1. <?php
    2. /**
    3.  * @param $content
    4.  * @return mixed|string
    5.  * @author DingLipeng<https://www.gznotes.com>
    6.  * @last_modify 2015-08-22
    7.  */
    8. function article_index($content) {
    9.     if (!is_singular()) {
    10.         return $content;
    11.     }
    12.     $index = '';
    13.     $ul = '';
    14.     $arr = array();
    15.     $pattern = '/<h([2-6]).*?\>(.*?)<\/h[2-6]>/is';
    16.     if (preg_match_all($pattern, $content, $arr)):
    17.         $count = count($arr[0]);
    18.         foreach ($arr[1] as $k => $v) {
    19.             //添加列表头
    20.             if ($k <= 0) {
    21.                 $index = '<ul class="ljfl">'; //顶级
    23.             } else {
    24.                 if ($v > $arr[1][$k - 1]) {
    25.                     if ($v - $arr[1][$k - 1] == 1) {
    26.                         $index.= '<ul>'; //上层小，层级高，当前为子层，先输出ul
    28.                     } elseif ($v == $arr[1][$k - 1]) {
    29.                     } else {
    30.                         $index.= '文章目录层级不合法';
    31.                         return false;
    32.                     }
    33.                 }
    34.             }
    35.             $title = strip_tags($arr[2][$k]);
    36.             $content = str_replace($arr[0][$k], '<h' . $v . ' id="index-' . $k . '">' . $title . '</h' . $v . '>', $content);
    37.             $index.= '<li class="h-' . $v . '"><a rel="contents chapter" href="#index-' . $k . '">' . $title . '</a></li>';//输出本层li
    38.             //列表封闭规则
    39.             if ($k < $count - 1) {
    40.                 if ($v > $arr[1][$k + 1]) { //当前层大于下一层，本层结束，封底
    41.                     $c = $v - $arr[1][$k + 1];
    42.                     for ($i = 0;$i < $c;$i++) {
    43.                         $ul.= '</ul>';
    44.                         $index.= $ul;
    45.                         $ul = '';
    46.                     }
    47.                 }
    48.             } else {
    49.                 $index.= '</ul>';
    50.             }
    51.         }
    52.         $index = '<div id="ribs_article_nav" class="p-3 border w-50 mb-3"><div id="article_nav_title"><i class="fa fa-bars mr-2"></i>文章大纲</div><nav class="mt-3" role="navigation">' . $index . '</nav></div>';
    53.         $content =   $index . $content;
    54.     endif;
    55.     return $content;
    56. }
    57. add_filter("the_content", "article_index");