package meta

type ChangedFields struct {
	fieldNames map[string]struct{}
}

func NewChangedFields(fieldCount int) ChangedFields {
	cf := ChangedFields{
		fieldNames: make(map[string]struct{}, fieldCount),
	}
	return cf
}

func (cf *ChangedFields) Reset() {
	if cf.fieldNames == nil {
		cf.fieldNames = make(map[string]struct{})
	} else {
		for k := range cf.fieldNames {
			delete(cf.fieldNames, k)
		}
	}
}

func (cf ChangedFields) Changed(field string) bool {
	_, ok := cf.fieldNames[field]
	return ok
}

func (cf *ChangedFields) SetChanged(fields ...string) {
	for _, field := range fields {
		cf.fieldNames[field] = struct{}{}
	}
}

func (cf ChangedFields) Empty() bool {
	return len(cf.fieldNames) == 0
}