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.EvalContext;
020 import org.apache.commons.jxpath.ri.InfoSetUtil;
021
022 /**
023 * Implementation of {@link Expression} for the operation unary "-".
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 CoreOperationNegate extends CoreOperation {
029
030 /**
031 * Create a new CoreOperationNegate.
032 * @param arg the Expression to negate
033 */
034 public CoreOperationNegate(Expression arg) {
035 super(new Expression[] { arg });
036 }
037
038 public Object computeValue(EvalContext context) {
039 double a = InfoSetUtil.doubleValue(args[0].computeValue(context));
040 return new Double(-a);
041 }
042
043 protected int getPrecedence() {
044 return NEGATE_PRECEDENCE;
045 }
046
047 protected boolean isSymmetric() {
048 return false;
049 }
050
051 public String getSymbol() {
052 return "-";
053 }
054 }