# File lib/treetop/compiler/metagrammar.rb, line 785
      def _nt_parsing_rule
        start_index = index
        if node_cache[:parsing_rule].has_key?(index)
          cached = node_cache[:parsing_rule][index]
          @index = cached.interval.end if cached
          return cached
        end

        i0, s0 = index, []
        if input.index('rule', index) == index
          r1 = instantiate_node(SyntaxNode,input, index...(index + 4))
          @index += 4
        else
          terminal_parse_failure('rule')
          r1 = nil
        end
        s0 << r1
        if r1
          r2 = _nt_space
          s0 << r2
          if r2
            r3 = _nt_nonterminal
            s0 << r3
            if r3
              r4 = _nt_space
              s0 << r4
              if r4
                i6, s6 = index, []
                if input.index('do', index) == index
                  r7 = instantiate_node(SyntaxNode,input, index...(index + 2))
                  @index += 2
                else
                  terminal_parse_failure('do')
                  r7 = nil
                end
                s6 << r7
                if r7
                  r8 = _nt_space
                  s6 << r8
                end
                if s6.last
                  r6 = instantiate_node(SyntaxNode,input, i6...index, s6)
                  r6.extend(ParsingRule0)
                else
                  self.index = i6
                  r6 = nil
                end
                if r6
                  r5 = r6
                else
                  r5 = instantiate_node(SyntaxNode,input, index...index)
                end
                s0 << r5
                if r5
                  r9 = _nt_parsing_expression
                  s0 << r9
                  if r9
                    r10 = _nt_space
                    s0 << r10
                    if r10
                      if input.index('end', index) == index
                        r11 = instantiate_node(SyntaxNode,input, index...(index + 3))
                        @index += 3
                      else
                        terminal_parse_failure('end')
                        r11 = nil
                      end
                      s0 << r11
                    end
                  end
                end
              end
            end
          end
        end
        if s0.last
          r0 = instantiate_node(ParsingRule,input, i0...index, s0)
          r0.extend(ParsingRule1)
        else
          self.index = i0
          r0 = nil
        end

        node_cache[:parsing_rule][start_index] = r0

        return r0
      end