php简单中文分词系统

class trie
{
        private $trie;

        function __construct()
        {
                 $trie = array('children' => array(),'isword'=>false);
        }

        /**
         * 把词加入词典
         *
         * @param string $key
         */
        function &setword($word='')
        {
                $trienode = &$this->trie;
                for($i = 0;$i < strlen($word);$i++)
                {
                        $character = $word[$i];
                        if(!isset($trienode['children'][$character]))
                        {
                                $trienode['children'][$character] = array('isword'=>false);
                        }
                        if($i == strlen($word)-1)
                        {
                                        $trienode['children'][$character] = array('isword'=>true);
                        }
                        $trienode = &$trienode['children'][$character];
                }
        }

        /**
         * 判断是否为词典词
         *
         * @param string $word
         * @return bool true/false
         */
        function & isword($word)
        {
                $trienode = &$this->trie;
                for($i = 0;$i < strlen($word);$i++)
                {
                        $character = $word[$i];
                        if(!isset($trienode['children'][$character]))
 &