Class: PolynomialInterpreter

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

Defined Under Namespace

Modules: Errors

Class Method Summary collapse

Class Method Details

.read_coeffs(input_polynomial) ⇒ Object 



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# File 'lib/polynomial_interpreter.rb', line 48

def self.read_coeffs(input_polynomial)
  if input_polynomial == ""
    raise Errors::POLYNOMIAL_INVALID
  end

  last_var = nil
  coeffs = Array.new

  unless input_polynomial[0].match /[-+]/
    input_polynomial = "+" + input_polynomial
  end

  while input_polynomial.length > 0 do
    op = input_polynomial.slice!(0)
    unless op =~ /[-+]/
      raise Errors::POLYNOMIAL_INVALID
    end

    input_polynomial.slice!(/^(\d+)\*?/)
    match_data_coe = Regexp.last_match

    input_polynomial.slice!(/^([a-zA-Z])(?:\^(\d+))?/)
    match_data_exp = Regexp.last_match

    if match_data_coe.nil? and match_data_exp.nil?
      raise Errors::POLYNOMIAL_INVALID
    else
      if match_data_exp.nil?
        coe = match_data_coe[1].to_i
        exp = 0
      else
        unless last_var.nil? or last_var == match_data_exp[1]
            raise Errors::POLYNOMIAL_INVALID
        end

        last_var = match_data_exp[1]

        if match_data_coe.nil?
          coe = 1
        else
          coe = match_data_coe[1].to_i
        end

        if match_data_exp[2].nil?
            exp = 1
        else
          exp = match_data_exp[2].to_i
        end
      end
    end

    coeffs[exp] ||= 0
    if op == "-"
      coeffs[exp] -= coe.to_i
    else
      coeffs[exp] += coe.to_i
    end
  end

  0.upto(coeffs.length-1) do |idx|
    coeffs[idx] ||= 0
  end

  coeffs
end

.read_congruence(input_congruence) ⇒ Object 



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# File 'lib/polynomial_interpreter.rb', line 11

def self.read_congruence(input_congruence)
  match_data = input_congruence.match(/^(.*)=(.*) +(?:mod +(.*)|\(mod +(.*)\))$/)

  if match_data.nil?
    raise Errors::CONGRUENCE_INVALID
  end

  lhs = match_data[1]
  rhs = match_data[2]
  mod = match_data[3] || match_data[4]

  begin
    lh_coeffs = read_coeffs(lhs.gsub(" ", ""))
  rescue ArgumentError
      raise Errors::LHS_POLYNOMIAL_INVALID
  end

  begin
    rh_coeffs = read_coeffs(rhs.gsub(" ", ""))
  rescue ArgumentError
      raise Errors::RHS_POLYNOMIAL_INVALID
  end

  if mod !~ /\d+/ or mod.to_i < 2
    raise Errors::MOD_INVALID
  end

  0.upto rh_coeffs.length-1 do |idx|
    unless rh_coeffs[idx].nil?
      lh_coeffs[idx] ||= 0
      lh_coeffs[idx] -= rh_coeffs[idx]
    end
  end

  [lh_coeffs, mod.to_i]
end