diff --git a/src/libcollections/lib.rs b/src/libcollections/lib.rs index 23d6edd6d794e..f6d83b25b0d89 100644 --- a/src/libcollections/lib.rs +++ b/src/libcollections/lib.rs @@ -36,6 +36,7 @@ #![cfg_attr(not(test), feature(char_escape_debug))] #![feature(core_intrinsics)] #![feature(dropck_parametricity)] +#![feature(exact_size_is_empty)] #![feature(fmt_internals)] #![feature(fused)] #![feature(heap_api)] diff --git a/src/libcollections/vec.rs b/src/libcollections/vec.rs index 24f8e3a2d9181..f26324127003b 100644 --- a/src/libcollections/vec.rs +++ b/src/libcollections/vec.rs @@ -1988,7 +1988,11 @@ impl DoubleEndedIterator for IntoIter { } #[stable(feature = "rust1", since = "1.0.0")] -impl ExactSizeIterator for IntoIter {} +impl ExactSizeIterator for IntoIter { + fn is_empty(&self) -> bool { + self.ptr == self.end + } +} #[unstable(feature = "fused", issue = "35602")] impl FusedIterator for IntoIter {} @@ -2082,7 +2086,11 @@ impl<'a, T> Drop for Drain<'a, T> { #[stable(feature = "drain", since = "1.6.0")] -impl<'a, T> ExactSizeIterator for Drain<'a, T> {} +impl<'a, T> ExactSizeIterator for Drain<'a, T> { + fn is_empty(&self) -> bool { + self.iter.is_empty() + } +} #[unstable(feature = "fused", issue = "35602")] impl<'a, T> FusedIterator for Drain<'a, T> {} diff --git a/src/libcollectionstest/lib.rs b/src/libcollectionstest/lib.rs index 14ec8d58bef61..1e08074b14db8 100644 --- a/src/libcollectionstest/lib.rs +++ b/src/libcollectionstest/lib.rs @@ -18,6 +18,7 @@ #![feature(const_fn)] #![feature(dedup_by)] #![feature(enumset)] +#![feature(exact_size_is_empty)] #![feature(pattern)] #![feature(rand)] #![feature(repeat_str)] diff --git a/src/libcollectionstest/slice.rs b/src/libcollectionstest/slice.rs index a6230ef471cec..0e63e8d4a1ec8 100644 --- a/src/libcollectionstest/slice.rs +++ b/src/libcollectionstest/slice.rs @@ -633,6 +633,16 @@ fn test_iter_clone() { assert_eq!(it.next(), jt.next()); } +#[test] +fn test_iter_is_empty() { + let xs = [1, 2, 5, 10, 11]; + for i in 0..xs.len() { + for j in i..xs.len() { + assert_eq!(xs[i..j].iter().is_empty(), xs[i..j].is_empty()); + } + } +} + #[test] fn test_mut_iterator() { let mut xs = [1, 2, 3, 4, 5]; diff --git a/src/libcore/slice.rs b/src/libcore/slice.rs index 871b63145ca6d..ede45111ebbc5 100644 --- a/src/libcore/slice.rs +++ b/src/libcore/slice.rs @@ -983,7 +983,11 @@ impl<'a, T> Iter<'a, T> { iterator!{struct Iter -> *const T, &'a T} #[stable(feature = "rust1", since = "1.0.0")] -impl<'a, T> ExactSizeIterator for Iter<'a, T> {} +impl<'a, T> ExactSizeIterator for Iter<'a, T> { + fn is_empty(&self) -> bool { + self.ptr == self.end + } +} #[unstable(feature = "fused", issue = "35602")] impl<'a, T> FusedIterator for Iter<'a, T> {} @@ -1107,7 +1111,11 @@ impl<'a, T> IterMut<'a, T> { iterator!{struct IterMut -> *mut T, &'a mut T} #[stable(feature = "rust1", since = "1.0.0")] -impl<'a, T> ExactSizeIterator for IterMut<'a, T> {} +impl<'a, T> ExactSizeIterator for IterMut<'a, T> { + fn is_empty(&self) -> bool { + self.ptr == self.end + } +} #[unstable(feature = "fused", issue = "35602")] impl<'a, T> FusedIterator for IterMut<'a, T> {}