WordPress文章标签自动添加已有标签链接 优化内链建设

/*
*Wordpress文章关键词自动添加内链链接代码
*/
//连接数量
 $match_num_from = 1; //关键字标签出现几次才加链接
 $match_num_to = 1; //同一个关键字标签加几次链接
 //连接到WordPress的模块
 add_filter('the_content','tag_link',1);
 //按长度排序
 function tag_sort($a, $b){
 if ( $a->name == $b->name ) return 0;
 return ( strlen($a->name) > strlen($b->name) ) ? -1 : 1;
 }
 //改变标签关键字
 function tag_link($content){
 global $match_num_from,$match_num_to;
 $posttags = get_the_tags();
 if ($posttags) {
 usort($posttags, "tag_sort");
 foreach($posttags as $tag) {
 $link = get_tag_link($tag->term_id);
 $keyword = $tag->name;
 //连接代码
 $cleankeyword = stripslashes($keyword);
 $url = "<a href=\"$link\" title=\"".str_replace('%s',addcslashes($cleankeyword, '$'),__('查看所有文章关于 %s'))."\"";
 $url .= 'target="_blank"';
 $url .= ">".addcslashes($cleankeyword, '$')."</a>";
 $limit = rand($match_num_from,$match_num_to);
 //不连接的代码
 $content = preg_replace( '|(<a[^>]+>)(.*)('.$ex_word.')(.*)(</a[^>]*>)|U'.$case, '$1$2%&&&&&%$4$5', $content);
 $content = preg_replace( '|(<img)(.*?)('.$ex_word.')(.*?)(>)|U'.$case, '$1$2%&&&&&%$4$5', $content);
 $cleankeyword = preg_quote($cleankeyword,'\'');
 $regEx = '\'(?!((<.*?)|(<a.*?)))('. $cleankeyword . ')(?!(([^<>]*?)>)|([^>]*?</a>))\'s' . $case;
 $content = preg_replace($regEx,$url,$content,$limit);
 $content = str_replace( '%&&&&&%', stripslashes($ex_word), $content);
 }
 }
 return $content; 
 }