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
018package org.apache.commons.jxpath.ri.compiler;
019
020import java.util.Arrays;
021
022import org.apache.commons.jxpath.Function;
023import org.apache.commons.jxpath.JXPathFunctionNotFoundException;
024import org.apache.commons.jxpath.NodeSet;
025import org.apache.commons.jxpath.ri.EvalContext;
026import org.apache.commons.jxpath.ri.QName;
027import org.apache.commons.jxpath.ri.axes.NodeSetContext;
028
029/**
030 * Represents an element of the parse tree representing an extension function call.
031 */
032public class ExtensionFunction extends Operation {
033
034    private final QName functionName;
035
036    /**
037     * Constructs a new ExtensionFunction.
038     *
039     * @param functionName name of the function
040     * @param args         Expression[] of function args
041     */
042    public ExtensionFunction(final QName functionName, final Expression[] args) {
043        super(args);
044        this.functionName = functionName;
045    }
046
047    @Override
048    public Object compute(final EvalContext context) {
049        return computeValue(context);
050    }
051
052    /**
053     * An extension function gets the current context, therefore it MAY be context dependent.
054     *
055     * @return true
056     */
057    @Override
058    public boolean computeContextDependent() {
059        return true;
060    }
061
062    @Override
063    public Object computeValue(final EvalContext context) {
064        Object[] parameters = null;
065        if (args != null) {
066            parameters = new Object[args.length];
067            for (int i = 0; i < args.length; i++) {
068                parameters[i] = convert(args[i].compute(context));
069            }
070        }
071        final Function function = context.getRootContext().getFunction(functionName, parameters);
072        if (function == null) {
073            throw new JXPathFunctionNotFoundException("No such function: " + functionName + Arrays.asList(parameters));
074        }
075        final Object result = function.invoke(context, parameters);
076        return result instanceof NodeSet ? new NodeSetContext(context, (NodeSet) result) : result;
077    }
078
079    /**
080     * Convert any incoming context to a value.
081     *
082     * @param object Object to convert
083     * @return context value or {@code object} unscathed.
084     */
085    private Object convert(final Object object) {
086        return object instanceof EvalContext ? ((EvalContext) object).getValue() : object;
087    }
088
089    /**
090     * Gets the function name
091     *
092     * @return QName
093     */
094    public QName getFunctionName() {
095        return functionName;
096    }
097
098    @Override
099    public String toString() {
100        final StringBuilder buffer = new StringBuilder();
101        buffer.append(functionName);
102        buffer.append('(');
103        final Expression[] args = getArguments();
104        if (args != null) {
105            for (int i = 0; i < args.length; i++) {
106                if (i > 0) {
107                    buffer.append(", ");
108                }
109                buffer.append(args[i]);
110            }
111        }
112        buffer.append(')');
113        return buffer.toString();
114    }
115}