| /* |
| * 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. |
| */ |
| /* |
| * $Id$ |
| */ |
| |
| package org.apache.xml.dtm.ref; |
| import java.util.Hashtable; |
| |
| /** <p>CustomStringPool is an example of appliction provided data structure |
| * for a DTM implementation to hold symbol references, e.g. elelment names. |
| * It will follow the DTMDStringPool interface and use two simple methods |
| * indexToString(int i) and stringToIndex(Sring s) to map between a set of |
| * string values and a set of integer index values. Therefore, an application |
| * may improve DTM processing speed by substituting the DTM symbol resolution |
| * tables with application specific quick symbol resolution tables.</p> |
| * |
| * %REVIEW% The only difference between this an DTMStringPool seems to be that |
| * it uses a java.lang.Hashtable full of Integers rather than implementing its |
| * own hashing. Joe deliberately avoided that approach when writing |
| * DTMStringPool, since it is both much more memory-hungry and probably slower |
| * -- especially in JDK 1.1.x, where Hashtable is synchronized. We need to |
| * either justify this implementation or discard it. |
| * |
| * %REVIEW% Xalan-J has dropped support for 1.1.x and we can now use |
| * the colletion classes in 1.2, such as java.util.HashMap which is |
| * similar to java.util.Hashtable but not synchronized. For performance reasons |
| * one could change m_stringToInt to be a HashMap, but is it OK to do that? |
| * Are such CustomStringPool objects already used in a thread-safe way? |
| * |
| * <p>Status: In progress, under discussion.</p> |
| * */ |
| public class CustomStringPool extends DTMStringPool { |
| //final Vector m_intToString; |
| //static final int HASHPRIME=101; |
| //int[] m_hashStart=new int[HASHPRIME]; |
| final Hashtable m_stringToInt = new Hashtable(); // can this be a HashMap instead? |
| public static final int NULL=-1; |
| |
| public CustomStringPool() |
| { |
| super(); |
| /*m_intToString=new Vector(); |
| System.out.println("In constructor m_intToString is " + |
| ((null == m_intToString) ? "null" : "not null"));*/ |
| //m_stringToInt=new Hashtable(); |
| //removeAllElements(); |
| } |
| |
| public void removeAllElements() |
| { |
| m_intToString.removeAllElements(); |
| if (m_stringToInt != null) |
| m_stringToInt.clear(); |
| } |
| |
| /** @return string whose value is uniquely identified by this integer index. |
| * @throws java.lang.ArrayIndexOutOfBoundsException |
| * if index doesn't map to a string. |
| * */ |
| public String indexToString(int i) |
| throws java.lang.ArrayIndexOutOfBoundsException |
| { |
| return(String) m_intToString.elementAt(i); |
| } |
| |
| /** @return integer index uniquely identifying the value of this string. */ |
| public int stringToIndex(String s) |
| { |
| if (s==null) return NULL; |
| Integer iobj=(Integer)m_stringToInt.get(s); |
| if (iobj==null) { |
| m_intToString.addElement(s); |
| iobj=new Integer(m_intToString.size()); |
| m_stringToInt.put(s,iobj); |
| } |
| return iobj.intValue(); |
| } |
| } |