Class: MultiCompress::Database::Dictionary

Inherits:
Object
  • Object
show all
Defined in:
lib/multi_compress/database.rb

Overview

A strict, immutable MCDB2 dictionary. It is intentionally distinct from MultiCompress::Dictionary: MCDB2 accepts only conformant zstd dictionaries with a non-zero zstd DictID and an application-level registry id.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(id:, native: nil, bytes: nil) ⇒ Dictionary

Returns a new instance of Dictionary.

Raises:

  • (ArgumentError) 


45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
 
# File 'lib/multi_compress/database.rb', line 45

def initialize(id:, native: nil, bytes: nil)
  @id = normalize_id(id)
  raise ArgumentError, "provide exactly one of native: or bytes:" if (!!native) == (!!bytes)

  @native = native || MultiCompress::Dictionary.new(bytes, algo: :zstd)
  unless @native.is_a?(MultiCompress::Dictionary) && @native.algo == :zstd
    raise TypeError, "MCDB2 dictionary must be a MultiCompress::Dictionary with algo: :zstd"
  end

  @bytes = @native.bytes.b.freeze
  if @bytes.empty? || @bytes.bytesize > MAX_DICTIONARY_BYTES
    raise ArgumentError,
          "MCDB2 dictionary is #{@bytes.bytesize} bytes; allowed range is 1..#{MAX_DICTIONARY_BYTES}"
  end

  @zstd_id = @native.zstd_id
  raise ArgumentError, "MCDB2 dictionary must be a conformant zstd dictionary with a non-zero DictID" if @zstd_id.zero?

  @sha256 = Digest::SHA256.digest(@bytes).freeze
  freeze
end

Instance Attribute Details

#bytes ⇒ Object (readonly)

Returns the value of attribute bytes.



35
36
37
 
# File 'lib/multi_compress/database.rb', line 35

def bytes
  @bytes
end

#id ⇒ Object (readonly)

Returns the value of attribute id.



35
36
37
 
# File 'lib/multi_compress/database.rb', line 35

def id
  @id
end

#native ⇒ Object (readonly)

Returns the value of attribute native.



35
36
37
 
# File 'lib/multi_compress/database.rb', line 35

def native
  @native
end

#sha256 ⇒ Object (readonly)

Returns the value of attribute sha256.



35
36
37
 
# File 'lib/multi_compress/database.rb', line 35

def sha256
  @sha256
end

#zstd_id ⇒ Object (readonly)

Returns the value of attribute zstd_id.



35
36
37
 
# File 'lib/multi_compress/database.rb', line 35

def zstd_id
  @zstd_id
end

Class Method Details

.train(samples, id:, size: 32 * 1024) ⇒ Object 



37
38
39
 
# File 'lib/multi_compress/database.rb', line 37

def self.train(samples, id:, size: 32 * 1024)
  new(id: id, native: MultiCompress::Zstd.train_dictionary(samples, size: size))
end

.wrap(native, id:) ⇒ Object 



41
42
43
 
# File 'lib/multi_compress/database.rb', line 41

def self.wrap(native, id:)
  new(id: id, native: native)
end

Instance Method Details

#registry_attributes ⇒ Object 



71
72
73
 
# File 'lib/multi_compress/database.rb', line 71

def registry_attributes
  { id: @id, zstd_dict_id: @zstd_id, sha256: @sha256, bytes: @bytes }
end

#sha256_hex ⇒ Object 



67
68
69
 
# File 'lib/multi_compress/database.rb', line 67

def sha256_hex
  @sha256.unpack1("H*")
end