LogicExpression.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */
package org.apache.activemq.artemis.selector.filter;

/**
 * A filter performing a comparison of two objects
 *
 * @version $Revision: 1.2 $
 */
public abstract class LogicExpression extends BinaryExpression implements BooleanExpression {

   /**
    * @param left
    * @param right
    */
   public LogicExpression(BooleanExpression left, BooleanExpression right) {
      super(left, right);
   }

   public static BooleanExpression createOR(BooleanExpression lvalue, BooleanExpression rvalue) {
      return new LogicExpression(lvalue, rvalue) {

         @Override
         public Object evaluate(Filterable message) throws FilterException {

            Boolean lv = (Boolean) left.evaluate(message);
            // Can we do an OR shortcut??
            if (lv != null && lv.booleanValue()) {
               return Boolean.TRUE;
            }

            Boolean rv = (Boolean) right.evaluate(message);
            return rv == null ? null : rv;
         }

         @Override
         public String getExpressionSymbol() {
            return "OR";
         }
      };
   }

   public static BooleanExpression createAND(BooleanExpression lvalue, BooleanExpression rvalue) {
      return new LogicExpression(lvalue, rvalue) {

         @Override
         public Object evaluate(Filterable message) throws FilterException {

            Boolean lv = (Boolean) left.evaluate(message);

            // Can we do an AND shortcut??
            if (lv == null) {
               return null;
            }
            if (!lv.booleanValue()) {
               return Boolean.FALSE;
            }

            Boolean rv = (Boolean) right.evaluate(message);
            return rv == null ? null : rv;
         }

         @Override
         public String getExpressionSymbol() {
            return "AND";
         }
      };
   }

   @Override
   public abstract Object evaluate(Filterable message) throws FilterException;

   @Override
   public boolean matches(Filterable message) throws FilterException {
      Object object = evaluate(message);
      return object == Boolean.TRUE;
   }

}