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Java > Open Source Codes > org > objectstyle > cayenne > access > RelationshipUpdate


1 /* ====================================================================
2  *
3  * The ObjectStyle Group Software License, version 1.1
4  * ObjectStyle Group - http://objectstyle.org/
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6  * Copyright (c) 2002-2005, Andrei (Andrus) Adamchik and individual authors
7  * of the software. All rights reserved.
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10  * modification, are permitted provided that the following conditions
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13  * 1. Redistributions of source code must retain the above copyright
14  * notice, this list of conditions and the following disclaimer.
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22  * must include the following acknowlegement:
23  * "This product includes software developed by independent contributors
24  * and hosted on ObjectStyle Group web site (http://objectstyle.org/)."
25  * Alternately, this acknowlegement may appear in the software itself,
26  * if and wherever such third-party acknowlegements normally appear.
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51  * This software consists of voluntary contributions made by many
52  * individuals and hosted on ObjectStyle Group web site. For more
53  * information on the ObjectStyle Group, please see
54  * <http://objectstyle.org/>.
55  */
56 package org.objectstyle.cayenne.access;
57
58 import org.objectstyle.cayenne.DataObject;
59 import org.objectstyle.cayenne.map.ObjRelationship;
60
61 /**
62  * A holder of relationship modification data. Used for tracking relationship
63  * modifications that can't be derived on the fly from object graph. Overrides
64  * Object.equals() and Object.hasCode() to allow smart comparison of different
65  * RelationshipUpdate objects.
66  *
67  * @author Andrei Adamchik
68  * @since 1.2
69  */
70 class RelationshipUpdate {
71
72     DataObject source;
73     DataObject destination;
74     ObjRelationship relationship;
75     ObjRelationship reverseRelationship;
76     String JavaDoc compareToken;
77
78     RelationshipUpdate(DataObject source, DataObject destination,
79             ObjRelationship relationship) {
80
81         this.source = source;
82         this.destination = destination;
83         this.relationship = relationship;
84         this.reverseRelationship = relationship.getReverseRelationship();
85
86         // build a string token to make comparison (or at least hashcode) indepent from
87 // direction
88 String JavaDoc relName1 = relationship.getName();
89         if (reverseRelationship != null) {
90             String JavaDoc relName2 = reverseRelationship.getName();
91
92             // Find the lexically lesser name and use it as the name of the source, then
93 // use the second.
94 // If equal (the same name), it doesn't matter which order...
95 if (relName1.compareTo(relName2) <= 0) {
96                 this.compareToken = relName1 + "." + relName2;
97             }
98             else {
99                 this.compareToken = relName2 + "." + relName1;
100             }
101         }
102         else {
103             this.compareToken = relName1;
104         }
105     }
106
107     boolean isBidirectional() {
108         return reverseRelationship != null;
109     }
110
111     /**
112      * Defines equal based on whether the relationship is bidirectional.
113      */
114     public boolean equals(Object JavaDoc object) {
115
116         if (!(object instanceof RelationshipUpdate)) {
117             return false;
118         }
119
120         if (this == object) {
121             return true;
122         }
123
124         RelationshipUpdate update = (RelationshipUpdate) object;
125
126         if (!this.compareToken.equals(update.compareToken)) {
127             return false;
128         }
129
130         boolean bidi = isBidirectional();
131         if (bidi != update.isBidirectional()) {
132             return false;
133         }
134
135         return (bidi) ? bidiEquals(update) : uniEquals(update);
136     }
137
138     public int hashCode() {
139         // TODO: use hashcode builder to make a better hashcode...though
140 // RelationshipUpdate is stored in collections, not maps, so it is probably
141 // irrelevant.
142 return source.hashCode() + destination.hashCode() + compareToken.hashCode();
143     }
144
145     boolean bidiEquals(RelationshipUpdate update) {
146         return (this.source.equals(update.source) && this.destination
147                 .equals(update.destination))
148                 || (this.source.equals(update.destination) && this.destination
149                         .equals(update.source));
150     }
151
152     boolean uniEquals(RelationshipUpdate update) {
153         return (this.source.equals(update.source) && this.destination
154                 .equals(update.destination));
155     }
156
157     ObjRelationship getRelationship() {
158         return relationship;
159     }
160
161     ObjRelationship getReverseRelationship() {
162         return reverseRelationship;
163     }
164
165     /**
166      * Returns the destination object of the relationship.
167      */
168     DataObject getDestination() {
169         return destination;
170     }
171
172     /**
173      * Returns the source object of the relationship.
174      */
175     DataObject getSource() {
176         return source;
177     }
178
179 }
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