| /* |
| * $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//jxpath/src/java/org/apache/commons/jxpath/PackageFunctions.java,v 1.6 2002/06/16 03:22:22 dmitri Exp $ |
| * $Revision: 1.6 $ |
| * $Date: 2002/06/16 03:22:22 $ |
| * |
| * ==================================================================== |
| * The Apache Software License, Version 1.1 |
| * |
| * |
| * Copyright (c) 1999-2001 The Apache Software Foundation. All rights |
| * reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in |
| * the documentation and/or other materials provided with the |
| * distribution. |
| * |
| * 3. The end-user documentation included with the redistribution, if |
| * any, must include the following acknowlegement: |
| * "This product includes software developed by the |
| * Apache Software Foundation (http://www.apache.org/)." |
| * Alternately, this acknowlegement may appear in the software itself, |
| * if and wherever such third-party acknowlegements normally appear. |
| * |
| * 4. The names "The Jakarta Project", "Commons", and "Apache Software |
| * Foundation" must not be used to endorse or promote products derived |
| * from this software without prior written permission. For written |
| * permission, please contact apache@apache.org. |
| * |
| * 5. Products derived from this software may not be called "Apache" |
| * nor may "Apache" appear in their names without prior written |
| * permission of the Apache Group. |
| * |
| * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED |
| * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
| * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR |
| * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF |
| * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
| * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
| * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| * ==================================================================== |
| * |
| * This software consists of voluntary contributions made by many |
| * individuals on behalf of the Apache Software Foundation and was |
| * originally based on software copyright (c) 2001, Plotnix, Inc, |
| * <http://www.plotnix.com/>. |
| * For more information on the Apache Software Foundation, please see |
| * <http://www.apache.org/>. |
| */ |
| package org.apache.commons.jxpath; |
| |
| import java.lang.reflect.Constructor; |
| import java.lang.reflect.Method; |
| import java.util.Collections; |
| import java.util.Set; |
| |
| import org.apache.commons.jxpath.functions.ConstructorFunction; |
| import org.apache.commons.jxpath.functions.MethodFunction; |
| import org.apache.commons.jxpath.util.MethodLookupUtils; |
| |
| /** |
| * Extension functions provided by Java classes. The class prefix specified |
| * in the constructor is used when a constructor or a static method is called. |
| * Usually, a class prefix is a package name (hence the name of this class). |
| * |
| * Let's say, we declared a PackageFunction like this: |
| * <blockquote><pre> |
| * new PackageFunctions("java.util.", "util") |
| * </pre></blockquote> |
| * |
| * We can now use XPaths like: |
| * <dl> |
| * <dt><code>"util:Date.new()"</code></dt> |
| * <dd>Equivalent to <code>new java.util.Date()</code></dd> |
| * <dt><code>"util:Collections.singleton('foo')"</code></dt> |
| * <dd>Equivalent to <code>java.util.Collections.singleton("foo")</code></dd> |
| * <dt><code>"util:substring('foo', 1, 2)"</code></dt> |
| * <dd>Equivalent to <code>"foo".substring(1, 2)</code>. Note that in |
| * this case, the class prefix is not used. JXPath does not check that |
| * the first parameter of the function (the method target) is in fact |
| * a member of the package described by this PackageFunctions object.</dd> |
| * </dl> |
| * |
| * <p> |
| * If the first argument of a method or constructor is ExpressionContext, the |
| * expression context in which the function is evaluated is passed to |
| * the method. |
| * </p> |
| * <p> |
| * There is one PackageFunctions object registered by default with each |
| * JXPathContext. It does not have a namespace and uses no class prefix. |
| * The existence of this object allows us to use XPaths like: |
| * <code>"java.util.Date.new()"</code> and <code>"length('foo')"</code> |
| * without the explicit registration of any extension functions. |
| * </p> |
| |
| * |
| * @author Dmitri Plotnikov |
| * @version $Revision: 1.6 $ $Date: 2002/06/16 03:22:22 $ |
| */ |
| public class PackageFunctions implements Functions { |
| private String classPrefix; |
| private String namespace; |
| private static final Object[] EMPTY_ARRAY = new Object[0]; |
| |
| public PackageFunctions(String classPrefix, String namespace) { |
| this.classPrefix = classPrefix; |
| this.namespace = namespace; |
| } |
| |
| /** |
| * Returns the namespace specified in the constructor |
| */ |
| public Set getUsedNamespaces() { |
| return Collections.singleton(namespace); |
| } |
| |
| /** |
| * Returns a Function, if any, for the specified namespace, |
| * name and parameter types. |
| * <p> |
| * @param namespace - if it is not the same as specified in the construction, |
| * this method returns null |
| * @param name - name of the method, which can one these forms: |
| * <ul> |
| * <li><b>methodname</b>, if invoking a method on an object passed as the first parameter</li> |
| * <li><b>Classname.new</b>, if looking for a constructor</li> |
| * <li><b>subpackage.subpackage.Classname.new</b>, if looking for a constructor in |
| * a subpackage</li> |
| * <li><b>Classname.methodname</b>, if looking for a static method</li> |
| * <li><b>subpackage.subpackage.Classname.methodname</b>, if looking for a |
| * static method of a class in a subpackage</li> |
| * </ul> |
| * |
| * @return a MethodFunction, a ConstructorFunction or null if no function is found |
| */ |
| public Function getFunction(String namespace, String name, Object[] parameters) { |
| if ((namespace == null && this.namespace != null) |
| || (namespace != null && !namespace.equals(this.namespace))) { |
| return null; |
| } |
| |
| if (parameters == null) { |
| parameters = EMPTY_ARRAY; |
| } |
| |
| if (parameters.length >= 1) { |
| Object target = parameters[0]; |
| if (target != null) { |
| if (target instanceof ExpressionContext) { |
| Pointer pointer = ((ExpressionContext) target).getContextNodePointer(); |
| if (pointer != null) { |
| target = pointer.getValue(); |
| } |
| else { |
| target = null; |
| } |
| } |
| } |
| if (target != null) { |
| Method method = MethodLookupUtils. |
| lookupMethod(target.getClass(), name, parameters); |
| if (method != null) { |
| return new MethodFunction(method); |
| } |
| } |
| } |
| |
| String fullName = classPrefix + name; |
| int inx = fullName.lastIndexOf('.'); |
| if (inx == -1) { |
| return null; |
| } |
| |
| String className = fullName.substring(0, inx); |
| String methodName = fullName.substring(inx + 1); |
| |
| Class functionClass; |
| try { |
| functionClass = Class.forName(className); |
| } |
| catch (ClassNotFoundException ex) { |
| throw new JXPathException("Cannot invoke extension function " |
| + (namespace != null ? namespace + ":" + name : name), |
| ex); |
| } |
| |
| if (methodName.endsWith("new")) { |
| Constructor constructor = |
| MethodLookupUtils.lookupConstructor(functionClass, parameters); |
| if (constructor != null) { |
| return new ConstructorFunction(constructor); |
| } |
| } |
| else { |
| Method method = |
| MethodLookupUtils. |
| lookupStaticMethod(functionClass, methodName, parameters); |
| if (method != null) { |
| return new MethodFunction(method); |
| } |
| } |
| return null; |
| } |
| } |
