Add RemoteObjectId

rse/plugins/org.eclipse.rse.core/src/org/eclipse/rse/internal/core/model/RemoteObjectId.java

@@ -0,0 +1,118 @@
+/*******************************************************************************
+ * Copyright (c) 2008 Wind River Systems, Inc. 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:
+ * Martin Oberhuber (Wind River) - initial API and implementation
+ *******************************************************************************/
+
+package org.eclipse.rse.internal.core.model;
+
+import org.eclipse.rse.core.subsystems.IRemoteObjectIdentifier;
+import org.eclipse.rse.core.subsystems.ISubSystem;
+import org.eclipse.rse.core.subsystems.ISystemDragDropAdapter;
+
+/**
+ * A RemoteObjectId uniquely identifies an object in the RSE Tree, and is valid
+ * as long as its parent subsystem exists.
+ * 
+ * It holds a Subsystem instance, and an absolute name. This class is meant as a
+ * short-lived object for using in local comparisons only. Since it is only
+ * valid as long as its parent subsystem exists, RemoteObjectId's cannot be
+ * usefully persisted.
+ * 
+ * This class is immutable and therefore thread-safe.
+ *
+ * TODO It is unfortunate that we need to access an ISystemDragDropAdapter just
+ * to get the ISubSystem. A lower-level object identifier should be available,
+ * but making that happen would break almost all clients since their adapter
+ * factories are not prepared for it.
+ * 
+ * TODO This class is currently nowhere used and is therefore dead code. But it
+ * is kept here in order to be convey the original idea and have it available
+ * when needed.
+ * 
+ * @since org.eclipse.rse.core 3.0
+ */
+public final class RemoteObjectId {
+	// Subsystem instance, may be null
+	private final ISubSystem fSubSystem;
+	// Absolute name, must not be null
+	private final String fAbsoluteName;
+
+	/**
+	 * Construct a RemoteObjectId.
+	 *
+	 * @param ss subsystem instance. May be <code>null</code> if unknown.
+	 * @param absoluteName absolute name. Must not be <code>null</code>.
+	 */
+	private RemoteObjectId(ISubSystem ss, String absoluteName) {
+		assert absoluteName != null;
+		fSubSystem = ss;
+		fAbsoluteName = absoluteName;
+	}
+
+	/**
+	 * Create an RemoteObjectId for any kind of Object. Tries to adapt the given
+	 * object to an RSE {@link ISystemDragDropAdapter} or
+	 * {@link IRemoteObjectIdentifier}, in order to obtain an absolute name
+	 * and subsystem instance.
+	 *
+	 * @param element an element that needs to be adaptable such that an
+	 *            absolute name can be obtained.
+	 * @return an RemoteObjectId for the given element, or <code>null</code> if
+	 *         the given element is not adaptable to the necessary RSE
+	 *         adapter type, or no absolute name can be obtained.
+	 */
+	public static RemoteObjectId create(Object element) {
+		ISystemDragDropAdapter dda = SystemRegistry.getSystemDragDropAdapter(element);
+		if (dda != null) {
+			String absoluteName = dda.getAbsoluteName(element);
+			if (absoluteName != null) {
+				return new RemoteObjectId(dda.getSubSystem(element), absoluteName);
+			}
+		}
+		return null;
+	}
+
+	/**
+	 * Return the absolute name of this object id.
+	 *
+	 * @return the absolute name
+	 */
+	public final String getAbsoluteName() {
+		return fAbsoluteName;
+	}
+
+	/**
+	 * Return the subsystem instance of this object id.
+	 *
+	 * @return the subsystem instance. May be <code>null</code> if the
+	 *         subsystem instance could not be determined.
+	 */
+	public final ISubSystem getSubSystem() {
+		return fSubSystem;
+	}
+
+	public final boolean equals(Object o) {
+		try {
+			// We're optimistic and think nobody will ever call
+			// equals() on us with any other kind of Object
+			RemoteObjectId other = (RemoteObjectId) o;
+			return (fSubSystem == other.fSubSystem) && (fAbsoluteName.equals(other.fAbsoluteName));
+		} catch (Exception e) {
+			return false;
+		}
+	}
+
+	public final int hashCode() {
+		int hashCode = fAbsoluteName.hashCode();
+		if (fSubSystem != null) {
+			hashCode = hashCode * 31 + fSubSystem.hashCode();
+		}
+		return hashCode;
+	}
+}