_nt_white (Treetop::Compiler::Metagrammar)

    # File lib/treetop/compiler/metagrammar.rb, line 3070
          def _nt_white
            start_index = index
            if node_cache[:white].has_key?(index)
              cached = node_cache[:white][index]
              @index = cached.interval.end if cached
              return cached
            end

            if input.index(Regexp.new('[ \\t\\n\\r]'), index) == index
              r0 = instantiate_node(SyntaxNode,input, index...(index + 1))
              @index += 1
            else
              r0 = nil
            end

            node_cache[:white][start_index] = r0

            return r0
          end