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Diffstat (limited to 'library/core/src/slice/index.rs')
-rw-r--r-- | library/core/src/slice/index.rs | 730 |
1 files changed, 730 insertions, 0 deletions
diff --git a/library/core/src/slice/index.rs b/library/core/src/slice/index.rs new file mode 100644 index 000000000..fd7ecf3da --- /dev/null +++ b/library/core/src/slice/index.rs @@ -0,0 +1,730 @@ +//! Indexing implementations for `[T]`. + +use crate::intrinsics::assert_unsafe_precondition; +use crate::intrinsics::const_eval_select; +use crate::ops; +use crate::ptr; + +#[stable(feature = "rust1", since = "1.0.0")] +#[rustc_const_unstable(feature = "const_slice_index", issue = "none")] +impl<T, I> const ops::Index<I> for [T] +where + I: ~const SliceIndex<[T]>, +{ + type Output = I::Output; + + #[inline] + fn index(&self, index: I) -> &I::Output { + index.index(self) + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +#[rustc_const_unstable(feature = "const_slice_index", issue = "none")] +impl<T, I> const ops::IndexMut<I> for [T] +where + I: ~const SliceIndex<[T]>, +{ + #[inline] + fn index_mut(&mut self, index: I) -> &mut I::Output { + index.index_mut(self) + } +} + +#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))] +#[cfg_attr(feature = "panic_immediate_abort", inline)] +#[cold] +#[track_caller] +#[rustc_const_unstable(feature = "const_slice_index", issue = "none")] +const fn slice_start_index_len_fail(index: usize, len: usize) -> ! { + // SAFETY: we are just panicking here + unsafe { + const_eval_select( + (index, len), + slice_start_index_len_fail_ct, + slice_start_index_len_fail_rt, + ) + } +} + +// FIXME const-hack +fn slice_start_index_len_fail_rt(index: usize, len: usize) -> ! { + panic!("range start index {index} out of range for slice of length {len}"); +} + +const fn slice_start_index_len_fail_ct(_: usize, _: usize) -> ! { + panic!("slice start index is out of range for slice"); +} + +#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))] +#[cfg_attr(feature = "panic_immediate_abort", inline)] +#[cold] +#[track_caller] +#[rustc_const_unstable(feature = "const_slice_index", issue = "none")] +const fn slice_end_index_len_fail(index: usize, len: usize) -> ! { + // SAFETY: we are just panicking here + unsafe { + const_eval_select((index, len), slice_end_index_len_fail_ct, slice_end_index_len_fail_rt) + } +} + +// FIXME const-hack +fn slice_end_index_len_fail_rt(index: usize, len: usize) -> ! { + panic!("range end index {index} out of range for slice of length {len}"); +} + +const fn slice_end_index_len_fail_ct(_: usize, _: usize) -> ! { + panic!("slice end index is out of range for slice"); +} + +#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))] +#[cfg_attr(feature = "panic_immediate_abort", inline)] +#[cold] +#[track_caller] +#[rustc_const_unstable(feature = "const_slice_index", issue = "none")] +const fn slice_index_order_fail(index: usize, end: usize) -> ! { + // SAFETY: we are just panicking here + unsafe { const_eval_select((index, end), slice_index_order_fail_ct, slice_index_order_fail_rt) } +} + +// FIXME const-hack +fn slice_index_order_fail_rt(index: usize, end: usize) -> ! { + panic!("slice index starts at {index} but ends at {end}"); +} + +const fn slice_index_order_fail_ct(_: usize, _: usize) -> ! { + panic!("slice index start is larger than end"); +} + +#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))] +#[cfg_attr(feature = "panic_immediate_abort", inline)] +#[cold] +#[track_caller] +const fn slice_start_index_overflow_fail() -> ! { + panic!("attempted to index slice from after maximum usize"); +} + +#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))] +#[cfg_attr(feature = "panic_immediate_abort", inline)] +#[cold] +#[track_caller] +const fn slice_end_index_overflow_fail() -> ! { + panic!("attempted to index slice up to maximum usize"); +} + +mod private_slice_index { + use super::ops; + #[stable(feature = "slice_get_slice", since = "1.28.0")] + pub trait Sealed {} + + #[stable(feature = "slice_get_slice", since = "1.28.0")] + impl Sealed for usize {} + #[stable(feature = "slice_get_slice", since = "1.28.0")] + impl Sealed for ops::Range<usize> {} + #[stable(feature = "slice_get_slice", since = "1.28.0")] + impl Sealed for ops::RangeTo<usize> {} + #[stable(feature = "slice_get_slice", since = "1.28.0")] + impl Sealed for ops::RangeFrom<usize> {} + #[stable(feature = "slice_get_slice", since = "1.28.0")] + impl Sealed for ops::RangeFull {} + #[stable(feature = "slice_get_slice", since = "1.28.0")] + impl Sealed for ops::RangeInclusive<usize> {} + #[stable(feature = "slice_get_slice", since = "1.28.0")] + impl Sealed for ops::RangeToInclusive<usize> {} + #[stable(feature = "slice_index_with_ops_bound_pair", since = "1.53.0")] + impl Sealed for (ops::Bound<usize>, ops::Bound<usize>) {} +} + +/// A helper trait used for indexing operations. +/// +/// Implementations of this trait have to promise that if the argument +/// to `get_unchecked(_mut)` is a safe reference, then so is the result. +#[stable(feature = "slice_get_slice", since = "1.28.0")] +#[rustc_diagnostic_item = "SliceIndex"] +#[rustc_on_unimplemented( + on(T = "str", label = "string indices are ranges of `usize`",), + on( + all(any(T = "str", T = "&str", T = "std::string::String"), _Self = "{integer}"), + note = "you can use `.chars().nth()` or `.bytes().nth()`\n\ + for more information, see chapter 8 in The Book: \ + <https://doc.rust-lang.org/book/ch08-02-strings.html#indexing-into-strings>" + ), + message = "the type `{T}` cannot be indexed by `{Self}`", + label = "slice indices are of type `usize` or ranges of `usize`" +)] +pub unsafe trait SliceIndex<T: ?Sized>: private_slice_index::Sealed { + /// The output type returned by methods. + #[stable(feature = "slice_get_slice", since = "1.28.0")] + type Output: ?Sized; + + /// Returns a shared reference to the output at this location, if in + /// bounds. + #[unstable(feature = "slice_index_methods", issue = "none")] + fn get(self, slice: &T) -> Option<&Self::Output>; + + /// Returns a mutable reference to the output at this location, if in + /// bounds. + #[unstable(feature = "slice_index_methods", issue = "none")] + fn get_mut(self, slice: &mut T) -> Option<&mut Self::Output>; + + /// Returns a shared reference to the output at this location, without + /// performing any bounds checking. + /// Calling this method with an out-of-bounds index or a dangling `slice` pointer + /// is *[undefined behavior]* even if the resulting reference is not used. + /// + /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html + #[unstable(feature = "slice_index_methods", issue = "none")] + unsafe fn get_unchecked(self, slice: *const T) -> *const Self::Output; + + /// Returns a mutable reference to the output at this location, without + /// performing any bounds checking. + /// Calling this method with an out-of-bounds index or a dangling `slice` pointer + /// is *[undefined behavior]* even if the resulting reference is not used. + /// + /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html + #[unstable(feature = "slice_index_methods", issue = "none")] + unsafe fn get_unchecked_mut(self, slice: *mut T) -> *mut Self::Output; + + /// Returns a shared reference to the output at this location, panicking + /// if out of bounds. + #[unstable(feature = "slice_index_methods", issue = "none")] + #[track_caller] + fn index(self, slice: &T) -> &Self::Output; + + /// Returns a mutable reference to the output at this location, panicking + /// if out of bounds. + #[unstable(feature = "slice_index_methods", issue = "none")] + #[track_caller] + fn index_mut(self, slice: &mut T) -> &mut Self::Output; +} + +#[stable(feature = "slice_get_slice_impls", since = "1.15.0")] +#[rustc_const_unstable(feature = "const_slice_index", issue = "none")] +unsafe impl<T> const SliceIndex<[T]> for usize { + type Output = T; + + #[inline] + fn get(self, slice: &[T]) -> Option<&T> { + // SAFETY: `self` is checked to be in bounds. + if self < slice.len() { unsafe { Some(&*self.get_unchecked(slice)) } } else { None } + } + + #[inline] + fn get_mut(self, slice: &mut [T]) -> Option<&mut T> { + // SAFETY: `self` is checked to be in bounds. + if self < slice.len() { unsafe { Some(&mut *self.get_unchecked_mut(slice)) } } else { None } + } + + #[inline] + unsafe fn get_unchecked(self, slice: *const [T]) -> *const T { + // SAFETY: the caller guarantees that `slice` is not dangling, so it + // cannot be longer than `isize::MAX`. They also guarantee that + // `self` is in bounds of `slice` so `self` cannot overflow an `isize`, + // so the call to `add` is safe. + unsafe { + assert_unsafe_precondition!(self < slice.len()); + slice.as_ptr().add(self) + } + } + + #[inline] + unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut T { + // SAFETY: see comments for `get_unchecked` above. + unsafe { + assert_unsafe_precondition!(self < slice.len()); + slice.as_mut_ptr().add(self) + } + } + + #[inline] + fn index(self, slice: &[T]) -> &T { + // N.B., use intrinsic indexing + &(*slice)[self] + } + + #[inline] + fn index_mut(self, slice: &mut [T]) -> &mut T { + // N.B., use intrinsic indexing + &mut (*slice)[self] + } +} + +#[stable(feature = "slice_get_slice_impls", since = "1.15.0")] +#[rustc_const_unstable(feature = "const_slice_index", issue = "none")] +unsafe impl<T> const SliceIndex<[T]> for ops::Range<usize> { + type Output = [T]; + + #[inline] + fn get(self, slice: &[T]) -> Option<&[T]> { + if self.start > self.end || self.end > slice.len() { + None + } else { + // SAFETY: `self` is checked to be valid and in bounds above. + unsafe { Some(&*self.get_unchecked(slice)) } + } + } + + #[inline] + fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> { + if self.start > self.end || self.end > slice.len() { + None + } else { + // SAFETY: `self` is checked to be valid and in bounds above. + unsafe { Some(&mut *self.get_unchecked_mut(slice)) } + } + } + + #[inline] + unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T] { + // SAFETY: the caller guarantees that `slice` is not dangling, so it + // cannot be longer than `isize::MAX`. They also guarantee that + // `self` is in bounds of `slice` so `self` cannot overflow an `isize`, + // so the call to `add` is safe. + + unsafe { + assert_unsafe_precondition!(self.end >= self.start && self.end <= slice.len()); + ptr::slice_from_raw_parts(slice.as_ptr().add(self.start), self.end - self.start) + } + } + + #[inline] + unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T] { + // SAFETY: see comments for `get_unchecked` above. + unsafe { + assert_unsafe_precondition!(self.end >= self.start && self.end <= slice.len()); + ptr::slice_from_raw_parts_mut(slice.as_mut_ptr().add(self.start), self.end - self.start) + } + } + + #[inline] + fn index(self, slice: &[T]) -> &[T] { + if self.start > self.end { + slice_index_order_fail(self.start, self.end); + } else if self.end > slice.len() { + slice_end_index_len_fail(self.end, slice.len()); + } + // SAFETY: `self` is checked to be valid and in bounds above. + unsafe { &*self.get_unchecked(slice) } + } + + #[inline] + fn index_mut(self, slice: &mut [T]) -> &mut [T] { + if self.start > self.end { + slice_index_order_fail(self.start, self.end); + } else if self.end > slice.len() { + slice_end_index_len_fail(self.end, slice.len()); + } + // SAFETY: `self` is checked to be valid and in bounds above. + unsafe { &mut *self.get_unchecked_mut(slice) } + } +} + +#[stable(feature = "slice_get_slice_impls", since = "1.15.0")] +#[rustc_const_unstable(feature = "const_slice_index", issue = "none")] +unsafe impl<T> const SliceIndex<[T]> for ops::RangeTo<usize> { + type Output = [T]; + + #[inline] + fn get(self, slice: &[T]) -> Option<&[T]> { + (0..self.end).get(slice) + } + + #[inline] + fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> { + (0..self.end).get_mut(slice) + } + + #[inline] + unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T] { + // SAFETY: the caller has to uphold the safety contract for `get_unchecked`. + unsafe { (0..self.end).get_unchecked(slice) } + } + + #[inline] + unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T] { + // SAFETY: the caller has to uphold the safety contract for `get_unchecked_mut`. + unsafe { (0..self.end).get_unchecked_mut(slice) } + } + + #[inline] + fn index(self, slice: &[T]) -> &[T] { + (0..self.end).index(slice) + } + + #[inline] + fn index_mut(self, slice: &mut [T]) -> &mut [T] { + (0..self.end).index_mut(slice) + } +} + +#[stable(feature = "slice_get_slice_impls", since = "1.15.0")] +#[rustc_const_unstable(feature = "const_slice_index", issue = "none")] +unsafe impl<T> const SliceIndex<[T]> for ops::RangeFrom<usize> { + type Output = [T]; + + #[inline] + fn get(self, slice: &[T]) -> Option<&[T]> { + (self.start..slice.len()).get(slice) + } + + #[inline] + fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> { + (self.start..slice.len()).get_mut(slice) + } + + #[inline] + unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T] { + // SAFETY: the caller has to uphold the safety contract for `get_unchecked`. + unsafe { (self.start..slice.len()).get_unchecked(slice) } + } + + #[inline] + unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T] { + // SAFETY: the caller has to uphold the safety contract for `get_unchecked_mut`. + unsafe { (self.start..slice.len()).get_unchecked_mut(slice) } + } + + #[inline] + fn index(self, slice: &[T]) -> &[T] { + if self.start > slice.len() { + slice_start_index_len_fail(self.start, slice.len()); + } + // SAFETY: `self` is checked to be valid and in bounds above. + unsafe { &*self.get_unchecked(slice) } + } + + #[inline] + fn index_mut(self, slice: &mut [T]) -> &mut [T] { + if self.start > slice.len() { + slice_start_index_len_fail(self.start, slice.len()); + } + // SAFETY: `self` is checked to be valid and in bounds above. + unsafe { &mut *self.get_unchecked_mut(slice) } + } +} + +#[stable(feature = "slice_get_slice_impls", since = "1.15.0")] +#[rustc_const_unstable(feature = "const_slice_index", issue = "none")] +unsafe impl<T> const SliceIndex<[T]> for ops::RangeFull { + type Output = [T]; + + #[inline] + fn get(self, slice: &[T]) -> Option<&[T]> { + Some(slice) + } + + #[inline] + fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> { + Some(slice) + } + + #[inline] + unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T] { + slice + } + + #[inline] + unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T] { + slice + } + + #[inline] + fn index(self, slice: &[T]) -> &[T] { + slice + } + + #[inline] + fn index_mut(self, slice: &mut [T]) -> &mut [T] { + slice + } +} + +#[stable(feature = "inclusive_range", since = "1.26.0")] +#[rustc_const_unstable(feature = "const_slice_index", issue = "none")] +unsafe impl<T> const SliceIndex<[T]> for ops::RangeInclusive<usize> { + type Output = [T]; + + #[inline] + fn get(self, slice: &[T]) -> Option<&[T]> { + if *self.end() == usize::MAX { None } else { self.into_slice_range().get(slice) } + } + + #[inline] + fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> { + if *self.end() == usize::MAX { None } else { self.into_slice_range().get_mut(slice) } + } + + #[inline] + unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T] { + // SAFETY: the caller has to uphold the safety contract for `get_unchecked`. + unsafe { self.into_slice_range().get_unchecked(slice) } + } + + #[inline] + unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T] { + // SAFETY: the caller has to uphold the safety contract for `get_unchecked_mut`. + unsafe { self.into_slice_range().get_unchecked_mut(slice) } + } + + #[inline] + fn index(self, slice: &[T]) -> &[T] { + if *self.end() == usize::MAX { + slice_end_index_overflow_fail(); + } + self.into_slice_range().index(slice) + } + + #[inline] + fn index_mut(self, slice: &mut [T]) -> &mut [T] { + if *self.end() == usize::MAX { + slice_end_index_overflow_fail(); + } + self.into_slice_range().index_mut(slice) + } +} + +#[stable(feature = "inclusive_range", since = "1.26.0")] +#[rustc_const_unstable(feature = "const_slice_index", issue = "none")] +unsafe impl<T> const SliceIndex<[T]> for ops::RangeToInclusive<usize> { + type Output = [T]; + + #[inline] + fn get(self, slice: &[T]) -> Option<&[T]> { + (0..=self.end).get(slice) + } + + #[inline] + fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> { + (0..=self.end).get_mut(slice) + } + + #[inline] + unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T] { + // SAFETY: the caller has to uphold the safety contract for `get_unchecked`. + unsafe { (0..=self.end).get_unchecked(slice) } + } + + #[inline] + unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T] { + // SAFETY: the caller has to uphold the safety contract for `get_unchecked_mut`. + unsafe { (0..=self.end).get_unchecked_mut(slice) } + } + + #[inline] + fn index(self, slice: &[T]) -> &[T] { + (0..=self.end).index(slice) + } + + #[inline] + fn index_mut(self, slice: &mut [T]) -> &mut [T] { + (0..=self.end).index_mut(slice) + } +} + +/// Performs bounds-checking of a range. +/// +/// This method is similar to [`Index::index`] for slices, but it returns a +/// [`Range`] equivalent to `range`. You can use this method to turn any range +/// into `start` and `end` values. +/// +/// `bounds` is the range of the slice to use for bounds-checking. It should +/// be a [`RangeTo`] range that ends at the length of the slice. +/// +/// The returned [`Range`] is safe to pass to [`slice::get_unchecked`] and +/// [`slice::get_unchecked_mut`] for slices with the given range. +/// +/// [`Range`]: ops::Range +/// [`RangeTo`]: ops::RangeTo +/// [`slice::get_unchecked`]: slice::get_unchecked +/// [`slice::get_unchecked_mut`]: slice::get_unchecked_mut +/// +/// # Panics +/// +/// Panics if `range` would be out of bounds. +/// +/// # Examples +/// +/// ``` +/// #![feature(slice_range)] +/// +/// use std::slice; +/// +/// let v = [10, 40, 30]; +/// assert_eq!(1..2, slice::range(1..2, ..v.len())); +/// assert_eq!(0..2, slice::range(..2, ..v.len())); +/// assert_eq!(1..3, slice::range(1.., ..v.len())); +/// ``` +/// +/// Panics when [`Index::index`] would panic: +/// +/// ```should_panic +/// #![feature(slice_range)] +/// +/// use std::slice; +/// +/// let _ = slice::range(2..1, ..3); +/// ``` +/// +/// ```should_panic +/// #![feature(slice_range)] +/// +/// use std::slice; +/// +/// let _ = slice::range(1..4, ..3); +/// ``` +/// +/// ```should_panic +/// #![feature(slice_range)] +/// +/// use std::slice; +/// +/// let _ = slice::range(1..=usize::MAX, ..3); +/// ``` +/// +/// [`Index::index`]: ops::Index::index +#[track_caller] +#[unstable(feature = "slice_range", issue = "76393")] +#[must_use] +pub fn range<R>(range: R, bounds: ops::RangeTo<usize>) -> ops::Range<usize> +where + R: ops::RangeBounds<usize>, +{ + let len = bounds.end; + + let start: ops::Bound<&usize> = range.start_bound(); + let start = match start { + ops::Bound::Included(&start) => start, + ops::Bound::Excluded(start) => { + start.checked_add(1).unwrap_or_else(|| slice_start_index_overflow_fail()) + } + ops::Bound::Unbounded => 0, + }; + + let end: ops::Bound<&usize> = range.end_bound(); + let end = match end { + ops::Bound::Included(end) => { + end.checked_add(1).unwrap_or_else(|| slice_end_index_overflow_fail()) + } + ops::Bound::Excluded(&end) => end, + ops::Bound::Unbounded => len, + }; + + if start > end { + slice_index_order_fail(start, end); + } + if end > len { + slice_end_index_len_fail(end, len); + } + + ops::Range { start, end } +} + +/// Convert pair of `ops::Bound`s into `ops::Range` without performing any bounds checking and (in debug) overflow checking +fn into_range_unchecked( + len: usize, + (start, end): (ops::Bound<usize>, ops::Bound<usize>), +) -> ops::Range<usize> { + use ops::Bound; + let start = match start { + Bound::Included(i) => i, + Bound::Excluded(i) => i + 1, + Bound::Unbounded => 0, + }; + let end = match end { + Bound::Included(i) => i + 1, + Bound::Excluded(i) => i, + Bound::Unbounded => len, + }; + start..end +} + +/// Convert pair of `ops::Bound`s into `ops::Range`. +/// Returns `None` on overflowing indices. +fn into_range( + len: usize, + (start, end): (ops::Bound<usize>, ops::Bound<usize>), +) -> Option<ops::Range<usize>> { + use ops::Bound; + let start = match start { + Bound::Included(start) => start, + Bound::Excluded(start) => start.checked_add(1)?, + Bound::Unbounded => 0, + }; + + let end = match end { + Bound::Included(end) => end.checked_add(1)?, + Bound::Excluded(end) => end, + Bound::Unbounded => len, + }; + + // Don't bother with checking `start < end` and `end <= len` + // since these checks are handled by `Range` impls + + Some(start..end) +} + +/// Convert pair of `ops::Bound`s into `ops::Range`. +/// Panics on overflowing indices. +fn into_slice_range( + len: usize, + (start, end): (ops::Bound<usize>, ops::Bound<usize>), +) -> ops::Range<usize> { + use ops::Bound; + let start = match start { + Bound::Included(start) => start, + Bound::Excluded(start) => { + start.checked_add(1).unwrap_or_else(|| slice_start_index_overflow_fail()) + } + Bound::Unbounded => 0, + }; + + let end = match end { + Bound::Included(end) => { + end.checked_add(1).unwrap_or_else(|| slice_end_index_overflow_fail()) + } + Bound::Excluded(end) => end, + Bound::Unbounded => len, + }; + + // Don't bother with checking `start < end` and `end <= len` + // since these checks are handled by `Range` impls + + start..end +} + +#[stable(feature = "slice_index_with_ops_bound_pair", since = "1.53.0")] +unsafe impl<T> SliceIndex<[T]> for (ops::Bound<usize>, ops::Bound<usize>) { + type Output = [T]; + + #[inline] + fn get(self, slice: &[T]) -> Option<&Self::Output> { + into_range(slice.len(), self)?.get(slice) + } + + #[inline] + fn get_mut(self, slice: &mut [T]) -> Option<&mut Self::Output> { + into_range(slice.len(), self)?.get_mut(slice) + } + + #[inline] + unsafe fn get_unchecked(self, slice: *const [T]) -> *const Self::Output { + // SAFETY: the caller has to uphold the safety contract for `get_unchecked`. + unsafe { into_range_unchecked(slice.len(), self).get_unchecked(slice) } + } + + #[inline] + unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut Self::Output { + // SAFETY: the caller has to uphold the safety contract for `get_unchecked_mut`. + unsafe { into_range_unchecked(slice.len(), self).get_unchecked_mut(slice) } + } + + #[inline] + fn index(self, slice: &[T]) -> &Self::Output { + into_slice_range(slice.len(), self).index(slice) + } + + #[inline] + fn index_mut(self, slice: &mut [T]) -> &mut Self::Output { + into_slice_range(slice.len(), self).index_mut(slice) + } +} |