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         // currently, only id="toc" is supported, which means there can
  16         // only be one table of contents per page
  17         $container = $this->query("//html:div[@id='toc']")->item(0);
  18         if (!$container) return;
  19
  20         // grab all headings h2 and down from the document
  21         $headings = array('h2', 'h3', 'h4', 'h5', 'h6');
  22         foreach ($headings as $k => $v) $headings[$k] = "self::html:$v";
  23         $query_headings = implode(' or ', $headings);
  24         $query = "//*[$query_headings]"; // looks like "//*[self::html:h2 or ...]"
  25         $headings = $this->query($query);
  26
  27         // setup the table of contents element
  28         $toc = $dom->createElement('ul');
  29         $toc->setAttribute('class', 'toc-base');
  30         $container->appendChild($dom->createElement('h2', 'Table of Contents'));
  31         $container->appendChild($toc);
  32
  33         // iterate through headings and build the table of contents
  34         $current_level = 2;
  35         $parents = array(false, $toc);
  36         $indexes = array(0);
  37         $i = 0;
  38         foreach ($headings as $node) {
  39             $level = (int) $node->tagName[1];
  40             $name  = $node->textContent; // no support for formatting
  41
  42             while ($level > $current_level) {
  43                 if (!$parents[$current_level-1]->lastChild) {
  44                     $parents[$current_level-1]->appendChild(
  45                         $dom->createElement('li')
  46                     );
  47                 }
  48                 $sublist = $dom->createElement('ul');
  49                 $parents[$current_level - 1]->lastChild->appendChild($sublist);
  50                 $parents[$current_level] = $sublist;
  51                 $current_level++;
  52                 $indexes[$current_level - 2] = 0;
  53             }
  54
  55             while ($level < $current_level) {
  56                 unset($indexes[$current_level - 2]);
  57                 $current_level--;
  58             }
  59
  60             $indexes[$current_level - 2]++;
  61
  62
  63             $line = $dom->createElement('li');
  64             $label = $dom->createElement('span', implode('.', $indexes) . '.');
  65             $label->setAttribute('class', 'toc-label');
  66             $line->appendChild($label);
  67             $link = $dom->createElement('a', htmlspecialchars($name));
  68             $line->appendChild($link);
  69             $parents[$current_level-1]->appendChild($line);
  70
  71             // setup the anchors
  72             $header_id = $node->getAttribute('id');
  73             if (!$header_id) {
  74                 // automatically generate a header. These are volatile,
  75                 // so it's highly recommended that you manually specify
  76                 // them
  77                 // TODO: generate based on the contents of the header node
  78                 $header_id = 'toclink' . $i;
  79                 $node->setAttribute('id', $header_id);
  80                 $i++;
  81             }
  82             $link->setAttribute('href', '#' . $header_id);
  83
  84         }
  85     }
  86
  87 }