# File lib/mail/parsers/rfc2822.rb, line 193
    def _nt_FWS
      start_index = index
      if node_cache[:FWS].has_key?(index)
        cached = node_cache[:FWS][index]
        if cached
          cached = SyntaxNode.new(input, index...(index + 1)) if cached == true
          @index = cached.interval.end
        end
        return cached
      end

      i0 = index
      i1, s1 = index, []
      s2, i2 = [], index
      loop do
        r3 = _nt_WSP
        if r3
          s2 << r3
        else
          break
        end
      end
      r2 = instantiate_node(SyntaxNode,input, i2...index, s2)
      s1 << r2
      if r2
        r4 = _nt_CRLF
        s1 << r4
        if r4
          s5, i5 = [], index
          loop do
            r6 = _nt_WSP
            if r6
              s5 << r6
            else
              break
            end
          end
          if s5.empty?
            @index = i5
            r5 = nil
          else
            r5 = instantiate_node(SyntaxNode,input, i5...index, s5)
          end
          s1 << r5
        end
      end
      if s1.last
        r1 = instantiate_node(SyntaxNode,input, i1...index, s1)
        r1.extend(FWS0)
      else
        @index = i1
        r1 = nil
      end
      if r1
        r0 = r1
      else
        i7, s7 = index, []
        r8 = _nt_CRLF
        s7 << r8
        if r8
          s9, i9 = [], index
          loop do
            r10 = _nt_WSP
            if r10
              s9 << r10
            else
              break
            end
          end
          if s9.empty?
            @index = i9
            r9 = nil
          else
            r9 = instantiate_node(SyntaxNode,input, i9...index, s9)
          end
          s7 << r9
        end
        if s7.last
          r7 = instantiate_node(SyntaxNode,input, i7...index, s7)
          r7.extend(FWS1)
        else
          @index = i7
          r7 = nil
        end
        if r7
          r0 = r7
        else
          r11 = _nt_obs_FWS
          if r11
            r0 = r11
          else
            @index = i0
            r0 = nil
          end
        end
      end

      node_cache[:FWS][start_index] = r0

      r0
    end