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use crate::*;
pub(crate) fn slice_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(|| panic!("attempted to index slice from after maximum usize")),
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(|| panic!("attempted to index slice up to maximum usize")),
ops::Bound::Excluded(&end) => end,
ops::Bound::Unbounded => len,
};
if start > end {
panic!("slice index starts at {start} but ends at {end}");
}
if end > len {
panic!("range end index {end} out of range for slice of length {len}",);
}
ops::Range { start, end }
}
pub struct Drain<'a, T: 'a, A: Array<T>> {
pub(super) tail_start: usize,
pub(super) tail_len: usize,
pub(super) iter: slice::Iter<'a, T>,
pub(super) vec: NonNull<A>,
}
impl<T: fmt::Debug, A: Array<T>> fmt::Debug for Drain<'_, T, A> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_tuple("Drain").field(&self.iter.as_slice()).finish()
}
}
impl<'a, T, A: Array<T>> Drain<'a, T, A> {
#[must_use]
pub fn as_slice(&self) -> &[T] {
self.iter.as_slice()
}
}
impl<'a, T, A: Array<T>> AsRef<[T]> for Drain<'a, T, A> {
fn as_ref(&self) -> &[T] {
self.as_slice()
}
}
unsafe impl<T: Sync, A: Sync + Array<T>> Sync for Drain<'_, T, A> {}
unsafe impl<T: Send, A: Send + Array<T>> Send for Drain<'_, T, A> {}
impl<T, A: Array<T>> Iterator for Drain<'_, T, A> {
type Item = T;
#[inline]
fn next(&mut self) -> Option<T> {
self.iter
.next()
.map(|elt| unsafe { ptr::read(elt as *const _) })
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
}
impl<T, A: Array<T>> DoubleEndedIterator for Drain<'_, T, A> {
#[inline]
fn next_back(&mut self) -> Option<T> {
self.iter
.next_back()
.map(|elt| unsafe { ptr::read(elt as *const _) })
}
}
impl<T, A: Array<T>> Drop for Drain<'_, T, A> {
fn drop(&mut self) {
struct DropGuard<'r, 'a, T, A: Array<T>>(&'r mut Drain<'a, T, A>);
impl<'r, 'a, T, A: Array<T>> Drop for DropGuard<'r, 'a, T, A> {
fn drop(&mut self) {
if self.0.tail_len > 0 {
unsafe {
let source_vec = self.0.vec.as_mut();
let start = source_vec.len();
let tail = self.0.tail_start;
if tail != start {
let src = source_vec.as_ptr().add(tail);
let dst = source_vec.as_mut_ptr().add(start);
ptr::copy(src, dst, self.0.tail_len);
}
source_vec.set_len(start + self.0.tail_len);
}
}
}
}
let iter = mem::replace(&mut self.iter, (& []).iter());
let drop_len = iter.len();
let mut vec = self.vec;
if mem::size_of::<T>() == 0 {
unsafe {
let vec = vec.as_mut();
let old_len = vec.len();
vec.set_len(old_len + drop_len + self.tail_len);
vec.truncate(old_len + self.tail_len);
}
return;
}
let _guard = DropGuard(self);
if drop_len == 0 {
return;
}
let drop_ptr = iter.as_slice().as_ptr();
unsafe {
let vec_ptr = vec.as_mut().as_mut_ptr();
let drop_offset = drop_ptr.offset_from(vec_ptr) as usize;
let to_drop = ptr::slice_from_raw_parts_mut(vec_ptr.add(drop_offset), drop_len);
ptr::drop_in_place(to_drop);
}
}
}
impl<T, A: Array<T>> core::iter::FusedIterator for Drain<'_, T, A> {}