SymbolTable


1   /*
2    * The contents of this file are subject to the terms 
3    * of the Common Development and Distribution License 
4    * (the License).  You may not use this file except in
5    * compliance with the License.
6    * 
7    * You can obtain a copy of the license at 
8    * https://glassfish.dev.java.net/public/CDDLv1.0.html or
9    * glassfish/bootstrap/legal/CDDLv1.0.txt.
10   * See the License for the specific language governing 
11   * permissions and limitations under the License.
12   * 
13   * When distributing Covered Code, include this CDDL 
14   * Header Notice in each file and include the License file 
15   * at glassfish/bootstrap/legal/CDDLv1.0.txt.  
16   * If applicable, add the following below the CDDL Header, 
17   * with the fields enclosed by brackets [] replaced by
18   * you own identifying information: 
19   * "Portions Copyrighted [year] [name of copyright owner]"
20   * 
21   * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
22   */
23  
24  
25  
26  /*
27   * SymbolTable.java
28   *
29   * Created on November 19, 2001
30   */
31  
32  package com.sun.jdo.spi.persistence.support.ejb.ejbqlc;
33  
34  import java.util.Map  ;
35  import java.util.HashMap  ;
36  
37  /**
38   * The symbol table handling declared identifies.
39   *
40   * @author  Michael Bouschen
41   */
42  public class SymbolTable
43  {
44      /**
45       * The table of declared identifier (symbols).
46       */
47      protected Map   symbols = new HashMap  ();
48  
49      /**
50       * This method adds the specified identifier to this SymbolTable. 
51       * The specified decl object provides details anbout the declaration. 
52       * If this SymbolTable already defines an identifier with the same name, 
53       * the SymbolTable is not changed and the existing declaration is returned. 
54       * Otherwise <code>null</code> is returned.
55       * @param   ident   identifier to be declared
56       * @param   definition new definition of identifier
57       * @return  the old definition if the identifier was already declared; 
58       * <code>null</code> otherwise
59       */
60      public Object   declare(String   ident, Object   decl)
61      {
62          Object   old = symbols.get(ident);
63          if (old == null) {
64              symbols.put(ident.toUpperCase(), decl);
65          }
66          return old;
67      }
68  
69      /**
70       * Checks whether the specified identifier is declared.  
71       * @param ident the name of identifier to be tested
72       * @return <code>true</code> if the identifier is declared; 
73       * <code>false</code> otherwise.
74       */
75      public boolean isDeclared(String   ident)
76      {
77          return (getDeclaration(ident) != null);
78      }
79  
80      /**
81       * Checks the symbol table for the actual declaration of the specified 
82       * identifier. The method returns the declaration object if available or
83       * <code>null</code> for an undeclared identifier. 
84       * @param ident the name of identifier
85       * @return the declaration object if ident is declared;
86       * <code>null</code> otherise.
87       */
88      public Object   getDeclaration(String   ident)
89      {
90          return symbols.get(ident.toUpperCase());
91      }
92      
93  }
94
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