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Java > Open Source Codes > com > caucho > el > BooleanLiteral


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.el;
30
31 import com.caucho.vfs.WriteStream;
32
33 import javax.el.ELContext;
34 import javax.el.ELException;
35 import java.io.IOException JavaDoc;
36
37 /**
38  * A boolean literal expression.
39  */
40 public class BooleanLiteral extends AbstractBooleanExpr {
41   private boolean _value;
42
43   /**
44    * Creates a new boolean literal.
45    *
46    * @param value the value
47    */
48   public BooleanLiteral(boolean value)
49   {
50     _value = value;
51   }
52
53   /**
54    * Returns true if the expression is constant.
55    */
56   public boolean isConstant()
57   {
58     return true;
59   }
60   
61   /**
62    * Evaluate the expression as an boolean
63    *
64    * @param env the variable environment
65    *
66    * @return the value as a boolean
67    */
68   @Override JavaDoc
69   public boolean evalBoolean(ELContext env)
70     throws ELException
71   {
72     return _value;
73   }
74
75   /**
76    * Prints the Java code to recreate the BooleanLiteral.
77    *
78    * @param os the output stream to the *.java code.
79    */
80   public void printCreate(WriteStream os)
81     throws IOException JavaDoc
82   {
83     os.print("new com.caucho.el.BooleanLiteral(");
84     os.print(_value);
85     os.print(")");
86   }
87
88   /**
89    * Returns true for equal strings.
90    */
91   public boolean equals(Object JavaDoc o)
92   {
93     if (! (o instanceof BooleanLiteral))
94       return false;
95
96     BooleanLiteral literal = (BooleanLiteral) o;
97
98     return _value == literal._value;
99   }
100   
101   /**
102    * Returns a readable representation of the expr.
103    */
104   public String JavaDoc toString()
105   {
106     return String.valueOf(_value);
107   }
108 }
109
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