Rollup merge of #58924 - cuviper:more-as_slice, r=dtolnay
Add as_slice() to slice::IterMut and vec::Drain In bluss/indexmap#88, we found that there was no easy way to implement `Debug` for our `IterMut` and `Drain` iterators. Those are built on `slice::IterMut` and `vec::Drain`, which implement `Debug` themselves, but have no other way to access their data. With a new `as_slice()` method, we can read the data and customize its presentation.
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commit
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@ -2468,6 +2468,25 @@ impl<T: fmt::Debug> fmt::Debug for Drain<'_, T> {
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}
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}
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impl<'a, T> Drain<'a, T> {
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/// Returns the remaining items of this iterator as a slice.
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///
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/// # Examples
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///
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/// ```
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/// # #![feature(vec_drain_as_slice)]
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/// let mut vec = vec!['a', 'b', 'c'];
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/// let mut drain = vec.drain(..);
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/// assert_eq!(drain.as_slice(), &['a', 'b', 'c']);
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/// let _ = drain.next().unwrap();
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/// assert_eq!(drain.as_slice(), &['b', 'c']);
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/// ```
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#[unstable(feature = "vec_drain_as_slice", reason = "recently added", issue = "58957")]
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pub fn as_slice(&self) -> &[T] {
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self.iter.as_slice()
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}
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}
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#[stable(feature = "drain", since = "1.6.0")]
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unsafe impl<T: Sync> Sync for Drain<'_, T> {}
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#[stable(feature = "drain", since = "1.6.0")]
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@ -3288,6 +3288,34 @@ impl<'a, T> IterMut<'a, T> {
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pub fn into_slice(self) -> &'a mut [T] {
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unsafe { from_raw_parts_mut(self.ptr, len!(self)) }
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}
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/// Views the underlying data as a subslice of the original data.
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///
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/// To avoid creating `&mut [T]` references that alias, the returned slice
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/// borrows its lifetime from the iterator the method is applied on.
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///
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/// # Examples
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///
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/// Basic usage:
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///
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/// ```
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/// # #![feature(slice_iter_mut_as_slice)]
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/// let mut slice: &mut [usize] = &mut [1, 2, 3];
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///
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/// // First, we get the iterator:
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/// let mut iter = slice.iter_mut();
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/// // So if we check what the `as_slice` method returns here, we have "[1, 2, 3]":
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/// assert_eq!(iter.as_slice(), &[1, 2, 3]);
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///
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/// // Next, we move to the second element of the slice:
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/// iter.next();
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/// // Now `as_slice` returns "[2, 3]":
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/// assert_eq!(iter.as_slice(), &[2, 3]);
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/// ```
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#[unstable(feature = "slice_iter_mut_as_slice", reason = "recently added", issue = "58957")]
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pub fn as_slice(&self) -> &[T] {
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self.make_slice()
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}
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}
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iterator!{struct IterMut -> *mut T, &'a mut T, mut, {mut}, {}}
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