    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}