Generate table of contents from html.

generate_toc.php

function _generate_toc( $content , $headings, $first_heading) {
  preg_match_all( '/<h([' . $headings . '])(.*)>([^<]+)<\/h[' . $headings . ']>/i', $content, $matches, PREG_SET_ORDER );

  global $anchors;

  $anchors = array();
  $toc 	 = '<ul class="nav">'."\n";
  $i 		 = 0;

  //add the fist anchor link
  $toc .= '<li><a href="#page-top">'.$first_heading.'</a></li>';

  foreach ( $matches as $heading ) {

    if ($i == 0)
      $startlvl = $heading[1];
    $lvl 		= $heading[1];

    $ret = preg_match( '/id=[\'|"](.*)?[\'|"]/i', stripslashes($heading[2]), $anchor );
    if ( $ret && $anchor[1] != '' ) {
      $anchor = stripslashes( $anchor[1] );
      $add_id = false;
    } else {
      $anchor = preg_replace( '/\s+/', '-', preg_replace('/[^a-z\s]/', '', strtolower( $heading[3] ) ) );
      $add_id = true;
    }

    if ( !in_array( $anchor, $anchors ) ) {
      $anchors[] = $anchor;
    } else {
      $orig_anchor = $anchor;
      $i = 2;
      while ( in_array( $anchor, $anchors ) ) {
        $anchor = $orig_anchor.'-'.$i;
        $i++;
      }
      $anchors[] = $anchor;
    }

    if ( $add_id ) {
      $content = substr_replace( $content, '<h'.$lvl.' id="'.$anchor.'"'.$heading[2].'>'.$heading[3].'</h'.$lvl.'>', strpos( $content, $heading[0] ), strlen( $heading[0] ) );
    }

    $ret = preg_match( '/title=[\'|"](.*)?[\'|"]/i', stripslashes( $heading[2] ), $title );
    if ( $ret && $title[1] != '' )
      $title = stripslashes( $title[1] );
    else
      $title = $heading[3];
    $title 		= trim( strip_tags( $title ) );

    if ($i > 0) {
      if ($prevlvl < $lvl) {
        $toc .= "\n"."<ul>"."\n";
      } else if ($prevlvl > $lvl) {
        $toc .= '</li>'."\n";
        while ($prevlvl > $lvl) {
          $toc .= "</ul>"."\n".'</li>'."\n";
          $prevlvl--;
        }
      } else {
        $toc .= '</li>'."\n";
      }
    }

    $j = 0;
    $title = explode(':', $title);
    $toc .= '<li><a href="#'.$anchor.'">'.$title[0].'</a>';
    $prevlvl = $lvl;

    $i++;
  }

  unset( $anchors );

  while ( $lvl > $startlvl ) {
    $toc .= "\n</ul>";
    $lvl--;
  }

  $toc .= '</li>'."\n";
  $toc .= '</ul>'."\n";

  return array('toc' => $toc, 'content' => $content);
}