Method Format

format.go:156–217

*Decimal must implement fmt.Formatter Format implements fmt.Formatter. It accepts many of the regular formats for floating-point numbers ('e', 'E', 'f', 'F', 'g', 'G') as well as 's' and 'v', which are handled like 'G'. Format also supports the output field width, as well as the format flags '+' and

(s fmt.State, format rune)

// padding, and '-' for left or right justification. It does not support
// precision. See the fmt package for details.
func (d *Decimal) Format(s fmt.State, format rune) {
	switch format {
	case 'e', 'E', 'f', 'g', 'G':
		// nothing to do
	case 'F':
		// (*Decimal).Text doesn't support 'F'; handle like 'f'
		format = 'f'
	case 'v', 's':
		// handle like 'G'
		format = 'G'
	default:
		fmt.Fprintf(s, "%%!%c(*apd.Decimal=%s)", format, d.String())
		return
	}
	var buf []byte
	buf = d.Append(buf, byte(format))
	if len(buf) == 0 {
		buf = []byte("?") // should never happen, but don't crash
	}
	// len(buf) > 0

	var sign string
	switch {
	case buf[0] == '-':
		sign = "-"
		buf = buf[1:]
	case buf[0] == '+':
		// +Inf
		sign = "+"
		if s.Flag(' ') {
			sign = " "
		}
		buf = buf[1:]
	case s.Flag('+'):
		sign = "+"
	case s.Flag(' '):
		sign = " "
	}

	var padding int
	if width, hasWidth := s.Width(); hasWidth && width > len(sign)+len(buf) {
		padding = width - len(sign) - len(buf)
	}

	switch {
	case s.Flag('0') && d.Form == Finite:
		// 0-padding on left
		writeMultiple(s, sign, 1)
		writeMultiple(s, "0", padding)
		s.Write(buf)
	case s.Flag('-'):
		// padding on right
		writeMultiple(s, sign, 1)
		s.Write(buf)
		writeMultiple(s, " ", padding)
	default:
		// padding on left
		writeMultiple(s, " ", padding)