Class CustomStringPool

  extended by org.apache.xml.dtm.ref.DTMStringPool
      extended by org.apache.xml.dtm.ref.CustomStringPool

public class CustomStringPool
extends DTMStringPool

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.

%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?

Status: In progress, under discussion.

Field Summary
(package private)  java.util.Hashtable m_stringToInt
static int NULL
Fields inherited from class org.apache.xml.dtm.ref.DTMStringPool
HASHPRIME, m_hashChain, m_hashStart, m_intToString
Constructor Summary
Method Summary
 java.lang.String indexToString(int i)
 void removeAllElements()
 int stringToIndex(java.lang.String s)
Methods inherited from class org.apache.xml.dtm.ref.DTMStringPool
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail


final java.util.Hashtable m_stringToInt


public static final int NULL
See Also:
Constant Field Values
Constructor Detail


public CustomStringPool()
Method Detail


public void removeAllElements()
removeAllElements in class DTMStringPool


public java.lang.String indexToString(int i)
                               throws java.lang.ArrayIndexOutOfBoundsException
indexToString in class DTMStringPool
string whose value is uniquely identified by this integer index.
java.lang.ArrayIndexOutOfBoundsException - if index doesn't map to a string.


public int stringToIndex(java.lang.String s)
stringToIndex in class DTMStringPool
integer index uniquely identifying the value of this string.