KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > com > caucho > db > sql > BooleanLiteralExpr


1 /*
2  * Copyright (c) 1998-2006 Caucho Technology -- all rights reserved
3  *
4  * This file is part of Resin(R) Open Source
5  *
6  * Each copy or derived work must preserve the copyright notice and this
7  * notice unmodified.
8  *
9  * Resin Open Source is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation; either version 2 of the License, or
12  * (at your option) any later version.
13  *
14  * Resin Open Source is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
17  * of NON-INFRINGEMENT. See the GNU General Public License for more
18  * details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with Resin Open Source; if not, write to the
22  *
23  * Free Software Foundation, Inc.
24  * 59 Temple Place, Suite 330
25  * Boston, MA 02111-1307 USA
26  *
27  * @author Scott Ferguson
28  */
29
30 package com.caucho.db.sql;
31
32 import com.caucho.log.Log;
33
34 import java.sql.SQLException JavaDoc;
35 import java.util.ArrayList JavaDoc;
36 import java.util.logging.Logger JavaDoc;
37
38 class BooleanLiteralExpr extends Expr {
39   private static final Logger JavaDoc log = Log.open(NullExpr.class);
40
41   private static BooleanLiteralExpr TRUE_EXPR = new BooleanLiteralExpr(true);
42   private static BooleanLiteralExpr FALSE_EXPR = new BooleanLiteralExpr(false);
43
44   private final boolean _value;
45
46   private BooleanLiteralExpr(boolean value)
47   {
48     _value = value;
49   }
50
51   static BooleanLiteralExpr create(boolean value)
52   {
53     return value ? TRUE_EXPR : FALSE_EXPR;
54   }
55
56   /**
57    * Returns false because the literal is never null;
58    */
59   public boolean isNull(QueryContext context)
60     throws SQLException JavaDoc
61   {
62     return false;
63   }
64
65   /**
66    * Returns the type of the expression.
67    */
68   public Class JavaDoc getType()
69   {
70     return boolean.class;
71   }
72
73   /**
74    * Returns true if the expression returns a boolean.
75    */
76   public boolean isBoolean()
77   {
78     return true;
79   }
80
81   /**
82    * Returns the cost based on the given FromList.
83    */
84   public long subCost(ArrayList JavaDoc<FromItem> fromList)
85   {
86     return 0;
87   }
88
89   /**
90    * Evaluates the literal as a string.
91    */
92   public String JavaDoc evalString(QueryContext context)
93     throws SQLException JavaDoc
94   {
95     return _value ? "1" : "0";
96   }
97
98   /**
99    * Evaluates the literal as a string.
100    */
101   public int evalBoolean(QueryContext context)
102     throws SQLException JavaDoc
103   {
104     return _value ? TRUE : FALSE;
105   }
106
107   public String JavaDoc toString()
108   {
109     return _value ? "TRUE" : "FALSE";
110   }
111 }
112
Popular Tags