clear method

void clear()

Zeros length but keeps the order and reverse-index buffers allocated so follow-up inserts can reuse them without realloc. Callers that want the reverse map cleared too must call resetIndexAll separately, since this method does not touch it, nor the subtree-size cache, nor roots. For a full reset use reset.

Implementation

void clear() {
  _len = 0;
  _onMutated();
}