_parse (RParsec::SequenceParser)

    # File rparsec/parsers.rb, line 282
      def _parse ctxt
        if @proc.nil?
          for p in @parsers
            return false unless p._parse(ctxt)
          end
        else
          results = []
          for p in @parsers
            return false unless p._parse(ctxt)
            results << ctxt.result
          end
          ctxt.retn(@proc.call(*results))
        end
        return true
      end