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Xerces2 is the next generation of high performance, fully compliant XML parsers in the Apache Xerces family.
This new version of Xerces introduces the Xerces Native Interface (XNI), a complete framework for building
parser components and configurations that is extremely modular and easy to program. The Apache Xerces2 parser is
the reference implementation of XNI but other parser components, configurations, and parsers can be written
using the Xerces Native Interface. For complete design and implementation documents, refer to the XNI Manual.
Xerces2 is a fully conforming XML Schema 1.0 processor. A partial experimental implementation of the XML Schema
1.1 Structures and Datatypes Working Drafts (December 2009) and an experimental implementation of the XML Schema
Definition Language (XSD): Component Designators (SCD) Candidate Recommendation (January 2010) are provided for
evaluation. For more information, refer to the XML Schema page. Xerces2 also provides a complete implementation
of the Document Object Model Level 3 Core and Load/Save W3C Recommendations and provides a complete
implementation of the XML Inclusions (XInclude) W3C Recommendation. It also provides support for OASIS XML
Catalogs v1.1. Xerces2 is able to parse documents written according to the XML 1.1 Recommendation, except that
it does not yet provide an option to enable normalization checking as described in section 2.13 of this
specification. It also handles namespaces according to the XML Namespaces 1.1 Recommendation, and will correctly
serialize XML 1.1 documents if the DOM level 3 load/save APIs are in use.
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.xerces.jaxp.validation;
import java.lang.ref.Reference;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.SoftReference;
import org.apache.xerces.xni.grammars.Grammar;
import org.apache.xerces.xni.grammars.XMLGrammarDescription;
import org.apache.xerces.xni.grammars.XMLGrammarPool;
import org.apache.xerces.xni.grammars.XMLSchemaDescription;
/**
* This grammar pool is a memory sensitive cache. The grammars
* stored in the pool are softly reachable and may be cleared by
* the garbage collector in response to memory demand. Equality
* of XMLSchemaDescriptions is determined using both
* the target namespace for the schema and schema location.
*
* @author Michael Glavassevich, IBM
* @version $Id: SoftReferenceGrammarPool.java 699892 2008-09-28 21:08:27Z mrglavas $
*/
final class SoftReferenceGrammarPool implements XMLGrammarPool {
//
// Constants
//
/** Default size. */
protected static final int TABLE_SIZE = 11;
/** Zero length grammar array. */
protected static final Grammar [] ZERO_LENGTH_GRAMMAR_ARRAY = new Grammar [0];
//
// Data
//
/** Grammars. */
protected Entry [] fGrammars = null;
/** Flag indicating whether this pool is locked */
protected boolean fPoolIsLocked;
/** The number of grammars in the pool */
protected int fGrammarCount = 0;
/** Reference queue for cleared grammar references */
protected final ReferenceQueue fReferenceQueue = new ReferenceQueue();
//
// Constructors
//
/** Constructs a grammar pool with a default number of buckets. */
public SoftReferenceGrammarPool() {
fGrammars = new Entry[TABLE_SIZE];
fPoolIsLocked = false;
} // ()
/** Constructs a grammar pool with a specified number of buckets. */
public SoftReferenceGrammarPool(int initialCapacity) {
fGrammars = new Entry[initialCapacity];
fPoolIsLocked = false;
}
//
// XMLGrammarPool methods
//
/* Retrieve the initial known set of grammars. This method is
* called by a validator before the validation starts. The application
* can provide an initial set of grammars available to the current
* validation attempt.
*
* @param grammarType The type of the grammar, from the
* org.apache.xerces.xni.grammars.XMLGrammarDescription
* interface.
* @return The set of grammars the validator may put in its "bucket"
*/
public Grammar [] retrieveInitialGrammarSet (String grammarType) {
synchronized (fGrammars) {
clean();
// Return no grammars. This allows the garbage collector to sift
// out grammars which are not in use when memory demand is high.
// It also allows the pool to return the "right" schema grammar
// based on schema locations.
return ZERO_LENGTH_GRAMMAR_ARRAY;
}
} // retrieveInitialGrammarSet (String): Grammar[]
/* Return the final set of grammars that the validator ended up
* with. This method is called after the validation finishes. The
* application may then choose to cache some of the returned grammars.
* In this implementation, we make our choice based on whether this object
* is "locked"--that is, whether the application has instructed
* us not to accept any new grammars.
*
* @param grammarType The type of the grammars being returned;
* @param grammars An array containing the set of grammars being
* returned; order is not significant.
*/
public void cacheGrammars(String grammarType, Grammar[] grammars) {
if (!fPoolIsLocked) {
for (int i = 0; i < grammars.length; ++i) {
putGrammar(grammars[i]);
}
}
} // cacheGrammars(String, Grammar[]);
/* This method requests that the application retrieve a grammar
* corresponding to the given GrammarIdentifier from its cache.
* If it cannot do so it must return null; the parser will then
* call the EntityResolver.
* An application must not call its EntityResolver itself
* from this method; this may result in infinite recursions.
*
* This implementation chooses to use the root element name to identify a DTD grammar
* and the target namespace to identify a Schema grammar.
*
* @param desc The description of the Grammar being requested.
* @return The Grammar corresponding to this description or null if
* no such Grammar is known.
*/
public Grammar retrieveGrammar(XMLGrammarDescription desc) {
return getGrammar(desc);
} // retrieveGrammar(XMLGrammarDescription): Grammar
//
// Public methods
//
/**
* Puts the specified grammar into the grammar pool and associates it to
* its root element name or its target namespace.
*
* @param grammar The Grammar.
*/
public void putGrammar(Grammar grammar) {
if (!fPoolIsLocked) {
synchronized (fGrammars) {
clean();
XMLGrammarDescription desc = grammar.getGrammarDescription();
int hash = hashCode(desc);
int index = (hash & 0x7FFFFFFF) % fGrammars.length;
for (Entry entry = fGrammars[index]; entry != null; entry = entry.next) {
if (entry.hash == hash && equals(entry.desc, desc)) {
if (entry.grammar.get() != grammar) {
entry.grammar = new SoftGrammarReference(entry, grammar, fReferenceQueue);
}
return;
}
}
// create a new entry
Entry entry = new Entry(hash, index, desc, grammar, fGrammars[index], fReferenceQueue);
fGrammars[index] = entry;
fGrammarCount++;
}
}
} // putGrammar(Grammar)
/**
* Returns the grammar associated to the specified grammar description.
* Currently, the root element name is used as the key for DTD grammars
* and the target namespace is used as the key for Schema grammars.
*
* @param desc The Grammar Description.
*/
public Grammar getGrammar(XMLGrammarDescription desc) {
synchronized (fGrammars) {
clean();
int hash = hashCode(desc);
int index = (hash & 0x7FFFFFFF) % fGrammars.length;
for (Entry entry = fGrammars[index]; entry != null; entry = entry.next) {
Grammar tempGrammar = (Grammar) entry.grammar.get();
/** If the soft reference has been cleared, remove this entry from the pool. */
if (tempGrammar == null) {
removeEntry(entry);
}
else if ((entry.hash == hash) && equals(entry.desc, desc)) {
return tempGrammar;
}
}
return null;
}
} // getGrammar(XMLGrammarDescription):Grammar
/**
* Removes the grammar associated to the specified grammar description from the
* grammar pool and returns the removed grammar. Currently, the root element name
* is used as the key for DTD grammars and the target namespace is used
* as the key for Schema grammars.
*
* @param desc The Grammar Description.
* @return The removed grammar.
*/
public Grammar removeGrammar(XMLGrammarDescription desc) {
synchronized (fGrammars) {
clean();
int hash = hashCode(desc);
int index = (hash & 0x7FFFFFFF) % fGrammars.length;
for (Entry entry = fGrammars[index]; entry != null; entry = entry.next) {
if ((entry.hash == hash) && equals(entry.desc, desc)) {
return removeEntry(entry);
}
}
return null;
}
} // removeGrammar(XMLGrammarDescription):Grammar
/**
* Returns true if the grammar pool contains a grammar associated
* to the specified grammar description. Currently, the root element name
* is used as the key for DTD grammars and the target namespace is used
* as the key for Schema grammars.
*
* @param desc The Grammar Description.
*/
public boolean containsGrammar(XMLGrammarDescription desc) {
synchronized (fGrammars) {
clean();
int hash = hashCode(desc);
int index = (hash & 0x7FFFFFFF) % fGrammars.length;
for (Entry entry = fGrammars[index]; entry != null ; entry = entry.next) {
Grammar tempGrammar = (Grammar) entry.grammar.get();
/** If the soft reference has been cleared, remove this entry from the pool. */
if (tempGrammar == null) {
removeEntry(entry);
}
else if ((entry.hash == hash) && equals(entry.desc, desc)) {
return true;
}
}
return false;
}
} // containsGrammar(XMLGrammarDescription):boolean
/* Sets this grammar pool to a "locked" state--i.e.,
* no new grammars will be added until it is "unlocked".
*/
public void lockPool() {
fPoolIsLocked = true;
} // lockPool()
/*
Sets this grammar pool to an "unlocked" state--i.e.,
* new grammars will be added when putGrammar or cacheGrammars
* are called.
*/
public void unlockPool() {
fPoolIsLocked = false;
} // unlockPool()
/*
*
This method clears the pool-i.e., removes references
* to all the grammars in it.
*/
public void clear() {
for (int i=0; i