Auto merge of #51622 - kennytm:three-field-range-inclusive, r=SimonSapin
Change RangeInclusive to a three-field struct. Fix #45222. This PR also reverts #48012 (i.e. removed the `try_fold`/`try_rfold` specialization for `RangeInclusive`) because LLVM no longer has trouble recognizing a RangeInclusive loop.
This commit is contained in:
commit
c0955a34bc
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@ -787,17 +787,19 @@ where
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#[inline]
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fn spec_next(&mut self) -> Option<Self::Item> {
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self.first_take = false;
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if !(self.iter.start <= self.iter.end) {
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self.iter.compute_is_empty();
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if self.iter.is_empty.unwrap_or_default() {
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return None;
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}
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// add 1 to self.step to get original step size back
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// it was decremented for the general case on construction
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if let Some(n) = self.iter.start.add_usize(self.step+1) {
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self.iter.is_empty = Some(!(n <= self.iter.end));
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let next = mem::replace(&mut self.iter.start, n);
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Some(next)
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} else {
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let last = self.iter.start.replace_one();
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self.iter.end.replace_zero();
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let last = self.iter.start.clone();
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self.iter.is_empty = Some(true);
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Some(last)
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}
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}
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@ -10,7 +10,7 @@
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use convert::TryFrom;
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use mem;
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use ops::{self, Add, Sub, Try};
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use ops::{self, Add, Sub};
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use usize;
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use super::{FusedIterator, TrustedLen};
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@ -330,23 +330,23 @@ impl<A: Step> Iterator for ops::RangeInclusive<A> {
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#[inline]
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fn next(&mut self) -> Option<A> {
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if self.start <= self.end {
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if self.start < self.end {
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let n = self.start.add_one();
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Some(mem::replace(&mut self.start, n))
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} else {
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let last = self.start.replace_one();
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self.end.replace_zero();
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Some(last)
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}
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} else {
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None
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self.compute_is_empty();
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if self.is_empty.unwrap_or_default() {
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return None;
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}
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let is_iterating = self.start < self.end;
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self.is_empty = Some(!is_iterating);
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Some(if is_iterating {
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let n = self.start.add_one();
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mem::replace(&mut self.start, n)
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} else {
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self.start.clone()
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})
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}
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#[inline]
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fn size_hint(&self) -> (usize, Option<usize>) {
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if !(self.start <= self.end) {
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if self.is_empty() {
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return (0, Some(0));
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}
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@ -358,25 +358,29 @@ impl<A: Step> Iterator for ops::RangeInclusive<A> {
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#[inline]
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fn nth(&mut self, n: usize) -> Option<A> {
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self.compute_is_empty();
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if self.is_empty.unwrap_or_default() {
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return None;
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}
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if let Some(plus_n) = self.start.add_usize(n) {
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use cmp::Ordering::*;
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match plus_n.partial_cmp(&self.end) {
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Some(Less) => {
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self.is_empty = Some(false);
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self.start = plus_n.add_one();
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return Some(plus_n)
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}
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Some(Equal) => {
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self.start.replace_one();
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self.end.replace_zero();
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self.is_empty = Some(true);
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return Some(plus_n)
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}
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_ => {}
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}
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}
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self.start.replace_one();
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self.end.replace_zero();
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self.is_empty = Some(true);
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None
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}
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@ -394,68 +398,24 @@ impl<A: Step> Iterator for ops::RangeInclusive<A> {
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fn max(mut self) -> Option<A> {
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self.next_back()
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}
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#[inline]
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fn try_fold<B, F, R>(&mut self, init: B, mut f: F) -> R where
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Self: Sized, F: FnMut(B, Self::Item) -> R, R: Try<Ok=B>
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{
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let mut accum = init;
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if self.start <= self.end {
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loop {
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let (x, done) =
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if self.start < self.end {
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let n = self.start.add_one();
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(mem::replace(&mut self.start, n), false)
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} else {
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self.end.replace_zero();
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(self.start.replace_one(), true)
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};
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accum = f(accum, x)?;
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if done { break }
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}
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}
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Try::from_ok(accum)
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}
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}
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#[stable(feature = "inclusive_range", since = "1.26.0")]
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impl<A: Step> DoubleEndedIterator for ops::RangeInclusive<A> {
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#[inline]
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fn next_back(&mut self) -> Option<A> {
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if self.start <= self.end {
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if self.start < self.end {
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let n = self.end.sub_one();
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Some(mem::replace(&mut self.end, n))
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} else {
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let last = self.end.replace_zero();
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self.start.replace_one();
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Some(last)
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}
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self.compute_is_empty();
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if self.is_empty.unwrap_or_default() {
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return None;
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}
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let is_iterating = self.start < self.end;
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self.is_empty = Some(!is_iterating);
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Some(if is_iterating {
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let n = self.end.sub_one();
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mem::replace(&mut self.end, n)
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} else {
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None
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}
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}
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#[inline]
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fn try_rfold<B, F, R>(&mut self, init: B, mut f: F) -> R where
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Self: Sized, F: FnMut(B, Self::Item) -> R, R: Try<Ok=B>
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{
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let mut accum = init;
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if self.start <= self.end {
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loop {
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let (x, done) =
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if self.start < self.end {
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let n = self.end.sub_one();
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(mem::replace(&mut self.end, n), false)
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} else {
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self.start.replace_one();
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(self.end.replace_zero(), true)
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};
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accum = f(accum, x)?;
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if done { break }
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}
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}
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Try::from_ok(accum)
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self.end.clone()
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})
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}
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}
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@ -9,6 +9,7 @@
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// except according to those terms.
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use fmt;
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use hash::{Hash, Hasher};
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/// An unbounded range (`..`).
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///
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@ -326,15 +327,56 @@ impl<Idx: PartialOrd<Idx>> RangeTo<Idx> {
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/// assert_eq!(arr[1..=2], [ 1,2 ]); // RangeInclusive
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/// ```
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#[doc(alias = "..=")]
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#[derive(Clone, PartialEq, Eq, Hash)] // not Copy -- see #27186
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#[derive(Clone)] // not Copy -- see #27186
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#[stable(feature = "inclusive_range", since = "1.26.0")]
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pub struct RangeInclusive<Idx> {
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// FIXME: The current representation follows RFC 1980,
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// but it is known that LLVM is not able to optimize loops following that RFC.
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// Consider adding an extra `bool` field to indicate emptiness of the range.
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// See #45222 for performance test cases.
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pub(crate) start: Idx,
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pub(crate) end: Idx,
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pub(crate) is_empty: Option<bool>,
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// This field is:
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// - `None` when next() or next_back() was never called
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// - `Some(false)` when `start <= end` assuming no overflow
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// - `Some(true)` otherwise
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// The field cannot be a simple `bool` because the `..=` constructor can
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// accept non-PartialOrd types, also we want the constructor to be const.
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}
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trait RangeInclusiveEquality: Sized {
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fn canonicalized_is_empty(range: &RangeInclusive<Self>) -> bool;
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}
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impl<T> RangeInclusiveEquality for T {
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#[inline]
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default fn canonicalized_is_empty(range: &RangeInclusive<Self>) -> bool {
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range.is_empty.unwrap_or_default()
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}
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}
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impl<T: PartialOrd> RangeInclusiveEquality for T {
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#[inline]
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fn canonicalized_is_empty(range: &RangeInclusive<Self>) -> bool {
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range.is_empty()
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}
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}
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#[stable(feature = "inclusive_range", since = "1.26.0")]
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impl<Idx: PartialEq> PartialEq for RangeInclusive<Idx> {
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#[inline]
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fn eq(&self, other: &Self) -> bool {
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self.start == other.start && self.end == other.end
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&& RangeInclusiveEquality::canonicalized_is_empty(self)
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== RangeInclusiveEquality::canonicalized_is_empty(other)
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}
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}
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#[stable(feature = "inclusive_range", since = "1.26.0")]
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impl<Idx: Eq> Eq for RangeInclusive<Idx> {}
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#[stable(feature = "inclusive_range", since = "1.26.0")]
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impl<Idx: Hash> Hash for RangeInclusive<Idx> {
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fn hash<H: Hasher>(&self, state: &mut H) {
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self.start.hash(state);
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self.end.hash(state);
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RangeInclusiveEquality::canonicalized_is_empty(self).hash(state);
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}
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}
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impl<Idx> RangeInclusive<Idx> {
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@ -350,7 +392,7 @@ impl<Idx> RangeInclusive<Idx> {
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#[stable(feature = "inclusive_range_methods", since = "1.27.0")]
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#[inline]
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pub const fn new(start: Idx, end: Idx) -> Self {
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Self { start, end }
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Self { start, end, is_empty: None }
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}
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/// Returns the lower bound of the range (inclusive).
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@ -492,8 +534,17 @@ impl<Idx: PartialOrd<Idx>> RangeInclusive<Idx> {
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/// assert!(r.is_empty());
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/// ```
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#[unstable(feature = "range_is_empty", reason = "recently added", issue = "48111")]
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#[inline]
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pub fn is_empty(&self) -> bool {
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!(self.start <= self.end)
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self.is_empty.unwrap_or_else(|| !(self.start <= self.end))
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}
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// If this range's `is_empty` is field is unknown (`None`), update it to be a concrete value.
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#[inline]
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pub(crate) fn compute_is_empty(&mut self) {
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if self.is_empty.is_none() {
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self.is_empty = Some(!(self.start <= self.end));
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}
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}
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}
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@ -2265,36 +2265,36 @@ impl<T> SliceIndex<[T]> for ops::RangeInclusive<usize> {
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#[inline]
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fn get(self, slice: &[T]) -> Option<&[T]> {
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if self.end == usize::max_value() { None }
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else { (self.start..self.end + 1).get(slice) }
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if *self.end() == usize::max_value() { None }
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else { (*self.start()..self.end() + 1).get(slice) }
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}
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#[inline]
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fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
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if self.end == usize::max_value() { None }
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else { (self.start..self.end + 1).get_mut(slice) }
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if *self.end() == usize::max_value() { None }
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else { (*self.start()..self.end() + 1).get_mut(slice) }
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}
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#[inline]
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unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
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(self.start..self.end + 1).get_unchecked(slice)
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(*self.start()..self.end() + 1).get_unchecked(slice)
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}
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#[inline]
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unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
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(self.start..self.end + 1).get_unchecked_mut(slice)
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(*self.start()..self.end() + 1).get_unchecked_mut(slice)
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}
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#[inline]
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fn index(self, slice: &[T]) -> &[T] {
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if self.end == usize::max_value() { slice_index_overflow_fail(); }
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(self.start..self.end + 1).index(slice)
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if *self.end() == usize::max_value() { slice_index_overflow_fail(); }
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(*self.start()..self.end() + 1).index(slice)
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}
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#[inline]
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fn index_mut(self, slice: &mut [T]) -> &mut [T] {
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if self.end == usize::max_value() { slice_index_overflow_fail(); }
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(self.start..self.end + 1).index_mut(slice)
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if *self.end() == usize::max_value() { slice_index_overflow_fail(); }
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(*self.start()..self.end() + 1).index_mut(slice)
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}
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}
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@ -2004,31 +2004,31 @@ mod traits {
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type Output = str;
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#[inline]
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fn get(self, slice: &str) -> Option<&Self::Output> {
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if self.end == usize::max_value() { None }
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else { (self.start..self.end+1).get(slice) }
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if *self.end() == usize::max_value() { None }
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else { (*self.start()..self.end()+1).get(slice) }
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}
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#[inline]
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fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output> {
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if self.end == usize::max_value() { None }
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else { (self.start..self.end+1).get_mut(slice) }
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if *self.end() == usize::max_value() { None }
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else { (*self.start()..self.end()+1).get_mut(slice) }
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}
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#[inline]
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unsafe fn get_unchecked(self, slice: &str) -> &Self::Output {
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(self.start..self.end+1).get_unchecked(slice)
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(*self.start()..self.end()+1).get_unchecked(slice)
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}
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#[inline]
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unsafe fn get_unchecked_mut(self, slice: &mut str) -> &mut Self::Output {
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(self.start..self.end+1).get_unchecked_mut(slice)
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(*self.start()..self.end()+1).get_unchecked_mut(slice)
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}
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#[inline]
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fn index(self, slice: &str) -> &Self::Output {
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if self.end == usize::max_value() { str_index_overflow_fail(); }
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(self.start..self.end+1).index(slice)
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if *self.end() == usize::max_value() { str_index_overflow_fail(); }
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(*self.start()..self.end()+1).index(slice)
|
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}
|
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#[inline]
|
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fn index_mut(self, slice: &mut str) -> &mut Self::Output {
|
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if self.end == usize::max_value() { str_index_overflow_fail(); }
|
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(self.start..self.end+1).index_mut(slice)
|
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if *self.end() == usize::max_value() { str_index_overflow_fail(); }
|
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(*self.start()..self.end()+1).index_mut(slice)
|
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}
|
||||
}
|
||||
|
||||
|
|
|
@ -0,0 +1,74 @@
|
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// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
|
||||
// file at the top-level directory of this distribution and at
|
||||
// http://rust-lang.org/COPYRIGHT.
|
||||
//
|
||||
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
|
||||
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
|
||||
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
|
||||
// option. This file may not be copied, modified, or distributed
|
||||
// except according to those terms.
|
||||
|
||||
// compile-flags: -O
|
||||
// min-llvm-version 6.0
|
||||
|
||||
#![crate_type = "lib"]
|
||||
|
||||
// verify that LLVM recognizes a loop involving 0..=n and will const-fold it.
|
||||
|
||||
//------------------------------------------------------------------------------
|
||||
// Example from original issue #45222
|
||||
|
||||
fn foo2(n: u64) -> u64 {
|
||||
let mut count = 0;
|
||||
for _ in 0..n {
|
||||
for j in (0..=n).rev() {
|
||||
count += j;
|
||||
}
|
||||
}
|
||||
count
|
||||
}
|
||||
|
||||
// CHECK-LABEL: @check_foo2
|
||||
#[no_mangle]
|
||||
pub fn check_foo2() -> u64 {
|
||||
// CHECK: ret i64 500005000000000
|
||||
foo2(100000)
|
||||
}
|
||||
|
||||
//------------------------------------------------------------------------------
|
||||
// Simplified example of #45222
|
||||
|
||||
fn triangle_inc(n: u64) -> u64 {
|
||||
let mut count = 0;
|
||||
for j in 0 ..= n {
|
||||
count += j;
|
||||
}
|
||||
count
|
||||
}
|
||||
|
||||
// CHECK-LABEL: @check_triangle_inc
|
||||
#[no_mangle]
|
||||
pub fn check_triangle_inc() -> u64 {
|
||||
// CHECK: ret i64 5000050000
|
||||
triangle_inc(100000)
|
||||
}
|
||||
|
||||
//------------------------------------------------------------------------------
|
||||
// Demo in #48012
|
||||
|
||||
fn foo3r(n: u64) -> u64 {
|
||||
let mut count = 0;
|
||||
(0..n).for_each(|_| {
|
||||
(0 ..= n).rev().for_each(|j| {
|
||||
count += j;
|
||||
})
|
||||
});
|
||||
count
|
||||
}
|
||||
|
||||
// CHECK-LABEL: @check_foo3r
|
||||
#[no_mangle]
|
||||
pub fn check_foo3r() -> u64 {
|
||||
// CHECK: ret i64 500005000000000
|
||||
foo3r(100000)
|
||||
}
|
|
@ -10,12 +10,18 @@
|
|||
|
||||
// Test inclusive range syntax.
|
||||
|
||||
use std::ops::{RangeInclusive, RangeToInclusive};
|
||||
#![feature(range_is_empty)]
|
||||
#![allow(unused_comparisons)]
|
||||
|
||||
use std::ops::RangeToInclusive;
|
||||
|
||||
fn foo() -> isize { 42 }
|
||||
|
||||
// Test that range syntax works in return statements
|
||||
fn return_range_to() -> RangeToInclusive<i32> { return ..=1; }
|
||||
pub fn return_range_to() -> RangeToInclusive<i32> { return ..=1; }
|
||||
|
||||
#[derive(Debug)]
|
||||
struct P(u8);
|
||||
|
||||
pub fn main() {
|
||||
let mut count = 0;
|
||||
|
@ -26,7 +32,7 @@ pub fn main() {
|
|||
assert_eq!(count, 55);
|
||||
|
||||
let mut count = 0;
|
||||
let mut range = 0_usize..=10;
|
||||
let range = 0_usize..=10;
|
||||
for i in range {
|
||||
assert!(i >= 0 && i <= 10);
|
||||
count += i;
|
||||
|
@ -80,7 +86,7 @@ pub fn main() {
|
|||
short.next();
|
||||
assert_eq!(long.size_hint(), (255, Some(255)));
|
||||
assert_eq!(short.size_hint(), (0, Some(0)));
|
||||
assert_eq!(short, 1..=0);
|
||||
assert!(short.is_empty());
|
||||
|
||||
assert_eq!(long.len(), 255);
|
||||
assert_eq!(short.len(), 0);
|
||||
|
@ -95,28 +101,31 @@ pub fn main() {
|
|||
for i in 3..=251 {
|
||||
assert_eq!(long.next(), Some(i));
|
||||
}
|
||||
assert_eq!(long, 1..=0);
|
||||
assert!(long.is_empty());
|
||||
|
||||
// check underflow
|
||||
let mut narrow = 1..=0;
|
||||
assert_eq!(narrow.next_back(), None);
|
||||
assert_eq!(narrow, 1..=0);
|
||||
assert!(narrow.is_empty());
|
||||
let mut zero = 0u8..=0;
|
||||
assert_eq!(zero.next_back(), Some(0));
|
||||
assert_eq!(zero.next_back(), None);
|
||||
assert_eq!(zero, 1..=0);
|
||||
assert!(zero.is_empty());
|
||||
let mut high = 255u8..=255;
|
||||
assert_eq!(high.next_back(), Some(255));
|
||||
assert_eq!(high.next_back(), None);
|
||||
assert_eq!(high, 1..=0);
|
||||
assert!(high.is_empty());
|
||||
|
||||
// what happens if you have a nonsense range?
|
||||
let mut nonsense = 10..=5;
|
||||
assert_eq!(nonsense.next(), None);
|
||||
assert_eq!(nonsense, 10..=5);
|
||||
assert!(nonsense.is_empty());
|
||||
|
||||
// output
|
||||
assert_eq!(format!("{:?}", 0..=10), "0..=10");
|
||||
assert_eq!(format!("{:?}", ..=10), "..=10");
|
||||
assert_eq!(format!("{:?}", long), "1..=0");
|
||||
assert_eq!(format!("{:?}", 9..=6), "9..=6");
|
||||
|
||||
// ensure that constructing a RangeInclusive does not need PartialOrd bound
|
||||
assert_eq!(format!("{:?}", P(1)..=P(2)), "P(1)..=P(2)");
|
||||
}
|
||||
|
|
Loading…
Reference in New Issue