From: Simon Strandgaard <neoneye@...>
Date: 2004-09-23T04:52:52+09:00
Subject: Re: Regexp Arity

On Wednesday 22 September 2004 21:47, David A. Black wrote:
> > <transami@runbox.com> writes:
> > > |Just ran into a need to know how many parenthetical groupings a Regexp
> > > | has. Would #arity for Regexp be a good idea?
[snip]
> > Hmm... that brings up a good point. Would zero-width positive lookheads
> > and/or non-backreferencing groups be counted?
>
> To back up slightly: I can't help wondering under what conditions you
> would need to know this.  Can you present the problem you were trying
> to solve?  Maybe there's a simpler way.


Maybe I should advertise some more for my regexp package

irb(main):001:0> require 'regexp'
=> true
irb(main):002:0> puts /this(feels(like)lisp|scheme)/.tree
+-Sequence
  +-Inside set="t"
  +-Inside set="h"
  +-Inside set="i"
  +-Inside set="s"
  +-Group capture=1
    +-Alternation
      +-Sequence
      | +-Inside set="f"
      | +-Inside set="e"
      | +-Inside set="e"
      | +-Inside set="l"
      | +-Inside set="s"
      | +-Group capture=2
      | | +-Sequence
      | |   +-Inside set="l"
      | |   +-Inside set="i"
      | |   +-Inside set="k"
      | |   +-Inside set="e"
      | +-Inside set="l"
      | +-Inside set="i"
      | +-Inside set="s"
      | +-Inside set="p"
      +-Sequence
        +-Inside set="s"
        +-Inside set="c"
        +-Inside set="h"
        +-Inside set="e"
        +-Inside set="m"
        +-Inside set="e"
=> nil
irb(main):003:0>

to install just type

rpa install re

--
Simon Strandgaard