content: /*
   * Copyright 1999-2012 Alibaba Group.
   *  
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *  
   *      http://www.apache.org/licenses/LICENSE-2.0
   *  
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  /**
   * (created at 2011-1-20)
   */
  package com.alibaba.cobar.parser.ast.expression.arithmeic;
  
  import java.math.BigDecimal;
  import java.math.BigInteger;
  import java.util.Map;
  
  import com.alibaba.cobar.parser.ast.expression.Expression;
  import com.alibaba.cobar.parser.ast.expression.UnaryOperatorExpression;
  import com.alibaba.cobar.parser.util.ExprEvalUtils;
  import com.alibaba.cobar.parser.util.UnaryOperandCalculator;
  
  /**
   * <code>'-' higherExpr</code>
   * 
   * @author <a href="mailto:shuo.qius@alibaba-inc.com">QIU Shuo</a>
   */
  public class MinusExpression extends UnaryOperatorExpression implements UnaryOperandCalculator {
      public MinusExpression(Expression operand) {
          super(operand, PRECEDENCE_UNARY_OP);
      }
  
      @Override
      public String getOperator() {
          return "-";
      }
  
      @Override
      public Object evaluationInternal(Map<? extends Object, ? extends Object> parameters) {
          Object operand = getOperand().evaluation(parameters);
          if (operand == null)
              return null;
          if (operand == UNEVALUATABLE)
              return UNEVALUATABLE;
          Number num = null;
          if (operand instanceof String) {
              num = ExprEvalUtils.string2Number((String) operand);
          } else {
              num = (Number) operand;
          }
          return ExprEvalUtils.calculate(this, num);
      }
  
      @Override
      public Number calculate(Integer num) {
          if (num == null)
              return null;
          int n = num.intValue();
          if (n == Integer.MIN_VALUE) {
              return new Long(-(long) n);
          }
          return new Integer(-n);
      }
  
      @Override
      public Number calculate(Long num) {
          if (num == null)
              return null;
          long n = num.longValue();
          if (n == Long.MIN_VALUE) {
              return new Long(-(long) n);
          }
          return new Long(-n);
      }
  
      @Override
      public Number calculate(BigInteger num) {
          if (num == null)
              return null;
          return num.negate();
      }
  
      @Override
      public Number calculate(BigDecimal num) {
          if (num == null)
              return null;
          return num.negate();
      }
  }
  