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/*******************************************************************************
* Copyright (c) 2011 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:
* Wind River Systems - initial API and implementation
*******************************************************************************/
package org.eclipse.tcf.te.runtime.extensions;
import org.eclipse.core.runtime.Assert;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Platform;
import org.eclipse.core.runtime.Status;
import org.eclipse.osgi.util.NLS;
import org.eclipse.tcf.te.runtime.activator.CoreBundleActivator;
import org.eclipse.tcf.te.runtime.nls.Messages;
/**
* Executable extension proxy implementation.
*/
public class ExecutableExtensionProxy<V> {
// The extension instance. Created on first access
private V instance;
// The configuration element
private final IConfigurationElement element;
// The unique id of the extension.
private String id;
/**
* Constructor.
*
* @param element The configuration element. Must not be <code>null</code>.
* @throws CoreException In case the configuration element attribute <i>id</i> is <code>null</code> or empty.
*/
public ExecutableExtensionProxy(IConfigurationElement element) throws CoreException {
Assert.isNotNull(element);
this.element = element;
// Extract the extension attributes
id = element.getAttribute("id"); //$NON-NLS-1$
if (id == null || id.trim().length() == 0) {
throw new CoreException(new Status(IStatus.ERROR,
CoreBundleActivator.getUniqueIdentifier(),
0,
NLS.bind(Messages.Extension_error_missingRequiredAttribute, "id", element.getContributor().getName()), //$NON-NLS-1$
null));
}
instance = null;
}
/**
* Constructor.
*
* @param id The id for this instance.
* @param instance The instance to add to proxy.
*/
public ExecutableExtensionProxy(String id, V instance) {
Assert.isNotNull(id);
Assert.isNotNull(instance);
this.id = id;
this.instance = instance;
this.element = null;
}
/**
* Returns the extensions unique id.
*
* @return The unique id.
*/
public String getId() {
return id;
}
/**
* Returns the configuration element for this extension.
*
* @return The configuration element.
*/
public IConfigurationElement getConfigurationElement() {
return element;
}
/**
* Reset the extension instance to <code>null</code> and force the
* creation of a new extension instance on the next {@link #getInstance()}
* method invocation.
*
* @return The current extension instance or <code>null</code> if none.
*/
public V reset() {
V oldExtension = instance;
instance = null;
return oldExtension;
}
/**
* Returns the extension class instance. The contributing
* plug-in will be activated if not yet activated anyway.
*
* @return The extension class instance or <code>null</code> if the instantiation fails.
*/
public V getInstance() {
if (instance == null) instance = newInstance();
return instance;
}
/**
* Returns always a new extension class instance which is different
* to what {@link #getInstance()} would return.
*
* @return A new extension class instance or <code>null</code> if the instantiation fails.
*/
public V newInstance() {
IConfigurationElement element = getConfigurationElement();
Assert.isNotNull(element);
// The "class" to load can be specified either as attribute or as child element
String attributeName = getExecutableExtensionAttributeName();
Assert.isNotNull(attributeName);
if (element.getAttribute(attributeName) != null || element.getChildren(attributeName).length > 0) {
try {
return (V)element.createExecutableExtension(attributeName);
} catch (Exception e) {
// Possible exceptions: CoreException, ClassCastException.
Platform.getLog(CoreBundleActivator.getContext().getBundle()).log(new Status(IStatus.ERROR,
CoreBundleActivator.getUniqueIdentifier(),
NLS.bind(Messages.Extension_error_invalidExtensionPoint, element.getDeclaringExtension().getUniqueIdentifier()), e));
}
}
return null;
}
/**
* Return the attribute name for the executable extension.
*/
protected String getExecutableExtensionAttributeName() {
return "class"; //$NON-NLS-1$
}
/* (non-Javadoc)
* @see java.lang.Object#equals(java.lang.Object)
*/
@Override
public boolean equals(Object obj) {
// Proxie's are equal if they have encapsulate an element
// with the same unique id
if (obj instanceof ExecutableExtensionProxy<?>) {
return getId().equals(((ExecutableExtensionProxy<?>)obj).getId());
}
return super.equals(obj);
}
/* (non-Javadoc)
* @see java.lang.Object#hashCode()
*/
@Override
public int hashCode() {
// The hash code of a proxy is the one from the id
return getId().hashCode();
}
}
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