'lang' file editor ...

anyone know of a decent script (or something I can rip out of an existing OS tool) that is capable of comparing, editing and saving 'old skool' lang files - you know the ones which define tons of array elements e.g.: $Lang['foo'] = 'bar'; I'm looking for something that can handle quotes properly and 'weird' array keys (that include constants, for instance) as well as sprintf markers in the 'translation' text (e.g. "my %s hurts") and if at all possible the abiltiy to recognise and not f'up stuff like: $Lang['foo'] = 'my '.$Lang['bar'].' really hurts'; and I'd prefer it to be able to keep file formatting, item ordering and comments as they were when saving back into the file. I can't find anything really useful - the firefox 'php lang file' editor plugin, is, for instance, not up to the job. tar, Jochem