Calculate text diffs in PHP [duplicate]

Are there any libraries (3rd party or built-in) in PHP to calculate text diffs?

What sort of diffs? File diffs? There is array_diff() which acts on arrays. Then there is also xdiff, which "enables you to create and apply patch files containing differences between different revisions of files.". The latter acts on files or strings.

Edit: I should add xdiff doesn't appear to be out in a release yet. You have to build from source to use it.

it depends exactly what you mean and what you want to do but there is

PEAR Text_Diff - Engine for performing and rendering text diffs

There is a nice and tiny Simplediff project on Github which creates text and HTML diffs.

The output of this is in GNU diff format. It might be what you're looking for.