read_chunk

# File lib/csv/parser.rb, line 173
      def read_chunk
        return false if @last_scanner

        unless @keeps.empty?
          keep = @keeps.last
          keep_start = keep[0]
          string = @scanner.string
          keep_data = string.byteslice(keep_start, @scanner.pos - keep_start)
          if keep_data
            keep_buffer = keep[1]
            if keep_buffer
              keep_buffer << keep_data
            else
              keep[1] = keep_data.dup
            end
          end
          keep[0] = 0
        end

        input = @inputs.first
        case input
        when StringIO
          string = input.string
          raise InvalidEncoding unless string.valid_encoding?
          @scanner = StringScanner.new(string)
          @inputs.shift
          @last_scanner = @inputs.empty?
          true
        else
          chunk = input.gets(nil, @chunk_size)
          if chunk
            raise InvalidEncoding unless chunk.valid_encoding?
            @scanner = StringScanner.new(chunk)
            if input.respond_to?(:eof?) and input.eof?
              @inputs.shift
              @last_scanner = @inputs.empty?
            end
            true
          else
            @scanner = StringScanner.new("".encode(@encoding))
            @inputs.shift
            @last_scanner = @inputs.empty?
            if @last_scanner
              false
            else
              read_chunk
            end
          end
        end
      end