diff options
Diffstat (limited to 'activesupport/lib/active_support/number_helper/number_to_rounded_converter.rb')
-rw-r--r-- | activesupport/lib/active_support/number_helper/number_to_rounded_converter.rb | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/number_helper/number_to_rounded_converter.rb b/activesupport/lib/active_support/number_helper/number_to_rounded_converter.rb new file mode 100644 index 0000000000..c42354fc83 --- /dev/null +++ b/activesupport/lib/active_support/number_helper/number_to_rounded_converter.rb @@ -0,0 +1,92 @@ +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 + if significant + @number = BigDecimal(number, digit_count(number.to_i) + precision) + else + @number = BigDecimal(number, precision) + end + 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 = + case rounded_number + when BigDecimal + s = rounded_number.to_s('F') + '0'*precision + a, b = s.split('.', 2) + a + '.' + b[0, precision] + else + "%01.#{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) + (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 |