org.apache.xerces.parsers.XMLGrammarPreparser Maven / Gradle / Ivy
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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.parsers;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Locale;
import org.apache.xerces.impl.Constants;
import org.apache.xerces.impl.XMLEntityManager;
import org.apache.xerces.impl.XMLErrorReporter;
import org.apache.xerces.util.SymbolTable;
import org.apache.xerces.xni.XNIException;
import org.apache.xerces.xni.grammars.Grammar;
import org.apache.xerces.xni.grammars.XMLGrammarDescription;
import org.apache.xerces.xni.grammars.XMLGrammarLoader;
import org.apache.xerces.xni.grammars.XMLGrammarPool;
import org.apache.xerces.xni.parser.XMLEntityResolver;
import org.apache.xerces.xni.parser.XMLErrorHandler;
import org.apache.xerces.xni.parser.XMLInputSource;
/**
* This class provides an easy way for a user to preparse grammars
* of various types. By default, it knows how to preparse external
* DTD's and schemas; it provides an easy way for user applications to
* register classes that know how to parse additional grammar types.
* By default, it does no grammar caching; but it provides ways for
* user applications to do so.
*
* @author Neil Graham, IBM
*
* @version $Id: XMLGrammarPreparser.java 713638 2008-11-13 04:42:18Z mrglavas $
*/
public class XMLGrammarPreparser {
//
// Constants
//
// feature: continue-after-fatal-error
private final static String CONTINUE_AFTER_FATAL_ERROR =
Constants.XERCES_FEATURE_PREFIX + Constants.CONTINUE_AFTER_FATAL_ERROR_FEATURE;
/** Property identifier: symbol table. */
protected static final String SYMBOL_TABLE =
Constants.XERCES_PROPERTY_PREFIX + Constants.SYMBOL_TABLE_PROPERTY;
/** Property identifier: error reporter. */
protected static final String ERROR_REPORTER =
Constants.XERCES_PROPERTY_PREFIX + Constants.ERROR_REPORTER_PROPERTY;
/** Property identifier: error handler. */
protected static final String ERROR_HANDLER =
Constants.XERCES_PROPERTY_PREFIX + Constants.ERROR_HANDLER_PROPERTY;
/** Property identifier: entity resolver. */
protected static final String ENTITY_RESOLVER =
Constants.XERCES_PROPERTY_PREFIX + Constants.ENTITY_RESOLVER_PROPERTY;
/** Property identifier: grammar pool . */
protected static final String GRAMMAR_POOL =
Constants.XERCES_PROPERTY_PREFIX + Constants.XMLGRAMMAR_POOL_PROPERTY;
// the "built-in" grammar loaders
private static final Hashtable KNOWN_LOADERS = new Hashtable();
static {
KNOWN_LOADERS.put(XMLGrammarDescription.XML_SCHEMA,
"org.apache.xerces.impl.xs.XMLSchemaLoader");
KNOWN_LOADERS.put(XMLGrammarDescription.XML_DTD,
"org.apache.xerces.impl.dtd.XMLDTDLoader");
}
/** Recognized properties. */
private static final String[] RECOGNIZED_PROPERTIES = {
SYMBOL_TABLE,
ERROR_REPORTER,
ERROR_HANDLER,
ENTITY_RESOLVER,
GRAMMAR_POOL,
};
// Data
protected final SymbolTable fSymbolTable;
protected final XMLErrorReporter fErrorReporter;
protected XMLEntityResolver fEntityResolver;
protected XMLGrammarPool fGrammarPool;
protected Locale fLocale;
// Hashtable holding our loaders
private final Hashtable fLoaders;
// The number of times the configuration has been modified.
private int fModCount = 1;
//
// Constructors
//
/** Default constructor. */
public XMLGrammarPreparser() {
this(new SymbolTable());
} // ()
/**
* Constructs a preparser using the specified symbol table.
*
* @param symbolTable The symbol table to use.
*/
public XMLGrammarPreparser (SymbolTable symbolTable) {
fSymbolTable = symbolTable;
fLoaders = new Hashtable();
fErrorReporter = new XMLErrorReporter();
setLocale(Locale.getDefault());
fEntityResolver = new XMLEntityManager();
// those are all the basic properties...
} // (SymbolTable)
//
// Public methods
//
/*
* Register a type of grammar to make it preparsable. If
* the second parameter is null, the parser will use its built-in
* facilities for that grammar type.
* This should be called by the application immediately
* after creating this object and before initializing any properties/features.
* @param type URI identifying the type of the grammar
* @param loader an object capable of preparsing that type; null if the ppreparser should use built-in knowledge.
* @return true if successful; false if no built-in knowledge of
* the type or if unable to instantiate the string we know about
*/
public boolean registerPreparser(String grammarType, XMLGrammarLoader loader) {
if(loader == null) { // none specified!
if(KNOWN_LOADERS.containsKey(grammarType)) {
// got one; just instantiate it...
String loaderName = (String)KNOWN_LOADERS.get(grammarType);
try {
ClassLoader cl = ObjectFactory.findClassLoader();
XMLGrammarLoader gl = (XMLGrammarLoader)(ObjectFactory.newInstance(loaderName, cl, true));
fLoaders.put(grammarType, new XMLGrammarLoaderContainer(gl));
} catch (Exception e) {
return false;
}
return true;
}
return false;
}
// were given one
fLoaders.put(grammarType, new XMLGrammarLoaderContainer(loader));
return true;
} // registerPreparser(String, XMLGrammarLoader): boolean
/**
* Parse a grammar from a location identified by an
* XMLInputSource.
* This method also adds this grammar to the XMLGrammarPool
*
* @param type The type of the grammar to be constructed
* @param is The XMLInputSource containing this grammar's
* information
* If a URI is included in the systemId field, the parser will not expand this URI or make it
* available to the EntityResolver
* @return The newly created Grammar.
* @exception XNIException thrown on an error in grammar
* construction
* @exception IOException thrown if an error is encountered
* in reading the file
*/
public Grammar preparseGrammar(String type, XMLInputSource
is) throws XNIException, IOException {
if (fLoaders.containsKey(type)) {
XMLGrammarLoaderContainer xglc = (XMLGrammarLoaderContainer) fLoaders.get(type);
XMLGrammarLoader gl = xglc.loader;
if (xglc.modCount != fModCount) {
// make sure gl's been set up with all the "basic" properties:
gl.setProperty(SYMBOL_TABLE, fSymbolTable);
gl.setProperty(ENTITY_RESOLVER, fEntityResolver);
gl.setProperty(ERROR_REPORTER, fErrorReporter);
// potentially, not all will support this one...
if (fGrammarPool != null) {
try {
gl.setProperty(GRAMMAR_POOL, fGrammarPool);
} catch(Exception e) {
// too bad...
}
}
xglc.modCount = fModCount;
}
return gl.loadGrammar(is);
}
return null;
} // preparseGrammar(String, XMLInputSource): Grammar
/**
* Set the locale to use for messages.
*
* @param locale The locale object to use for localization of messages.
*
* @exception XNIException Thrown if the parser does not support the
* specified locale.
*/
public void setLocale(Locale locale) {
fLocale = locale;
fErrorReporter.setLocale(locale);
} // setLocale(Locale)
/** Return the Locale the XMLGrammarLoader is using. */
public Locale getLocale() {
return fLocale;
} // getLocale(): Locale
/**
* Sets the error handler.
*
* @param errorHandler The error handler.
*/
public void setErrorHandler(XMLErrorHandler errorHandler) {
fErrorReporter.setProperty(ERROR_HANDLER, errorHandler);
} // setErrorHandler(XMLErrorHandler)
/** Returns the registered error handler. */
public XMLErrorHandler getErrorHandler() {
return fErrorReporter.getErrorHandler();
} // getErrorHandler(): XMLErrorHandler
/**
* Sets the entity resolver.
*
* @param entityResolver The new entity resolver.
*/
public void setEntityResolver(XMLEntityResolver entityResolver) {
if (fEntityResolver != entityResolver) {
// Overflow. We actually need to reset the
// modCount on every XMLGrammarLoaderContainer.
if (++fModCount < 0) {
clearModCounts();
}
fEntityResolver = entityResolver;
}
} // setEntityResolver(XMLEntityResolver)
/** Returns the registered entity resolver. */
public XMLEntityResolver getEntityResolver() {
return fEntityResolver;
} // getEntityResolver(): XMLEntityResolver
/**
* Sets the grammar pool.
*
* @param grammarPool The new grammar pool.
*/
public void setGrammarPool(XMLGrammarPool grammarPool) {
if (fGrammarPool != grammarPool) {
// Overflow. We actually need to reset the
// modCount on every XMLGrammarLoaderContainer.
if (++fModCount < 0) {
clearModCounts();
}
fGrammarPool = grammarPool;
}
} // setGrammarPool(XMLGrammarPool)
/** Returns the registered grammar pool. */
public XMLGrammarPool getGrammarPool() {
return fGrammarPool;
} // getGrammarPool(): XMLGrammarPool
// it's possible the application may want access to a certain loader to do
// some custom work.
public XMLGrammarLoader getLoader(String type) {
XMLGrammarLoaderContainer xglc = (XMLGrammarLoaderContainer) fLoaders.get(type);
return (xglc != null) ? xglc.loader : null;
} // getLoader(String): XMLGrammarLoader
// set a feature. This method tries to set it on all
// registered loaders; it eats any resulting exceptions. If
// an app needs to know if a particular feature is supported
// by a grammar loader of a particular type, it will have
// to retrieve that loader and use the loader's setFeature method.
public void setFeature(String featureId, boolean value) {
Enumeration loaders = fLoaders.elements();
while (loaders.hasMoreElements()) {
XMLGrammarLoader gl = ((XMLGrammarLoaderContainer)loaders.nextElement()).loader;
try {
gl.setFeature(featureId, value);
} catch(Exception e) {
// eat it up...
}
}
// since our error reporter is a property we set later,
// make sure features it understands are also set.
if(featureId.equals(CONTINUE_AFTER_FATAL_ERROR)) {
fErrorReporter.setFeature(CONTINUE_AFTER_FATAL_ERROR, value);
}
} //setFeature(String, boolean)
// set a property. This method tries to set it on all
// registered loaders; it eats any resulting exceptions. If
// an app needs to know if a particular property is supported
// by a grammar loader of a particular type, it will have
// to retrieve that loader and use the loader's setProperty method.
// An application should use the explicit method
// in this class to set "standard" properties like error handler etc.
public void setProperty(String propId, Object value) {
Enumeration loaders = fLoaders.elements();
while (loaders.hasMoreElements()) {
XMLGrammarLoader gl = ((XMLGrammarLoaderContainer)loaders.nextElement()).loader;
try {
gl.setProperty(propId, value);
} catch(Exception e) {
// eat it up...
}
}
} //setProperty(String, Object)
// get status of feature in a particular loader. This
// catches no exceptions--including NPE's--so the application had
// better make sure the loader exists and knows about this feature.
// @param type type of grammar to look for the feature in.
// @param featureId the feature string to query.
// @return the value of the feature.
public boolean getFeature(String type, String featureId) {
XMLGrammarLoader gl = ((XMLGrammarLoaderContainer)fLoaders.get(type)).loader;
return gl.getFeature(featureId);
} // getFeature (String, String): boolean
// get status of property in a particular loader. This
// catches no exceptions--including NPE's--so the application had
// better make sure the loader exists and knows about this property.
// For standard properties--that will be supported
// by all loaders--the specific methods should be queried!
// @param type type of grammar to look for the property in.
// @param propertyId the property string to query.
// @return the value of the property.
public Object getProperty(String type, String propertyId) {
XMLGrammarLoader gl = ((XMLGrammarLoaderContainer)fLoaders.get(type)).loader;
return gl.getProperty(propertyId);
} // getProperty(String, String): Object
/**
* Container for an XMLGrammarLoader. Also holds the modCount
* that the XMLGrammarPreparser had the last time it was used.
*/
static class XMLGrammarLoaderContainer {
public final XMLGrammarLoader loader;
public int modCount = 0;
public XMLGrammarLoaderContainer(XMLGrammarLoader loader) {
this.loader = loader;
}
}
private void clearModCounts() {
Enumeration loaders = fLoaders.elements();
while (loaders.hasMoreElements()) {
XMLGrammarLoaderContainer xglc = (XMLGrammarLoaderContainer) loaders.nextElement();
xglc.modCount = 0;
}
fModCount = 1;
}
} // class XMLGrammarPreparser