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Java > Open Source Codes > com > caucho > quercus > expr > LiteralExpr


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.quercus.expr;
31
32 import com.caucho.quercus.Location;
33 import com.caucho.quercus.env.BooleanValue;
34 import com.caucho.quercus.env.Env;
35 import com.caucho.quercus.env.LongValue;
36 import com.caucho.quercus.env.Value;
37
38 /**
39  * Represents a literal expression.
40  */
41 public class LiteralExpr extends Expr {
42   private final Value _value;
43
44   protected LiteralExpr(Location location, Value value)
45   {
46     super(location);
47     _value = value;
48   }
49
50   public LiteralExpr(Value value)
51   {
52     this(Location.UNKNOWN, value);// acceptable, for compiled code
53 }
54
55   protected Value getValue()
56   {
57     return _value;
58   }
59
60   /**
61    * Returns true for a literal expression.
62    */
63   public boolean isLiteral()
64   {
65     return true;
66   }
67
68   /**
69    * Returns true if a static true value.
70    */
71   public boolean isTrue()
72   {
73     if (_value == BooleanValue.TRUE)
74       return true;
75     else if (_value instanceof LongValue)
76       return _value.toLong() != 0;
77     else
78       return false;
79   }
80
81   /**
82    * Returns true if a static true value.
83    */
84   public boolean isFalse()
85   {
86     if (_value == BooleanValue.FALSE)
87       return true;
88     else if (_value instanceof LongValue)
89       return _value.toLong() == 0;
90     else
91       return false;
92   }
93
94   /**
95    * Returns true for a long value.
96    */
97   public boolean isLong()
98   {
99     return _value.isLongConvertible();
100   }
101
102   /**
103    * Returns true for a double value.
104    */
105   public boolean isDouble()
106   {
107     return _value.isDoubleConvertible();
108   }
109
110   /**
111    * Evaluates the expression as a constant.
112    *
113    * @return the expression value.
114    */
115   public Value evalConstant()
116   {
117     return _value;
118   }
119
120   /**
121    * Evaluates the expression.
122    *
123    * @param env the calling environment.
124    *
125    * @return the expression value.
126    */
127   public Value eval(Env env)
128   {
129     return _value;
130   }
131
132   public String JavaDoc toString()
133   {
134     return _value.toString();
135   }
136 }
137
138
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