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 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/*

 * Licensed to the Apache Software Foundation (ASF) under one or more

 * contributor license agreements.  See the NOTICE file distributed with

 * this work for additional information regarding copyright ownership.

 * The ASF licenses this file to You under the Apache License, Version 2.0

 * (the "License"); you may not use this file except in compliance with

 * the License.  You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.sun.org.apache.xerces.internal.util;

/**

 * Shadowed symbol table.

 *

 * The table has a reference to the main symbol table and is

 * not allowed to add new symbols to the main symbol table.

 * New symbols are added to the shadow symbol table and are local

 * to the component using this table.

 *

 * @author Andy Clark IBM

 */

public final class ShadowedSymbolTable

extends SymbolTable {

    //

    // Data

    //

    /** Main symbol table. */

    protected SymbolTable fSymbolTable;

    //

    // Constructors

    //

    /** Constructs a shadow of the specified symbol table. */

    public ShadowedSymbolTable(SymbolTable symbolTable) {

        fSymbolTable = symbolTable;

    } // <init>(SymbolTable)

    //

    // SymbolTable methods

    //

    /**

     * Adds the specified symbol to the symbol table and returns a

     * reference to the unique symbol. If the symbol already exists,

     * the previous symbol reference is returned instead, in order

     * guarantee that symbol references remain unique.

     *

     * @param symbol The new symbol.

     */

    public String addSymbol(String symbol) {

        if (fSymbolTable.containsSymbol(symbol)) {

            return fSymbolTable.addSymbol(symbol);

        }

        return super.addSymbol(symbol);

    } // addSymbol(String)

    /**

     * Adds the specified symbol to the symbol table and returns a

     * reference to the unique symbol. If the symbol already exists,

     * the previous symbol reference is returned instead, in order

     * guarantee that symbol references remain unique.

     *

     * @param buffer The buffer containing the new symbol.

     * @param offset The offset into the buffer of the new symbol.

     * @param length The length of the new symbol in the buffer.

     */

    public String addSymbol(char[] buffer, int offset, int length) {

        if (fSymbolTable.containsSymbol(buffer, offset, length)) {

            return fSymbolTable.addSymbol(buffer, offset, length);

        }

        return super.addSymbol(buffer, offset, length);

    } // addSymbol(char[],int,int):String

    /**

     * Returns a hashcode value for the specified symbol. The value

     * returned by this method must be identical to the value returned

     * by the <code>hash(char[],int,int)</code> method when called

     * with the character array that comprises the symbol string.

     *

     * @param symbol The symbol to hash.

     */

    public int hash(String symbol) {

        return fSymbolTable.hash(symbol);

    } // hash(String):int

    /**

     * Returns a hashcode value for the specified symbol information.

     * The value returned by this method must be identical to the value

     * returned by the <code>hash(String)</code> method when called

     * with the string object created from the symbol information.

     *

     * @param buffer The character buffer containing the symbol.

     * @param offset The offset into the character buffer of the start

     *               of the symbol.

     * @param length The length of the symbol.

     */

    public int hash(char[] buffer, int offset, int length) {

        return fSymbolTable.hash(buffer, offset, length);

    } // hash(char[],int,int):int

} // class ShadowedSymbolTable