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Java > Open Source Codes > net > sf > jasperreports > engine > fill > JRExtendedIncrementer


1 /*
2  * ============================================================================
3  * GNU Lesser General Public License
4  * ============================================================================
5  *
6  * JasperReports - Free Java report-generating library.
7  * Copyright (C) 2001-2006 JasperSoft Corporation http://www.jaspersoft.com
8  *
9  * This library is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU Lesser General Public
11  * License as published by the Free Software Foundation; either
12  * version 2.1 of the License, or (at your option) any later version.
13  *
14  * This library is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17  * Lesser General Public License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with this library; if not, write to the Free Software
21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
22  *
23  * JasperSoft Corporation
24  * 303 Second Street, Suite 450 North
25  * San Francisco, CA 94107
26  * http://www.jaspersoft.com
27  */
28 package net.sf.jasperreports.engine.fill;
29
30 import net.sf.jasperreports.engine.JRException;
31
32 /**
33  * Extended incrementer interface.
34  * <p>
35  * The {@link net.sf.jasperreports.engine.fill.JRIncrementer JRIncrementer} has been
36  * kept for backward compatibility.
37  * <p>
38  * The crosstab calculation engine requires extended incrementers. An incrementer implementing
39  * {@link net.sf.jasperreports.engine.fill.JRIncrementer JRIncrementer} can be used for report
40  * variables only.
41  *
42  * @author Lucian Chirita (lucianc@users.sourceforge.net)
43  * @version $Id: JRExtendedIncrementer.java 1229 2006-04-19 13:27:35 +0300 (Wed, 19 Apr 2006) teodord $
44  */
45 public interface JRExtendedIncrementer extends JRIncrementer
46 {
47     /**
48      * Increments a calculable object with a value.
49      *
50      * @param calculable the calculable
51      * @param expressionValue the value
52      * @param valueProvider value provider
53      * @return the incremented value
54      * @throws JRException
55      */
56     public Object JavaDoc increment(
57             JRCalculable calculable,
58             Object JavaDoc expressionValue,
59             AbstractValueProvider valueProvider
60             ) throws JRException;
61
62     /**
63      * Returns the initial value for this calculation.
64      * <p>
65      * This method should return a neutral value for this calculation
66      * (e.g. 0 for sum, 1 for product, etc) or a default value if no neutral value exists.
67      *
68      * @return the initial value for this calculation
69      */
70     public Object JavaDoc initialValue();
71
72     /**
73      * Combines two calculated values into one.
74      *
75      * @param calculable the first calculated value
76      * @param calculableValue the second calculated value
77      * @param valueProvider the value provider used for the helper variables
78      * @return the combined value
79      * @throws JRException
80      */
81     public Object JavaDoc combine(
82         JRCalculable calculable,
83         JRCalculable calculableValue,
84         AbstractValueProvider valueProvider
85         ) throws JRException;
86
87 }
88
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