1/*
2 * reserved comment block
3 * DO NOT REMOVE OR ALTER!
4 */
5/*
6 * Licensed to the Apache Software Foundation (ASF) under one or more
7 * contributor license agreements.  See the NOTICE file distributed with
8 * this work for additional information regarding copyright ownership.
9 * The ASF licenses this file to You under the Apache License, Version 2.0
10 * (the "License"); you may not use this file except in compliance with
11 * the License.  You may obtain a copy of the License at
12 *
13 *      http://www.apache.org/licenses/LICENSE-2.0
14 *
15 * Unless required by applicable law or agreed to in writing, software
16 * distributed under the License is distributed on an "AS IS" BASIS,
17 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
18 * See the License for the specific language governing permissions and
19 * limitations under the License.
20 */
21
22package com.sun.org.apache.xerces.internal.util;
23
24
25/**
26 * Shadowed symbol table.
27 *
28 * The table has a reference to the main symbol table and is
29 * not allowed to add new symbols to the main symbol table.
30 * New symbols are added to the shadow symbol table and are local
31 * to the component using this table.
32 *
33 * @author Andy Clark IBM
34 */
35
36public final class ShadowedSymbolTable
37extends SymbolTable {
38
39    //
40    // Data
41    //
42
43    /** Main symbol table. */
44    protected SymbolTable fSymbolTable;
45
46    //
47    // Constructors
48    //
49
50    /** Constructs a shadow of the specified symbol table. */
51    public ShadowedSymbolTable(SymbolTable symbolTable) {
52        fSymbolTable = symbolTable;
53    } // <init>(SymbolTable)
54
55    //
56    // SymbolTable methods
57    //
58
59    /**
60     * Adds the specified symbol to the symbol table and returns a
61     * reference to the unique symbol. If the symbol already exists,
62     * the previous symbol reference is returned instead, in order
63     * guarantee that symbol references remain unique.
64     *
65     * @param symbol The new symbol.
66     */
67    public String addSymbol(String symbol) {
68
69        if (fSymbolTable.containsSymbol(symbol)) {
70            return fSymbolTable.addSymbol(symbol);
71        }
72        return super.addSymbol(symbol);
73
74    } // addSymbol(String)
75
76    /**
77     * Adds the specified symbol to the symbol table and returns a
78     * reference to the unique symbol. If the symbol already exists,
79     * the previous symbol reference is returned instead, in order
80     * guarantee that symbol references remain unique.
81     *
82     * @param buffer The buffer containing the new symbol.
83     * @param offset The offset into the buffer of the new symbol.
84     * @param length The length of the new symbol in the buffer.
85     */
86    public String addSymbol(char[] buffer, int offset, int length) {
87
88        if (fSymbolTable.containsSymbol(buffer, offset, length)) {
89            return fSymbolTable.addSymbol(buffer, offset, length);
90        }
91        return super.addSymbol(buffer, offset, length);
92
93    } // addSymbol(char[],int,int):String
94
95    /**
96     * Returns a hashcode value for the specified symbol. The value
97     * returned by this method must be identical to the value returned
98     * by the <code>hash(char[],int,int)</code> method when called
99     * with the character array that comprises the symbol string.
100     *
101     * @param symbol The symbol to hash.
102     */
103    public int hash(String symbol) {
104        return fSymbolTable.hash(symbol);
105    } // hash(String):int
106
107    /**
108     * Returns a hashcode value for the specified symbol information.
109     * The value returned by this method must be identical to the value
110     * returned by the <code>hash(String)</code> method when called
111     * with the string object created from the symbol information.
112     *
113     * @param buffer The character buffer containing the symbol.
114     * @param offset The offset into the character buffer of the start
115     *               of the symbol.
116     * @param length The length of the symbol.
117     */
118    public int hash(char[] buffer, int offset, int length) {
119        return fSymbolTable.hash(buffer, offset, length);
120    } // hash(char[],int,int):int
121
122} // class ShadowedSymbolTable
123