1 files changed, 125 insertions, 0 deletions

diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/single/RepresentativeElectionNode.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/single/RepresentativeElectionNode.java
new file mode 100644
index 00000000..95018c4f
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/single/RepresentativeElectionNode.java
@@ -0,0 +1,125 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2012, Tamas Szabo, Gabor Bergmann, Istvan Rath and Daniel Varro
+ * Copyright (c) 2023 The Refinery Authors <https://refinery.tools/>
+ * 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.single;
+
+import tools.refinery.viatra.runtime.rete.itc.alg.representative.RepresentativeElectionAlgorithm;
+import tools.refinery.viatra.runtime.rete.itc.alg.representative.RepresentativeObserver;
+import tools.refinery.viatra.runtime.rete.itc.graphimpl.Graph;
+import tools.refinery.viatra.runtime.matchers.tuple.Tuple;
+import tools.refinery.viatra.runtime.matchers.tuple.Tuples;
+import tools.refinery.viatra.runtime.matchers.util.Clearable;
+import tools.refinery.viatra.runtime.matchers.util.Direction;
+import tools.refinery.viatra.runtime.matchers.util.timeline.Timeline;
+import tools.refinery.viatra.runtime.rete.network.ReinitializedNode;
+import tools.refinery.viatra.runtime.rete.network.ReteContainer;
+import tools.refinery.viatra.runtime.rete.network.communication.Timestamp;
+
+import java.util.Collection;
+import java.util.Map;
+
+public class RepresentativeElectionNode extends SingleInputNode implements Clearable, RepresentativeObserver,
+                ReinitializedNode {
+        private final RepresentativeElectionAlgorithm.Factory algorithmFactory;
+        private Graph<Object> graph;
+        private RepresentativeElectionAlgorithm algorithm;
+
+        public RepresentativeElectionNode(ReteContainer reteContainer,
+                                                                          RepresentativeElectionAlgorithm.Factory algorithmFactory) {
+                super(reteContainer);
+                this.algorithmFactory = algorithmFactory;
+                graph = new Graph<>();
+                algorithm = algorithmFactory.create(graph);
+                algorithm.setObserver(this);
+                reteContainer.registerClearable(this);
+        }
+
+        @Override
+        public void networkStructureChanged() {
+                if (reteContainer.isTimelyEvaluation() && reteContainer.getCommunicationTracker().isInRecursiveGroup(this)) {
+                        throw new IllegalStateException(this + " cannot be used in recursive differential dataflow evaluation!");
+                }
+                super.networkStructureChanged();
+        }
+
+        @Override
+        public void reinitializeWith(Collection<Tuple> tuples) {
+                algorithm.dispose();
+                graph = new Graph<>();
+                for (var tuple : tuples) {
+                        insertEdge(tuple.get(0), tuple.get(1));
+                }
+                algorithm = algorithmFactory.create(graph);
+                algorithm.setObserver(this);
+        }
+
+        @Override
+        public void tupleChanged(Object source, Object representative, Direction direction) {
+                var tuple = Tuples.staticArityFlatTupleOf(source, representative);
+                propagateUpdate(direction, tuple, Timestamp.ZERO);
+        }
+
+        @Override
+        public void clear() {
+                algorithm.dispose();
+                graph = new Graph<>();
+                algorithm = algorithmFactory.create(graph);
+        }
+
+        @Override
+        public void update(Direction direction, Tuple updateElement, Timestamp timestamp) {
+                var source = updateElement.get(0);
+                var target = updateElement.get(1);
+                switch (direction) {
+                case INSERT -> insertEdge(source, target);
+                case DELETE -> deleteEdge(source, target);
+                default -> throw new IllegalArgumentException("Unknown direction: " + direction);
+                }
+        }
+
+        private void insertEdge(Object source, Object target) {
+                graph.insertNode(source);
+                graph.insertNode(target);
+                graph.insertEdge(source, target);
+        }
+
+        private void deleteEdge(Object source, Object target) {
+                graph.deleteEdgeIfExists(source, target);
+                if (isIsolated(source)) {
+                        graph.deleteNode(source);
+                }
+                if (!source.equals(target) && isIsolated(target)) {
+                        graph.deleteNode(target);
+                }
+        }
+
+        private boolean isIsolated(Object node) {
+                return graph.getTargetNodes(node).isEmpty() && graph.getSourceNodes(node).isEmpty();
+        }
+
+        @Override
+        public void pullInto(Collection<Tuple> collector, boolean flush) {
+                for (var entry : algorithm.getComponents().entrySet()) {
+                        var representative = entry.getKey();
+                        for (var node : entry.getValue()) {
+                                collector.add(Tuples.staticArityFlatTupleOf(node, representative));
+                        }
+                }
+        }
+
+        @Override
+        public void pullIntoWithTimeline(Map<Tuple, Timeline<Timestamp>> collector, boolean flush) {
+                // Use all zero timestamps because this node cannot be used in recursive groups anyway.
+                for (var entry : algorithm.getComponents().entrySet()) {
+                        var representative = entry.getKey();
+                        for (var node : entry.getValue()) {
+                                collector.put(Tuples.staticArityFlatTupleOf(node, representative), Timestamp.INSERT_AT_ZERO_TIMELINE);
+                        }
+                }
+        }
+}