trie的运用

class TTrie {

  protected $buffer = array();

  protected $dict = array( array() );

  protected $input = 0; //字符串当前偏移

  protected $backtracking = 0; //字符串回溯位置

  public $debug = 0;

  public $savematch = 1;



  function set($word, $action='') {

	if(is_array($word)) {

		foreach($word as $k=>$v) $this->set($k, $v);

		return;

	}

	$p = count($this->dict);

	$cur = 0; //当前节点号

	foreach(str_split($word) as $c) {

		if (isset($this->dict[$cur][$c])) { //已存在就下移

			$cur = $this->dict[$cur][$c];

			continue;

		}

		$this->dict[$p]= array(); //创建新节点

		$this->dict[$cur][$c] = $p; //在父节点记录子节点号

		$cur = $p; //把当前节点设为新插入的

		$p++;

	}

	$this->dict[$cur]['acc'] = $action; //一个词结束，标记叶子节点

  }



  function match($s) {

	$ret = array();

	$cur = 0; //当前节点，初始为根节点

	$i =& $this->input; //字符串当前偏移

	$p =& $this->backtracking; //字符串回溯位置

	$s .= "\0"; //附加结束符

	$len = strlen($s);

	$buf = '';

	while($i < $len) {

		$c = $s{$i};

		if(isset($this->dict[$cur][$c])) { //如果存在

			$cur = $this->dict[$cur][$c]; //转到对应的位置

			if(isset($this->dict[$cur][$s[$i+1]])) {//检查下一个字符是否也能匹配，长度优先

				$i++;

				continue;

			}

			if(isset($this->dict[$cur]['acc'])) { //是叶子节点，单词匹配！

				if($buf != '') {

					$this->buffer[] = $buf;

					$buf = '';

				}

				if($this->savematch) $this->buffer[] = substr($s, $p, $i - $p + 1); //取出匹配位置和匹配的词



				$ar = explode(',', $this->dict[$cur]['acc']);

				call_user_func_array( array($this, array_shift($ar)), $ar );



				$p = $i + 1; //设置下一个回溯位置

				$cur = 0; //重置当前节点为根节点

			}

		} else { //不匹配

			$buf .= $s{$p}; //substr($s, $p, $i - $p + 1); //保存未匹配位置和未匹配的内容

			$cur = 0; //重置当前节点为根节点

			$i = $p; //把当前偏移设为回溯位置

			$p = $i + 1; //设置下一个回溯位置

		}

		$i++; //下一个字符

	}

	if(trim($buf, "\0")) $this->buffer[] = trim($buf, "\0");

  }



  function __call($method, $param) {

	if($this->debug) printf("偏移:%d 回溯:%d\n", $this->input, $this->backtracking);



  }

}