- /*
- * 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.apache.commons.jxpath;
-
- import java.lang.reflect.Constructor;
- import java.lang.reflect.Method;
- import java.util.Collection;
- import java.util.Collections;
- import java.util.Iterator;
- 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;
- import org.apache.commons.jxpath.util.TypeUtils;
-
- /**
- * 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: 1.14 $ $Date: 2004/04/04 23:16:23 $
- */
- 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 = TypeUtils.convert(parameters[0], Object.class);
- if (target != null) {
- Method method =
- MethodLookupUtils.lookupMethod(
- target.getClass(),
- name,
- parameters);
- if (method != null) {
- return new MethodFunction(method);
- }
-
- if (target instanceof NodeSet) {
- target = ((NodeSet) target).getPointers();
- }
-
- method =
- MethodLookupUtils.lookupMethod(
- target.getClass(),
- name,
- parameters);
- if (method != null) {
- return new MethodFunction(method);
- }
-
- if (target instanceof Collection) {
- Iterator iter = ((Collection) target).iterator();
- if (iter.hasNext()) {
- target = iter.next();
- if (target instanceof Pointer) {
- target = ((Pointer) target).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.equals("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;
- }
- }