Question

A bit like this from WordPress:

Or this from MediaWiki:

I have tried several diff engines in PHP, the most comprehensive seem to be (http://www.raymondhill.net/finediff/viewdiff-ex.php) and PEAR’s Text_Diff, but I can’t seem to find any option to have both versions stacked side by side like in the above images. I think that is easier to read than having both version in one.

Answer 1

Have found a solution – by taking the WP_Text_Diff_Renderer_Table class from WordPress (wp-includes/wp-diff.php) which is used in conjuction with PEAR Text_Diff:

$diff = new Text_Diff('auto', array($lines1, $lines2));
$render = new WP_Text_Diff_Renderer_Table;
echo $render->render($diff);

When wrapped in tags the above code produces the same HTML layout as the above WordPress screenshot. There are then four CSS rules to style:

• .diff-deletedline – the
  paragraph/line that is changed from
  the source text
• .diff-addedline – the paragraph/line
  that is changed in the destination
  text
• del – the individual word changed
  from the source
• ins – the individual word that is
  changed in the destination

More details here: http://www.webdevguides.co.uk/php-2/wordpress-style-diff-in-php