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}