regexp matching in svn?

Hi,

Is there any existing regexp matching functionality somewhere in de
svn codebase, in a way that is reusable for new functionality? If not,
does anyone know of a reusable third-party library that could be
easily intregrated (I know, it would be Yet Another Dependency, but
I'm just asking for options ...)?

Use-case: I like the '-x-p' (show C-function) option for 'svn diff',
but this is limited to C-like syntax. GNU diff also has a '-F RE'
option, where RE is a regular expression that is used for matching the
"function-line". I know I could make use of this functionality by
invoking GNU diff as external diff command, but for several reasons it
would be interesting if svn could do this internally (for one thing:
GNU diff isn't always available / installed).

And I'm sure there would be other useful things people could do with
regexp functionality ...

Thoughts?

-- 
Johan