[#39] service/object: Add query filters to search right child

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

pkg/services/object/search/query/v1/keys.go

@@ -0,0 +1,27 @@
+package query
+
+import (
+	"github.com/nspcc-dev/neofs-api-go/pkg/object"
+	"github.com/nspcc-dev/neofs-node/pkg/services/object/search/query"
+)
+
+// FIXME: this is a temporary solution for object fields filters
+
+const keyChildrenField = "Object.Header.Split.Children"
+
+const keyParentIDField = "Object.Header.Split.Parent"
+
+func NewEmptyChildrenFilter() *Filter {
+	return NewFilterEqual(keyChildrenField, "")
+}
+
+func NewParentIDFilter(par *object.ID) *Filter {
+	return NewFilterEqual(keyParentIDField, idValue(par))
+}
+
+func NewRightChildQuery(par *object.ID) query.Query {
+	return New(
+		NewParentIDFilter(par),
+		NewEmptyChildrenFilter(),
+	)
+}

pkg/services/object/search/query/v1/v1.go

@@ -97,6 +97,10 @@ func headerEqual(obj *object.Object, key, value string) bool {
 		return value == cidValue(obj.GetContainerID())
 	case objectSDK.HdrSysNameOwnerID:
 		return value == ownerIDValue(obj.GetOwnerID())
+	case keyChildrenField:
+		return len(obj.GetChildren()) == 0
+	case keyParentIDField:
+		return idValue(obj.GetParent().GetID()) == value
 		// TODO: add other headers
 	}
 }