GetHistoricalIDQuery


1   /*
2    *    Copyright 2004 Dusty Phillips
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *     http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package com.buchuki.ensmer.prevayler.queries;
17  
18  import java.util.Date  ;
19  import com.buchuki.ensmer.prevayler.*;
20  
21  import org.prevayler.*;
22  
23  /**
24   * Query to retrieve the area that has a particular position in the history
25   * of areas visited.
26   *
27   * @author   Dusty Phillips [dusty@buchuki.com]
28   */
29  public class GetHistoricalIDQuery implements Query {
30  
31      /**
32       * Construct the Query with a reference to the identifier that needs to be
33       * queried.
34       *
35       * @param index the position in history to retrieve an ID for. 0 is the
36       * current area, 1 is the previous area, positive numbers are previous areas
37       * -1 is the next area, negative numbers are next areas.
38       */
39      public GetHistoricalIDQuery(int index) {
40          this.index = index;
41      }
42  
43      /**
44       * Execute the query
45       *
46       * @param system   the EnsmerPrevayler to interact with
47       * @param ignored  the date the item is executed, ignored in this case
48       * @return         the query's result
49       */
50      public Object   query(Object   system, Date   ignored) {
51          return ((EnsmerPrevayler) system).getAreaPrevayler().getHistoricalAreaID(index);
52      }
53  
54      /**
55       * The identifier of the Object that we want to retrieve the identifier for.
56       */
57      private int index;
58  }
59  
60
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