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         $manager->addDependency(__FILE__);
  20
  21         // grab all headings h2 and down from the document
  22         $headings = array('h2', 'h3', 'h4', 'h5', 'h6');
  23         foreach ($headings as $k => $v) $headings[$k] = "self::html:$v";
  24         $query_headings = implode(' or ', $headings);
  25         $query = "//*[$query_headings]"; // looks like "//*[self::html:h2 or ...]"
  26         $headings = $this->query($query);
  27
  28         // setup the table of contents element
  29         $toc = $dom->createElement('ul');
  30         $toc->setAttribute('class', 'toc-base');
  31         $container->appendChild($dom->createElement('h2', 'Table of Contents'));
  32         $container->appendChild($toc);
  33
  34         // iterate through headings and build the table of contents
  35         $current_level = 2;
  36         $parents = array(false, $toc);
  37         $indexes = array(0);
  38         $i = 0;
  39         foreach ($headings as $node) {
  40             $level = (int) $node->tagName[1];
  41             $name  = $node->textContent; // no support for formatting
  42
  43             while ($level > $current_level) {
  44                 if (!$parents[$current_level-1]->lastChild) {
  45                     $parents[$current_level-1]->appendChild(
  46                         $dom->createElement('li')
  47                     );
  48                 }
  49                 $sublist = $dom->createElement('ul');
  50                 $parents[$current_level - 1]->lastChild->appendChild($sublist);
  51                 $parents[$current_level] = $sublist;
  52                 $current_level++;
  53                 $indexes[$current_level - 2] = 0;
  54             }
  55
  56             while ($level < $current_level) {
  57                 unset($indexes[$current_level - 2]);
  58                 $current_level--;
  59             }
  60
  61             $indexes[$current_level - 2]++;
  62
  63
  64             $line = $dom->createElement('li');
  65             $label = $dom->createElement('span', implode('.', $indexes) . '.');
  66             $label->setAttribute('class', 'toc-label');
  67             $line->appendChild($label);
  68             $link = $dom->createElement('a', htmlspecialchars($name));
  69             $line->appendChild($link);
  70             $parents[$current_level-1]->appendChild($line);
  71
  72             // setup the anchors
  73             $header_id = $node->getAttribute('id');
  74             if (!$header_id) {
  75                 // automatically generate a header. These are volatile,
  76                 // so it's highly recommended that you manually specify
  77                 // them
  78                 // TODO: generate based on the contents of the header node
  79                 $header_id = 'toclink' . $i;
  80                 $node->setAttribute('id', $header_id);
  81                 $i++;
  82             }
  83             $link->setAttribute('href', '#' . $header_id);
  84
  85         }
  86     }
  87
  88 }