org.apache.xml.dtm.ref
Class CustomStringPool

java.lang.Object
  org.apache.xml.dtm.ref.DTMStringPool
      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

CustomStringPool()

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

main

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

m_stringToInt

final java.util.Hashtable m_stringToInt

NULL

public static final int NULL

See Also:

Constant Field Values

Constructor Detail

CustomStringPool

public CustomStringPool()

Method Detail

removeAllElements

public void removeAllElements()

Overrides:

removeAllElements in class DTMStringPool

indexToString

public java.lang.String indexToString(int i)
                               throws java.lang.ArrayIndexOutOfBoundsException

Overrides:

indexToString in class DTMStringPool

Returns:

string whose value is uniquely identified by this integer index.

Throws:

java.lang.ArrayIndexOutOfBoundsException - if index doesn't map to a string.

stringToIndex

public int stringToIndex(java.lang.String s)

Overrides:

stringToIndex in class DTMStringPool

Returns:

integer index uniquely identifying the value of this string.