function wp_article_index() {
    global $post;
    $content = $post->post_content;
    $matches = array();
    $output = '';
    preg_match_all('/<h([1-6])[^>]*>(.*)<\/h[1-6]>/i', $content, $matches, PREG_SET_ORDER);
    if (!empty($matches)) {
        $output .= '<div id="wp-article-index">';
        $output .= '<h2>目录</h2>';
        $output .= '<ul>';
        foreach($matches as $match) {
            $output .= '<li><a href="#' . sanitize_title($match[2]) . '">' . $match[2] . '</a></li>';
        }
        $output .= '</ul>';
        $output .= '</div>';
    }
    return $output;
}