# File lib/treetop/compiler/metagrammar.rb, line 4210
      def _nt_white
        start_index = index
        if node_cache[:white].has_key?(index)
          cached = node_cache[:white][index]
          if cached
            node_cache[:white][index] = cached = SyntaxNode.new(input, index...(index + 1)) if cached == true
            @index = cached.interval.end
          end
          return cached
        end

        if has_terminal?(@regexps[gr = '\A[ \\t\\n\\r]'] ||= Regexp.new(gr), :regexp, index)
          r0 = instantiate_node(SyntaxNode,input, index...(index + 1))
          @index += 1
        else
          terminal_parse_failure('[ \\t\\n\\r]')
          r0 = nil
        end

        node_cache[:white][start_index] = r0

        r0
      end