1 package org.drools.tags.rule;
2
3 /*
4 $Id: RuleTagSupport.java,v 1.7 2003/03/25 19:47:32 tdiesler Exp $
5
6 Copyright 2002 (C) The Werken Company. All Rights Reserved.
7
8 Redistribution and use of this software and associated documentation
9 ("Software"), with or without modification, are permitted provided
10 that the following conditions are met:
11
12 1. Redistributions of source code must retain copyright
13 statements and notices. Redistributions must also contain a
14 copy of this document.
15
16 2. Redistributions in binary form must reproduce the
17 above copyright notice, this list of conditions and the
18 following disclaimer in the documentation and/or other
19 materials provided with the distribution.
20
21 3. The name "drools" must not be used to endorse or promote
22 products derived from this Software without prior written
23 permission of The Werken Company. For written permission,
24 please contact bob@werken.com.
25
26 4. Products derived from this Software may not be called "drools"
27 nor may "drools" appear in their names without prior written
28 permission of The Werken Company. "drools" is a registered
29 trademark of The Werken Company.
30
31 5. Due credit should be given to The Werken Company.
32 (http://drools.werken.com/).
33
34 THIS SOFTWARE IS PROVIDED BY THE WERKEN COMPANY AND CONTRIBUTORS
35 ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
36 NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
37 FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
38 THE WERKEN COMPANY OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
39 INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
40 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
41 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
42 HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
43 STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
44 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
45 OF THE POSSIBILITY OF SUCH DAMAGE.
46
47 */
48
49 import org.apache.commons.jelly.JellyTagException;
50 import org.apache.commons.jelly.MissingAttributeException;
51 import org.apache.commons.jelly.TagSupport;
52 import org.drools.rule.Declaration;
53 import org.drools.rule.Rule;
54 import org.drools.rule.RuleSet;
55
56 /*** Support for rule tags.
57 *
58 * @author <a href="mailto:bob@eng.werken.com">bob mcwhirter</a>
59 *
60 * @version $Id: RuleTagSupport.java,v 1.7 2003/03/25 19:47:32 tdiesler Exp $
61 */
62 public abstract class RuleTagSupport extends TagSupport
63 {
64 // ------------------------------------------------------------
65 // Constructors
66 // ------------------------------------------------------------
67
68 /*** Construct.
69 */
70 protected RuleTagSupport()
71 {
72 super( true );
73 }
74
75 // ------------------------------------------------------------
76 // Instance methods
77 // ------------------------------------------------------------
78
79 /*** Retrieve the current <code>RuleSet</code>.
80 *
81 * @return The current rule-set or <code>null</code> if
82 * no rule-set is in scope.
83 */
84 protected RuleSet getRuleSet()
85 {
86 RuleSetTag ruleSetTag = (RuleSetTag) findAncestorWithClass( RuleSetTag.class );
87
88 if ( ruleSetTag == null )
89 {
90 return null;
91 }
92
93 return ruleSetTag.getRuleSet();
94 }
95
96 /*** Retrieve the current <code>Rule<code>.
97 *
98 * @return The current rule.
99 */
100 protected Rule getRule()
101 {
102 RuleTag ruleTag = (RuleTag) findAncestorWithClass( RuleTag.class );
103
104 if ( ruleTag == null )
105 {
106 return null;
107 }
108
109 return ruleTag.getRule();
110 }
111
112 /*** Retrieve the array of available <code>Declaration</code>s.
113 *
114 * @return The array of declarations.
115 *
116 * @throws JellyTagException If no declarations are currently
117 * available in scope.
118 */
119 public Declaration[] getAvailableDeclarations() throws JellyTagException
120 {
121 Rule rule = getRule();
122
123 if ( rule == null )
124 {
125 throw new JellyTagException( "No rule available" );
126 }
127
128 return rule.getDeclarationsArray();
129 }
130
131 /*** Check required attribute.
132 *
133 * @param name Attribute name.
134 * @param value Attribute value.
135 *
136 * @throws MissingAttributeException If the value is either <code>null</code>
137 * or contains only whitespace.
138 */
139 protected void requiredAttribute(String name,
140 String value) throws MissingAttributeException
141 {
142 if ( value == null
143 ||
144 value.trim().equals( "" ) )
145 {
146 throw new MissingAttributeException( name );
147 }
148 }
149 }
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