From: Rob Biedenharn <Rob@...>
Date: 2009-01-24T09:14:45+09:00
Subject: Re: regex extension to handle matching parens?

I think that you need to look at what Oniguruma might be able to do.
http://oniguruma.rubyforge.org/

I believe I've seen it demonstrated that balanced open/close pairs can  
be found with this regular expression engine. It might be ugly,  
however, but then you probably expected that.

-Rob

On Jan 23, 2009, at 5:33 PM, ivo welch wrote:

> Dear Experts:  I am very new to ruby, literally having just read the
> ruby book.
>
> I want to write a program that does basic LaTeX parsing, so I need to
> match '}' closings to the opening '{'.  (yes, I understand that LaTeX
> has very messy syntax, so this will only work for certain LaTeX docs.)
> Does a gem exist that facilitates closing-paren-matching fairly
> painlessly?  For example,
>
>  sample = " \caption{my table \label{table-label} example:
> $\sqrt{2+\sqrt{2}}$} more here {}"
>
> so, I want to find my "\caption" matcher ruby program to be able to
> detect the closing paren, and provide me with everything in between
> the opener and closer (i.e., "my table \label{table-label} example:
> $\sqrt{2+\sqrt{2}}$").  Possible?
>
> I searched this mailing list first, but I only found discussions from
> years back about this issue.  I understand that this is not strictly
> speaking a regular expression.  I come from a perl background.  There
> are now some regex extension libraries that make it possible for the
> built-in regex engine to parse matching parens
> (Regexp::Common::balanced and Text::Balanced).  I was hoping I could
> find some similar gem for ruby.
>
> help appreciated.
>
> Sincerely,
>
> /iaw
>