bundles/org.eclipse.wst.xsl.core/src_validation/org/eclipse/wst/xsl/core/internal/compiler/xslt10/extensions/XPathFunctionResolverImpl.java

/*******************************************************************************
 * Copyright (c) 2007 Standards for Technology in Automotive Retail
 * 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:
 *     David Carver - STAR - bug 224197 - initial API and implementation
 *                    based on work from Apache Xalan 2.7.0
 *******************************************************************************/

/*
 * Copyright 1999-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.eclipse.wst.xsl.core.internal.compiler.xslt10.extensions;

import javax.xml.namespace.QName;
import javax.xml.xpath.XPathFunction;
import javax.xml.xpath.XPathFunctionResolver;
import org.eclipse.wst.xsl.core.compiler.xslt10.res.Messages;
import org.eclipse.wst.xsl.core.compiler.xslt10.res.XSLTErrorResources;

/**
 * A sample implementation of XPathFunctionResolver, with support for EXSLT
 * extension functions and Java extension functions.
 */
public class XPathFunctionResolverImpl implements XPathFunctionResolver {
	/**
	 * Resolve an extension function from the qualified name and arity.
	 */
	public XPathFunction resolveFunction(QName qname, int arity) {
		if (qname == null)
			throw new NullPointerException(Messages.createMessage(
					XSLTErrorResources.ER_XPATH_RESOLVER_NULL_QNAME, null));

		if (arity < 0)
			throw new IllegalArgumentException(Messages.createMessage(
					XSLTErrorResources.ER_XPATH_RESOLVER_NEGATIVE_ARITY, null));

		String uri = qname.getNamespaceURI();
		if (uri == null || uri.length() == 0)
			return null;

		String className = null;
		String methodName = null;
		if (uri.startsWith("http://exslt.org")) {
			className = getEXSLTClassName(uri);
			methodName = qname.getLocalPart();
		} else if (!uri.equals(ExtensionNamespaceContext.JAVA_EXT_URI)) {
			int lastSlash = className.lastIndexOf("/");
			if (-1 != lastSlash)
				className = className.substring(lastSlash + 1);
		}

		String localPart = qname.getLocalPart();
		int lastDotIndex = localPart.lastIndexOf('.');
		if (lastDotIndex > 0) {
			if (className != null)
				className = className + "."
						+ localPart.substring(0, lastDotIndex);
			else
				className = localPart.substring(0, lastDotIndex);

			methodName = localPart.substring(lastDotIndex + 1);
		} else
			methodName = localPart;

		if (null == className || className.trim().length() == 0
				|| null == methodName || methodName.trim().length() == 0)
			return null;

		ExtensionHandler handler = null;
		try {
			ExtensionHandler.getClassForName(className);
			handler = new ExtensionHandlerJavaClass(uri, "javaclass", className);
		} catch (ClassNotFoundException e) {
			return null;
		}
		return new XPathFunctionImpl(handler, methodName);
	}

	/**
	 * Return the implementation class name of an EXSLT extension from a given
	 * namespace uri. The uri must starts with "http://exslt.org".
	 */
	private String getEXSLTClassName(String uri) {
		if (uri.equals(ExtensionNamespaceContext.EXSLT_MATH_URI))
			return "org.apache.xalan.lib.ExsltMath";
		else if (uri.equals(ExtensionNamespaceContext.EXSLT_SET_URI))
			return "org.apache.xalan.lib.ExsltSets";
		else if (uri.equals(ExtensionNamespaceContext.EXSLT_STRING_URI))
			return "org.apache.xalan.lib.ExsltStrings";
		else if (uri.equals(ExtensionNamespaceContext.EXSLT_DATETIME_URI))
			return "org.apache.xalan.lib.ExsltDatetime";
		else if (uri.equals(ExtensionNamespaceContext.EXSLT_DYNAMIC_URI))
			return "org.apache.xalan.lib.ExsltDynamic";
		else if (uri.equals(ExtensionNamespaceContext.EXSLT_URI))
			return "org.apache.xalan.lib.ExsltCommon";
		else
			return null;
	}
}