_nt_parenthesized_expression (Treetop::Compiler::Metagrammar)

    # File lib/treetop/compiler/metagrammar.rb, line 1828
          def _nt_parenthesized_expression
            start_index = index
            if node_cache[:parenthesized_expression].has_key?(index)
              cached = node_cache[:parenthesized_expression][index]
              @index = cached.interval.end if cached
              return cached
            end

            i0, s0 = index, []
            if input.index('(', index) == index
              r1 = instantiate_node(SyntaxNode,input, index...(index + 1))
              @index += 1
            else
              terminal_parse_failure('(')
              r1 = nil
            end
            s0 << r1
            if r1
              r3 = _nt_space
              if r3
                r2 = r3
              else
                r2 = instantiate_node(SyntaxNode,input, index...index)
              end
              s0 << r2
              if r2
                r4 = _nt_parsing_expression
                s0 << r4
                if r4
                  r6 = _nt_space
                  if r6
                    r5 = r6
                  else
                    r5 = instantiate_node(SyntaxNode,input, index...index)
                  end
                  s0 << r5
                  if r5
                    if input.index(')', index) == index
                      r7 = instantiate_node(SyntaxNode,input, index...(index + 1))
                      @index += 1
                    else
                      terminal_parse_failure(')')
                      r7 = nil
                    end
                    s0 << r7
                  end
                end
              end
            end
            if s0.last
              r0 = instantiate_node(ParenthesizedExpression,input, i0...index, s0)
              r0.extend(ParenthesizedExpression0)
              r0.extend(ParenthesizedExpression1)
            else
              self.index = i0
              r0 = nil
            end

            node_cache[:parenthesized_expression][start_index] = r0

            return r0
          end