1 files changed, 22 insertions, 0 deletions

diff --git a/subprojects/logic/src/main/java/tools/refinery/logic/term/StatefulAggregate.java b/subprojects/logic/src/main/java/tools/refinery/logic/term/StatefulAggregate.java
new file mode 100644
index 00000000..75e7ecff
--- /dev/null
+++ b/subprojects/logic/src/main/java/tools/refinery/logic/term/StatefulAggregate.java
@@ -0,0 +1,22 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package tools.refinery.logic.term;
+
+public interface StatefulAggregate<R, T> {
+        void add(T value);
+
+        void remove(T value);
+
+        R getResult();
+
+        boolean isEmpty();
+
+        StatefulAggregate<R, T> deepCopy();
+
+        default boolean contains(T value) {
+                throw new UnsupportedOperationException();
+        }
+}