001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *     http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.commons.jxpath.functions;
018    
019    import java.lang.reflect.InvocationTargetException;
020    import java.lang.reflect.Method;
021    import java.lang.reflect.Modifier;
022    
023    import org.apache.commons.jxpath.ExpressionContext;
024    import org.apache.commons.jxpath.Function;
025    import org.apache.commons.jxpath.JXPathInvalidAccessException;
026    import org.apache.commons.jxpath.util.TypeUtils;
027    import org.apache.commons.jxpath.util.ValueUtils;
028    
029    /**
030     * An XPath extension function implemented as an individual Java method.
031     *
032     * @author Dmitri Plotnikov
033     * @version $Revision: 652845 $ $Date: 2008-05-02 12:46:46 -0500 (Fri, 02 May 2008) $
034     */
035    public class MethodFunction implements Function {
036    
037        private Method method;
038        private static final Object[] EMPTY_ARRAY = new Object[0];
039    
040        /**
041         * Create a new MethodFunction.
042         * @param method implementing Method
043         */
044        public MethodFunction(Method method) {
045            this.method = ValueUtils.getAccessibleMethod(method);
046        }
047    
048        public Object invoke(ExpressionContext context, Object[] parameters) {
049            try {
050                Object target;
051                Object[] args;
052                if (Modifier.isStatic(method.getModifiers())) {
053                    target = null;
054                    if (parameters == null) {
055                        parameters = EMPTY_ARRAY;
056                    }
057                    int pi = 0;
058                    Class[] types = method.getParameterTypes();
059                    if (types.length >= 1
060                        && ExpressionContext.class.isAssignableFrom(types[0])) {
061                        pi = 1;
062                    }
063                    args = new Object[parameters.length + pi];
064                    if (pi == 1) {
065                        args[0] = context;
066                    }
067                    for (int i = 0; i < parameters.length; i++) {
068                        args[i + pi] =
069                            TypeUtils.convert(parameters[i], types[i + pi]);
070                    }
071                }
072                else {
073                    int pi = 0;
074                    Class[] types = method.getParameterTypes();
075                    if (types.length >= 1
076                        && ExpressionContext.class.isAssignableFrom(types[0])) {
077                        pi = 1;
078                    }
079                    target =
080                        TypeUtils.convert(
081                            parameters[0],
082                            method.getDeclaringClass());
083                    args = new Object[parameters.length - 1 + pi];
084                    if (pi == 1) {
085                        args[0] = context;
086                    }
087                    for (int i = 1; i < parameters.length; i++) {
088                        args[pi + i - 1] =
089                            TypeUtils.convert(parameters[i], types[i + pi - 1]);
090                    }
091                }
092    
093                return method.invoke(target, args);
094            }
095            catch (Throwable ex) {
096                if (ex instanceof InvocationTargetException) {
097                    ex = ((InvocationTargetException) ex).getTargetException();
098                }
099                throw new JXPathInvalidAccessException("Cannot invoke " + method,
100                        ex);
101            }
102        }
103    
104        public String toString() {
105            return method.toString();
106        }
107    }