    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.ri.compiler;
    018
    019    import java.util.Arrays;
    020
    021    import org.apache.commons.jxpath.Function;
    022    import org.apache.commons.jxpath.JXPathFunctionNotFoundException;
    023    import org.apache.commons.jxpath.NodeSet;
    024    import org.apache.commons.jxpath.ri.EvalContext;
    025    import org.apache.commons.jxpath.ri.QName;
    026    import org.apache.commons.jxpath.ri.axes.NodeSetContext;
    027
    028    /**
    029     * Represents an element of the parse tree representing an extension function
    030     * call.
    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 ExtensionFunction extends Operation {
    036
    037        private QName functionName;
    038
    039        /**
    040         * Create a new ExtensionFunction.
    041         * @param functionName name of the function
    042         * @param args Expression[] of function args
    043         */
    044        public ExtensionFunction(QName functionName, Expression[] args) {
    045            super(args);
    046            this.functionName = functionName;
    047        }
    048
    049        /**
    050         * Get the function name
    051         * @return QName
    052         */
    053        public QName getFunctionName() {
    054            return functionName;
    055        }
    056
    057        /**
    058         * An extension function gets the current context, therefore it MAY be
    059         * context dependent.
    060         * @return true
    061         */
    062        public boolean computeContextDependent() {
    063            return true;
    064        }
    065
    066        public String toString() {
    067            StringBuffer buffer = new StringBuffer();
    068            buffer.append(functionName);
    069            buffer.append('(');
    070            Expression[] args = getArguments();
    071            if (args != null) {
    072                for (int i = 0; i < args.length; i++) {
    073                    if (i > 0) {
    074                        buffer.append(", ");
    075                    }
    076                    buffer.append(args[i]);
    077                }
    078            }
    079            buffer.append(')');
    080            return buffer.toString();
    081        }
    082
    083        public Object compute(EvalContext context) {
    084            return computeValue(context);
    085        }
    086
    087        public Object computeValue(EvalContext context) {
    088            Object[] parameters = null;
    089            if (args != null) {
    090                parameters = new Object[args.length];
    091                for (int i = 0; i < args.length; i++) {
    092                    parameters[i] = convert(args[i].compute(context));
    093                }
    094            }
    095
    096            Function function =
    097                context.getRootContext().getFunction(functionName, parameters);
    098            if (function == null) {
    099                throw new JXPathFunctionNotFoundException("No such function: "
    100                        + functionName + Arrays.asList(parameters));
    101            }
    102            Object result = function.invoke(context, parameters);
    103            return result instanceof NodeSet ? new NodeSetContext(context,
    104                    (NodeSet) result) : result;
    105        }
    106
    107        /**
    108         * Convert any incoming context to a value.
    109         * @param object Object to convert
    110         * @return context value or <code>object</code> unscathed.
    111         */
    112        private Object convert(Object object) {
    113            return object instanceof EvalContext ? ((EvalContext) object).getValue() : object;
    114        }
    115    }