# File lib/treetop/compiler/metagrammar.rb, line 3074
      def _nt_alphanumeric_char
        start_index = index
        if node_cache[:alphanumeric_char].has_key?(index)
          cached = node_cache[:alphanumeric_char][index]
          @index = cached.interval.end if cached
          return cached
        end

        i0 = index
        r1 = _nt_alpha_char
        if r1
          r0 = r1
        else
          if has_terminal?('\G[0-9]', true, index)
            next_character = index + input[index..-1].match(/\A(.)/um).end(1)
            r2 = true
            @index = next_character
          else
            r2 = nil
          end
          if r2
            r0 = r2
          else
            @index = i0
            r0 = nil
          end
        end

        node_cache[:alphanumeric_char][start_index] = r0

        r0
      end