From: Bill Kelly <billk@...>
Date: 2001-12-17T11:22:23+09:00
Subject: [ruby-talk:28727] Re: Scanning for delimited substrings


From: "Martin DeMello" <mdemello@ruf.rice.edu>

[...]
> Also, I left out nested delimiters because I don't need them, and I couldn't
> think of a clean way to add them in without slowing things down, but if
> there's a more general method that trivially handles both cases I'd like to
> see it.

Here's a thought:  (not thoroughly tested (!))

    def nested_delim_scan(txt)
        tokens = []
        nestLvl = 0
        curTok = ""
        
        txt.scan(/<<|>>|(?:(?!<<|>>).)+/) { |s|
            curTok << s
            nestLvl += 1 if s == '<<'
            nestLvl -= 1 if s == '>>'
            if nestLvl < 1
                tokens.push curTok
                nestLvl = 0
                curTok = ""
            end
        }
    
        tokens.push curTok unless curTok == ""
        tokens
    end


  irb(main):001:0> nested_delim_scan("foo <<bar <<baz>> quux>>")
  ["foo ", "<<bar <<baz>> quux>>"]
  irb(main):002:0> nested_delim_scan("foo <<bar <<baz>> quux")
  ["foo ", "<<bar <<baz>> quux"]
  irb(main):003:0> nested_delim_scan("foo <<bar <<baz>> quux>> fleen >>")
  ["foo ", "<<bar <<baz>> quux>>", " fleen ", ">>"]


Regards,

Bill