diff options
Diffstat (limited to 'library/core/src/slice/iter/macros.rs')
| -rw-r--r-- | library/core/src/slice/iter/macros.rs | 22 |
1 files changed, 18 insertions, 4 deletions
diff --git a/library/core/src/slice/iter/macros.rs b/library/core/src/slice/iter/macros.rs index 89b92a7d5..392752f2a 100644 --- a/library/core/src/slice/iter/macros.rs +++ b/library/core/src/slice/iter/macros.rs @@ -176,11 +176,11 @@ macro_rules! iterator { } #[inline] - fn advance_by(&mut self, n: usize) -> Result<(), usize> { + fn advance_by(&mut self, n: usize) -> Result<(), NonZeroUsize> { let advance = cmp::min(len!(self), n); // SAFETY: By construction, `advance` does not exceed `self.len()`. unsafe { self.post_inc_start(advance) }; - if advance == n { Ok(()) } else { Err(advance) } + NonZeroUsize::new(n - advance).map_or(Ok(()), Err) } #[inline] @@ -371,11 +371,11 @@ macro_rules! iterator { } #[inline] - fn advance_back_by(&mut self, n: usize) -> Result<(), usize> { + fn advance_back_by(&mut self, n: usize) -> Result<(), NonZeroUsize> { let advance = cmp::min(len!(self), n); // SAFETY: By construction, `advance` does not exceed `self.len()`. unsafe { self.pre_dec_end(advance) }; - if advance == n { Ok(()) } else { Err(advance) } + NonZeroUsize::new(n - advance).map_or(Ok(()), Err) } } @@ -393,6 +393,20 @@ macro_rules! iterator { } } } + + #[stable(feature = "default_iters", since = "1.70.0")] + impl<T> Default for $name<'_, T> { + /// Creates an empty slice iterator. + /// + /// ``` + #[doc = concat!("# use core::slice::", stringify!($name), ";")] + #[doc = concat!("let iter: ", stringify!($name<'_, u8>), " = Default::default();")] + /// assert_eq!(iter.len(), 0); + /// ``` + fn default() -> Self { + (& $( $mut_ )? []).into_iter() + } + } } } |