org.apache.xerces.parsers: public class: CachingParserPool

org.apache.xerces.parsers
public class: CachingParserPool [javadoc | source]

java.lang.Object
   org.apache.xerces.parsers.CachingParserPool

A parser pool that enables caching of grammars. The caching parser pool is constructed with a specific symbol table and grammar pool that has already been populated with the grammars used by the application.

Once the caching parser pool is constructed, specific parser instances are created by calling the appropriate factory method on the parser pool.

Note: There is a performance penalty for using a caching parser pool due to thread safety. Access to the symbol table and grammar pool must be synchronized to ensure the safe operation of the symbol table and grammar pool.

Note: If performance is critical, then another mechanism needs to be used instead of the caching parser pool. One approach would be to create parser instances that do not share these structures. Instead, each instance would get its own copy to use while parsing. This avoids the synchronization overhead at the expense of more memory and the time required to copy the structures for each new parser instance. And even when a parser instance is re-used, there is a potential for a memory leak due to new symbols being added to the symbol table over time. In other words, always take caution to make sure that your application is thread-safe and avoids leaking memory.

author: Andy - Clark, IBM

version: $ - Id: CachingParserPool.java 447239 2006-09-18 05:08:26Z mrglavas $

Nested Class Summary:
public static final class	CachingParserPool.SynchronizedGrammarPool	Synchronized grammar pool.
public static final class	CachingParserPool.ShadowedGrammarPool	Shadowed grammar pool. This class is predicated on the existence of a concrete implementation; so using our own doesn't seem to bad an idea.

Field Summary
public static final boolean	DEFAULT_SHADOW_SYMBOL_TABLE	Default shadow symbol table (false).
public static final boolean	DEFAULT_SHADOW_GRAMMAR_POOL	Default shadow grammar pool (false).
protected SymbolTable	fSynchronizedSymbolTable	Symbol table. The symbol table that the caching parser pool is constructed with is automatically wrapped in a synchronized version for thread-safety.
protected XMLGrammarPool	fSynchronizedGrammarPool	Grammar pool. The grammar pool that the caching parser pool is constructed with is automatically wrapped in a synchronized version for thread-safety.
protected boolean	fShadowSymbolTable	Shadow the symbol table for new parser instances. If true, new parser instances use shadow copies of the main symbol table and are not allowed to add new symbols to the main symbol table. New symbols are added to the shadow symbol table and are local to the parser instance.
protected boolean	fShadowGrammarPool	Shadow the grammar pool for new parser instances. If true, new parser instances use shadow copies of the main grammar pool and are not allowed to add new grammars to the main grammar pool. New grammars are added to the shadow grammar pool and are local to the parser instance.

Constructor:

Constructor:
public CachingParserPool() { // // Constructors // this(new SymbolTable(), new XMLGrammarPoolImpl()); } Default constructor.
public CachingParserPool(SymbolTable symbolTable, XMLGrammarPool grammarPool) { fSynchronizedSymbolTable = new SynchronizedSymbolTable(symbolTable); fSynchronizedGrammarPool = new SynchronizedGrammarPool(grammarPool); } Constructs a caching parser pool with the specified symbol table and grammar pool. Parameters: `symbolTable` - The symbol table. `grammarPool` - The grammar pool.

 public CachingParserPool() {
    //
    // Constructors
    //
        this(new SymbolTable(), new XMLGrammarPoolImpl());
}

Default constructor.

 public CachingParserPool(SymbolTable symbolTable,
    XMLGrammarPool grammarPool) {
        fSynchronizedSymbolTable = new SynchronizedSymbolTable(symbolTable);
        fSynchronizedGrammarPool = new SynchronizedGrammarPool(grammarPool);
}

Constructs a caching parser pool with the specified symbol table and grammar pool.

Parameters:

symbolTable - The symbol table.

grammarPool - The grammar pool.

Method from org.apache.xerces.parsers.CachingParserPool Summary:
createDOMParser, createSAXParser, getSymbolTable, getXMLGrammarPool, setShadowSymbolTable

Methods from java.lang.Object:
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method from org.apache.xerces.parsers.CachingParserPool Detail:
public DOMParser createDOMParser() { SymbolTable symbolTable = fShadowSymbolTable ? new ShadowedSymbolTable(fSynchronizedSymbolTable) : fSynchronizedSymbolTable; XMLGrammarPool grammarPool = fShadowGrammarPool ? new ShadowedGrammarPool(fSynchronizedGrammarPool) : fSynchronizedGrammarPool; return new DOMParser(symbolTable, grammarPool); } Creates a new DOM parser.
public SAXParser createSAXParser() { SymbolTable symbolTable = fShadowSymbolTable ? new ShadowedSymbolTable(fSynchronizedSymbolTable) : fSynchronizedSymbolTable; XMLGrammarPool grammarPool = fShadowGrammarPool ? new ShadowedGrammarPool(fSynchronizedGrammarPool) : fSynchronizedGrammarPool; return new SAXParser(symbolTable, grammarPool); } Creates a new SAX parser.
public SymbolTable getSymbolTable() { return fSynchronizedSymbolTable; } Returns the symbol table.
public XMLGrammarPool getXMLGrammarPool() { return fSynchronizedGrammarPool; } Returns the grammar pool.
public void setShadowSymbolTable(boolean shadow) { fShadowSymbolTable = shadow; } Sets whether new parser instance receive shadow copies of the main symbol table.

Method from org.apache.xerces.parsers.CachingParserPool Detail:

 public DOMParser createDOMParser() {
        SymbolTable symbolTable = fShadowSymbolTable
                                ? new ShadowedSymbolTable(fSynchronizedSymbolTable)
                                : fSynchronizedSymbolTable;
        XMLGrammarPool grammarPool = fShadowGrammarPool
                                ? new ShadowedGrammarPool(fSynchronizedGrammarPool)
                                : fSynchronizedGrammarPool;
        return new DOMParser(symbolTable, grammarPool);
}

Creates a new DOM parser.

 public SAXParser createSAXParser() {
        SymbolTable symbolTable = fShadowSymbolTable
                                ? new ShadowedSymbolTable(fSynchronizedSymbolTable)
                                : fSynchronizedSymbolTable;
        XMLGrammarPool grammarPool = fShadowGrammarPool
                                ? new ShadowedGrammarPool(fSynchronizedGrammarPool)
                                : fSynchronizedGrammarPool;
        return new SAXParser(symbolTable, grammarPool);
}

Creates a new SAX parser.

 public SymbolTable getSymbolTable() {
        return fSynchronizedSymbolTable;
}

Returns the symbol table.

 public XMLGrammarPool getXMLGrammarPool() {
        return fSynchronizedGrammarPool;
}

Returns the grammar pool.

 public  void setShadowSymbolTable(boolean shadow) {
        fShadowSymbolTable = shadow;
}

Sets whether new parser instance receive shadow copies of the main symbol table.