Do a summary based on sections in a post

I wonder if it's possible in wordpress to create a summary, let's say at the begining of the post, that displays links to all the post section ?

Example:

[summary title="Summary"]

[section]Title 1[/section]
Content

[section]Title 2[/section]
Content

would display :

Summary 
    - Title 1
    - Title 2

Title 1
Content

Title 2
Content

What I tried is to define shortcodes [section] (that add a section to an array $sections for example) and [summary] (that iterate over $sections and display all titles). The problem is that I have access to all section items only at the end of the post (i.e. when all [section] have been parsed I suppose). If I put [summary] at the begining of the post, nothing appears.

Here is the code of myplugin.php:

$section_id     = 1;
$summary            = array();

//
add_shortcode('dc:summary', function($attr)
{
    global $summary;

    $title = isset($attr['title'])? $attr['title'] : 'Summary';

    $html  = '<div>';
    $html .= '<h1>' . $title . '</h1>';     
    $html .= '<ol>';    
    foreach($summary as $title)
    {
      $html .= '<li><a href="#{section_anchor}">'.$title.'</a></li>';
    }            
    $html .= '</ol></div>';
    return $html;
});

//
add_shortcode('dc:section', function($attr, $content = '')
{
  global $section_id, $summary;
  $html = '<h1>'.$section_id . '. ' . $content.'</h1>';
  $summary[$section_id] = $content;
  $section_id++;
  return $html;
});

The code of the post:

[dc:summary title="First summary"]

[dc:section]Title 1[/dc:section]
Content 

[dc:section]Title 2[/dc:section]
Content

[dc:summary title="Last summary"]

And the link to the post: http://ift.tt/1zxPLaO

Is there a way to order shortcode parsing ? or another way to implement this functionality ?

Thanks