package flags import ( "bytes" "fmt" "os" "reflect" "strings" "unicode/utf8" ) // Option flag information. Contains a description of the option, short and // long name as well as a default value and whether an argument for this // flag is optional. type Option struct { // The description of the option flag. This description is shown // automatically in the built-in help. Description string // The short name of the option (a single character). If not 0, the // option flag can be 'activated' using -<ShortName>. Either ShortName // or LongName needs to be non-empty. ShortName rune // The long name of the option. If not "", the option flag can be // activated using --<LongName>. Either ShortName or LongName needs // to be non-empty. LongName string // The default value of the option. Default []string // The optional environment default value key name. EnvDefaultKey string // The optional delimiter string for EnvDefaultKey values. EnvDefaultDelim string // If true, specifies that the argument to an option flag is optional. // When no argument to the flag is specified on the command line, the // value of OptionalValue will be set in the field this option represents. // This is only valid for non-boolean options. OptionalArgument bool // The optional value of the option. The optional value is used when // the option flag is marked as having an OptionalArgument. This means // that when the flag is specified, but no option argument is given, // the value of the field this option represents will be set to // OptionalValue. This is only valid for non-boolean options. OptionalValue []string // If true, the option _must_ be specified on the command line. If the // option is not specified, the parser will generate an ErrRequired type // error. Required bool // A name for the value of an option shown in the Help as --flag [ValueName] ValueName string // A mask value to show in the help instead of the default value. This // is useful for hiding sensitive information in the help, such as // passwords. DefaultMask string // If non empty, only a certain set of values is allowed for an option. Choices []string // If true, the option is not displayed in the help or man page Hidden bool // The group which the option belongs to group *Group // The struct field which the option represents. field reflect.StructField // The struct field value which the option represents. value reflect.Value // Determines if the option will be always quoted in the INI output iniQuote bool tag multiTag isSet bool isSetDefault bool preventDefault bool defaultLiteral string } // LongNameWithNamespace returns the option's long name with the group namespaces // prepended by walking up the option's group tree. Namespaces and the long name // itself are separated by the parser's namespace delimiter. If the long name is // empty an empty string is returned. func (option *Option) LongNameWithNamespace() string { if len(option.LongName) == 0 { return "" } // fetch the namespace delimiter from the parser which is always at the // end of the group hierarchy namespaceDelimiter := "" g := option.group for { if p, ok := g.parent.(*Parser); ok { namespaceDelimiter = p.NamespaceDelimiter break } switch i := g.parent.(type) { case *Command: g = i.Group case *Group: g = i } } // concatenate long name with namespace longName := option.LongName g = option.group for g != nil { if g.Namespace != "" { longName = g.Namespace + namespaceDelimiter + longName } switch i := g.parent.(type) { case *Command: g = i.Group case *Group: g = i case *Parser: g = nil } } return longName } // String converts an option to a human friendly readable string describing the // option. func (option *Option) String() string { var s string var short string if option.ShortName != 0 { data := make([]byte, utf8.RuneLen(option.ShortName)) utf8.EncodeRune(data, option.ShortName) short = string(data) if len(option.LongName) != 0 { s = fmt.Sprintf("%s%s, %s%s", string(defaultShortOptDelimiter), short, defaultLongOptDelimiter, option.LongNameWithNamespace()) } else { s = fmt.Sprintf("%s%s", string(defaultShortOptDelimiter), short) } } else if len(option.LongName) != 0 { s = fmt.Sprintf("%s%s", defaultLongOptDelimiter, option.LongNameWithNamespace()) } return s } // Value returns the option value as an interface{}. func (option *Option) Value() interface{} { return option.value.Interface() } // Field returns the reflect struct field of the option. func (option *Option) Field() reflect.StructField { return option.field } // IsSet returns true if option has been set func (option *Option) IsSet() bool { return option.isSet } // IsSetDefault returns true if option has been set via the default option tag func (option *Option) IsSetDefault() bool { return option.isSetDefault } // Set the value of an option to the specified value. An error will be returned // if the specified value could not be converted to the corresponding option // value type. func (option *Option) set(value *string) error { kind := option.value.Type().Kind() if (kind == reflect.Map || kind == reflect.Slice) && !option.isSet { option.empty() } option.isSet = true option.preventDefault = true if len(option.Choices) != 0 { found := false for _, choice := range option.Choices { if choice == *value { found = true break } } if !found { allowed := strings.Join(option.Choices[0:len(option.Choices)-1], ", ") if len(option.Choices) > 1 { allowed += " or " + option.Choices[len(option.Choices)-1] } return newErrorf(ErrInvalidChoice, "Invalid value `%s' for option `%s'. Allowed values are: %s", *value, option, allowed) } } if option.isFunc() { return option.call(value) } else if value != nil { return convert(*value, option.value, option.tag) } return convert("", option.value, option.tag) } func (option *Option) canCli() bool { return option.ShortName != 0 || len(option.LongName) != 0 } func (option *Option) canArgument() bool { if u := option.isUnmarshaler(); u != nil { return true } return !option.isBool() } func (option *Option) emptyValue() reflect.Value { tp := option.value.Type() if tp.Kind() == reflect.Map { return reflect.MakeMap(tp) } return reflect.Zero(tp) } func (option *Option) empty() { if !option.isFunc() { option.value.Set(option.emptyValue()) } } func (option *Option) clearDefault() { usedDefault := option.Default if envKey := option.EnvDefaultKey; envKey != "" { if value, ok := os.LookupEnv(envKey); ok { if option.EnvDefaultDelim != "" { usedDefault = strings.Split(value, option.EnvDefaultDelim) } else { usedDefault = []string{value} } } } option.isSetDefault = true if len(usedDefault) > 0 { option.empty() for _, d := range usedDefault { option.set(&d) option.isSetDefault = true } } else { tp := option.value.Type() switch tp.Kind() { case reflect.Map: if option.value.IsNil() { option.empty() } case reflect.Slice: if option.value.IsNil() { option.empty() } } } } func (option *Option) valueIsDefault() bool { // Check if the value of the option corresponds to its // default value emptyval := option.emptyValue() checkvalptr := reflect.New(emptyval.Type()) checkval := reflect.Indirect(checkvalptr) checkval.Set(emptyval) if len(option.Default) != 0 { for _, v := range option.Default { convert(v, checkval, option.tag) } } return reflect.DeepEqual(option.value.Interface(), checkval.Interface()) } func (option *Option) isUnmarshaler() Unmarshaler { v := option.value for { if !v.CanInterface() { break } i := v.Interface() if u, ok := i.(Unmarshaler); ok { return u } if !v.CanAddr() { break } v = v.Addr() } return nil } func (option *Option) isBool() bool { tp := option.value.Type() for { switch tp.Kind() { case reflect.Slice, reflect.Ptr: tp = tp.Elem() case reflect.Bool: return true case reflect.Func: return tp.NumIn() == 0 default: return false } } } func (option *Option) isSignedNumber() bool { tp := option.value.Type() for { switch tp.Kind() { case reflect.Slice, reflect.Ptr: tp = tp.Elem() case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Float32, reflect.Float64: return true default: return false } } } func (option *Option) isFunc() bool { return option.value.Type().Kind() == reflect.Func } func (option *Option) call(value *string) error { var retval []reflect.Value if value == nil { retval = option.value.Call(nil) } else { tp := option.value.Type().In(0) val := reflect.New(tp) val = reflect.Indirect(val) if err := convert(*value, val, option.tag); err != nil { return err } retval = option.value.Call([]reflect.Value{val}) } if len(retval) == 1 && retval[0].Type() == reflect.TypeOf((*error)(nil)).Elem() { if retval[0].Interface() == nil { return nil } return retval[0].Interface().(error) } return nil } func (option *Option) updateDefaultLiteral() { defs := option.Default def := "" if len(defs) == 0 && option.canArgument() { var showdef bool switch option.field.Type.Kind() { case reflect.Func, reflect.Ptr: showdef = !option.value.IsNil() case reflect.Slice, reflect.String, reflect.Array: showdef = option.value.Len() > 0 case reflect.Map: showdef = !option.value.IsNil() && option.value.Len() > 0 default: zeroval := reflect.Zero(option.field.Type) showdef = !reflect.DeepEqual(zeroval.Interface(), option.value.Interface()) } if showdef { def, _ = convertToString(option.value, option.tag) } } else if len(defs) != 0 { l := len(defs) - 1 for i := 0; i < l; i++ { def += quoteIfNeeded(defs[i]) + ", " } def += quoteIfNeeded(defs[l]) } option.defaultLiteral = def } func (option *Option) shortAndLongName() string { ret := &bytes.Buffer{} if option.ShortName != 0 { ret.WriteRune(defaultShortOptDelimiter) ret.WriteRune(option.ShortName) } if len(option.LongName) != 0 { if option.ShortName != 0 { ret.WriteRune('/') } ret.WriteString(option.LongName) } return ret.String() }