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


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.Env;
34 import com.caucho.quercus.env.StringValueImpl;
35 import com.caucho.quercus.env.Value;
36
37 /**
38  * Represents a PHP constant expression.
39  */
40 public class ConstExpr extends Expr {
41   protected final String JavaDoc _var;
42
43   public ConstExpr(Location location, String JavaDoc var)
44   {
45     super(location);
46     _var = var;
47   }
48
49   public ConstExpr(String JavaDoc var)
50   {
51     this(Location.UNKNOWN, var);// acceptable, for compiled code
52 }
53
54   /**
55    * Returns the variable.
56    */
57   public String JavaDoc getVar()
58   {
59     return _var;
60   }
61
62   /**
63    * Evaluates the expression.
64    *
65    * @param env the calling environment.
66    *
67    * @return the expression value.
68    */
69   public Value eval(Env env)
70   {
71     Value value = env.getConstant(_var);
72
73     if (value == null)
74       value = new StringValueImpl(_var);
75
76     return value;
77   }
78
79   public String JavaDoc toString()
80   {
81     return _var;
82   }
83 }
84
85
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