))
            }

            fn opt_len(iter: &Iter<$t>) -> Option<usize> {
                convert!(iter.opt_len())
            }
        }
    };
}

macro_rules! indexed_range_impl {
    ( $t:ty ) => {
        parallel_range_impl! { $t }

        impl IndexedRangeInteger for $t {
            private_impl! {}

            fn drive<C>(iter: Iter<$t>, consumer: C) -> C::Result
            where
                C: Consumer<$t>,
            {
                convert!(iter.drive(consumer))
            }

            fn len(iter: &Iter<$t>) -> usize {
                iter.range.len()
            }

            fn with_producer<CB>(iter: Iter<$t>, callback: CB) -> CB::Output
            where
                CB: ProducerCallback<$t>,
            {
                convert!(iter.with_producer(callback))
            }
        }
    };
}

// all RangeInclusive<T> with ExactSizeIterator
indexed_range_impl! {u8}
indexed_range_impl! {u16}
indexed_range_impl! {i8}
indexed_range_impl! {i16}

// other RangeInclusive<T> with just Iterator
parallel_range_impl! {usize}
parallel_range_impl! {isize}
parallel_range_impl! {u32}
parallel_range_impl! {i32}
parallel_range_impl! {u64}
parallel_range_impl! {i64}
parallel_range_impl! {u128}
parallel_range_impl! {i128}

// char is special
macro_rules! convert_char {
    ( $self:ident . $method:ident ( $( $arg:expr ),* ) ) => {
        if let Some((start, end)) = $self.bounds() {
            let start = start as u32;
            let end = end as u32;
            if start < 0xD800 && 0xE000 <= end {
                // chain the before and after surrogate range fragments
                (start..0xD800)
                    .into_par_iter()
                    .chain(0xE000..end + 1) // cannot use RangeInclusive, so add one to end
                    .map(|codepoint| unsafe { char::from_u32_unchecked(codepoint) })
                    .$method($( $arg ),*)
            } else {
                // no surrogate range to worry about
                (start..end + 1) // cannot use RangeInclusive, so add one to end
                    .into_par_iter()
                    .map(|codepoint| unsafe { char::from_u32_unchecked(codepoint) })
                    .$method($( $arg ),*)
            }
        } else {
            empty::<char>().$method($( $arg ),*)
        }
    };
}

impl ParallelIterator for Iter<char> {
    type Item = char;

    fn drive_unindexed<C>(self, consumer: C) -> C::Result
    where
        C: UnindexedConsumer<Self::Item>,
    {
        convert_char!(self.drive(consumer))
    }

    fn opt_len(&self) -> Option<usize> {
        Some(self.len())
    }
}

// Range<u32> is broken on 16 bit platforms, may as well benefit from it
impl IndexedParallelIterator for Iter<char> {
    // Split at the surrogate range first if we're allowed to
    fn drive<C>(self, consumer: C) -> C::Result
    where
        C: Consumer<Self::Item>,
    {
        convert_char!(self.drive(consumer))
    }

    fn len(&self) -> usize {
        if let Some((start, end)) = self.bounds() {
            // Taken from <char as Step>::steps_between
            let start = start as u32;
            let end = end as u32;
            let mut count = end - start;
            if start < 0xD800 && 0xE000 <= end {
                count -= 0x800
            }
            (count + 1) as usize // add one for inclusive
        } else {
            0
        }
    }

    fn with_producer<CB>(self, callback: CB) -> CB::Output
    where
        CB: ProducerCallback<Self::Item>,
    {
        convert_char!(self.with_producer(callback))
    }
}

#[test]
#[cfg(target_pointer_width = "64")]
fn test_u32_opt_len() {
    use std::u32;
    assert_eq!(Some(101), (0..=100u32).into_par_iter().opt_len());
    assert_eq!(
        Some(u32::MAX as usize),
        (0..=u32::MAX - 1).into_par_iter().opt_len()
    );
    assert_eq!(
        Some(u32::MAX as usize + 1),
        (0..=u32::MAX).into_par_iter().opt_len()
    );
}

#[test]
fn test_u64_opt_len() {
    use std::{u64, usize};
    assert_eq!(Some(101), (0..=100u64).into_par_iter().opt_len());
    assert_eq!(
        Some(usize::MAX),
        (0..=usize::MAX as u64 - 1).into_par_iter().opt_len()
    );
    assert_eq!(None, (0..=usize::MAX as u64).into_par_iter().opt_len());
    assert_eq!(None, (0..=u64::MAX).into_par_iter().opt_len());
}

#[test]
fn test_u128_opt_len() {
    use std::{u128, usize};
    assert_eq!(Some(101), (0..=100u128).into_par_iter().opt_len());
    assert_eq!(
        Some(usize::MAX),
        (0..=usize::MAX as u128 - 1).into_par_iter().opt_len()
    );
    assert_eq!(None, (0..=usize::MAX as u128).into_par_iter().opt_len());
    assert_eq!(None, (0..=u128::MAX).into_par_iter().opt_len());
}

// `usize as i64` can overflow, so make sure to wrap it appropriately
// when using the `opt_len` "indexed" mode.
#[test]
#[cfg(target_pointer_width = "64")]
fn test_usize_i64_overflow() {
    use crate::ThreadPoolBuilder;
    use std::i64;

    let iter = (-2..=i64::MAX).into_par_iter();
    assert_eq!(iter.opt_len(), Some(i64::MAX as usize + 3));

    // always run with multiple threads to split into, or this will take forever...
    let pool = ThreadPoolBuilder::new().num_threads(8).build().unwrap();
    pool.install(|| assert_eq!(iter.find_last(|_| true), Some(i64::MAX)));
}

#[test]
fn test_issue_833() {
    fn is_even(n: i64) -> bool {
        n % 2 == 0
    }

    // The integer type should be inferred from `is_even`
    let v: Vec<_> = (1..=100).into_par_iter().filter(|&x| is_even(x)).collect();
    assert!(v.into_iter().eq((2..=100).step_by(2)));

    // Try examples with indexed iterators too
    let pos = (0..=100).into_par_iter().position_any(|x| x == 50i16);
    assert_eq!(pos, Some(50usize));

    assert!((0..=100)
        .into_par_iter()
        .zip(0..=100)
        .all(|(a, b)| i16::eq(&a, &b)));
}