# File lib/treetop/compiler/metagrammar.rb, line 509
      def _nt_grammar_name
        start_index = index
        if node_cache[:grammar_name].has_key?(index)
          cached = node_cache[:grammar_name][index]
          if cached
            cached = SyntaxNode.new(input, index...(index + 1)) if cached == true
            @index = cached.interval.end
          end
          return cached
        end

        i0, s0 = index, []
        if has_terminal?('\G[A-Z]', true, index)
          r1 = true
          @index += 1
        else
          r1 = nil
        end
        s0 << r1
        if r1
          s2, i2 = [], index
          loop do
            r3 = _nt_alphanumeric_char
            if r3
              s2 << r3
            else
              break
            end
          end
          r2 = instantiate_node(SyntaxNode,input, i2...index, s2)
          s0 << r2
        end
        if s0.last
          r0 = instantiate_node(SyntaxNode,input, i0...index, s0)
          r0.extend(GrammarName0)
        else
          @index = i0
          r0 = nil
        end

        node_cache[:grammar_name][start_index] = r0

        r0
      end