func()

in pkg/mflag/flag.go [997:1079]

• 78 lines of code
• 30 McCabe index (conditional complexity)

func (fs *FlagSet) parseOne() (bool, string, error) {
	if len(fs.args) == 0 {
		return false, "", nil
	}
	s := fs.args[0]
	if len(s) == 0 || s[0] != '-' || len(s) == 1 {
		return false, "", nil
	}
	if s[1] == '-' && len(s) == 2 { // "--" terminates the flags
		fs.args = fs.args[1:]
		return false, "", nil
	}
	name := s[1:]
	if len(name) == 0 || name[0] == '=' {
		return false, "", fs.failf("bad flag syntax: %s", s)
	}

	// it's a flag. does it have an argument?
	fs.args = fs.args[1:]
	hasValue := false
	value := ""
	if i := strings.Index(name, "="); i != -1 {
		value = trimQuotes(name[i+1:])
		hasValue = true
		name = name[:i]
	}

	m := fs.formal
	flag, alreadythere := m[name] // BUG
	if !alreadythere {
		if name == "-help" || name == "help" || name == "h" { // special case for nice help message.
			fs.usage()
			return false, "", ErrHelp
		}
		if len(name) > 0 && name[0] == '-' {
			return false, "", fs.failf("flag provided but not defined: -%s", name)
		}
		return false, name, ErrRetry
	}
	if fv, ok := flag.Value.(boolFlag); ok && fv.IsBoolFlag() { // special case: doesn't need an arg
		if hasValue {
			if err := fv.Set(value); err != nil {
				return false, "", fs.failf("invalid boolean value %q for  -%s: %v", value, name, err)
			}
		} else {
			fv.Set("true")
		}
	} else {
		// It must have a value, which might be the next argument.
		if !hasValue && len(fs.args) > 0 {
			// value is the next arg
			hasValue = true
			value, fs.args = fs.args[0], fs.args[1:]
		}
		if !hasValue {
			return false, "", fs.failf("flag needs an argument: -%s", name)
		}
		if err := flag.Value.Set(value); err != nil {
			return false, "", fs.failf("invalid value %q for flag -%s: %v", value, name, err)
		}
	}
	if fs.actual == nil {
		fs.actual = make(map[string]*Flag)
	}
	fs.actual[name] = flag
	for i, n := range flag.Names {
		if n == fmt.Sprintf("#%s", name) {
			replacement := ""
			for j := i; j < len(flag.Names); j++ {
				if flag.Names[j][0] != '#' {
					replacement = flag.Names[j]
					break
				}
			}
			if replacement != "" {
				fmt.Fprintf(fs.Out(), "Warning: '-%s' is deprecated, it will be replaced by '-%s' soon. See usage.\n", name, replacement)
			} else {
				fmt.Fprintf(fs.Out(), "Warning: '-%s' is deprecated, it will be removed soon. See usage.\n", name)
			}
		}
	}
	return true, "", nil
}