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1   /*
2    * Copyright (c) 2011.  The Apache Software Foundation
3    *
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *     http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing, software
15   * distributed under the License is distributed on an "AS IS" BASIS,
16   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17   * See the License for the specific language governing permissions and
18   * limitations under the License.
19   */
20  
21  package org.apache.hadoop.hbase.hbql.statement;
22  
23  import org.apache.expreval.client.InternalErrorException;
24  import org.apache.hadoop.hbase.hbql.client.ExecutionResults;
25  import org.apache.hadoop.hbase.hbql.client.HBqlException;
26  import org.apache.hadoop.hbase.hbql.impl.HConnectionImpl;
27  
28  public abstract class GenericStatement {
29  
30      private StatementPredicate predicate = null;
31  
32      public GenericStatement() {
33      }
34  
35      protected GenericStatement(final StatementPredicate predicate) {
36          this.predicate = predicate;
37      }
38  
39      private StatementPredicate getPredicate() {
40          return this.predicate;
41      }
42  
43      public ExecutionResults evaluatePredicateAndExecute(final HConnectionImpl conn) throws HBqlException {
44          if (this.getPredicate() == null || this.getPredicate().evaluate(conn)) {
45              return this.execute(conn);
46          }
47          else {
48              final ExecutionResults results = new ExecutionResults("False predicate");
49              results.setPredicate(false);
50              return results;
51          }
52      }
53  
54      protected ExecutionResults execute(HConnectionImpl connection) throws HBqlException {
55          throw new InternalErrorException();
56      }
57  
58      public void validate() throws HBqlException {
59          // Default
60      }
61  }