/*******************************************************************************
* Copyright (c) 2007 IBM Corporation 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:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.core.internal.expressions;
import java.util.HashMap;
import java.util.Map;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IExtensionDelta;
import org.eclipse.core.runtime.IExtensionRegistry;
import org.eclipse.core.runtime.IRegistryChangeEvent;
import org.eclipse.core.runtime.IRegistryChangeListener;
import org.eclipse.core.runtime.InvalidRegistryObjectException;
import org.eclipse.core.runtime.Platform;
import org.eclipse.core.expressions.Expression;
import org.eclipse.core.expressions.ExpressionConverter;
/**
* This manages the extension point that allows core expression reuse.
*
* @since 3.3
*/
public class DefinitionRegistry implements IRegistryChangeListener {
private Map cache= null;
private Map getCache() {
if (cache == null) {
cache= new HashMap();
}
return cache;
}
public DefinitionRegistry() {
Platform.getExtensionRegistry().addRegistryChangeListener(this, "org.eclipse.core.expressions"); //$NON-NLS-1$
}
/**
* Get the expression with the id defined by an extension. This class will
* cache the expressions when appropriate, so it's OK to always ask the
* registry.
*
* @param id The unique ID of the expression definition
* @return the expression
* @throws CoreException If the expression cannot be found.
*/
public Expression getExpression(String id) throws CoreException {
Expression cachedExpression= (Expression)getCache().get(id);
if (cachedExpression != null) {
return cachedExpression;
}
IExtensionRegistry registry= Platform.getExtensionRegistry();
IConfigurationElement[] ces= registry.getConfigurationElementsFor("org.eclipse.core.expressions", "definitions"); //$NON-NLS-1$ //$NON-NLS-2$
Expression foundExpression= null;
for (int i= 0; i < ces.length; i++) {
String cid= ces[i].getAttribute("id"); //$NON-NLS-1$
if (cid != null && cid.equals(id)) {
try {
foundExpression= getExpression(id, ces[i]);
break;
} catch (InvalidRegistryObjectException e) {
throw new CoreException(new ExpressionStatus(ExpressionStatus.MISSING_EXPRESSION, Messages.format(
ExpressionMessages.Missing_Expression, id)));
}
}
}
if (foundExpression == null) {
throw new CoreException(new ExpressionStatus(ExpressionStatus.MISSING_EXPRESSION, Messages.format(
ExpressionMessages.Missing_Expression, id)));
}
return foundExpression;
}
private Expression getExpression(String id, IConfigurationElement element) throws InvalidRegistryObjectException,
CoreException {
Expression expr= ExpressionConverter.getDefault().perform(element.getChildren()[0]);
if (expr != null) {
getCache().put(id, expr);
}
return expr;
}
public void registryChanged(IRegistryChangeEvent event) {
IExtensionDelta[] extensionDeltas= event.getExtensionDeltas("org.eclipse.core.expressions", "definitions"); //$NON-NLS-1$//$NON-NLS-2$
for (int i= 0; i < extensionDeltas.length; i++) {
if (extensionDeltas[i].getKind() == IExtensionDelta.REMOVED) {
IConfigurationElement[] ces= extensionDeltas[i].getExtension().getConfigurationElements();
for (int j= 0; j < ces.length; j++) {
String id= ces[j].getAttribute("id"); //$NON-NLS-1$
if (id != null) {
getCache().remove(id);
}
}
}
}
}
}