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Java > Open Source Codes > net > sf > jasperreports > engine > JRExpression


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;
29
30
31 /**
32  * @author Teodor Danciu (teodord@users.sourceforge.net)
33  * @version $Id: JRExpression.java 1229 2006-04-19 13:27:35 +0300 (Wed, 19 Apr 2006) teodord $
34  */
35 public interface JRExpression
36 {
37
38
39     /**
40      * A constant specifying that an expression should be evaluated at the exact moment in the filling process
41      * when it is encountered.
42      */
43     public static final byte EVALUATION_TIME_NOW = 1;
44
45
46     /**
47      * A constant specifying that an expression should be evaluated at the end of the filling process.
48      */
49     public static final byte EVALUATION_TIME_REPORT = 2;
50
51
52     /**
53      * A constant specifying that an expression should be evaluated after each page is filled.
54      */
55     public static final byte EVALUATION_TIME_PAGE = 3;
56
57
58     /**
59      * A constant specifying that an expression should be evaluated after each column is filled.
60      */
61     public static final byte EVALUATION_TIME_COLUMN = 4;
62
63
64     /**
65      * A constant specifying that an expression should be evaluated after each group break.
66      */
67     public static final byte EVALUATION_TIME_GROUP = 5;
68
69
70     /**
71      * The element will be evaluated at band end.
72      */
73     public static final byte EVALUATION_TIME_BAND = 6;
74
75     
76     /**
77      * Evaluation time indicating that each variable participating in the expression
78      * should be evaluated at a time decided by the engine.
79      * <p/>
80      * Variables will be evaluated at a time corresponding to their reset type.
81      * Fields are evaluated "now", i.e. at the time the band the element lies on gets filled.
82      * <p/>
83      * This evaluation type should be used when report elements having expressions that combine
84      * values evaluated at different times are required (e.g. percentage out of a total).
85      * <p/>
86      * NB: avoid using this evaluation type when other types suffice as it can lead
87      * to performance loss.
88      */
89     public static final byte EVALUATION_TIME_AUTO = 7;
90
91     /**
92      *
93      */
94     public static final byte EVALUATION_OLD = 1;
95     public static final byte EVALUATION_ESTIMATED = 2;
96     public static final byte EVALUATION_DEFAULT = 3;
97
98     /**
99      * Dummy ID that is assigned to expression that are not used (and not collected).
100      */
101     public static final Integer JavaDoc NOT_USED_ID = new Integer JavaDoc(-1);
102
103     /**
104      * Returns the expression return value class.
105      */
106     public Class JavaDoc getValueClass();
107     
108     /**
109      * Returns the expression return value class.
110      */
111     public String JavaDoc getValueClassName();
112     
113     /**
114      *
115      */
116     public int getId();
117             
118     /**
119      *
120      */
121     public JRExpressionChunk[] getChunks();
122
123     /**
124      *
125      */
126     public String JavaDoc getText();
127
128
129 }
130
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