Timwi wrote:
It uses the standard Linux tool "diff", doesn't it?
No, since per-character instead of per-line granularity is needed. MediaWiki ships its own PHP diff implementation. A tremendously faster-performing C++ implementation is available in CVS along with a SWIG interface, module 'wikidiff', which is in use at Wikimedia sites.
Jakob, I imagine the C++ code would be the quickest way to see how the diff is done. It's been a while since I looked at it, so I don't recall the algorithm used anymore.
-IK