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


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.util.ArrayList JavaDoc;
47 import java.util.Vector JavaDoc;
48
49 import java.sql.SQLException JavaDoc;
50
51 import com.quadcap.sql.types.Op;
52 import com.quadcap.sql.types.Type;
53 import com.quadcap.sql.types.Value;
54
55 import com.quadcap.util.Debug;
56 import com.quadcap.util.Util;
57
58 /**
59  * Expression class for names (typically column or function names).
60  *
61  * @author Stan Bailes
62  */
63 public class NameExpression extends Expression implements Externalizable JavaDoc {
64     String JavaDoc name;
65     boolean not = false;
66
67     /**
68      * Default constructor
69      */
70     public NameExpression() {}
71     
72     public NameExpression(String JavaDoc name) {
73     this.name = name;
74     }
75
76     /**
77      * I'm a scalar, basically
78      */
79     public int rank() { return 0; }
80     
81     public Type getType(Session session, Cursor cursor) throws SQLException JavaDoc {
82         String JavaDoc rname = session.getConnection().resolveColname(name, cursor);
83         Column c = cursor.getColumn(rname);
84         return c.getType();
85    }
86     
87     public Value getValue(Session session, Cursor cursor) throws SQLException JavaDoc {
88     Cursor effectiveCursor = cursor;
89         if (cursor == null) {
90             throw new SQLException JavaDoc("No cursor for name expression: " + name, "42000");
91         }
92         String JavaDoc rname = session.getConnection().resolveColname(name, cursor);
93         Column c = cursor.getColumn(rname);
94         if (c == null) {
95             throw new SQLException JavaDoc("Bad column: " + name, "Q000S");
96         }
97         Tuple tc = c.getRelation();
98         if (tc instanceof Cursor && !(cursor instanceof StaticCursor)) {
99             effectiveCursor = (Cursor)tc;
100         }
101             
102         int col = c.getColumn();
103     Row row = effectiveCursor.getRow();
104     if (row == null) {
105         throw new SQLException JavaDoc("no cursor", "Q000T");
106     }
107     Value v = row.item(col);
108     if (not) v = v.unop(Op.NOT);
109     return v;
110     }
111
112     public Row getValues(Session session, Cursor cursor) throws SQLException JavaDoc {
113     ArrayList JavaDoc v = new ArrayList JavaDoc();
114     v.add(getValue(session, cursor));
115     return new Row(v);
116     }
117
118     public String JavaDoc getName() { return name; }
119     
120     public void invert() {
121     not = !not;
122     }
123
124     public void visitSubExpressions(ExpressionVisitor ev) {
125     }
126
127     public void readExternal(ObjectInput JavaDoc in)
128     throws IOException JavaDoc, ClassNotFoundException JavaDoc
129     {
130     name = (String JavaDoc)in.readObject();
131     }
132     
133     public void writeExternal(ObjectOutput JavaDoc out) throws IOException JavaDoc {
134     out.writeObject(name);
135     }
136
137     public String JavaDoc toString() {
138     return name;
139     }
140 }
141
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