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Java > Open Source Codes > com > quadcap > sql > AddConstraint


1 package com.quadcap.sql;
2
3 /* Copyright 1999 - 2003 Quadcap Software. All rights reserved.
4  *
5  * This software is distributed under the Quadcap Free Software License.
6  * This software may be used or modified for any purpose, personal or
7  * commercial. Open Source redistributions are permitted. Commercial
8  * redistribution of larger works derived from, or works which bundle
9  * this software requires a "Commercial Redistribution License"; see
10  * http://www.quadcap.com/purchase.
11  *
12  * Redistributions qualify as "Open Source" under one of the following terms:
13  *
14  * Redistributions are made at no charge beyond the reasonable cost of
15  * materials and delivery.
16  *
17  * Redistributions are accompanied by a copy of the Source Code or by an
18  * irrevocable offer to provide a copy of the Source Code for up to three
19  * years at the cost of materials and delivery. Such redistributions
20  * must allow further use, modification, and redistribution of the Source
21  * Code under substantially the same terms as this license.
22  *
23  * Redistributions of source code must retain the copyright notices as they
24  * appear in each source code file, these license terms, and the
25  * disclaimer/limitation of liability set forth as paragraph 6 below.
26  *
27  * Redistributions in binary form must reproduce this Copyright Notice,
28  * these license terms, and the disclaimer/limitation of liability set
29  * forth as paragraph 6 below, in the documentation and/or other materials
30  * provided with the distribution.
31  *
32  * The Software is provided on an "AS IS" basis. No warranty is
33  * provided that the Software is free of defects, or fit for a
34  * particular purpose.
35  *
36  * Limitation of Liability. Quadcap Software shall not be liable
37  * for any damages suffered by the Licensee or any third party resulting
38  * from use of the Software.
39  */
40
41 import java.io.Externalizable JavaDoc;
42 import java.io.IOException JavaDoc;
43 import java.io.ObjectInput JavaDoc;
44 import java.io.ObjectOutput JavaDoc;
45
46 import java.sql.SQLException JavaDoc;
47
48 import com.quadcap.sql.io.Extern;
49
50 import com.quadcap.util.Debug;
51
52 /**
53  * Log step to add a constraint to a table.
54  *
55  * @author Stan Bailes
56  */
57 public class AddConstraint extends LogStep implements Externalizable JavaDoc {
58     transient Table table;
59
60     Constraint constraint;
61     String JavaDoc tableName = null;
62     boolean global;
63
64     /**
65      * Default constructor
66      */
67     public AddConstraint() {}
68
69     /**
70      * Explicit constructor: {table, constraint, global flag}
71      */
72     public AddConstraint(Session session, Table table, Constraint constraint,
73              boolean global) {
74         super(session);
75     this.table = table;
76     this.constraint = constraint;
77         table.nameConstraint(constraint);
78     this.global = global;
79     this.tableName = table.getName();
80     }
81
82     /**
83      * Constructor for a non-global constraint
84      */
85     public AddConstraint(Session session, Table table, Constraint constraint) {
86     this(session, table, constraint, false);
87     }
88
89     /**
90      * Lazy table accessor
91      */
92     Table getTable(Database db) throws IOException JavaDoc {
93     if (table == null) {
94         table = (Table)db.getRelation(tableName);
95     }
96     return table;
97     }
98
99     /**
100      * LogStep.undo(): delete the constraint; perform any constraint-specified
101      * cleanup, and remove the constraint from the table.
102      */
103     public void undo(Session session) throws IOException JavaDoc, SQLException JavaDoc {
104     Database db = session.getDatabase();
105     getTable(db);
106     constraint = table.getConstraint(constraint.getName());
107         // Generally, we will have a constraint here. But if things have
108 // already gone badly, the constraint might not have actually been
109 // added. So don't freak out if you can't find it.
110 if (constraint != null) {
111             table.deleteConstraint(constraint.getName());
112             constraint.undoAdd(session);
113             db.updateRelation(table);
114             db.deleteIndex(constraint.getName());
115         }
116     }
117
118     /**
119      * LogStep.redo(): add the constrtaint, perform any constraint-specific
120      * initialization, and update the table with the new constraint
121      */
122     public void redo(Session session) throws IOException JavaDoc, SQLException JavaDoc {
123     Database db = session.getDatabase();
124     getTable(db);
125     table.addConstraint(constraint);
126     constraint.add(session);
127     db.updateRelation(table);
128     db.addIndex(constraint.getName(), tableName);
129     }
130
131     /**
132      * LogStep.prepare(): A good constraint prepares his table, anyway
133      */
134     public void prepare(Session session) throws IOException JavaDoc, SQLException JavaDoc {
135     constraint.setTable(getTable(session.getDatabase()));
136     }
137
138     /**
139      * Read me from a stream
140      */
141     public void readExternal(ObjectInput JavaDoc in)
142     throws IOException JavaDoc, ClassNotFoundException JavaDoc
143     {
144     super.readExternal(in);
145     this.constraint = (Constraint)in.readObject();
146     this.tableName = (String JavaDoc)in.readObject();
147     this.global = in.read() == 1;
148     }
149
150     /**
151      * Write me to a stream
152      */
153     public void writeExternal(ObjectOutput JavaDoc out) throws IOException JavaDoc {
154     super.writeExternal(out);
155     out.writeObject(constraint);
156     out.writeObject(tableName);
157     out.write(global ? 1 : 0);
158     }
159
160     /**
161      * My class's Extern object
162      */
163     static Extern extern;
164     public void setExtern(Extern extern) { AddConstraint.extern = extern; }
165     public Extern getExtern() { return extern; }
166
167     //#ifdef DEBUG
168 public String JavaDoc toString() {
169     StringBuffer JavaDoc sb = new StringBuffer JavaDoc(super.toString());
170         sb.append(" AddConstraint(");
171     sb.append(tableName);
172     sb.append(',');
173     sb.append(constraint == null ? "null" : constraint.toString());
174     return sb.toString();
175     }
176     //#endif
177
178 }
179
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