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Stabilize Range[Inclusive]::is_empty

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I would like to propose these two simple methods for stabilization:
- Knowing that a range is exhaused isn't otherwise trivial
- Clippy would like to suggest them, but had to do extra work to disable that path <https://github.com/rust-lang/rust-clippy/issues/3807> because they're unstable
- These work on `PartialOrd`, consistently with now-stable `contains`, and are thus more general than iterator-based approaches that need `Step`
- They've been unchanged for some time, and have picked up uses in the compiler
- Stabilizing them doesn't block any future iterator-based is_empty plans, as the inherent ones are preferred in name resolution
This commit is contained in:
Scott McMurray 2020-08-03 23:18:34 -07:00
parent e6d85ea5cb
commit c20ad72323
6 changed files with 2 additions and 17 deletions
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14
library/core/src/ops/range.rs
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@ -125,8 +125,6 @@ impl<Idx: PartialOrd<Idx>> Range<Idx> {
/// # Examples
///
/// ```
/// #![feature(range_is_empty)]
///
/// assert!(!(3..5).is_empty());
/// assert!( (3..3).is_empty());
/// assert!( (3..2).is_empty());
@ -135,13 +133,11 @@ impl<Idx: PartialOrd<Idx>> Range<Idx> {
/// The range is empty if either side is incomparable:
///
/// ```
/// #![feature(range_is_empty)]
///
/// assert!(!(3.0..5.0).is_empty());
/// assert!( (3.0..f32::NAN).is_empty());
/// assert!( (f32::NAN..5.0).is_empty());
/// ```
#[unstable(feature = "range_is_empty", reason = "recently added", issue = "48111")]
#[stable(feature = "range_is_empty", since = "1.47.0")]
pub fn is_empty(&self) -> bool {
!(self.start < self.end)
}
@ -481,8 +477,6 @@ impl<Idx: PartialOrd<Idx>> RangeInclusive<Idx> {
/// # Examples
///
/// ```
/// #![feature(range_is_empty)]
///
/// assert!(!(3..=5).is_empty());
/// assert!(!(3..=3).is_empty());
/// assert!( (3..=2).is_empty());
@ -491,8 +485,6 @@ impl<Idx: PartialOrd<Idx>> RangeInclusive<Idx> {
/// The range is empty if either side is incomparable:
///
/// ```
/// #![feature(range_is_empty)]
///
/// assert!(!(3.0..=5.0).is_empty());
/// assert!( (3.0..=f32::NAN).is_empty());
/// assert!( (f32::NAN..=5.0).is_empty());
@ -501,14 +493,12 @@ impl<Idx: PartialOrd<Idx>> RangeInclusive<Idx> {
/// This method returns `true` after iteration has finished:
///
/// ```
/// #![feature(range_is_empty)]
///
/// let mut r = 3..=5;
/// for _ in r.by_ref() {}
/// // Precise field values are unspecified here
/// assert!(r.is_empty());
/// ```
#[unstable(feature = "range_is_empty", reason = "recently added", issue = "48111")]
#[stable(feature = "range_is_empty", since = "1.47.0")]
#[inline]
pub fn is_empty(&self) -> bool {
self.exhausted || !(self.start <= self.end)