From: Bill Kelly <billk@...>
Date: 2001-12-17T10:47:29+09:00
Subject: [ruby-talk:28725] Re: Scanning for delimited substrings


From: "Martin DeMello" <mdemello@ruf.rice.edu>
>
> I need to scan a string for delimited substrings, and return an array (as in
> String#scan) broken into the substrings and the bits between them. For
> example, "one <<two>> three <<four>> five six <<seven>>" scanned for
> ("<<",">>") should return ["one ", "<<two>>", " three ", "<<four>>",
> " five six ", "<<seven>>"]. The task is made somewhat easier by the fact
> that delimiters are strictly not nested ("foo <<bar <<baz>> quux>>" should
> return ["foo ", "<<bar <<baz>>", " quux"])

How about:
  scan(/<<.*?>>|(?:.(?!<<))+/)


  irb(main):001:0> "foo <<bar <<baz>> quux>>".scan(/<<.*?>>|(?:.(?!<<))+/)
  ["foo", "<<bar <<baz>>", " quux>>"]

Hmm, note that the above would miss a single character in the case of
a starting delimiter with no terminating closing delimiter before the
end of the string, as in:

  irb(main):002:0> "fooa<<bar".scan(/<<.*?>>|(?:.(?!<<))+/)
  ["foo", "<<bar"]

Missed the "a" after foo.  This should correct it:

  irb(main):005:0> "fooa<<bar".scan(/<<.*?>>|(?:.(?!<<.*?>>))+/)
  ["fooa<<bar"]



Hope this helps,

Regards,

Bill