Class: Omnizip::Formats::Rar::Compression::Dispatcher

Inherits:
Object
  • Object
show all
Defined in:
lib/omnizip/formats/rar/compression/dispatcher.rb

Overview

Algorithm dispatcher for RAR compression

Selects appropriate compression algorithm based on RAR method and dispatches to correct encoder/decoder.

Responsibilities:

  • Algorithm selection based on compression method
  • Dispatch to appropriate decoder/encoder
  • Error handling for unsupported/unknown methods

Note: Does NOT perform actual compression/decompression (delegated to decoder/encoder classes)

Defined Under Namespace

Classes: CompressionError, DecompressionError, UnsupportedMethodError

Constant Summary collapse

METHOD_STORE =

RAR compression methods

0x30
METHOD_FASTEST =

No compression

0x31
METHOD_FAST =

LZ77+Huffman (fast)

0x32
METHOD_NORMAL =

LZ77+Huffman

0x33
METHOD_GOOD =

LZ77+Huffman (default)

0x34
METHOD_BEST =

LZ77+Huffman or PPMd

0x35

Class Method Summary collapse

Class Method Details

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

Compress data using appropriate algorithm

Parameters:

  • method (Integer) —

    RAR compression method

  • input (IO) —

    Input stream

  • output (IO) —

    Output stream

  • options (Hash) (defaults to: {}) —

    Encoder options

Raises:



74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
 
# File 'lib/omnizip/formats/rar/compression/dispatcher.rb', line 74

def compress(method, input, output, options = {})
  case method
  when METHOD_STORE
    compress_store(input, output)
  when METHOD_FASTEST, METHOD_FAST, METHOD_NORMAL
    compress_lz77_huffman(input, output, options)
  when METHOD_GOOD
    compress_good(input, output, options)
  when METHOD_BEST
    compress_ppmd(input, output, options)
  else
    raise UnsupportedMethodError,
          "Unknown compression method: 0x#{method.to_s(16).upcase}"
  end
rescue StandardError => e
  raise CompressionError, "Compression failed: #{e.message}" unless
    e.is_a?(UnsupportedMethodError) || e.is_a?(NotImplementedError)

  raise
end

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

Decompress data using appropriate algorithm

Parameters:

  • method (Integer) —

    RAR compression method (0x30-0x35)

  • input (IO) —

    Input stream

  • output (IO) —

    Output stream

  • options (Hash) (defaults to: {}) —

    Decoder options

Raises:



42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
 
# File 'lib/omnizip/formats/rar/compression/dispatcher.rb', line 42

def decompress(method, input, output, options = {})
  case method
  when METHOD_STORE
    decompress_store(input, output)
  when METHOD_FASTEST, METHOD_FAST, METHOD_NORMAL
    decompress_lz77_huffman(input, output, options)
  when METHOD_GOOD
    decompress_good(input, output, options)
  when METHOD_BEST
    decompress_ppmd(input, output, options)
  else
    raise UnsupportedMethodError,
          "Unknown compression method: 0x#{method.to_s(16).upcase}"
  end
rescue StandardError => e
  unless e.is_a?(UnsupportedMethodError)
    raise DecompressionError,
          "Decompression failed: #{e.message}"
  end

  raise
end