XHTMLCompiler/DOMFilter/GenerateTableOfContents.php

   1 <?php
   2
   3 /**
   4  * Generates a table of contents based on the heading structure of the
   5  * document.
   6  */
   7 class XHTMLCompiler_DOMFilter_GenerateTableOfContents extends XHTMLCompiler_DOMFilter
   8 {
   9
  10     protected $name = 'GenerateTableOfContents';
  11
  12     public function process(DOMDocument $dom, $page, $manager) {
  13
  14         // test for ToC container, if not present don't bother
  15         $container = $this->query("//html:div[@id='toc']")->item(0);
  16         if (!$container) return;
  17
  18         // grab all headings h2 and down from the document
  19         $headings = array('h2', 'h3', 'h4', 'h5', 'h6');
  20         foreach ($headings as $k => $v) $headings[$k] = "self::html:$v";
  21         $query_headings = implode(' or ', $headings);
  22         $query = "//*[$query_headings]"; // looks like "//*[self::html:h2 or ...]"
  23         $headings = $this->query($query);
  24
  25         // setup the table of contents element
  26         $toc = $dom->createElement('ul');
  27         $container->appendChild($dom->createElement('h2', 'Table of Contents'));
  28         $container->appendChild($toc);
  29
  30         // iterate through headings and build the table of contents
  31         $current_level = 2;
  32         $parents = array(false, $toc);
  33         $indexes = array(0);
  34         $i = 0;
  35         foreach ($headings as $node) {
  36             $level = (int) $node->tagName[1];
  37             $name  = $node->textContent; // no support for formatting
  38
  39             while ($level > $current_level) {
  40                 if (!$parents[$current_level-1]->lastChild) {
  41                     $parents[$current_level-1]->appendChild(
  42                         $dom->createElement('li')
  43                     );
  44                 }
  45                 $sublist = $dom->createElement('ul');
  46                 $parents[$current_level - 1]->lastChild->appendChild($sublist);
  47                 $parents[$current_level] = $sublist;
  48                 $current_level++;
  49                 $indexes[$current_level - 2] = 0;
  50             }
  51
  52             while ($level < $current_level) {
  53                 unset($indexes[$current_level - 2]);
  54                 $current_level--;
  55             }
  56
  57             $indexes[$current_level - 2]++;
  58
  59
  60             $line = $dom->createElement('li');
  61             $label = $dom->createElement('span', implode('.', $indexes) . '.');
  62             $label->setAttribute('class', 'toc-label');
  63             $line->appendChild($label);
  64             $link = $dom->createElement('a', $name);
  65             $line->appendChild($link);
  66             $parents[$current_level-1]->appendChild($line);
  67
  68             // setup the anchors
  69                 $header_id = $node->getAttribute('id');
  70             if (!$header_id) {
  71                 $header_id = 'toclink' . $i;
  72                 $node->setAttribute('id', $header_id);
  73                 }
  74             $link->setAttribute('href', '#' . $header_id);
  75
  76         }
  77     }
  78
  79 }
  80
  81 ?>