// IsEmpty returns true if filter is not set
func (f Filter) IsEmpty() bool {
	return f.And.isEmpty() && f.Tag.IsEmpty() && f.Prefix == ""
}

// MarshalXML - produces the xml representation of the Filter struct
// only one of Prefix, And and Tag should be present in the output.
func (f Filter) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
	if err := e.EncodeToken(start); err != nil {
		return err
	}

	switch {

// well-known interface methods from the standard library has the correct
// signature for that interface.
//
// Checked method names include:
//
//	Format GobEncode GobDecode MarshalJSON MarshalXML
//	Peek ReadByte ReadFrom ReadRune Scan Seek
//	UnmarshalJSON UnreadByte UnreadRune WriteByte
//	WriteTo

	case string(AES256):
		*alg = AES256
	case string(AWSKms):
		*alg = AWSKms
	default:
		return errors.New("Unknown SSE algorithm")
	}

	return nil
}

// MarshalXML - Marshals given SSE algorithm to valid XML
func (alg *Algorithm) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
	return e.EncodeElement(string(*alg), start)
}

// EncryptionAction - for ApplyServerSideEncryptionByDefault XML tag

		return err
	}
	switch strings.ToLower(s) {
	default:
		*a = Unknown
	case "gopher":
		*a = Gopher
	case "zebra":
		*a = Zebra
	}

	return nil
}

func (a Animal) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
	var s string
	switch a {
	default:
		s = "unknown"
	case Gopher:
		s = "gopher"
	case Zebra:
		s = "zebra"
	}
	return e.EncodeElement(s, start)
}

	And    And
	andSet bool

	Tag    Tag
	tagSet bool

	// Caching tags, only once
	cachedTags map[string]string
}

// MarshalXML - produces the xml representation of the Filter struct
// only one of Prefix, And and Tag should be present in the output.
func (f Filter) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
	if err := e.EncodeToken(start); err != nil {
		return err
	}

	switch {

	"Is":            {[]string{"error"}, []string{"bool"}},                             // errors.Is
	"MarshalJSON":   {[]string{}, []string{"[]byte", "error"}},                         // json.Marshaler
	"MarshalXML":    {[]string{"*xml.Encoder", "xml.StartElement"}, []string{"error"}}, // xml.Marshaler
	"ReadByte":      {[]string{}, []string{"byte", "error"}},                           // io.ByteReader