Module: CousinRoman::Roman

Extended by:
Roman
Included in:
Roman
Defined in:
lib/cousin_roman/roman.rb

Instance Method Summary collapse

Instance Method Details

#convert(number) ⇒ Object

Convert Roman number represented as a string to an Integer.

It is essential that numer is a valid Roman numeral.

The steps are:

  1. Replace factors with their numeric values

starting from subtractive factors (cause they are compound).

  1. Sum this numeric values to get the final answer



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# File 'lib/cousin_roman/roman.rb', line 19

def convert(number)
  intermediate = number.dup.downcase
  compound = braketize_value_of SUBTRACTIVES
  singular = braketize_value_of ONES.merge(FIVES)

  [compound, singular].each { |factors| factors.each { |literal, val| intermediate.gsub!(literal, val) } }

  intermediate.scan(/\((\d*)\)/).reduce(0) do |sum, term|
    sum + term.first.to_i
  end
end

#roman_regex ⇒ Object 



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# File 'lib/cousin_roman/roman.rb', line 42

def roman_regex
  /^(M{0,3})(D?C{0,3}|C[DM])(L?X{0,3}|X[LC])(V?I{0,3}|I[VX])$/i
end

#to_arabian(number) ⇒ Object 



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# File 'lib/cousin_roman/roman.rb', line 31

def to_arabian(number)
  clean = number.strip
  convert clean if valid? clean
end

#to_arabian!(number) ⇒ Object 



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# File 'lib/cousin_roman/roman.rb', line 36

def to_arabian!(number)
  clean = number.strip
  valid? clean or raise TypeError, 'not a valid roman number'
  convert clean
end

#valid?(number) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/cousin_roman/roman.rb', line 5

def valid?(number)
  matches = number.match roman_regex
  matches and !matches[0].empty?
end