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/*******************************************************************************
* Copyright (c) 2009, 2010 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.tm.tcf.extensions;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.osgi.util.NLS;
import org.eclipse.tm.tcf.Activator;
import org.eclipse.tm.tcf.internal.nls.TcfPluginMessages;
/**
* TCF extension proxy implementation. The use of the proxy asures the
* lazy plug-in activation policy for the contributing plug-in.
*/
public class TcfExtensionProxy<V> {
// The extension instance. Create on first access
private V fInstance;
// The configuration element
private final IConfigurationElement fElement;
// The unique id of the extension.
private String fId;
/**
* Constructor.
*
* @param element The configuration element. Must be not <code>null</code>.
*
* @throws CoreException In case the configuration element attribute <i>id</i> is <code>null</code> or empty.
*/
public TcfExtensionProxy(IConfigurationElement element) throws CoreException {
assert element != null;
fElement = element;
// The <id> attribute is mandatory.
fId = element.getAttribute("id"); //$NON-NLS-1$
if (fId == null || fId.trim().length() == 0) {
throw new CoreException(new Status(IStatus.ERROR,
Activator.PLUGIN_ID,
0,
NLS.bind(TcfPluginMessages.Extension_error_missingRequiredAttribute, "id", element.getContributor().getName()), //$NON-NLS-1$
null));
}
fInstance = null;
}
/**
* Returns the extensions unique id.
*
* @return The unique id.
*/
public String getId() {
return fId;
}
/**
* Returns the configuration element for this extension.
*
* @return The configuration element.
*/
protected IConfigurationElement getConfigurationElement() {
return fElement;
}
/**
* Returns the extension class instance. The contributing
* plug-in will be activated if not yet activated anyway.
*
* @return The extension class instance. Might be <code>null</code> if the instanciation fails.
*/
@SuppressWarnings("unchecked")
public V getInstance() {
if (fInstance == null) {
IConfigurationElement element = getConfigurationElement();
assert element != null;
if (element != null && element.getAttribute("class") != null) { //$NON-NLS-1$
try {
fInstance = (V)element.createExecutableExtension("class"); //$NON-NLS-1$
} catch (Exception e) {
// Possible exceptions: CoreException, ClassCastException.
IStatus status = new Status(IStatus.ERROR, Activator.PLUGIN_ID,
NLS.bind(TcfPluginMessages.Extension_error_invalidExtensionPoint, element.getDeclaringExtension().getUniqueIdentifier()),
e);
Activator.getDefault().getLog().log(status);
}
}
}
return fInstance;
}
/* (non-Javadoc)
* @see java.lang.Object#equals(java.lang.Object)
*/
@Override
public boolean equals(Object obj) {
// Proxies are equal if they have encapsulate an element
// with the same unique id
if (obj instanceof TcfExtensionProxy<?>) {
return getId().equals(((TcfExtensionProxy<?>)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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