module ActiveSupport module NumberHelper class NumberToRoundedConverter < NumberConverter # :nodoc: self.namespace = :precision self.validate_float = true def convert precision = options.delete :precision significant = options.delete :significant case number when Float, String @number = BigDecimal(number.to_s) when Rational @number = BigDecimal(number, digit_count(number.to_i) + precision) else @number = number.to_d end if significant && precision > 0 digits, rounded_number = digits_and_rounded_number(precision) precision -= digits precision = 0 if precision < 0 # don't let it be negative else rounded_number = number.round(precision) rounded_number = rounded_number.to_i if precision == 0 rounded_number = rounded_number.abs if rounded_number.zero? # prevent showing negative zeros end formatted_string = if BigDecimal === rounded_number && rounded_number.finite? s = rounded_number.to_s('F') + '0'*precision a, b = s.split('.', 2) a + '.' + b[0, precision] else "%00.#{precision}f" % rounded_number end delimited_number = NumberToDelimitedConverter.convert(formatted_string, options) format_number(delimited_number) end private def digits_and_rounded_number(precision) if zero? [1, 0] else digits = digit_count(number) multiplier = 10 ** (digits - precision) rounded_number = calculate_rounded_number(multiplier) digits = digit_count(rounded_number) # After rounding, the number of digits may have changed [digits, rounded_number] end end def calculate_rounded_number(multiplier) (number / BigDecimal.new(multiplier.to_f.to_s)).round * multiplier end def digit_count(number) number.zero? ? 1 : (Math.log10(absolute_number(number)) + 1).floor end def strip_insignificant_zeros options[:strip_insignificant_zeros] end def format_number(number) if strip_insignificant_zeros escaped_separator = Regexp.escape(options[:separator]) number.sub(/(#{escaped_separator})(\d*[1-9])?0+\z/, '\1\2').sub(/#{escaped_separator}\z/, '') else number end end def absolute_number(number) number.respond_to?(:abs) ? number.abs : number.to_d.abs end def zero? number.respond_to?(:zero?) ? number.zero? : number.to_d.zero? end end end end