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Java > Open Source Codes > com > mckoi > database > GroupResolver


1 /**
2  * com.mckoi.database.GroupResolver 14 Jul 2000
3  *
4  * Mckoi SQL Database ( http://www.mckoi.com/database )
5  * Copyright (C) 2000, 2001, 2002 Diehl and Associates, Inc.
6  *
7  * This program is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU General Public License
9  * Version 2 as published by the Free Software Foundation.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14  * GNU General Public License Version 2 for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * Version 2 along with this program; if not, write to the Free Software
18  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
19  *
20  * Change Log:
21  *
22  *
23  */
24
25 package com.mckoi.database;
26
27 import com.mckoi.util.IntegerVector;
28
29 /**
30  * Similar to VariableResolver, this method is used by grouping Functions to
31  * find information about the current group being evaluated (used for
32  * evaluating aggregate functions).
33  *
34  * @author Tobias Downer
35  */
36
37 public interface GroupResolver {
38
39   /**
40    * A number that uniquely identifies this group from all the others in the
41    * set of groups.
42    */
43   public int groupID();
44
45   /**
46    * The total number of set items in this group.
47    */
48   public int size();
49
50   /**
51    * Returns the value of a variable of a group. The set index signifies the
52    * set item of the group. For example, if the group contains 10 items, then
53    * set_index may be between 0 and 9. Return types must be either
54    * a String, BigDecimal or Boolean.
55    */
56   public TObject resolve(Variable variable, int set_index);
57
58   /**
59    * Returns a VariableResolver that can be used to resolve variable in the
60    * get set of the group. The object returned is undefined after the next
61    * call to this method.
62    */
63   public VariableResolver getVariableResolver(int set_index);
64
65 }
66
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