Finding nested expressions in regexs

[Phil Hunt]

In article <373C39C5.6135 at cs.bham.ac.uk>
           S.I.Reynolds at cs.bham.ac.uk "Stuart I Reynolds" writes:
> Hi all,
> 
> I need to extract nested expressions contained within paired symbols e.g
> "{ .. }" or "( .. )"
> 
>     input                  => matched
> 123{abc}4567               => {abc}
> 123{abc}456}7              => {abc}
> hij{123{abc}4568}def       => {123{abc}4568}
> hij{123{a\{bc}45\}68}def   => {123{a\{bc}45\}68}
> 
> Note:
> -  "\{" and "\}" should be completely ignored
> -  Expressions may be nested as above but also repeating:
> 
> ab{cd{ef}gh}ijkl{mn{o}}qrstu  => {cd{ef}gh}, {mn{o}}
> 
> Is there an easy way to do this with regular expressions?

I don't think you can do it with REs.  I think you need to use a
parser, such as yacc. (Does something like this exist for Python?)


-- 
Phil Hunt....philh at vision25.demon.co.uk