Method: Decimal#add

Defined in:

lib/decimal/decimal.rb

#add(other, context = nil) ⇒ Object

Addition

# File 'lib/decimal/decimal.rb', line 1417

def add(other, context=nil)

  context = Decimal.define_context(context)
  other = _convert(other)

  if self.special? || other.special?
    ans = _check_nans(context,other)
    return ans if ans

    if self.infinite?
      if self.sign != other.sign && other.infinite?
        return context.exception(InvalidOperation, '-INF + INF')
      end
      return Decimal(self)
    end

    return Decimal(other) if other.infinite?
  end

  exp = [self.exponent, other.exponent].min
  negativezero = (context.rounding == ROUND_FLOOR && self.sign != other.sign)

  if self.zero? && other.zero?
    sign = [self.sign, other.sign].max
    sign = -1 if negativezero
    ans = Decimal.new([sign, 0, exp])._fix(context)
    return ans
  end

  if self.zero?
    exp = [exp, other.exponent - context.precision - 1].max unless context.exact?
    return other._rescale(exp, context.rounding)._fix(context)
  end

  if other.zero?
    exp = [exp, self.exponent - context.precision - 1].max unless context.exact?
    return self._rescale(exp, context.rounding)._fix(context)
  end

  op1, op2 = _normalize(self, other, context.precision)

  result_sign = result_coeff = result_exp = nil
  if op1.sign != op2.sign
    return ans = Decimal.new([negativezero ? -1 : +1, 0, exp])._fix(context) if op1.coefficient == op2.coefficient
    op1,op2 = op2,op1 if op1.coefficient < op2.coefficient
    result_sign = op1.sign
    op1,op2 = op1.copy_negate, op2.copy_negate if result_sign < 0
  elsif op1.sign < 0
    result_sign = -1
    op1,op2 = op1.copy_negate, op2.copy_negate
  else
    result_sign = +1
  end

  if op2.sign == +1
    result_coeff = op1.coefficient + op2.coefficient
  else
    result_coeff = op1.coefficient - op2.coefficient
  end

  result_exp = op1.exponent

  return Decimal([result_sign, result_coeff, result_exp])._fix(context)

end