    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    }