public function getOpCodes()
	{
		if(!empty($this->opCodes)) {
			return $this->opCodes;
		}

		$i = 0;
		$j = 0;
		$this->opCodes = array();

		$blocks = $this->getMatchingBlocks();
		foreach($blocks as $block) {
			list($ai, $bj, $size) = $block;
			$tag = '';
			if($i < $ai && $j < $bj) {
				$tag = 'replace';
			}
			else if($i < $ai) {
				$tag = 'delete';
			}
			else if($j < $bj) {
				$tag = 'insert';
			}

			if($tag) {
				$this->opCodes[] = array(
					$tag,
					$i,
					$ai,
					$j,
					$bj
				);
			}

			$i = $ai + $size;
			$j = $bj + $size;

			if($size) {
				$this->opCodes[] = array(
					'equal',
					$ai,
					$i,
					$bj,
					$j
				);
			}
		}
		return $this->opCodes;
	}