1 files changed, 136 insertions, 0 deletions
diff --git a/plugins/org.eclipse.emf.cdo/src/org/eclipse/emf/internal/cdo/util/AbstractRegistry.java b/plugins/org.eclipse.emf.cdo/src/org/eclipse/emf/internal/cdo/util/AbstractRegistry.java
new file mode 100644
index 0000000000..9ba36ef4bd
--- /dev/null
+++ b/plugins/org.eclipse.emf.cdo/src/org/eclipse/emf/internal/cdo/util/AbstractRegistry.java
@@ -0,0 +1,136 @@
+/*
+ * Copyright (c) 2022 Eike Stepper (Loehne, Germany) and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *   Eike Stepper - initial API and implementation
+ */
+package org.eclipse.emf.internal.cdo.util;
+
+import org.eclipse.net4j.util.container.Container;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * @author Eike Stepper
+ */
+public abstract class AbstractRegistry<T, R> extends Container<R>
+{
+  public static final int NOT_REGISTERED = 0;
+
+  private final Map<Integer, R> registrationsByID = new HashMap<>();
+
+  private final Map<T, R> registrationsByElement = new HashMap<>();
+
+  private int lastID;
+
+  public AbstractRegistry()
+  {
+  }
+
+  public T[] getRegisteredElements()
+  {
+    R[] registrations = getElements();
+    T[] registeredElements = newArray(registrations.length);
+  
+    for (int i = 0; i < registeredElements.length; i++)
+    {
+      registeredElements[i] = getRegisteredElement(registrations[i]);
+    }
+  
+    return registeredElements;
+  }
+
+  @Override
+  public synchronized R[] getElements()
+  {
+    int size = registrationsByID.size();
+    R[] array = newRegistrationArray(size);
+    return registrationsByID.values().toArray(array);
+  }
+
+  public synchronized T getElement(int id)
+  {
+    R registration = registrationsByID.get(id);
+    if (registration != null)
+    {
+      return getRegisteredElement(registration);
+    }
+  
+    return null;
+  }
+
+  public synchronized int[] getIDs()
+  {
+    int[] result = new int[registrationsByID.size()];
+
+    int i = 0;
+    for (Integer id : registrationsByID.keySet())
+    {
+      result[i++] = id;
+    }
+
+    return result;
+  }
+
+  public synchronized int getID(T element)
+  {
+    R registration = registrationsByElement.get(element);
+    if (registration != null)
+    {
+      return getRegisteredID(registration);
+    }
+
+    return NOT_REGISTERED;
+  }
+
+  protected final void registerElement(T element)
+  {
+    R registration;
+    synchronized (this)
+    {
+      if (registrationsByElement.containsKey(element))
+      {
+        return;
+      }
+
+      int id = ++lastID;
+      registration = newRegistration(id, element);
+
+      registrationsByID.put(id, registration);
+      registrationsByElement.put(element, registration);
+    }
+
+    fireElementAddedEvent(registration);
+  }
+
+  protected final void deregisterElement(T element)
+  {
+    R registration;
+    synchronized (this)
+    {
+      registration = registrationsByElement.remove(element);
+      if (registration != null)
+      {
+        int id = getRegisteredID(registration);
+        registrationsByID.remove(id);
+      }
+    }
+
+    fireElementRemovedEvent(registration);
+  }
+
+  protected abstract T[] newArray(int size);
+
+  protected abstract R[] newRegistrationArray(int size);
+
+  protected abstract R newRegistration(int id, T element);
+
+  protected abstract int getRegisteredID(R registration);
+
+  protected abstract T getRegisteredElement(R registration);
+}