core/
range.rs

1//! # Replacement range types
2//!
3//! The types within this module are meant to replace the legacy `Range`,
4//! `RangeInclusive`, `RangeToInclusive` and `RangeFrom` types in a future edition.
5//!
6//! ```
7//! use core::range::{Range, RangeFrom, RangeInclusive, RangeToInclusive};
8//!
9//! let arr = [0, 1, 2, 3, 4];
10//! assert_eq!(arr[                        ..   ], [0, 1, 2, 3, 4]);
11//! assert_eq!(arr[                        .. 3 ], [0, 1, 2      ]);
12//! assert_eq!(arr[RangeToInclusive::from( ..=3)], [0, 1, 2, 3   ]);
13//! assert_eq!(arr[       RangeFrom::from(1..  )], [   1, 2, 3, 4]);
14//! assert_eq!(arr[           Range::from(1..3 )], [   1, 2      ]);
15//! assert_eq!(arr[  RangeInclusive::from(1..=3)], [   1, 2, 3   ]);
16//! ```
17
18use crate::fmt;
19use crate::hash::Hash;
20
21mod iter;
22
23#[stable(feature = "new_range_api_legacy", since = "CURRENT_RUSTC_VERSION")]
24pub mod legacy;
25
26use core::ops::Bound::{self, Excluded, Included, Unbounded};
27
28#[doc(inline)]
29#[stable(feature = "new_range_from_api", since = "1.96.0")]
30pub use iter::RangeFromIter;
31#[doc(inline)]
32#[stable(feature = "new_range_inclusive_api", since = "1.95.0")]
33pub use iter::RangeInclusiveIter;
34#[doc(inline)]
35#[stable(feature = "new_range_api", since = "1.96.0")]
36pub use iter::RangeIter;
37
38use crate::iter::Step;
39// FIXME(one_sided_range): These types should move into this module.
40// FIXME(range_into_bounds): Ditto. Also consider re-exporting `RangeBounds` and related.
41use crate::ops::{IntoBounds, OneSidedRange, OneSidedRangeBound, RangeBounds};
42#[doc(inline)]
43#[stable(feature = "new_range_api_exports", since = "CURRENT_RUSTC_VERSION")]
44pub use crate::ops::{RangeFull, RangeTo};
45
46/// A (half-open) range bounded inclusively below and exclusively above.
47///
48/// The `Range` contains all values with `start <= x < end`.
49/// It is empty if `start >= end`.
50///
51/// # Examples
52///
53/// ```
54/// use core::range::Range;
55///
56/// assert_eq!(Range::from(3..5), Range { start: 3, end: 5 });
57/// assert_eq!(3 + 4 + 5, Range::from(3..6).into_iter().sum());
58/// ```
59///
60/// # Edition notes
61///
62/// It is planned that the syntax `start..end` will construct this
63/// type in a future edition, but it does not do so today.
64#[lang = "RangeCopy"]
65#[derive(Copy, Hash)]
66#[derive_const(Clone, Default, PartialEq, Eq)]
67#[stable(feature = "new_range_api", since = "1.96.0")]
68pub struct Range<Idx> {
69    /// The lower bound of the range (inclusive).
70    #[stable(feature = "new_range_api", since = "1.96.0")]
71    pub start: Idx,
72    /// The upper bound of the range (exclusive).
73    #[stable(feature = "new_range_api", since = "1.96.0")]
74    pub end: Idx,
75}
76
77#[stable(feature = "new_range_api", since = "1.96.0")]
78impl<Idx: fmt::Debug> fmt::Debug for Range<Idx> {
79    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
80        self.start.fmt(fmt)?;
81        write!(fmt, "..")?;
82        self.end.fmt(fmt)?;
83        Ok(())
84    }
85}
86
87impl<Idx: Step> Range<Idx> {
88    /// Creates an iterator over the elements within this range.
89    ///
90    /// Shorthand for `.clone().into_iter()`
91    ///
92    /// # Examples
93    ///
94    /// ```
95    /// use core::range::Range;
96    ///
97    /// let mut i = Range::from(3..9).iter().map(|n| n*n);
98    /// assert_eq!(i.next(), Some(9));
99    /// assert_eq!(i.next(), Some(16));
100    /// assert_eq!(i.next(), Some(25));
101    /// ```
102    #[stable(feature = "new_range_api", since = "1.96.0")]
103    #[inline]
104    pub fn iter(&self) -> RangeIter<Idx> {
105        self.clone().into_iter()
106    }
107}
108
109impl<Idx: PartialOrd<Idx>> Range<Idx> {
110    /// Returns `true` if `item` is contained in the range.
111    ///
112    /// # Examples
113    ///
114    /// ```
115    /// use core::range::Range;
116    ///
117    /// assert!(!Range::from(3..5).contains(&2));
118    /// assert!( Range::from(3..5).contains(&3));
119    /// assert!( Range::from(3..5).contains(&4));
120    /// assert!(!Range::from(3..5).contains(&5));
121    ///
122    /// assert!(!Range::from(3..3).contains(&3));
123    /// assert!(!Range::from(3..2).contains(&3));
124    ///
125    /// assert!( Range::from(0.0..1.0).contains(&0.5));
126    /// assert!(!Range::from(0.0..1.0).contains(&f32::NAN));
127    /// assert!(!Range::from(0.0..f32::NAN).contains(&0.5));
128    /// assert!(!Range::from(f32::NAN..1.0).contains(&0.5));
129    /// ```
130    #[inline]
131    #[stable(feature = "new_range_api", since = "1.96.0")]
132    #[rustc_const_unstable(feature = "const_range", issue = "none")]
133    pub const fn contains<U>(&self, item: &U) -> bool
134    where
135        Idx: [const] PartialOrd<U>,
136        U: ?Sized + [const] PartialOrd<Idx>,
137    {
138        <Self as RangeBounds<Idx>>::contains(self, item)
139    }
140
141    /// Returns `true` if the range contains no items.
142    ///
143    /// # Examples
144    ///
145    /// ```
146    /// use core::range::Range;
147    ///
148    /// assert!(!Range::from(3..5).is_empty());
149    /// assert!( Range::from(3..3).is_empty());
150    /// assert!( Range::from(3..2).is_empty());
151    /// ```
152    ///
153    /// The range is empty if either side is incomparable:
154    ///
155    /// ```
156    /// use core::range::Range;
157    ///
158    /// assert!(!Range::from(3.0..5.0).is_empty());
159    /// assert!( Range::from(3.0..f32::NAN).is_empty());
160    /// assert!( Range::from(f32::NAN..5.0).is_empty());
161    /// ```
162    #[inline]
163    #[stable(feature = "new_range_api", since = "1.96.0")]
164    #[rustc_const_unstable(feature = "const_range", issue = "none")]
165    pub const fn is_empty(&self) -> bool
166    where
167        Idx: [const] PartialOrd,
168    {
169        !(self.start < self.end)
170    }
171}
172
173#[stable(feature = "new_range_api", since = "1.96.0")]
174#[rustc_const_unstable(feature = "const_range", issue = "none")]
175const impl<T> RangeBounds<T> for Range<T> {
176    fn start_bound(&self) -> Bound<&T> {
177        Included(&self.start)
178    }
179    fn end_bound(&self) -> Bound<&T> {
180        Excluded(&self.end)
181    }
182}
183
184// This impl intentionally does not have `T: ?Sized`;
185// see https://github.com/rust-lang/rust/pull/61584 for discussion of why.
186//
187/// If you need to use this implementation where `T` is unsized,
188/// consider using the `RangeBounds` impl for a 2-tuple of [`Bound<&T>`][Bound],
189/// i.e. replace `start..end` with `(Bound::Included(start), Bound::Excluded(end))`.
190#[stable(feature = "new_range_api", since = "1.96.0")]
191#[rustc_const_unstable(feature = "const_range", issue = "none")]
192const impl<T> RangeBounds<T> for Range<&T> {
193    fn start_bound(&self) -> Bound<&T> {
194        Included(self.start)
195    }
196    fn end_bound(&self) -> Bound<&T> {
197        Excluded(self.end)
198    }
199}
200
201#[unstable(feature = "range_into_bounds", issue = "136903")]
202#[rustc_const_unstable(feature = "const_range", issue = "none")]
203const impl<T> IntoBounds<T> for Range<T> {
204    fn into_bounds(self) -> (Bound<T>, Bound<T>) {
205        (Included(self.start), Excluded(self.end))
206    }
207}
208
209#[stable(feature = "new_range_api", since = "1.96.0")]
210#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
211const impl<T> From<Range<T>> for legacy::Range<T> {
212    #[inline]
213    fn from(value: Range<T>) -> Self {
214        Self { start: value.start, end: value.end }
215    }
216}
217#[stable(feature = "new_range_api", since = "1.96.0")]
218#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
219const impl<T> From<legacy::Range<T>> for Range<T> {
220    #[inline]
221    fn from(value: legacy::Range<T>) -> Self {
222        Self { start: value.start, end: value.end }
223    }
224}
225
226/// A range bounded inclusively below and above.
227///
228/// The `RangeInclusive` contains all values with `x >= start`
229/// and `x <= last`. It is empty unless `start <= last`.
230///
231/// # Examples
232///
233/// ```
234/// use core::range::RangeInclusive;
235///
236/// assert_eq!(RangeInclusive::from(3..=5), RangeInclusive { start: 3, last: 5 });
237/// assert_eq!(3 + 4 + 5, RangeInclusive::from(3..=5).into_iter().sum());
238/// ```
239///
240/// # Edition notes
241///
242/// It is planned that the syntax  `start..=last` will construct this
243/// type in a future edition, but it does not do so today.
244#[lang = "RangeInclusiveCopy"]
245#[derive(Clone, Copy, PartialEq, Eq, Hash)]
246#[stable(feature = "new_range_inclusive_api", since = "1.95.0")]
247pub struct RangeInclusive<Idx> {
248    /// The lower bound of the range (inclusive).
249    #[stable(feature = "new_range_inclusive_api", since = "1.95.0")]
250    pub start: Idx,
251    /// The upper bound of the range (inclusive).
252    #[stable(feature = "new_range_inclusive_api", since = "1.95.0")]
253    pub last: Idx,
254}
255
256#[stable(feature = "new_range_inclusive_api", since = "1.95.0")]
257impl<Idx: fmt::Debug> fmt::Debug for RangeInclusive<Idx> {
258    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
259        self.start.fmt(fmt)?;
260        write!(fmt, "..=")?;
261        self.last.fmt(fmt)?;
262        Ok(())
263    }
264}
265
266impl<Idx: PartialOrd<Idx>> RangeInclusive<Idx> {
267    /// Returns `true` if `item` is contained in the range.
268    ///
269    /// # Examples
270    ///
271    /// ```
272    /// use core::range::RangeInclusive;
273    ///
274    /// assert!(!RangeInclusive::from(3..=5).contains(&2));
275    /// assert!( RangeInclusive::from(3..=5).contains(&3));
276    /// assert!( RangeInclusive::from(3..=5).contains(&4));
277    /// assert!( RangeInclusive::from(3..=5).contains(&5));
278    /// assert!(!RangeInclusive::from(3..=5).contains(&6));
279    ///
280    /// assert!( RangeInclusive::from(3..=3).contains(&3));
281    /// assert!(!RangeInclusive::from(3..=2).contains(&3));
282    ///
283    /// assert!( RangeInclusive::from(0.0..=1.0).contains(&1.0));
284    /// assert!(!RangeInclusive::from(0.0..=1.0).contains(&f32::NAN));
285    /// assert!(!RangeInclusive::from(0.0..=f32::NAN).contains(&0.0));
286    /// assert!(!RangeInclusive::from(f32::NAN..=1.0).contains(&1.0));
287    /// ```
288    #[inline]
289    #[stable(feature = "new_range_inclusive_api", since = "1.95.0")]
290    #[rustc_const_unstable(feature = "const_range", issue = "none")]
291    pub const fn contains<U>(&self, item: &U) -> bool
292    where
293        Idx: [const] PartialOrd<U>,
294        U: ?Sized + [const] PartialOrd<Idx>,
295    {
296        <Self as RangeBounds<Idx>>::contains(self, item)
297    }
298
299    /// Returns `true` if the range contains no items.
300    ///
301    /// # Examples
302    ///
303    /// ```
304    /// use core::range::RangeInclusive;
305    ///
306    /// assert!(!RangeInclusive::from(3..=5).is_empty());
307    /// assert!(!RangeInclusive::from(3..=3).is_empty());
308    /// assert!( RangeInclusive::from(3..=2).is_empty());
309    /// ```
310    ///
311    /// The range is empty if either side is incomparable:
312    ///
313    /// ```
314    /// use core::range::RangeInclusive;
315    ///
316    /// assert!(!RangeInclusive::from(3.0..=5.0).is_empty());
317    /// assert!( RangeInclusive::from(3.0..=f32::NAN).is_empty());
318    /// assert!( RangeInclusive::from(f32::NAN..=5.0).is_empty());
319    /// ```
320    #[stable(feature = "new_range_inclusive_api", since = "1.95.0")]
321    #[inline]
322    #[rustc_const_unstable(feature = "const_range", issue = "none")]
323    pub const fn is_empty(&self) -> bool
324    where
325        Idx: [const] PartialOrd,
326    {
327        !(self.start <= self.last)
328    }
329}
330
331impl<Idx: Step> RangeInclusive<Idx> {
332    /// Creates an iterator over the elements within this range.
333    ///
334    /// Shorthand for `.clone().into_iter()`
335    ///
336    /// # Examples
337    ///
338    /// ```
339    /// use core::range::RangeInclusive;
340    ///
341    /// let mut i = RangeInclusive::from(3..=8).iter().map(|n| n*n);
342    /// assert_eq!(i.next(), Some(9));
343    /// assert_eq!(i.next(), Some(16));
344    /// assert_eq!(i.next(), Some(25));
345    /// ```
346    #[stable(feature = "new_range_inclusive_api", since = "1.95.0")]
347    #[inline]
348    pub fn iter(&self) -> RangeInclusiveIter<Idx> {
349        self.clone().into_iter()
350    }
351}
352
353#[stable(feature = "new_range_inclusive_api", since = "1.95.0")]
354#[rustc_const_unstable(feature = "const_range", issue = "none")]
355const impl<T> RangeBounds<T> for RangeInclusive<T> {
356    fn start_bound(&self) -> Bound<&T> {
357        Included(&self.start)
358    }
359    fn end_bound(&self) -> Bound<&T> {
360        Included(&self.last)
361    }
362}
363
364// This impl intentionally does not have `T: ?Sized`;
365// see https://github.com/rust-lang/rust/pull/61584 for discussion of why.
366//
367/// If you need to use this implementation where `T` is unsized,
368/// consider using the `RangeBounds` impl for a 2-tuple of [`Bound<&T>`][Bound],
369/// i.e. replace `start..=end` with `(Bound::Included(start), Bound::Included(end))`.
370#[stable(feature = "new_range_inclusive_api", since = "1.95.0")]
371#[rustc_const_unstable(feature = "const_range", issue = "none")]
372const impl<T> RangeBounds<T> for RangeInclusive<&T> {
373    fn start_bound(&self) -> Bound<&T> {
374        Included(self.start)
375    }
376    fn end_bound(&self) -> Bound<&T> {
377        Included(self.last)
378    }
379}
380
381// #[stable(feature = "new_range_inclusive_api", since = "1.95.0")]
382#[unstable(feature = "range_into_bounds", issue = "136903")]
383#[rustc_const_unstable(feature = "const_range", issue = "none")]
384const impl<T> IntoBounds<T> for RangeInclusive<T> {
385    fn into_bounds(self) -> (Bound<T>, Bound<T>) {
386        (Included(self.start), Included(self.last))
387    }
388}
389
390#[stable(feature = "new_range_inclusive_api", since = "1.95.0")]
391#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
392const impl<T> From<RangeInclusive<T>> for legacy::RangeInclusive<T> {
393    #[inline]
394    fn from(value: RangeInclusive<T>) -> Self {
395        Self::new(value.start, value.last)
396    }
397}
398#[stable(feature = "new_range_inclusive_api", since = "1.95.0")]
399#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
400const impl<T> From<legacy::RangeInclusive<T>> for RangeInclusive<T> {
401    /// Converts from a legacy range to a non-legacy range, potentially panicking.
402    ///
403    /// # Panics
404    ///
405    /// If the legacy range iterator has been exhausted,
406    /// this function will either panic or return an empty range.
407    ///
408    /// # Examples
409    ///
410    /// ```
411    /// use core::range::legacy;
412    /// use core::range::RangeInclusive;
413    ///
414    /// let single: legacy::RangeInclusive<i32> = 0..=1;
415    /// let single = RangeInclusive::from(single);
416    /// assert_eq!((single.start, single.last), (0, 1));
417    ///
418    /// let empty: legacy::RangeInclusive<i32> = 0..=0;
419    /// let empty = RangeInclusive::from(empty);
420    /// assert_eq!((empty.start, empty.last), (0, 0));
421    /// ```
422    ///
423    /// ```
424    /// # // This test requires unwinding to work.
425    /// # // Disable it when unwinding isn't available.
426    /// # #[cfg(panic = "unwind")]
427    /// # fn main() {
428    /// use core::range::legacy;
429    /// use core::range::RangeInclusive;
430    /// use std::panic::catch_unwind;
431    ///
432    /// let mut exhausted: legacy::RangeInclusive<i32> = 0..=0;
433    /// exhausted.next();
434    /// let result = catch_unwind(|| RangeInclusive::from(exhausted));
435    /// // The `from` call either panicked or returned an empty range.
436    /// assert!(result.is_err() || result.is_ok_and(|range| range.is_empty()));
437    /// # }
438    /// # #[cfg(not(panic = "unwind"))]
439    /// # fn main() {}
440    /// ```
441    #[inline]
442    fn from(value: legacy::RangeInclusive<T>) -> Self {
443        assert!(
444            !value.exhausted,
445            "attempted to convert from an exhausted `legacy::RangeInclusive`"
446        );
447
448        let (start, last) = value.into_inner();
449        RangeInclusive { start, last }
450    }
451}
452
453/// A range only bounded inclusively below.
454///
455/// The `RangeFrom` contains all values with `x >= start`.
456///
457/// *Note*: Overflow in the [`IntoIterator`] implementation (when the contained
458/// data type reaches its numerical limit) is allowed to panic, wrap, or
459/// saturate. This behavior is defined by the implementation of the [`Step`]
460/// trait. For primitive integers, this follows the normal rules, and respects
461/// the overflow checks profile (panic in debug, wrap in release). Unlike
462/// its legacy counterpart, the iterator will only panic after yielding the
463/// maximum value when overflow checks are enabled.
464///
465/// [`Step`]: crate::iter::Step
466///
467/// # Examples
468///
469/// ```
470/// use core::range::RangeFrom;
471///
472/// assert_eq!(RangeFrom::from(2..), core::range::RangeFrom { start: 2 });
473/// assert_eq!(2 + 3 + 4, RangeFrom::from(2..).into_iter().take(3).sum());
474/// ```
475///
476/// # Edition notes
477///
478/// It is planned that the syntax  `start..` will construct this
479/// type in a future edition, but it does not do so today.
480#[lang = "RangeFromCopy"]
481#[derive(Copy, Hash)]
482#[derive_const(Clone, PartialEq, Eq)]
483#[stable(feature = "new_range_from_api", since = "1.96.0")]
484pub struct RangeFrom<Idx> {
485    /// The lower bound of the range (inclusive).
486    #[stable(feature = "new_range_from_api", since = "1.96.0")]
487    pub start: Idx,
488}
489
490#[stable(feature = "new_range_from_api", since = "1.96.0")]
491impl<Idx: fmt::Debug> fmt::Debug for RangeFrom<Idx> {
492    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
493        self.start.fmt(fmt)?;
494        write!(fmt, "..")?;
495        Ok(())
496    }
497}
498
499impl<Idx: Step> RangeFrom<Idx> {
500    /// Creates an iterator over the elements within this range.
501    ///
502    /// Shorthand for `.clone().into_iter()`
503    ///
504    /// # Examples
505    ///
506    /// ```
507    /// use core::range::RangeFrom;
508    ///
509    /// let mut i = RangeFrom::from(3..).iter().map(|n| n*n);
510    /// assert_eq!(i.next(), Some(9));
511    /// assert_eq!(i.next(), Some(16));
512    /// assert_eq!(i.next(), Some(25));
513    /// ```
514    #[stable(feature = "new_range_from_api", since = "1.96.0")]
515    #[inline]
516    pub fn iter(&self) -> RangeFromIter<Idx> {
517        self.clone().into_iter()
518    }
519}
520
521impl<Idx: PartialOrd<Idx>> RangeFrom<Idx> {
522    /// Returns `true` if `item` is contained in the range.
523    ///
524    /// # Examples
525    ///
526    /// ```
527    /// use core::range::RangeFrom;
528    ///
529    /// assert!(!RangeFrom::from(3..).contains(&2));
530    /// assert!( RangeFrom::from(3..).contains(&3));
531    /// assert!( RangeFrom::from(3..).contains(&1_000_000_000));
532    ///
533    /// assert!( RangeFrom::from(0.0..).contains(&0.5));
534    /// assert!(!RangeFrom::from(0.0..).contains(&f32::NAN));
535    /// assert!(!RangeFrom::from(f32::NAN..).contains(&0.5));
536    /// ```
537    #[inline]
538    #[stable(feature = "new_range_from_api", since = "1.96.0")]
539    #[rustc_const_unstable(feature = "const_range", issue = "none")]
540    pub const fn contains<U>(&self, item: &U) -> bool
541    where
542        Idx: [const] PartialOrd<U>,
543        U: ?Sized + [const] PartialOrd<Idx>,
544    {
545        <Self as RangeBounds<Idx>>::contains(self, item)
546    }
547}
548
549#[stable(feature = "new_range_from_api", since = "1.96.0")]
550#[rustc_const_unstable(feature = "const_range", issue = "none")]
551const impl<T> RangeBounds<T> for RangeFrom<T> {
552    fn start_bound(&self) -> Bound<&T> {
553        Included(&self.start)
554    }
555    fn end_bound(&self) -> Bound<&T> {
556        Unbounded
557    }
558}
559
560// This impl intentionally does not have `T: ?Sized`;
561// see https://github.com/rust-lang/rust/pull/61584 for discussion of why.
562//
563/// If you need to use this implementation where `T` is unsized,
564/// consider using the `RangeBounds` impl for a 2-tuple of [`Bound<&T>`][Bound],
565/// i.e. replace `start..` with `(Bound::Included(start), Bound::Unbounded)`.
566#[stable(feature = "new_range_from_api", since = "1.96.0")]
567#[rustc_const_unstable(feature = "const_range", issue = "none")]
568const impl<T> RangeBounds<T> for RangeFrom<&T> {
569    fn start_bound(&self) -> Bound<&T> {
570        Included(self.start)
571    }
572    fn end_bound(&self) -> Bound<&T> {
573        Unbounded
574    }
575}
576
577#[unstable(feature = "range_into_bounds", issue = "136903")]
578#[rustc_const_unstable(feature = "const_range", issue = "none")]
579const impl<T> IntoBounds<T> for RangeFrom<T> {
580    fn into_bounds(self) -> (Bound<T>, Bound<T>) {
581        (Included(self.start), Unbounded)
582    }
583}
584
585#[unstable(feature = "one_sided_range", issue = "69780")]
586#[rustc_const_unstable(feature = "const_range", issue = "none")]
587const impl<T> OneSidedRange<T> for RangeFrom<T>
588where
589    Self: RangeBounds<T>,
590{
591    fn bound(self) -> (OneSidedRangeBound, T) {
592        (OneSidedRangeBound::StartInclusive, self.start)
593    }
594}
595
596#[stable(feature = "new_range_from_api", since = "1.96.0")]
597#[rustc_const_unstable(feature = "const_index", issue = "143775")]
598const impl<T> From<RangeFrom<T>> for legacy::RangeFrom<T> {
599    #[inline]
600    fn from(value: RangeFrom<T>) -> Self {
601        Self { start: value.start }
602    }
603}
604#[stable(feature = "new_range_from_api", since = "1.96.0")]
605#[rustc_const_unstable(feature = "const_index", issue = "143775")]
606const impl<T> From<legacy::RangeFrom<T>> for RangeFrom<T> {
607    #[inline]
608    fn from(value: legacy::RangeFrom<T>) -> Self {
609        Self { start: value.start }
610    }
611}
612
613/// A range only bounded inclusively above.
614///
615/// The `RangeToInclusive` contains all values with `x <= last`.
616/// It cannot serve as an [`Iterator`] because it doesn't have a starting point.
617///
618/// # Examples
619///
620/// ```standalone_crate
621/// #![feature(new_range)]
622/// assert_eq!((..=5), std::range::RangeToInclusive { last: 5 });
623/// ```
624///
625/// It does not have an [`IntoIterator`] implementation, so you can't use it in a
626/// `for` loop directly. This won't compile:
627///
628/// ```compile_fail,E0277
629/// // error[E0277]: the trait bound `std::range::RangeToInclusive<{integer}>:
630/// // std::iter::Iterator` is not satisfied
631/// for i in ..=5 {
632///     // ...
633/// }
634/// ```
635///
636/// When used as a [slicing index], `RangeToInclusive` produces a slice of all
637/// array elements up to and including the index indicated by `last`.
638///
639/// ```
640/// let arr = [0, 1, 2, 3, 4];
641/// assert_eq!(arr[ ..  ], [0, 1, 2, 3, 4]);
642/// assert_eq!(arr[ .. 3], [0, 1, 2      ]);
643/// assert_eq!(arr[ ..=3], [0, 1, 2, 3   ]); // This is a `RangeToInclusive`
644/// assert_eq!(arr[1..  ], [   1, 2, 3, 4]);
645/// assert_eq!(arr[1.. 3], [   1, 2      ]);
646/// assert_eq!(arr[1..=3], [   1, 2, 3   ]);
647/// ```
648///
649/// [slicing index]: crate::slice::SliceIndex
650///
651/// # Edition notes
652///
653/// It is planned that the syntax  `..=last` will construct this
654/// type in a future edition, but it does not do so today.
655#[lang = "RangeToInclusiveCopy"]
656#[doc(alias = "..=")]
657#[derive(Copy, Clone, PartialEq, Eq, Hash)]
658#[stable(feature = "new_range_to_inclusive_api", since = "1.96.0")]
659pub struct RangeToInclusive<Idx> {
660    /// The upper bound of the range (inclusive)
661    #[stable(feature = "new_range_to_inclusive_api", since = "1.96.0")]
662    pub last: Idx,
663}
664
665#[stable(feature = "new_range_to_inclusive_api", since = "1.96.0")]
666impl<Idx: fmt::Debug> fmt::Debug for RangeToInclusive<Idx> {
667    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
668        write!(fmt, "..=")?;
669        self.last.fmt(fmt)?;
670        Ok(())
671    }
672}
673
674impl<Idx: PartialOrd<Idx>> RangeToInclusive<Idx> {
675    /// Returns `true` if `item` is contained in the range.
676    ///
677    /// # Examples
678    ///
679    /// ```
680    /// assert!( (..=5).contains(&-1_000_000_000));
681    /// assert!( (..=5).contains(&5));
682    /// assert!(!(..=5).contains(&6));
683    ///
684    /// assert!( (..=1.0).contains(&1.0));
685    /// assert!(!(..=1.0).contains(&f32::NAN));
686    /// assert!(!(..=f32::NAN).contains(&0.5));
687    /// ```
688    #[inline]
689    #[stable(feature = "new_range_to_inclusive_api", since = "1.96.0")]
690    #[rustc_const_unstable(feature = "const_range", issue = "none")]
691    pub const fn contains<U>(&self, item: &U) -> bool
692    where
693        Idx: [const] PartialOrd<U>,
694        U: ?Sized + [const] PartialOrd<Idx>,
695    {
696        <Self as RangeBounds<Idx>>::contains(self, item)
697    }
698}
699
700#[stable(feature = "new_range_to_inclusive_api", since = "1.96.0")]
701impl<T> From<legacy::RangeToInclusive<T>> for RangeToInclusive<T> {
702    fn from(value: legacy::RangeToInclusive<T>) -> Self {
703        Self { last: value.end }
704    }
705}
706#[stable(feature = "new_range_to_inclusive_api", since = "1.96.0")]
707impl<T> From<RangeToInclusive<T>> for legacy::RangeToInclusive<T> {
708    fn from(value: RangeToInclusive<T>) -> Self {
709        Self { end: value.last }
710    }
711}
712
713// RangeToInclusive<Idx> cannot impl From<RangeTo<Idx>>
714// because underflow would be possible with (..0).into()
715
716#[stable(feature = "new_range_to_inclusive_api", since = "1.96.0")]
717#[rustc_const_unstable(feature = "const_range", issue = "none")]
718const impl<T> RangeBounds<T> for RangeToInclusive<T> {
719    fn start_bound(&self) -> Bound<&T> {
720        Unbounded
721    }
722    fn end_bound(&self) -> Bound<&T> {
723        Included(&self.last)
724    }
725}
726
727#[stable(feature = "new_range_to_inclusive_api", since = "1.96.0")]
728#[rustc_const_unstable(feature = "const_range", issue = "none")]
729const impl<T> RangeBounds<T> for RangeToInclusive<&T> {
730    fn start_bound(&self) -> Bound<&T> {
731        Unbounded
732    }
733    fn end_bound(&self) -> Bound<&T> {
734        Included(self.last)
735    }
736}
737
738#[unstable(feature = "range_into_bounds", issue = "136903")]
739#[rustc_const_unstable(feature = "const_range", issue = "none")]
740const impl<T> IntoBounds<T> for RangeToInclusive<T> {
741    fn into_bounds(self) -> (Bound<T>, Bound<T>) {
742        (Unbounded, Included(self.last))
743    }
744}
745
746#[unstable(feature = "one_sided_range", issue = "69780")]
747#[rustc_const_unstable(feature = "const_range", issue = "none")]
748const impl<T> OneSidedRange<T> for RangeToInclusive<T>
749where
750    Self: RangeBounds<T>,
751{
752    fn bound(self) -> (OneSidedRangeBound, T) {
753        (OneSidedRangeBound::EndInclusive, self.last)
754    }
755}
core/range.rs

core/
range.rs
