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 org.apache.commons.jxpath.ri.QName;
020    import org.apache.commons.jxpath.ri.EvalContext;
021    
022    /**
023     * An element of the compile tree holding a variable reference.
024     *
025     * @author Dmitri Plotnikov
026     * @version $Revision: 652845 $ $Date: 2008-05-02 12:46:46 -0500 (Fri, 02 May 2008) $
027     */
028    public class VariableReference extends Expression {
029    
030        private QName varName;
031    
032        /**
033         * Create a new VariableReference.
034         * @param varName variable name
035         */
036        public VariableReference(QName varName) {
037            this.varName = varName;
038        }
039    
040        /**
041         * Get the variable name.
042         * @return QName
043         */
044        public QName getVariableName() {
045            return varName;
046        }
047    
048        public String toString() {
049            return "$" + varName;
050        }
051    
052        public boolean isContextDependent() {
053            return false;
054        }
055    
056        public boolean computeContextDependent() {
057            return false;
058        }
059    
060        public Object compute(EvalContext context) {
061            return computeValue(context);
062        }
063    
064        /**
065         * Returns the value of the variable.
066         * @param context EvalContext against which to compute the variable's value.
067         * @return Object
068         */
069        public Object computeValue(EvalContext context) {
070            return context.getRootContext().getVariableContext(varName);
071        }
072    }