FunctionInfo


1   /**
2    * com.mckoi.database.FunctionInfo  17 Aug 2001
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  /**
28   * Meta information about a function.  Used to compile information about a
29   * particular function.
30   *
31   * @author Tobias Downer
32   */
33  
34  public interface FunctionInfo {
35  
36    /**
37     * A type that represents a static function.  A static function is not
38     * an aggregate therefore does not require a GroupResolver.  The result of
39     * a static function is guarenteed the same given identical parameters over
40     * subsequent calls.
41     */
42    public static final int STATIC      = 1;
43  
44    /**
45     * A type that represents an aggregate function.  An aggregate function
46     * requires the GroupResolver variable to be present in able to resolve the
47     * function over some set.  The result of an aggregate function is
48     * guarenteed the same given the same set and identical parameters.
49     */
50    public static final int AGGREGATE   = 2;
51  
52    /**
53     * A function that is non-aggregate but whose return value is not guarenteed
54     * to be the same given the identical parameters over subsequent calls.  This
55     * would include functions such as RANDOM and UNIQUEKEY.  The result is
56     * dependant on some other state (a random seed and a sequence value).
57     */
58    public static final int STATE_BASED = 3;
59  
60  
61  
62    /**
63     * The name of the function as used by the SQL grammar to reference it.
64     */
65    String   getName();
66  
67    /**
68     * The type of function, either STATIC, AGGREGATE or STATE_BASED (eg. result
69     * is not dependant entirely from input but from another state for example
70     * RANDOM and UNIQUEKEY functions).
71     */
72    int getType();
73  
74    /**
75     * The name of the function factory class that this function is handled by.
76     * For example, "com.mckoi.database.InternalFunctionFactory".
77     */
78    String   getFunctionFactoryName();
79  
80  }
81
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