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Revert "Optimize VecDeque::append"

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This reverts commit 11e488b64fed181820280d494d4fcc157ee1adc5.
This commit is contained in:
Alex Crichton 2018-10-05 09:15:52 -07:00
parent 9a41cfabba
commit 90b9469121
1 changed files with 2 additions and 27 deletions
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29
src/liballoc/collections/vec_deque.rs
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@ -202,22 +202,6 @@ impl<T> VecDeque<T> {
len);
}
/// Copies all values from `src` to `self`, wrapping around if needed.
/// Assumes capacity is sufficient.
#[inline]
unsafe fn copy_slice(&mut self, src: &[T]) {
let dst_high_ptr = self.ptr().add(self.head);
let dst_high_len = self.cap() - self.head;
let split = cmp::min(src.len(), dst_high_len);
let (src_high, src_low) = src.split_at(split);
ptr::copy_nonoverlapping(src_high.as_ptr(), dst_high_ptr, src_high.len());
ptr::copy_nonoverlapping(src_low.as_ptr(), self.ptr(), src_low.len());
self.head = self.wrap_add(self.head, src.len());
}
/// Copies a potentially wrapping block of memory len long from src to dest.
/// (abs(dst - src) + len) must be no larger than cap() (There must be at
/// most one continuous overlapping region between src and dest).
@ -1850,17 +1834,8 @@ impl<T> VecDeque<T> {
#[inline]
#[stable(feature = "append", since = "1.4.0")]
pub fn append(&mut self, other: &mut Self) {
// Guarantees there is space in `self` for `other
self.reserve(other.len());
unsafe {
let (src_high, src_low) = other.as_slices();
self.copy_slice(src_low);
self.copy_slice(src_high);
}
// Some values now exist in both `other` and `self` but are made inaccessible in `other`.
other.tail = other.head;
// naive impl
self.extend(other.drain(..));
}
/// Retains only the elements specified by the predicate.