// Filter - a filter for a replication configuration Rule.
type Filter struct {
	XMLName xml.Name `xml:"Filter" json:"Filter"`
	Prefix  string
	And     And
	Tag     Tag

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

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

	ObjectSizeGreaterThan int64 `xml:"ObjectSizeGreaterThan,omitempty"`
	ObjectSizeLessThan    int64 `xml:"ObjectSizeLessThan,omitempty"`

	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.