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 org.apache.commons.jxpath.ri.EvalContext;
021import org.apache.commons.jxpath.ri.InfoSetUtil;
022
023/**
024 * Implementation of {@link Expression} for the operation unary "-".
025 */
026public class CoreOperationNegate extends CoreOperation {
027
028    /**
029     * Constructs a new CoreOperationNegate.
030     *
031     * @param arg the Expression to negate
032     */
033    public CoreOperationNegate(final Expression arg) {
034        super(new Expression[] { arg });
035    }
036
037    @Override
038    public Object computeValue(final EvalContext context) {
039        final double a = InfoSetUtil.doubleValue(args[0].computeValue(context));
040        return Double.valueOf(-a);
041    }
042
043    @Override
044    protected int getPrecedence() {
045        return NEGATE_PRECEDENCE;
046    }
047
048    @Override
049    public String getSymbol() {
050        return "-";
051    }
052
053    @Override
054    protected boolean isSymmetric() {
055        return false;
056    }
057}