01: /*
02: * Copyright 1999-2004 The Apache Software Foundation.
03: *
04: * Licensed under the Apache License, Version 2.0 (the "License");
05: * you may not use this file except in compliance with the License.
06: * You may obtain a copy of the License at
07: *
08: * http://www.apache.org/licenses/LICENSE-2.0
09: *
10: * Unless required by applicable law or agreed to in writing, software
11: * distributed under the License is distributed on an "AS IS" BASIS,
12: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13: * See the License for the specific language governing permissions and
14: * limitations under the License.
15: */
16: /*
17: * $Id: CustomStringPool.java,v 1.5 2004/02/16 23:06:11 minchau Exp $
18: */
19:
20: package org.apache.xml.dtm.ref;
21:
22: import java.util.Hashtable;
23:
24: /** <p>CustomStringPool is an example of appliction provided data structure
25: * for a DTM implementation to hold symbol references, e.g. elelment names.
26: * It will follow the DTMDStringPool interface and use two simple methods
27: * indexToString(int i) and stringToIndex(Sring s) to map between a set of
28: * string values and a set of integer index values. Therefore, an application
29: * may improve DTM processing speed by substituting the DTM symbol resolution
30: * tables with application specific quick symbol resolution tables.</p>
31: *
32: * %REVIEW% The only difference between this an DTMStringPool seems to be that
33: * it uses a java.lang.Hashtable full of Integers rather than implementing its
34: * own hashing. Joe deliberately avoided that approach when writing
35: * DTMStringPool, since it is both much more memory-hungry and probably slower
36: * -- especially in JDK 1.1.x, where Hashtable is synchronized. We need to
37: * either justify this implementation or discard it.
38: *
39: * <p>Status: In progress, under discussion.</p>
40: * */
41: public class CustomStringPool extends DTMStringPool {
42: //final Vector m_intToString;
43: //static final int HASHPRIME=101;
44: //int[] m_hashStart=new int[HASHPRIME];
45: final Hashtable m_stringToInt = new Hashtable();
46: public static final int NULL = -1;
47:
48: public CustomStringPool() {
49: super ();
50: /*m_intToString=new Vector();
51: System.out.println("In constructor m_intToString is " +
52: ((null == m_intToString) ? "null" : "not null"));*/
53: //m_stringToInt=new Hashtable();
54: //removeAllElements();
55: }
56:
57: public void removeAllElements() {
58: m_intToString.removeAllElements();
59: if (m_stringToInt != null)
60: m_stringToInt.clear();
61: }
62:
63: /** @return string whose value is uniquely identified by this integer index.
64: * @throws java.lang.ArrayIndexOutOfBoundsException
65: * if index doesn't map to a string.
66: * */
67: public String indexToString(int i)
68: throws java.lang.ArrayIndexOutOfBoundsException {
69: return (String) m_intToString.elementAt(i);
70: }
71:
72: /** @return integer index uniquely identifying the value of this string. */
73: public int stringToIndex(String s) {
74: if (s == null)
75: return NULL;
76: Integer iobj = (Integer) m_stringToInt.get(s);
77: if (iobj == null) {
78: m_intToString.addElement(s);
79: iobj = new Integer(m_intToString.size());
80: m_stringToInt.put(s, iobj);
81: }
82: return iobj.intValue();
83: }
84: }
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