diff options
| -rw-r--r-- | library/alloc/src/collections/vec_deque/drain.rs | 53 |
1 files changed, 22 insertions, 31 deletions
diff --git a/library/alloc/src/collections/vec_deque/drain.rs b/library/alloc/src/collections/vec_deque/drain.rs index aa5cc0fb1ce..7a413ddf971 100644 --- a/library/alloc/src/collections/vec_deque/drain.rs +++ b/library/alloc/src/collections/vec_deque/drain.rs @@ -109,7 +109,6 @@ impl<T, A: Allocator> Drop for Drain<'_, T, A> { let source_deque = unsafe { self.0.deque.as_mut() }; - let drain_start = source_deque.len(); let drain_len = self.0.drain_len; let new_len = self.0.new_len; @@ -119,40 +118,32 @@ impl<T, A: Allocator> Drop for Drain<'_, T, A> { return; } - let head_len = drain_start; + let head_len = source_deque.len(); let tail_len = new_len - head_len; - match (head_len, tail_len) { - (0, 0) => { - source_deque.head = 0; - source_deque.len = 0; - } - (0, _) => { - source_deque.head = source_deque.to_physical_idx(drain_len); - source_deque.len = new_len; - } - (_, 0) => { - source_deque.len = new_len; + if head_len != 0 && tail_len != 0 { + let (src, dst, len); + if head_len < tail_len { + src = source_deque.head; + dst = source_deque.to_physical_idx(drain_len); + len = head_len; + } else { + src = source_deque.to_physical_idx(head_len + drain_len); + dst = source_deque.to_physical_idx(head_len); + len = tail_len; + }; + + unsafe { + source_deque.wrap_copy(src, dst, len); } - _ => unsafe { - if head_len <= tail_len { - source_deque.wrap_copy( - source_deque.head, - source_deque.to_physical_idx(drain_len), - head_len, - ); - source_deque.head = source_deque.to_physical_idx(drain_len); - source_deque.len = new_len; - } else { - source_deque.wrap_copy( - source_deque.to_physical_idx(head_len + drain_len), - source_deque.to_physical_idx(head_len), - tail_len, - ); - source_deque.len = new_len; - } - }, } + + if new_len == 0 { + source_deque.head = 0; + } else if head_len < tail_len { + source_deque.head = source_deque.to_physical_idx(drain_len); + } + source_deque.len = new_len; } } |