From: Martin DeMello <martindemello@...>
Date: 2003-01-08T07:53:08+09:00
Subject: Re: Regular expressions alternative

Maur?cio <briqueabraque@yahoo.com> wrote:
>   Hi,
> 
>   Wouldn't it be a good idea to create a option (say, b) for regular 
> expressions such that all characters (except / and \) would match 
> themselves unless preceeded by a backslash? For instance:

Here's an alternative implementation. Usage:

a = Regexp.nonmagic('string') # converts 'string' to a normal regexp

The advantage is that you can now use a.source to embed your regexp into
a larger regexp and have the larger regexp be normal (if you're a vi
user you know how annoying having to escape metacharacters can be).

--begin--

class Regexp
  class << self
    def nonmagic(s)
      special = Regexp.compile('^['+'.|()[]^{}+$*?'.split.map{|i| 
        Regexp.quote(i)}.join+']$'
      )
      r = s.scan(/(\\.|.)/).flatten.map {|i|
        case i
        when '\\\\'; Regexp.quote('\\')
        when /(\\(.))/
          p, q = $1, $2
          (p =~ special) ? p : q
        else; Regexp.quote(i)
        end
      }.join
      Regexp.compile(r)
    end
  end
end

--end--