1 package org.drools.reteoo.impl;
2
3 /*
4 $Id: ObjectTypeNodeImpl.java,v 1.4 2002/08/25 21:15:06 bob 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.drools.WorkingMemory;
50 import org.drools.FactException;
51 import org.drools.AssertionException;
52 import org.drools.RetractionException;
53 import org.drools.reteoo.ObjectTypeNode;
54 import org.drools.spi.ObjectType;
55
56 import java.util.Set;
57 import java.util.HashSet;
58 import java.util.Collections;
59 import java.util.Iterator;
60
61 /*** Filters <code>Objects</code> coming from the <code>Rete</code>
62 * using a <code>ObjectType</code> semantic module.
63 *
64 * <p>
65 * It receives <code>Objects</code> from the <code>Rete</code>,
66 * uses a <code>ObjectType</code> instance to determine membership,
67 * and propagates matching <code>Objects</code> further to all
68 * matching <code>ParameterNode</code>s.
69 * </p>
70 *
71 * @see ObjectTypeNode
72 * @see ObjectType
73 * @see ParameterNodeImpl
74 * @see ReteImpl
75 *
76 * @author <a href="mailto:bob@eng.werken.com">bob@eng.werken.com</a>
77 */
78 public class ObjectTypeNodeImpl implements ObjectTypeNode
79 {
80 // ------------------------------------------------------------
81 // Instance members
82 // ------------------------------------------------------------
83
84 /*** The <code>ObjectType</code> semantic module. */
85 private ObjectType objectType;
86
87 /*** The <code>ParameterNode</code> children. */
88 private Set parameterNodes;
89
90 // ------------------------------------------------------------
91 // Constructors
92 // ------------------------------------------------------------
93
94 /*** Construct given a semantic <code>ObjectType</code>.
95 *
96 * @param objectType The semantic object-type differentiator.
97 */
98 public ObjectTypeNodeImpl(ObjectType objectType)
99 {
100 this.objectType = objectType;
101
102 this.parameterNodes = Collections.EMPTY_SET;
103 }
104
105 // ------------------------------------------------------------
106 // Instance methods
107 // ------------------------------------------------------------
108
109 /*** Retrieve the semantic <code>ObjectType</code> differentiator.
110 *
111 * @return The semantic <code>ObjectType</code> differentiator.
112 */
113 public ObjectType getObjectType()
114 {
115 return this.objectType;
116 }
117
118 /*** Add a <code>ParameterNode</code> child to this node.
119 *
120 * @param node The <code>ParameterNode</code> child to add.
121 */
122 void addParameterNode(ParameterNodeImpl node)
123 {
124 if ( this.parameterNodes == Collections.EMPTY_SET )
125 {
126 this.parameterNodes = new HashSet();
127 }
128
129 this.parameterNodes.add( node );
130 }
131
132 /*** Retrieve the <code>Set</code> of <code>ParameterNodes/code>
133 * children of this node.
134 *
135 * @return The <code>Set</code> of <code>ParameterNode</code>
136 * children.
137 */
138 Set getParameterNodes()
139 {
140 return this.parameterNodes;
141 }
142
143 /*** Retreive an <code>Iterator</code> over <code>ParameterNode</code>
144 * children of this node.
145 *
146 * @return An <code>Iterator</code> over <code>ParameterNode</code>
147 * children of this node.
148 */
149 Iterator getParameterNodeIterator()
150 {
151 return this.parameterNodes.iterator();
152 }
153
154 /*** Assert a new fact object into this <code>RuleBase</code>
155 * and the specified <code>WorkingMemory</code>.
156 *
157 * @param object The object to assert.
158 * @param workingMemory The working memory session.
159 *
160 * @throws AssertionException if an error occurs during assertion.
161 */
162 void assertObject(Object object,
163 WorkingMemory workingMemory) throws AssertionException
164 {
165 ObjectType objectType = getObjectType();
166
167 if ( ! objectType.matches( object ) )
168 {
169 return;
170 }
171
172 Iterator nodeIter = getParameterNodeIterator();
173 ParameterNodeImpl eachNode = null;
174
175 while ( nodeIter.hasNext() )
176 {
177 eachNode = (ParameterNodeImpl) nodeIter.next();
178
179 eachNode.assertObject( object,
180 workingMemory );
181 }
182 }
183
184 /*** Retract a fact object from this <code>RuleBase</code>
185 * and the specified <code>WorkingMemory</code>.
186 *
187 * @param object The object to retract.
188 * @param workingMemory The working memory session.
189 *
190 * @throws RetractionException if an error occurs during assertion.
191 */
192 void retractObject(Object object,
193 WorkingMemory workingMemory) throws RetractionException
194 {
195 ObjectType objectType = getObjectType();
196
197 if ( ! objectType.matches( object ) )
198 {
199 return;
200 }
201
202 Iterator nodeIter = getParameterNodeIterator();
203 ParameterNodeImpl eachNode = null;
204
205 while ( nodeIter.hasNext() )
206 {
207 eachNode = (ParameterNodeImpl) nodeIter.next();
208
209 eachNode.retractObject( object,
210 workingMemory );
211 }
212 }
213
214 /*** Modify a fact object in this <code>RuleBase</code>
215 * and the specified <code>WorkingMemory</code>.
216 *
217 * With the exception of time-based nodes, modification of
218 * a fact object is semantically equivelent to retracting and
219 * re-asserting it.
220 *
221 * @param object The object to modify.
222 * @param workingMemory The working memory session.
223 *
224 * @throws FactException if an error occurs during assertion.
225 */
226 void modifyObject(Object object,
227 WorkingMemory workingMemory) throws FactException
228 {
229 ObjectType objectType = getObjectType();
230
231 if ( ! objectType.matches( object ) )
232 {
233 return;
234 }
235
236 Iterator nodeIter = getParameterNodeIterator();
237 ParameterNodeImpl eachNode = null;
238
239 while ( nodeIter.hasNext() )
240 {
241 eachNode = (ParameterNodeImpl) nodeIter.next();
242
243 eachNode.modifyObject( object,
244 workingMemory );
245 }
246 }
247 }
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