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 */
017package org.apache.commons.jxpath.ri.compiler;
018
019import org.apache.commons.jxpath.ri.EvalContext;
020import 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 19:46:46 +0200 (Fr, 02 Mai 2008) $
027 */
028public 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}