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1 /*
2 * The Apache Software License, Version 1.1
3 *
4 *
5 * Copyright (c) 1999-2002 The Apache Software Foundation. All rights
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23 * Apache Software Foundation (http://www.apache.org/)."
24 * Alternately, this acknowledgment may appear in the software itself,
25 * if and wherever such third-party acknowledgments normally appear.
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27 * 4. The names "Xerces" and "Apache Software Foundation" must
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48 * ====================================================================
49 *
50 * This software consists of voluntary contributions made by many
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52 * originally based on software copyright (c) 2002, International
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54 * information on the Apache Software Foundation, please see
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56 */
57
58 package com.sun.org.apache.xerces.internal.util;
59
60
61 /**
62  * Shadowed symbol table.
63  *
64  * The table has a reference to the main symbol table and is
65  * not allowed to add new symbols to the main symbol table.
66  * New symbols are added to the shadow symbol table and are local
67  * to the component using this table.
68  *
69  * @author Andy Clark IBM
70  * @version $Id: ShadowedSymbolTable.java,v 1.2 2002/08/09 15:18:19 neilg Exp $
71  */
72
73 public final class ShadowedSymbolTable
74 extends SymbolTable {
75
76     //
77 // Data
78 //
79
80     /** Main symbol table. */
81     protected SymbolTable fSymbolTable;
82
83     //
84 // Constructors
85 //
86
87     /** Constructs a shadow of the specified symbol table. */
88     public ShadowedSymbolTable(SymbolTable symbolTable) {
89         fSymbolTable = symbolTable;
90     } // <init>(SymbolTable)
91
92     //
93 // SymbolTable methods
94 //
95
96     /**
97      * Adds the specified symbol to the symbol table and returns a
98      * reference to the unique symbol. If the symbol already exists,
99      * the previous symbol reference is returned instead, in order
100      * guarantee that symbol references remain unique.
101      *
102      * @param symbol The new symbol.
103      */
104     public String JavaDoc addSymbol(String JavaDoc symbol) {
105
106         if (fSymbolTable.containsSymbol(symbol)) {
107             return fSymbolTable.addSymbol(symbol);
108         }
109         return super.addSymbol(symbol);
110
111     } // addSymbol(String)
112
113     /**
114      * Adds the specified symbol to the symbol table and returns a
115      * reference to the unique symbol. If the symbol already exists,
116      * the previous symbol reference is returned instead, in order
117      * guarantee that symbol references remain unique.
118      *
119      * @param buffer The buffer containing the new symbol.
120      * @param offset The offset into the buffer of the new symbol.
121      * @param length The length of the new symbol in the buffer.
122      */
123     public String JavaDoc addSymbol(char[] buffer, int offset, int length) {
124
125         if (fSymbolTable.containsSymbol(buffer, offset, length)) {
126             return fSymbolTable.addSymbol(buffer, offset, length);
127         }
128         return super.addSymbol(buffer, offset, length);
129
130     } // addSymbol(char[],int,int):String
131
132     /**
133      * Returns a hashcode value for the specified symbol. The value
134      * returned by this method must be identical to the value returned
135      * by the <code>hash(char[],int,int)</code> method when called
136      * with the character array that comprises the symbol string.
137      *
138      * @param symbol The symbol to hash.
139      */
140     public int hash(String JavaDoc symbol) {
141         return fSymbolTable.hash(symbol);
142     } // hash(String):int
143
144     /**
145      * Returns a hashcode value for the specified symbol information.
146      * The value returned by this method must be identical to the value
147      * returned by the <code>hash(String)</code> method when called
148      * with the string object created from the symbol information.
149      *
150      * @param buffer The character buffer containing the symbol.
151      * @param offset The offset into the character buffer of the start
152      * of the symbol.
153      * @param length The length of the symbol.
154      */
155     public int hash(char[] buffer, int offset, int length) {
156         return fSymbolTable.hash(buffer, offset, length);
157     } // hash(char[],int,int):int
158
159 } // class ShadowedSymbolTable
160
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