Contents

module Polynomials
  class Term
    attr_accessor :coefficient, :exponent

    def initialize(exponent = 0, coefficient = 0)
      @coefficient, @exponent = coefficient, exponent
    end

    def self.parse(string)
      term = self.new
      float = /\d+(?:\.\d+)?/
      integer = /\d+/
      polynomial_regex = /
        \A\s*
          (?<algebraic_sign>[-+]?)
        \s*
          (?<coefficient>#{float})?
        \s*
          (?<power>x(?:\^(?<exponent>#{integer}))?)?
        \s*\Z
      /x

      raw_data = string.match(polynomial_regex)
      raise NotParsableError unless raw_data
      term.coefficient = (raw_data[:algebraic_sign] + ( raw_data[:coefficient] || "1")).to_f
      term.exponent = raw_data[:power] ? (raw_data[:exponent] || 1).to_i : 0
      term
    end

    def to_s
      pretty_coeffiecent = coefficient.denominator == 1 ? coefficient.abs.to_i : coefficient.abs
      algebraic_sign =  coefficient < 0 ? '-' : '+'
      power = "x#{"^#{exponent}" unless exponent == 1}"
      "#{algebraic_sign} #{pretty_coeffiecent}#{ power unless exponent.zero?} "
    end

    def dup
      duplicate = self.class.new
      duplicate.coefficient = self.coefficient
      duplicate.exponent = self.exponent
      duplicate
    end

    def ==(other)
      self.coefficient == other.coefficient && self.exponent == other.exponent
    end
  end
end

Version data entries

6 entries across 6 versions & 1 rubygems

Version	Path
polynomials-0.4.4	lib/polynomials/term.rb
polynomials-0.4.3	lib/polynomials/term.rb
polynomials-0.4.2	lib/polynomials/term.rb
polynomials-0.4.1	lib/polynomials/term.rb
polynomials-0.4.0	lib/polynomials/term.rb
polynomials-0.3.0	lib/polynomials/term.rb