core/range.rs
1//! # Experimental replacement range types
2//!
3//! The types within this module are meant to replace the existing
4//! `Range`, `RangeInclusive`, and `RangeFrom` types in a future edition.
5//!
6//! ```
7//! #![feature(new_range_api)]
8//! use core::range::{Range, RangeFrom, RangeInclusive};
9//!
10//! let arr = [0, 1, 2, 3, 4];
11//! assert_eq!(arr[ .. ], [0, 1, 2, 3, 4]);
12//! assert_eq!(arr[ .. 3 ], [0, 1, 2 ]);
13//! assert_eq!(arr[ ..=3 ], [0, 1, 2, 3 ]);
14//! assert_eq!(arr[ RangeFrom::from(1.. )], [ 1, 2, 3, 4]);
15//! assert_eq!(arr[ Range::from(1..3 )], [ 1, 2 ]);
16//! assert_eq!(arr[RangeInclusive::from(1..=3)], [ 1, 2, 3 ]);
17//! ```
18
19use crate::fmt;
20use crate::hash::Hash;
21
22mod iter;
23
24#[unstable(feature = "new_range_api", issue = "125687")]
25pub mod legacy;
26
27use Bound::{Excluded, Included, Unbounded};
28#[doc(inline)]
29pub use iter::{IterRange, IterRangeFrom, IterRangeInclusive};
30
31#[doc(inline)]
32pub use crate::iter::Step;
33#[doc(inline)]
34pub use crate::ops::{
35 Bound, IntoBounds, OneSidedRange, RangeBounds, RangeFull, RangeTo, RangeToInclusive,
36};
37
38/// A (half-open) range bounded inclusively below and exclusively above
39/// (`start..end` in a future edition).
40///
41/// The range `start..end` contains all values with `start <= x < end`.
42/// It is empty if `start >= end`.
43///
44/// # Examples
45///
46/// ```
47/// #![feature(new_range_api)]
48/// use core::range::Range;
49///
50/// assert_eq!(Range::from(3..5), Range { start: 3, end: 5 });
51/// assert_eq!(3 + 4 + 5, Range::from(3..6).into_iter().sum());
52/// ```
53#[lang = "RangeCopy"]
54#[derive(Clone, Copy, Default, PartialEq, Eq, Hash)]
55#[unstable(feature = "new_range_api", issue = "125687")]
56pub struct Range<Idx> {
57 /// The lower bound of the range (inclusive).
58 #[unstable(feature = "new_range_api", issue = "125687")]
59 pub start: Idx,
60 /// The upper bound of the range (exclusive).
61 #[unstable(feature = "new_range_api", issue = "125687")]
62 pub end: Idx,
63}
64
65#[unstable(feature = "new_range_api", issue = "125687")]
66impl<Idx: fmt::Debug> fmt::Debug for Range<Idx> {
67 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
68 self.start.fmt(fmt)?;
69 write!(fmt, "..")?;
70 self.end.fmt(fmt)?;
71 Ok(())
72 }
73}
74
75impl<Idx: Step> Range<Idx> {
76 /// Creates an iterator over the elements within this range.
77 ///
78 /// Shorthand for `.clone().into_iter()`
79 ///
80 /// # Examples
81 ///
82 /// ```
83 /// #![feature(new_range_api)]
84 /// use core::range::Range;
85 ///
86 /// let mut i = Range::from(3..9).iter().map(|n| n*n);
87 /// assert_eq!(i.next(), Some(9));
88 /// assert_eq!(i.next(), Some(16));
89 /// assert_eq!(i.next(), Some(25));
90 /// ```
91 #[unstable(feature = "new_range_api", issue = "125687")]
92 #[inline]
93 pub fn iter(&self) -> IterRange<Idx> {
94 self.clone().into_iter()
95 }
96}
97
98impl<Idx: PartialOrd<Idx>> Range<Idx> {
99 /// Returns `true` if `item` is contained in the range.
100 ///
101 /// # Examples
102 ///
103 /// ```
104 /// #![feature(new_range_api)]
105 /// use core::range::Range;
106 ///
107 /// assert!(!Range::from(3..5).contains(&2));
108 /// assert!( Range::from(3..5).contains(&3));
109 /// assert!( Range::from(3..5).contains(&4));
110 /// assert!(!Range::from(3..5).contains(&5));
111 ///
112 /// assert!(!Range::from(3..3).contains(&3));
113 /// assert!(!Range::from(3..2).contains(&3));
114 ///
115 /// assert!( Range::from(0.0..1.0).contains(&0.5));
116 /// assert!(!Range::from(0.0..1.0).contains(&f32::NAN));
117 /// assert!(!Range::from(0.0..f32::NAN).contains(&0.5));
118 /// assert!(!Range::from(f32::NAN..1.0).contains(&0.5));
119 /// ```
120 #[inline]
121 #[unstable(feature = "new_range_api", issue = "125687")]
122 pub fn contains<U>(&self, item: &U) -> bool
123 where
124 Idx: PartialOrd<U>,
125 U: ?Sized + PartialOrd<Idx>,
126 {
127 <Self as RangeBounds<Idx>>::contains(self, item)
128 }
129
130 /// Returns `true` if the range contains no items.
131 ///
132 /// # Examples
133 ///
134 /// ```
135 /// #![feature(new_range_api)]
136 /// use core::range::Range;
137 ///
138 /// assert!(!Range::from(3..5).is_empty());
139 /// assert!( Range::from(3..3).is_empty());
140 /// assert!( Range::from(3..2).is_empty());
141 /// ```
142 ///
143 /// The range is empty if either side is incomparable:
144 ///
145 /// ```
146 /// #![feature(new_range_api)]
147 /// use core::range::Range;
148 ///
149 /// assert!(!Range::from(3.0..5.0).is_empty());
150 /// assert!( Range::from(3.0..f32::NAN).is_empty());
151 /// assert!( Range::from(f32::NAN..5.0).is_empty());
152 /// ```
153 #[inline]
154 #[unstable(feature = "new_range_api", issue = "125687")]
155 pub fn is_empty(&self) -> bool {
156 !(self.start < self.end)
157 }
158}
159
160#[unstable(feature = "new_range_api", issue = "125687")]
161impl<T> RangeBounds<T> for Range<T> {
162 fn start_bound(&self) -> Bound<&T> {
163 Included(&self.start)
164 }
165 fn end_bound(&self) -> Bound<&T> {
166 Excluded(&self.end)
167 }
168}
169
170#[unstable(feature = "new_range_api", issue = "125687")]
171impl<T> RangeBounds<T> for Range<&T> {
172 fn start_bound(&self) -> Bound<&T> {
173 Included(self.start)
174 }
175 fn end_bound(&self) -> Bound<&T> {
176 Excluded(self.end)
177 }
178}
179
180// #[unstable(feature = "range_into_bounds", issue = "136903")]
181#[unstable(feature = "new_range_api", issue = "125687")]
182impl<T> IntoBounds<T> for Range<T> {
183 fn into_bounds(self) -> (Bound<T>, Bound<T>) {
184 (Included(self.start), Excluded(self.end))
185 }
186}
187
188#[unstable(feature = "new_range_api", issue = "125687")]
189#[rustc_const_unstable(feature = "const_index", issue = "143775")]
190impl<T> const From<Range<T>> for legacy::Range<T> {
191 #[inline]
192 fn from(value: Range<T>) -> Self {
193 Self { start: value.start, end: value.end }
194 }
195}
196
197#[unstable(feature = "new_range_api", issue = "125687")]
198#[rustc_const_unstable(feature = "const_index", issue = "143775")]
199impl<T> const From<legacy::Range<T>> for Range<T> {
200 #[inline]
201 fn from(value: legacy::Range<T>) -> Self {
202 Self { start: value.start, end: value.end }
203 }
204}
205
206/// A range bounded inclusively below and above (`start..=end`).
207///
208/// The `RangeInclusive` `start..=end` contains all values with `x >= start`
209/// and `x <= end`. It is empty unless `start <= end`.
210///
211/// # Examples
212///
213/// The `start..=end` syntax is a `RangeInclusive`:
214///
215/// ```
216/// #![feature(new_range_api)]
217/// use core::range::RangeInclusive;
218///
219/// assert_eq!(RangeInclusive::from(3..=5), RangeInclusive { start: 3, end: 5 });
220/// assert_eq!(3 + 4 + 5, RangeInclusive::from(3..=5).into_iter().sum());
221/// ```
222#[lang = "RangeInclusiveCopy"]
223#[derive(Clone, Copy, PartialEq, Eq, Hash)]
224#[unstable(feature = "new_range_api", issue = "125687")]
225pub struct RangeInclusive<Idx> {
226 /// The lower bound of the range (inclusive).
227 #[unstable(feature = "new_range_api", issue = "125687")]
228 pub start: Idx,
229 /// The upper bound of the range (inclusive).
230 #[unstable(feature = "new_range_api", issue = "125687")]
231 pub end: Idx,
232}
233
234#[unstable(feature = "new_range_api", issue = "125687")]
235impl<Idx: fmt::Debug> fmt::Debug for RangeInclusive<Idx> {
236 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
237 self.start.fmt(fmt)?;
238 write!(fmt, "..=")?;
239 self.end.fmt(fmt)?;
240 Ok(())
241 }
242}
243
244impl<Idx: PartialOrd<Idx>> RangeInclusive<Idx> {
245 /// Returns `true` if `item` is contained in the range.
246 ///
247 /// # Examples
248 ///
249 /// ```
250 /// #![feature(new_range_api)]
251 /// use core::range::RangeInclusive;
252 ///
253 /// assert!(!RangeInclusive::from(3..=5).contains(&2));
254 /// assert!( RangeInclusive::from(3..=5).contains(&3));
255 /// assert!( RangeInclusive::from(3..=5).contains(&4));
256 /// assert!( RangeInclusive::from(3..=5).contains(&5));
257 /// assert!(!RangeInclusive::from(3..=5).contains(&6));
258 ///
259 /// assert!( RangeInclusive::from(3..=3).contains(&3));
260 /// assert!(!RangeInclusive::from(3..=2).contains(&3));
261 ///
262 /// assert!( RangeInclusive::from(0.0..=1.0).contains(&1.0));
263 /// assert!(!RangeInclusive::from(0.0..=1.0).contains(&f32::NAN));
264 /// assert!(!RangeInclusive::from(0.0..=f32::NAN).contains(&0.0));
265 /// assert!(!RangeInclusive::from(f32::NAN..=1.0).contains(&1.0));
266 /// ```
267 #[inline]
268 #[unstable(feature = "new_range_api", issue = "125687")]
269 pub fn contains<U>(&self, item: &U) -> bool
270 where
271 Idx: PartialOrd<U>,
272 U: ?Sized + PartialOrd<Idx>,
273 {
274 <Self as RangeBounds<Idx>>::contains(self, item)
275 }
276
277 /// Returns `true` if the range contains no items.
278 ///
279 /// # Examples
280 ///
281 /// ```
282 /// #![feature(new_range_api)]
283 /// use core::range::RangeInclusive;
284 ///
285 /// assert!(!RangeInclusive::from(3..=5).is_empty());
286 /// assert!(!RangeInclusive::from(3..=3).is_empty());
287 /// assert!( RangeInclusive::from(3..=2).is_empty());
288 /// ```
289 ///
290 /// The range is empty if either side is incomparable:
291 ///
292 /// ```
293 /// #![feature(new_range_api)]
294 /// use core::range::RangeInclusive;
295 ///
296 /// assert!(!RangeInclusive::from(3.0..=5.0).is_empty());
297 /// assert!( RangeInclusive::from(3.0..=f32::NAN).is_empty());
298 /// assert!( RangeInclusive::from(f32::NAN..=5.0).is_empty());
299 /// ```
300 #[unstable(feature = "new_range_api", issue = "125687")]
301 #[inline]
302 pub fn is_empty(&self) -> bool {
303 !(self.start <= self.end)
304 }
305}
306
307impl<Idx: Step> RangeInclusive<Idx> {
308 /// Creates an iterator over the elements within this range.
309 ///
310 /// Shorthand for `.clone().into_iter()`
311 ///
312 /// # Examples
313 ///
314 /// ```
315 /// #![feature(new_range_api)]
316 /// use core::range::RangeInclusive;
317 ///
318 /// let mut i = RangeInclusive::from(3..=8).iter().map(|n| n*n);
319 /// assert_eq!(i.next(), Some(9));
320 /// assert_eq!(i.next(), Some(16));
321 /// assert_eq!(i.next(), Some(25));
322 /// ```
323 #[unstable(feature = "new_range_api", issue = "125687")]
324 #[inline]
325 pub fn iter(&self) -> IterRangeInclusive<Idx> {
326 self.clone().into_iter()
327 }
328}
329
330impl RangeInclusive<usize> {
331 /// Converts to an exclusive `Range` for `SliceIndex` implementations.
332 /// The caller is responsible for dealing with `end == usize::MAX`.
333 #[inline]
334 pub(crate) const fn into_slice_range(self) -> Range<usize> {
335 Range { start: self.start, end: self.end + 1 }
336 }
337}
338
339#[unstable(feature = "new_range_api", issue = "125687")]
340impl<T> RangeBounds<T> for RangeInclusive<T> {
341 fn start_bound(&self) -> Bound<&T> {
342 Included(&self.start)
343 }
344 fn end_bound(&self) -> Bound<&T> {
345 Included(&self.end)
346 }
347}
348
349#[unstable(feature = "new_range_api", issue = "125687")]
350impl<T> RangeBounds<T> for RangeInclusive<&T> {
351 fn start_bound(&self) -> Bound<&T> {
352 Included(self.start)
353 }
354 fn end_bound(&self) -> Bound<&T> {
355 Included(self.end)
356 }
357}
358
359// #[unstable(feature = "range_into_bounds", issue = "136903")]
360#[unstable(feature = "new_range_api", issue = "125687")]
361impl<T> IntoBounds<T> for RangeInclusive<T> {
362 fn into_bounds(self) -> (Bound<T>, Bound<T>) {
363 (Included(self.start), Included(self.end))
364 }
365}
366
367#[unstable(feature = "new_range_api", issue = "125687")]
368#[rustc_const_unstable(feature = "const_index", issue = "143775")]
369impl<T> const From<RangeInclusive<T>> for legacy::RangeInclusive<T> {
370 #[inline]
371 fn from(value: RangeInclusive<T>) -> Self {
372 Self::new(value.start, value.end)
373 }
374}
375#[unstable(feature = "new_range_api", issue = "125687")]
376impl<T> From<legacy::RangeInclusive<T>> for RangeInclusive<T> {
377 #[inline]
378 fn from(value: legacy::RangeInclusive<T>) -> Self {
379 assert!(
380 !value.exhausted,
381 "attempted to convert from an exhausted `legacy::RangeInclusive` (unspecified behavior)"
382 );
383
384 let (start, end) = value.into_inner();
385 RangeInclusive { start, end }
386 }
387}
388
389/// A range only bounded inclusively below (`start..`).
390///
391/// The `RangeFrom` `start..` contains all values with `x >= start`.
392///
393/// *Note*: Overflow in the [`Iterator`] implementation (when the contained
394/// data type reaches its numerical limit) is allowed to panic, wrap, or
395/// saturate. This behavior is defined by the implementation of the [`Step`]
396/// trait. For primitive integers, this follows the normal rules, and respects
397/// the overflow checks profile (panic in debug, wrap in release). Note also
398/// that overflow happens earlier than you might assume: the overflow happens
399/// in the call to `next` that yields the maximum value, as the range must be
400/// set to a state to yield the next value.
401///
402/// [`Step`]: crate::iter::Step
403///
404/// # Examples
405///
406/// The `start..` syntax is a `RangeFrom`:
407///
408/// ```
409/// #![feature(new_range_api)]
410/// use core::range::RangeFrom;
411///
412/// assert_eq!(RangeFrom::from(2..), core::range::RangeFrom { start: 2 });
413/// assert_eq!(2 + 3 + 4, RangeFrom::from(2..).into_iter().take(3).sum());
414/// ```
415#[lang = "RangeFromCopy"]
416#[derive(Clone, Copy, PartialEq, Eq, Hash)]
417#[unstable(feature = "new_range_api", issue = "125687")]
418pub struct RangeFrom<Idx> {
419 /// The lower bound of the range (inclusive).
420 #[unstable(feature = "new_range_api", issue = "125687")]
421 pub start: Idx,
422}
423
424#[unstable(feature = "new_range_api", issue = "125687")]
425impl<Idx: fmt::Debug> fmt::Debug for RangeFrom<Idx> {
426 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
427 self.start.fmt(fmt)?;
428 write!(fmt, "..")?;
429 Ok(())
430 }
431}
432
433impl<Idx: Step> RangeFrom<Idx> {
434 /// Creates an iterator over the elements within this range.
435 ///
436 /// Shorthand for `.clone().into_iter()`
437 ///
438 /// # Examples
439 ///
440 /// ```
441 /// #![feature(new_range_api)]
442 /// use core::range::RangeFrom;
443 ///
444 /// let mut i = RangeFrom::from(3..).iter().map(|n| n*n);
445 /// assert_eq!(i.next(), Some(9));
446 /// assert_eq!(i.next(), Some(16));
447 /// assert_eq!(i.next(), Some(25));
448 /// ```
449 #[unstable(feature = "new_range_api", issue = "125687")]
450 #[inline]
451 pub fn iter(&self) -> IterRangeFrom<Idx> {
452 self.clone().into_iter()
453 }
454}
455
456impl<Idx: PartialOrd<Idx>> RangeFrom<Idx> {
457 /// Returns `true` if `item` is contained in the range.
458 ///
459 /// # Examples
460 ///
461 /// ```
462 /// #![feature(new_range_api)]
463 /// use core::range::RangeFrom;
464 ///
465 /// assert!(!RangeFrom::from(3..).contains(&2));
466 /// assert!( RangeFrom::from(3..).contains(&3));
467 /// assert!( RangeFrom::from(3..).contains(&1_000_000_000));
468 ///
469 /// assert!( RangeFrom::from(0.0..).contains(&0.5));
470 /// assert!(!RangeFrom::from(0.0..).contains(&f32::NAN));
471 /// assert!(!RangeFrom::from(f32::NAN..).contains(&0.5));
472 /// ```
473 #[inline]
474 #[unstable(feature = "new_range_api", issue = "125687")]
475 pub fn contains<U>(&self, item: &U) -> bool
476 where
477 Idx: PartialOrd<U>,
478 U: ?Sized + PartialOrd<Idx>,
479 {
480 <Self as RangeBounds<Idx>>::contains(self, item)
481 }
482}
483
484#[unstable(feature = "new_range_api", issue = "125687")]
485impl<T> RangeBounds<T> for RangeFrom<T> {
486 fn start_bound(&self) -> Bound<&T> {
487 Included(&self.start)
488 }
489 fn end_bound(&self) -> Bound<&T> {
490 Unbounded
491 }
492}
493
494#[unstable(feature = "new_range_api", issue = "125687")]
495impl<T> RangeBounds<T> for RangeFrom<&T> {
496 fn start_bound(&self) -> Bound<&T> {
497 Included(self.start)
498 }
499 fn end_bound(&self) -> Bound<&T> {
500 Unbounded
501 }
502}
503
504// #[unstable(feature = "range_into_bounds", issue = "136903")]
505#[unstable(feature = "new_range_api", issue = "125687")]
506impl<T> IntoBounds<T> for RangeFrom<T> {
507 fn into_bounds(self) -> (Bound<T>, Bound<T>) {
508 (Included(self.start), Unbounded)
509 }
510}
511
512#[unstable(feature = "new_range_api", issue = "125687")]
513#[rustc_const_unstable(feature = "const_index", issue = "143775")]
514impl<T> const From<RangeFrom<T>> for legacy::RangeFrom<T> {
515 #[inline]
516 fn from(value: RangeFrom<T>) -> Self {
517 Self { start: value.start }
518 }
519}
520#[unstable(feature = "new_range_api", issue = "125687")]
521#[rustc_const_unstable(feature = "const_index", issue = "143775")]
522impl<T> const From<legacy::RangeFrom<T>> for RangeFrom<T> {
523 #[inline]
524 fn from(value: legacy::RangeFrom<T>) -> Self {
525 Self { start: value.start }
526 }
527}