Add graph.Search for substr

storage/operator/filter.go

@@ -6,6 +6,15 @@ import (
 	"go.mongodb.org/mongo-driver/bson"
 )
 
+type Regex struct {
+	Key   string
+	Value string
+}
+
+func (re Regex) MarshalBSON() ([]byte, error) {
+	return filterMarshal("$regex", re.Key, re.Value)
+}
+
 type FilterIn struct {
 	Key    string
 	Values []interface{}
@@ -46,12 +55,17 @@ func NewFilterIn(key string, values interface{}) FilterIn {
 }
 
 func (fi FilterIn) MarshalBSON() ([]byte, error) {
-	if len(fi.Key) == 0 {
+	return filterMarshal("$in", fi.Key, fi.Values)
+}
+
+func filterMarshal(op, key string, value interface{}) ([]byte, error) {
+	if len(key) == 0 {
 		return bson.Marshal(map[string]interface{}{})
 	}
-	return bson.Marshal(map[string]map[string][]interface{}{
-		fi.Key: map[string][]interface{}{
-			"$in": fi.Values,
+	m := map[string]map[string]interface{}{
+		key: map[string]interface{}{
+			op: value,
 		},
-	})
+	}
+	return bson.Marshal(m)
 }