php替换敏感字符

/**
* @todo 敏感词过滤，返回结果
* @param array $list 定义敏感词一维数组
* @param string $string 要过滤的内容
* @return string $log 处理结果
*/

function sensitive($string){
    $m_sensitive = Db::name("sensitive");

    $list = $m_sensitive->order("id desc")->column("name");
    $count = 0; //违规词的个数
    $sensitiveWord = ''; //违规词
    $stringAfter = $string; //替换后的内容
    $pattern = "/".implode("|",$list)."/i"; //定义正则表达式
    if(preg_match_all($pattern, $string, $matches)){ //匹配到了结果
        $patternList = $matches[0]; //匹配到的数组
        $count = count($patternList);
        $sensitiveWord = implode(',', $patternList); //敏感词数组转字符串
        $replaceArray = array_combine($patternList,array_fill(0,count($patternList),'*')); //把匹配到的数组进行合并，替换使用
        foreach ($replaceArray as $i => $v) {
            $count = mb_strlen($i,"utf-8");
            $replaceArray[$i] = str_repeat($v,$count);
        }
        $stringAfter = strtr($string, $replaceArray); //结果替换
    }else{
        $stringAfter = $string;
    }
    
    return $stringAfter;
}