01: /*
02: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
03: *
04: * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
05: *
06: * Portions Copyright Apache Software Foundation.
07: *
08: * The contents of this file are subject to the terms of either the GNU
09: * General Public License Version 2 only ("GPL") or the Common Development
10: * and Distribution License("CDDL") (collectively, the "License"). You
11: * may not use this file except in compliance with the License. You can obtain
12: * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
13: * or glassfish/bootstrap/legal/LICENSE.txt. See the License for the specific
14: * language governing permissions and limitations under the License.
15: *
16: * When distributing the software, include this License Header Notice in each
17: * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
18: * Sun designates this particular file as subject to the "Classpath" exception
19: * as provided by Sun in the GPL Version 2 section of the License file that
20: * accompanied this code. If applicable, add the following below the License
21: * Header, with the fields enclosed by brackets [] replaced by your own
22: * identifying information: "Portions Copyrighted [year]
23: * [name of copyright owner]"
24: *
25: * Contributor(s):
26: *
27: * If you wish your version of this file to be governed by only the CDDL or
28: * only the GPL Version 2, indicate your decision by adding "[Contributor]
29: * elects to include this software in this distribution under the [CDDL or GPL
30: * Version 2] license." If you don't indicate a single choice of license, a
31: * recipient has the option to distribute your version of this file under
32: * either the CDDL, the GPL Version 2 or to extend the choice of license to
33: * its licensees as provided above. However, if you add GPL Version 2 code
34: * and therefore, elected the GPL Version 2 license, then the option applies
35: * only if the new code is made subject to such option by the copyright
36: * holder.
37: */
38:
39: package org.apache.taglibs.standard.tag.common.core;
40:
41: import javax.servlet.jsp.JspException;
42: import javax.servlet.jsp.JspTagException;
43: import javax.servlet.jsp.jstl.core.ConditionalTagSupport;
44: import javax.servlet.jsp.tagext.Tag;
45:
46: import org.apache.taglibs.standard.resources.Resources;
47:
48: /**
49: * <p>WhenTagSupport is an abstract class that facilitates
50: * implementation of <when>-style tags in both the rtexprvalue
51: * and expression-evaluating libraries. It also supports
52: * <otherwise>.</p>
53: *
54: * <p>In particular, this base class does the following:</p>
55: *
56: * <ul>
57: * <li> overrides ConditionalTagSupport.doStartTag() to implement the
58: * appropriate semantics of subtags of <choose> </li>
59: * </ul>
60: *
61: * @author Shawn Bayern
62: */
63: public abstract class WhenTagSupport extends ConditionalTagSupport {
64: //*********************************************************************
65: // Implementation of exclusive-conditional behavior
66:
67: /*
68: * Includes its body if condition() evalutes to true AND its parent
69: * ChooseTag wants it to do so. The condition will not even be
70: * evaluated if ChooseTag instructs us not to run.
71: */
72: public int doStartTag() throws JspException {
73:
74: Tag parent;
75:
76: // make sure we're contained properly
77: if (!((parent = getParent()) instanceof ChooseTag))
78: throw new JspTagException(Resources
79: .getMessage("WHEN_OUTSIDE_CHOOSE"));
80:
81: // make sure our parent wants us to continue
82: if (!((ChooseTag) parent).gainPermission())
83: return SKIP_BODY; // we've been reeled in
84:
85: // handle conditional behavior
86: if (condition()) {
87: ((ChooseTag) parent).subtagSucceeded();
88: return EVAL_BODY_INCLUDE;
89: } else
90: return SKIP_BODY;
91: }
92: }
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