Utility to locate errors in regular expressions

[rusi]

On May 24, 5:58 pm, Malte Forkel <malte.for... at berlin.de> wrote:
> Finding out why a regular expression does not match a given string can
> very tedious. I would like to write a utility that identifies the
> sub-expression causing the non-match. My idea is to use a parser to
> create a tree representing the complete regular expression. Then I could
> simplify the expression by dropping sub-expressions one by one from
> right to left and from bottom to top until the remaining regex matches.
> The last sub-expression dropped should be (part of) the problem.
>
> As a first step, I am looking for a parser for Python regular
> expressions, or a Python regex grammar to create a parser from.
>
> But may be my idea is flawed? Or a similar (or better) tools already
> exists? Any advice will be highly appreciated!
>
> Malte



python-specific:  http://kodos.sourceforge.net/
Online: http://gskinner.com/RegExr/
emacs-specific: re-builder and regex-tool http://bc.tech.coop/blog/071103.html