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


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  * Free SoftwareFoundation, Inc.
23  * 59 Temple Place, Suite 330
24  * Boston, MA 02111-1307 USA
25  *
26  * @author Scott Ferguson
27  */
28
29 package com.caucho.db.sql;
30
31 import com.caucho.log.Log;
32
33 import java.sql.SQLException JavaDoc;
34 import java.util.ArrayList JavaDoc;
35 import java.util.logging.Logger JavaDoc;
36
37 class OrExpr extends Expr {
38   private static final Logger JavaDoc log = Log.open(OrExpr.class);
39
40   private Expr _left;
41   private Expr _right;
42
43   OrExpr(Expr left, Expr right)
44   {
45     _left = left;
46     _right = right;
47   }
48
49   protected Expr bind(Query query)
50     throws SQLException JavaDoc
51   {
52     Expr newLeft = _left.bind(query);
53     Expr newRight = _right.bind(query);
54
55     if (! newLeft.isBoolean())
56       throw new SQLException JavaDoc(L.l("OR requires boolean operands"));
57     if (! newRight.isBoolean())
58       throw new SQLException JavaDoc(L.l("OR requires boolean operands"));
59
60     if (_left == newLeft && _right == newRight)
61       return this;
62     else
63       return new OrExpr(newLeft, newRight);
64   }
65
66   /**
67    * Returns the type of the expression.
68    */
69   public Class JavaDoc getType()
70   {
71     return boolean.class;
72   }
73
74   /**
75    * Returns the cost based on the given FromList.
76    */
77   public long subCost(ArrayList JavaDoc<FromItem> fromList)
78   {
79     return Integer.MAX_VALUE;
80   }
81
82   /**
83    * Returns true if the expressoin evaluates to null
84    */
85   public boolean isNull(QueryContext context)
86     throws SQLException JavaDoc
87   {
88     return evalBoolean(context) == UNKNOWN;
89   }
90
91   /**
92    * Evaluates the expression as a boolean.
93    */
94   public int evalBoolean(QueryContext context)
95     throws SQLException JavaDoc
96   {
97     int leftValue = _left.evalBoolean(context);
98
99     if (leftValue == TRUE)
100       return TRUE;
101
102     int rightValue = _right.evalBoolean(context);
103
104     if (rightValue == TRUE)
105       return TRUE;
106
107     if (leftValue == FALSE && rightValue == FALSE)
108       return FALSE;
109     else
110       return UNKNOWN;
111   }
112
113   public String JavaDoc evalString(QueryContext context)
114     throws SQLException JavaDoc
115   {
116     switch (evalBoolean(context)) {
117     case TRUE:
118       return "1";
119     case FALSE:
120       return "0";
121     default:
122       return null;
123     }
124   }
125
126   public String JavaDoc toString()
127   {
128     return "(" + _left + " OR " + _right + ")";
129   }
130 }
131
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