1 files changed, 38 insertions, 0 deletions

diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/aggregation/CountNode.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/aggregation/CountNode.java
new file mode 100644
index 00000000..7c98de0d
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/aggregation/CountNode.java
@@ -0,0 +1,38 @@
+/*******************************************************************************
+ * Copyright (c) 2004-2009 Gabor Bergmann and Daniel Varro
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-v20.html.
+ * 
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+
+package tools.refinery.viatra.runtime.rete.aggregation;
+
+import java.util.Collection;
+
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.rete.network.ReteContainer;
+
+/**
+ * An aggregation node that simply counts the number of tuples conforming to the signature.
+ * 
+ * @author Gabor Bergmann
+ * @since 1.4
+ */
+public class CountNode extends IndexerBasedAggregatorNode {
+
+    public CountNode(ReteContainer reteContainer) {
+        super(reteContainer);
+    }
+
+    int sizeOf(Collection<Tuple> group) {
+        return group == null ? 0 : group.size();
+    }
+
+    @Override
+    public Object aggregateGroup(Tuple signature, Collection<Tuple> group) {
+        return sizeOf(group);
+    }
+
+}