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 2011-4-13)
   */
  package com.alibaba.cobar.parser.ast.expression;
  
  import java.util.Map;
  
  /**
   * an operator with arity of 3<br/>
   * left conbine in default
   * 
   * @author <a href="mailto:shuo.qius@alibaba-inc.com">QIU Shuo</a>
   */
  public abstract class BinaryOperatorExpression extends AbstractExpression {
      protected final Expression leftOprand;
      protected final Expression rightOprand;
      protected final int precedence;
      protected final boolean leftCombine;
  
      /**
       * {@link #leftCombine} is true
       */
      protected BinaryOperatorExpression(Expression leftOprand, Expression rightOprand, int precedence) {
          this.leftOprand = leftOprand;
          this.rightOprand = rightOprand;
          this.precedence = precedence;
          this.leftCombine = true;
      }
  
      protected BinaryOperatorExpression(Expression leftOprand, Expression rightOprand, int precedence,
                                         boolean leftCombine) {
          this.leftOprand = leftOprand;
          this.rightOprand = rightOprand;
          this.precedence = precedence;
          this.leftCombine = leftCombine;
      }
  
      public Expression getLeftOprand() {
          return leftOprand;
      }
  
      public Expression getRightOprand() {
          return rightOprand;
      }
  
      @Override
      public int getPrecedence() {
          return precedence;
      }
  
      public boolean isLeftCombine() {
          return leftCombine;
      }
  
      public abstract String getOperator();
  
      @Override
      public Object evaluationInternal(Map<? extends Object, ? extends Object> parameters) {
          return UNEVALUATABLE;
      }
  
  }
  