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}