From: Trans <transfire@...>
Date: 2005-04-21T05:59:33+09:00
Subject: Re: Linear complete variation of MatchData#to_a, possible?

Amazing Pit Capitain! Your hunch was right on the money. Not only was
your suggestion key to the solution, but the output was just as you
expected. Here's the solution I found. It's not all that elegant, but
it appears to work okay. I am certain there are much better solutions
to be had, so if anyone has one to offer...

class MatchData

  def matchset
    b = Hash.new(0)
    e = Hash.new(0)

    self.captures.size.times do |i|
      b[self.begin(i)] += 1
      e[self.end(i)] += 1
    end

    a = self.string.split(//)
    c = ""
    ca = []
    stack = []

    (a.size).times { |i|
      # end
      if e[i] and e[i] != 0
        ca << c
        e[i].times { ca = stack.pop }
        c = nil
      end
      # begin
      if b[i] and b[i] != 0
        ca << c if c
        b[i].times {
          stack << ca
          ca << []
          ca = ca.last
        }
        c = nil
      end
      # content
      c = "" unless c
      c << a[i] #if a[i]
    }
    ca << c

    return ca
  end

end #class Matchdata

md = /(bb)(cc(dd))(ee)/.match "XXaabbccddeeffXX"
p md.to_a
p md.matchset
#=> ["XXaa", [["bb"], ["cc", ["dd"]], "ee"], "ffXX"]