clear method
override
Removes all elements in the queue. The size of the queue becomes zero.
Implementation
void clear() {
var cursor = _sentinel._nextLink!;
while (true) {
var entry = cursor._asNonSentinelEntry();
if (entry == null) break;
cursor = cursor._nextLink!;
entry
.._nextLink = null
.._previousLink = null
.._queue = null;
}
_sentinel._nextLink = _sentinel;
_sentinel._previousLink = _sentinel;
_elementCount = 0;
}