Class: Omnizip::Algorithms::LZMA2

Inherits:
Omnizip::Algorithm show all
Defined in:
lib/omnizip/algorithms/lzma2.rb,
lib/omnizip/algorithms/lzma2.rb,
lib/omnizip/algorithms/lzma2/properties.rb,
lib/omnizip/algorithms/lzma2/lzma2_chunk.rb,
lib/omnizip/algorithms/lzma2/chunk_manager.rb,
lib/omnizip/algorithms/lzma2/simple_lzma2_encoder.rb

Overview

LZMA2 compression algorithm Improved version of LZMA with chunked format for better streaming

Defined Under Namespace

Classes: ChunkManager, LZMA2Chunk, Properties, SimpleLZMA2Encoder

Instance Attribute Summary

Attributes inherited from Omnizip::Algorithm

#filter, #options

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Omnizip::Algorithm

inherited, #with_filter

Constructor Details

#initialize(options = {}) ⇒ LZMA2

Returns a new instance of LZMA2.



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# File 'lib/omnizip/algorithms/lzma2.rb', line 60

def initialize(options = {})
  super()
  @dict_size = options[:dict_size] || (8 * 1024 * 1024) # 8 MB default
  @lc = options[:lc] || 3
  @lp = options[:lp] || 0
  @pb = options[:pb] || 2
  @level = options[:level] || 6
  @raw_mode = options[:raw_mode] # For 7-Zip format (no property byte)
end

Class Method Details

.encode_dict_size(dict_size) ⇒ Object

Encode dictionary size as single byte for LZMA2 properties



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# File 'lib/omnizip/algorithms/lzma2.rb', line 131

def self.encode_dict_size(dict_size)
  LZMA2Encoder.encode_dict_size(dict_size)
end

.metadata ⇒ Models::AlgorithmMetadata

Get algorithm metadata

Returns:



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# File 'lib/omnizip/algorithms/lzma2.rb', line 50

def metadata
  Models::AlgorithmMetadata.new.tap do |meta|
    meta.name = "lzma2"
    meta.description = "LZMA2 compression with improved chunking format for better streaming"
    meta.version = "1.0.0"
    meta.supports_streaming = true
  end
end

Instance Method Details

#compress(input, output, options = {}) ⇒ Object

Compress data using LZMA2



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# File 'lib/omnizip/algorithms/lzma2.rb', line 71

def compress(input, output, options = {})
  # For 7-Zip format, use raw_mode (no property byte in data stream)
  # Standalone LZMA2 files include a property byte
  standalone = options.fetch(:standalone, true)
  options.fetch(:raw_mode, !standalone)

  encoder = LZMA2Encoder.new(
    dict_size: @dict_size,
    lc: @lc,
    lp: @lp,
    pb: @pb,
    standalone: standalone, # Write property byte only for standalone files
  )

  # Read input
  input_data = input.respond_to?(:read) ? input.read : input

  # Encode with LZMA2
  compressed = encoder.encode(input_data)

  # Write to output
  if output.respond_to?(:write)
    output.write(compressed)
  else
    output.replace(compressed)
  end
end

#decompress(input, output, options = {}) ⇒ Object

Decompress LZMA2 data



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# File 'lib/omnizip/algorithms/lzma2.rb', line 100

def decompress(input, output, options = {})
  # Read input data
  input_data = input.respond_to?(:read) ? input.read : input
  input_stream = StringIO.new(input_data)
  input_stream.set_encoding(Encoding::BINARY)

  # Determine raw_mode:
  # - For 7-Zip format: raw_mode=true, dict_size from coder properties
  # - For standalone LZMA2 files: raw_mode=false, dict_size from property byte
  raw_mode = options.fetch(:raw_mode, @raw_mode || false)
  dict_size = options.fetch(:dict_size, @dict_size)

  # Create decoder using XZ Utils implementation
  decoder = Omnizip::Implementations::XZUtils::LZMA2::Decoder.new(
    input_stream,
    raw_mode: raw_mode,
    dict_size: dict_size,
  )

  # Decode LZMA2 data
  decompressed = decoder.decode_stream

  # Write to output
  if output.respond_to?(:write)
    output.write(decompressed)
  else
    output.replace(decompressed)
  end
end