1 files changed, 58 insertions, 0 deletions

diff --git a/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/registry/impl/RegistryChangeMultiplexer.java b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/registry/impl/RegistryChangeMultiplexer.java
new file mode 100644
index 00000000..450f36b8
--- /dev/null
+++ b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/registry/impl/RegistryChangeMultiplexer.java
@@ -0,0 +1,58 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2016, Abel Hegedus, IncQuery Labs Ltd.
+ * 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.registry.impl;
+
+import java.util.Collections;
+import java.util.Set;
+import java.util.WeakHashMap;
+
+import tools.refinery.viatra.runtime.registry.IQuerySpecificationRegistryChangeListener;
+import tools.refinery.viatra.runtime.registry.IQuerySpecificationRegistryEntry;
+
+/**
+ * Listener implementation that propagates all changes to a set of listeners.
+ * The listeners are stored with weak references to avoid a need for disposal.
+ * 
+ * @author Abel Hegedus
+ *
+ */
+public class RegistryChangeMultiplexer implements IQuerySpecificationRegistryChangeListener {
+
+    private Set<IQuerySpecificationRegistryChangeListener> listeners;
+    
+    /**
+     * Creates a new instance of the multiplexer.
+     */
+    public RegistryChangeMultiplexer() {
+        this.listeners = Collections.newSetFromMap(new WeakHashMap<IQuerySpecificationRegistryChangeListener, Boolean>());
+    }
+    
+    /**
+     * Adds a weak reference on the listener to the multiplexer. The listener will receive all further notifications and
+     * does not have to be removed, since the multiplexer will not keep it in memory when it can be collected.
+     */
+    public boolean addListener(IQuerySpecificationRegistryChangeListener listener) {
+        return listeners.add(listener);
+    }
+    
+    @Override
+    public void entryAdded(IQuerySpecificationRegistryEntry entry) {
+        for (IQuerySpecificationRegistryChangeListener listener : listeners) {
+            listener.entryAdded(entry);
+        }
+    }
+
+    @Override
+    public void entryRemoved(IQuerySpecificationRegistryEntry entry) {
+        for (IQuerySpecificationRegistryChangeListener listener : listeners) {
+            listener.entryRemoved(entry);
+        }
+    }
+
+}