class Zip::Deflater

def <<(data)
  val   = data.to_s
  @crc  = Zlib.crc32(val, @crc)
  @size += val.bytesize
  buffer = @zlib_deflater.deflate(data)
  if buffer.empty?
    @output_stream
  else
    @output_stream << @encrypter.encrypt(buffer)
  end
end

def finish
  @output_stream << @encrypter.encrypt(@zlib_deflater.finish) until @zlib_deflater.finished?
end

def initialize(output_stream, level = Zip.default_compression, encrypter = NullEncrypter.new)
  super()
  @output_stream = output_stream
  @zlib_deflater = ::Zlib::Deflate.new(level, -::Zlib::MAX_WBITS)
  @size          = 0
  @crc           = ::Zlib.crc32
  @encrypter     = encrypter
end