Automatically generate nested table of contents based on heading tags

Question

Which one of you crafty programmers can show me an elegant php coded solution for automatically generating a nested table of contents based on heading tags on the page?

Answer 1

I don't find it elegant, but might help in getting general idea how to create one ;)

It uses simple_html_dom to find and manipulate elements in original html

$htmlcode = <<< EOHTML
 Animals 
Some content goes here.
Some content goes here.
 Mammals 
Some content goes here.
Some content goes here.
 Terrestrial Mammals 
Some content goes here.
Some content goes here.
 Marine Mammals 
Some content goes here.
Some content goes here.
 Whales 
Some content goes here.
Some content goes here.
EOHTML;
// simpehtmldom or other dom manipulating library
require_once 'simple_html_dom.php';

$html = str_get_html($htmlcode);

$toc = '';
$last_level = 0;

foreach($html->find('h1,h2,h3,h4,h5,h6') as $h){
    $innerTEXT = trim($h->innertext);
    $id =  str_replace(' ','_',$innerTEXT);
    $h->id= $id; // add id attribute so we can jump to this element
    $level = intval($h->tag[1]);

    if($level > $last_level)
        $toc .= "
";
    else{
        $toc .= str_repeat('
', $last_level - $level);
        $toc .= '