org.apache.xerces.util
Class SoftReferenceSymbolTable

java.lang.Object
  extended by org.apache.xerces.util.SymbolTable
      extended by org.apache.xerces.util.SoftReferenceSymbolTable

public class SoftReferenceSymbolTable
extends SymbolTable

This symbol table uses SoftReferences to its String entries, which means that table entries that have no references to them can be garbage collected when memory is needed. Thus, in documents with very very large numbers of unique strings, using this SymbolTable will prevent an out of memory error from occuring.

Version:
$Id: SoftReferenceSymbolTable.java 924298 2010-03-17 13:57:20Z mrglavas $
Author:
Peter McCracken, IBM
See Also:
SymbolTable

Nested Class Summary
protected static class SoftReferenceSymbolTable.SREntry
          This class is a symbol table entry.
protected static class SoftReferenceSymbolTable.SREntryData
           
 
Nested classes/interfaces inherited from class org.apache.xerces.util.SymbolTable
SymbolTable.Entry
 
Field Summary
protected  SoftReferenceSymbolTable.SREntry[] fBuckets
           
 
Fields inherited from class org.apache.xerces.util.SymbolTable
fCount, fLoadFactor, fTableSize, fThreshold, TABLE_SIZE
 
Constructor Summary
SoftReferenceSymbolTable()
          Constructs a new, empty SymbolTable with a default initial capacity (101) and load factor, which is 0.75.
SoftReferenceSymbolTable(int initialCapacity)
          Constructs a new, empty SymbolTable with the specified initial capacity and default load factor, which is 0.75.
SoftReferenceSymbolTable(int initialCapacity, float loadFactor)
          Constructs a new, empty SymbolTable with the specified initial capacity and the specified load factor.
 
Method Summary
 java.lang.String addSymbol(char[] buffer, int offset, int length)
          Adds the specified symbol to the symbol table and returns a reference to the unique symbol.
 java.lang.String addSymbol(java.lang.String symbol)
          Adds the specified symbol to the symbol table and returns a reference to the unique symbol.
 boolean containsSymbol(char[] buffer, int offset, int length)
          Returns true if the symbol table already contains the specified symbol.
 boolean containsSymbol(java.lang.String symbol)
          Returns true if the symbol table already contains the specified symbol.
protected  void rehash()
          Increases the capacity of and internally reorganizes this SymbolTable, in order to accommodate and access its entries more efficiently.
 
Methods inherited from class org.apache.xerces.util.SymbolTable
hash, hash
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

fBuckets

protected SoftReferenceSymbolTable.SREntry[] fBuckets
Constructor Detail

SoftReferenceSymbolTable

public SoftReferenceSymbolTable(int initialCapacity,
                                float loadFactor)
Constructs a new, empty SymbolTable with the specified initial capacity and the specified load factor.

Parameters:
initialCapacity - the initial capacity of the SymbolTable.
loadFactor - the load factor of the SymbolTable.
Throws:
java.lang.IllegalArgumentException - if the initial capacity is less than zero, or if the load factor is nonpositive.

SoftReferenceSymbolTable

public SoftReferenceSymbolTable(int initialCapacity)
Constructs a new, empty SymbolTable with the specified initial capacity and default load factor, which is 0.75.

Parameters:
initialCapacity - the initial capacity of the hashtable.
Throws:
java.lang.IllegalArgumentException - if the initial capacity is less than zero.

SoftReferenceSymbolTable

public SoftReferenceSymbolTable()
Constructs a new, empty SymbolTable with a default initial capacity (101) and load factor, which is 0.75.

Method Detail

addSymbol

public java.lang.String addSymbol(java.lang.String symbol)
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.

Overrides:
addSymbol in class SymbolTable
Parameters:
symbol - The new symbol.

addSymbol

public java.lang.String addSymbol(char[] buffer,
                                  int offset,
                                  int length)
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.

Overrides:
addSymbol in class SymbolTable
Parameters:
buffer - The buffer containing the new symbol.
offset - The offset into the buffer of the new symbol.
length - The length of the new symbol in the buffer.

rehash

protected void rehash()
Increases the capacity of and internally reorganizes this SymbolTable, in order to accommodate and access its entries more efficiently. This method is called automatically when the number of keys in the SymbolTable exceeds this hashtable's capacity and load factor.

Overrides:
rehash in class SymbolTable

containsSymbol

public boolean containsSymbol(java.lang.String symbol)
Returns true if the symbol table already contains the specified symbol.

Overrides:
containsSymbol in class SymbolTable
Parameters:
symbol - The symbol to look for.

containsSymbol

public boolean containsSymbol(char[] buffer,
                              int offset,
                              int length)
Returns true if the symbol table already contains the specified symbol.

Overrides:
containsSymbol in class SymbolTable
Parameters:
buffer - The buffer containing the symbol to look for.
offset - The offset into the buffer.
length - The length of the symbol in the buffer.


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