From: Patrick Hurley <phurley@...>
Date: 2007-06-03T13:48:50+09:00
Subject: Re: No way of looking for a regrexp match starting from a particular point in a string?

On 6/2/07, Kenneth McDonald <kenneth.m.mcdonald@sbcglobal.net> wrote:
> I'm probably just missing something obvious, but I haven't found a way
> to match a regular expression against only part of a string, in
> particular only past a certain point of a string, as a way of finding
> successive matches. Of course, one could do a match against a string,
> take the substring past that match and do a match against the substring,
> and so on, to find all of the matches for the string, but that could be
> very expensive for very large strings.
>
> I'm aware of the String.scan method, but that doesn't work for me
> because it doesn't return MatchData instances.
>
> What I want is just something like regexp.match(string, n), where the
> regexp starts looking for a match at or after position n in the string.
>
>
> Thanks,
> Ken
>
>

I don't know of anything obvious, but I would probably do something a
little more like:


class String
  def match_each(exp)
    str = self
    while md = str.match(exp)
      yield md
      str = md.post_match
    end
  end
end

foo = "foo bar foo bar foo"
foo.match_each /[oa][or]/ do |md|
  puts "Found: #{md}"
end

# pth