# File rexml/xpath_parser.rb, line 586
  def get_group string
			ind = 0
			depth = 0
			st = string[0,1]
			en = (st == "(" ? ")" : "]")
			begin
				case string[ind,1]
				when st
					depth += 1
				when en
					depth -= 1
				end
				ind += 1
			end while depth > 0 and ind < string.length
			return nil unless depth==0
			[string[ind..-1], string[0..ind-1]]
		end