Class: LZ4::StreamEncoder

Inherits:
Object
  • Object
show all
Includes:
BasicStream
Defined in:
lib/extlz4/oldstream.rb

Overview

LZ4 stream encoder

Constant Summary collapse

OPTIONS = 
{
  legacy: false,
  blocksize: 7,
  block_dependency: false,
  block_checksum: false,
  stream_checksum: true,
}

Constants included from BasicStream

BasicStream::BLOCK_CHECKSUM, BasicStream::BLOCK_INDEPENDENCY, BasicStream::BLOCK_MAXIMUM_SIZES, BasicStream::LITERAL_DATA_BLOCK_FLAG, BasicStream::MAGIC_NUMBER, BasicStream::MAGIC_NUMBER_LEGACY, BasicStream::PRESET_DICTIONARY, BasicStream::STREAM_CHECKSUM, BasicStream::STREAM_SIZE, BasicStream::VERSION_NUMBER, BasicStream::VERSION_NUMBER_MASK

Instance Method Summary collapse

Constructor Details

#initialize(io, level, blocksize, block_dependency, block_checksum, stream_checksum) ⇒ StreamEncoder

Returns a new instance of StreamEncoder.

Raises:

  • (ArgumentError) 


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# File 'lib/extlz4/oldstream.rb', line 231

def initialize(io, level, blocksize, block_dependency,
               block_checksum, stream_checksum)
  @block_checksum = !!block_checksum
  @stream_checksum = XXhash::XXhashInternal::StreamingHash32.new(0) if stream_checksum

  @blocksize = BLOCK_MAXIMUM_SIZES[blocksize]
  raise ArgumentError, "wrong blocksize (#{blocksize})" unless @blocksize

  @block_dependency = !!block_dependency
  level = level ? level.to_i : nil
  case
  when level.nil? || level < 4
    level = nil
  when level > 16
    level = 16
  end
  @encoder = get_encoder(level, @block_dependency)
  @io = io
  @buf = "".force_encoding(Encoding::BINARY)

  header = [MAGIC_NUMBER].pack("V")
  sd = VERSION_NUMBER |
       (@block_dependency ? 0 : BLOCK_INDEPENDENCY) |
       (@block_checksum ? BLOCK_CHECKSUM : 0) |
       (false ? STREAM_SIZE : 0) |
       (@stream_checksum ? STREAM_CHECKSUM : 0) |
       (false ? PRESET_DICTIONARY : 0)
  bd = (blocksize << 4)
  desc = [sd, bd].pack("CC")
  header << desc
  # TODO: header << [stream_size].pack("Q<") if stream_size
  # TODO: header << [XXhash.xxh32(predict)].pack("V") if predict # preset dictionary
  header << [XXhash.xxh32(desc) >> 8].pack("C")
  @io << header
end

Instance Method Details

#<<(data) ⇒ Object

Same as ‘write` method, but return self always.



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# File 'lib/extlz4/oldstream.rb', line 301

def <<(data)
  write data
  self
end

#close ⇒ Object 



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# File 'lib/extlz4/oldstream.rb', line 306

def close
  export_block unless @buf.empty?
  @io << [0].pack("V")
  @io << [@stream_checksum.digest].pack("V") if @stream_checksum
  @io.flush if @io.respond_to?(:flush)
  @io = nil
end

#write(data) ⇒ Object

call-seq:

write(data) -> nil or self

Write data to lz4 stream.

If data is nil, return to process nothing.

RETURN (self)

Success write process.

RETURN (nil)

Given nil to data.

data (String) 


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# File 'lib/extlz4/oldstream.rb', line 283

def write(data)
  return nil if data.nil?
  @slicebuf ||= ""
  @inputproxy ||= StringIO.new
  @inputproxy.string = String(data)
  until @inputproxy.eof?
    slicesize = @blocksize - @buf.bytesize
    slicesize = @blocksize if slicesize > @blocksize
    @buf << @inputproxy.read(slicesize, @slicebuf)
    export_block if @buf.bytesize >= @blocksize
  end

  self
end