Go expandShortFlags

expandShortFlags.go

// turn -abc5 into -a -b -c5
// ex:
// takesValue := map[rune]bool{'c': true}
// expandedArgs := expandShortOpts(os.Args[1:], takesValue)
func expandShortFlags(args []string, withValue map[rune]bool) []string {
	var out []string
	doubledash := false
	for _, arg := range args {
		if doubledash {
			out = append(out, arg)
			continue
		}
		if arg == "--" {
			out = append(out, arg)
			doubledash = true
			continue
		}
		if len(arg) > 2 && arg[0] == '-' && arg[1] != '-' {
			runes := []rune(arg[1:])
			for i := 0; i < len(runes); i++ {
				opt := runes[i]
				if withValue[opt] {
					// this option consumes the rest as its value
					out = append(out, "-"+string(opt), string(runes[i+1:]))
					break
				}
				out = append(out, "-"+string(opt))
			}
		} else {
			out = append(out, arg)
		}
	}
	return out
}