Class: Xencoder::Encoder

Inherits:
Object
  • Object
show all
Defined in:
lib/xencoder/encoder.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(chars, length: 6, seed: 1) ⇒ Encoder

Returns a new instance of Encoder.



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# File 'lib/xencoder/encoder.rb', line 5

def initialize(chars, length: 6, seed: 1)
  @chars = build_chars(chars).freeze
  @length = length
  @seed = seed
  @xbase = Xbase.new(@chars)
  @base = @xbase.to_i("#{chars[1]}#{chars[0] * (length - 1)}")
  @max = @xbase.to_i(chars[-1] * length) - @base
end

Instance Attribute Details

#chars ⇒ Object (readonly)

Returns the value of attribute chars.



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# File 'lib/xencoder/encoder.rb', line 3

def chars
  @chars
end

#length ⇒ Object (readonly)

Returns the value of attribute length.



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# File 'lib/xencoder/encoder.rb', line 3

def length
  @length
end

#max ⇒ Object (readonly)

Returns the value of attribute max.



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# File 'lib/xencoder/encoder.rb', line 3

def max
  @max
end

#seed ⇒ Object (readonly)

Returns the value of attribute seed.



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# File 'lib/xencoder/encoder.rb', line 3

def seed
  @seed
end

Instance Method Details

#decode(str) ⇒ Object 



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# File 'lib/xencoder/encoder.rb', line 25

def decode(str)
  str = str.dup
  0.upto(str.length - 2).each do |i|
    idx = chars.index(str[i + 1])
    idx2 = (chars.index(str[i]) - idx + chars.size) % chars.size
    str[i] = mappings.at(idx2)
    str[i + 1] = mappings.at(idx)
  end
  @xbase.to_i(str) - @base
end

#encode(number) ⇒ Object 



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# File 'lib/xencoder/encoder.rb', line 14

def encode(number)
  str = @xbase.to_x(number + @base)
  (str.length - 1).downto(1).each do |i|
    idx = mappings.index(str[i])
    idx2 = (mappings.index(str[i - 1]) + idx) % mappings.size
    str[i] = chars.at(idx)
    str[i - 1] = chars.at(idx2)
  end
  str
end