ExtensionsNamespaceResolver.java

/*******************************************************************************
 * Copyright (c) 2008 Ralf Ebert
 * 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:
 *     Ralf Ebert - initial API and implementation
 *******************************************************************************/
package com.swtxml.extensions;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IExtension;
import org.eclipse.core.runtime.IExtensionPoint;
import org.eclipse.core.runtime.Platform;

import com.swtxml.definition.INamespaceDefinition;
import com.swtxml.definition.INamespaceResolver;
import com.swtxml.util.parser.ParseException;

/**
 * @author Ralf Ebert <info@ralfebert.de>
 */
public class ExtensionsNamespaceResolver implements INamespaceResolver {

	private static final String NAMESPACE_EXTENSION_POINT_ID = "com.swtxml.namespaces";

	public INamespaceDefinition resolveNamespace(String uri) {

		IExtensionPoint extensionPoint = Platform.getExtensionRegistry().getExtensionPoint(
				NAMESPACE_EXTENSION_POINT_ID);

		for (IExtension extension : extensionPoint.getExtensions()) {
			for (IConfigurationElement configurationElement : extension.getConfigurationElements()) {
				if (!"namespaceResolver".equals(configurationElement.getName())) {
					throw new ParseException("Invalid " + NAMESPACE_EXTENSION_POINT_ID
							+ " element: " + configurationElement);
				}
				INamespaceResolver resolver = getNamespaceResolver(configurationElement);
				INamespaceDefinition namespace = resolver.resolveNamespace(uri);
				if (namespace != null) {
					return namespace;
				}
			}
		}

		return null;
	}

	private INamespaceResolver getNamespaceResolver(IConfigurationElement configurationElement) {
		try {
			return (INamespaceResolver) configurationElement.createExecutableExtension("class");
		} catch (CoreException e) {
			throw new ParseException(e.getMessage(), e);
		}
	}

}