179 lines
6.5 KiB
C++
179 lines
6.5 KiB
C++
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*
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* $Id: XMLEntityResolver.hpp 527149 2007-04-10 14:56:39Z amassari $
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*/
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#if !defined(XERCESC_INCLUDE_GUARD_XMLENTITYRESOLVER_HPP)
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#define XERCESC_INCLUDE_GUARD_XMLENTITYRESOLVER_HPP
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#include <xercesc/util/XercesDefs.hpp>
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#include <xercesc/util/XMemory.hpp>
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#include <xercesc/util/XMLResourceIdentifier.hpp>
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XERCES_CPP_NAMESPACE_BEGIN
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class InputSource;
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/**
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* Revised interface for resolving entities.
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*
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* <p>If an application needs to implement customized handling
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* for external entities, it can implement this interface and
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* register an instance with the parser using the parser's
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* setXMLEntityResolver method or it can use the basic SAX interface
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* (EntityResolver). The difference between the two interfaces is
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* the arguments to the resolveEntity() method. With the SAX
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* EntityResolve the arguments are systemId and publicId. With this
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* interface the argument is a XMLResourceIdentifier object. <i>Only
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* one EntityResolver can be set using setEntityResolver() or
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* setXMLEntityResolver, if both are set the last one set is
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* used.</i></p>
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*
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* <p>The parser will then allow the application to intercept any
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* external entities (including the external DTD subset and external
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* parameter entities, if any) before including them.</p>
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*
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* <p>Many applications will not need to implement this interface,
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* but it will be especially useful for applications that build
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* XML documents from databases or other specialised input sources,
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* or for applications that use URI types other than URLs.</p>
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*
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* <p>The following resolver would provide the application
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* with a special character stream for the entity with the system
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* identifier "http://www.myhost.com/today":</p>
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*
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*<code>
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* \#include <xercesc/util/XMLEntityResolver.hpp><br>
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* \#include <xercesc/sax/InputSource.hpp><br>
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*<br>
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* class MyResolver : public XMLEntityResolver {<br>
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* public:<br>
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* InputSource resolveEntity (XMLResourceIdentifier* xmlri);<br>
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* ...<br>
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* };<br>
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*<br>
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* MyResolver::resolveEntity(XMLResourceIdentifier* xmlri) {<br>
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* switch(xmlri->getResourceIdentifierType()) {<br>
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* case XMLResourceIdentifier::SystemId:<br>
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* if (XMLString::compareString(xmlri->getSystemId(), "http://www.myhost.com/today")) {<br>
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* MyReader* reader = new MyReader();<br>
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* return new InputSource(reader);<br>
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* } else {<br>
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* return null;<br>
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* }<br>
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* break;<br>
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* default:<br>
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* return null;<br>
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* }<br>
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* }</code>
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*
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* <p>The application can also use this interface to redirect system
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* identifiers to local URIs or to look up replacements in a catalog
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* (possibly by using the public identifier).</p>
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*
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* <p>The HandlerBase class implements the default behaviour for
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* this interface, which is simply always to return null (to request
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* that the parser use the default system identifier).</p>
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*
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* @see XMLResourceIdentifier
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* @see Parser#setXMLEntityResolver
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* @see InputSource#InputSource
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* @see HandlerBase#HandlerBase
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*/
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class XMLUTIL_EXPORT XMLEntityResolver
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{
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public:
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/** @name Constructors and Destructor */
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//@{
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/** Destructor */
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virtual ~XMLEntityResolver()
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{
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}
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//@}
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/** @name The XMLEntityResolver interface */
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//@{
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/**
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* Allow the application to resolve external entities.
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*
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* <p>The Parser will call this method before opening any external
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* entity except the top-level document entity (including the
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* external DTD subset, external entities referenced within the
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* DTD, and external entities referenced within the document
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* element): the application may request that the parser resolve
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* the entity itself, that it use an alternative URI, or that it
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* use an entirely different input source.</p>
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*
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* <p>Application writers can use this method to redirect external
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* system identifiers to secure and/or local URIs, to look up
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* public identifiers in a catalogue, or to read an entity from a
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* database or other input source (including, for example, a dialog
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* box).</p>
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*
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* <p>If the system identifier is a URL, the SAX parser must
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* resolve it fully before reporting it to the application.</p>
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*
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* @param resourceIdentifier An object containing the type of
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* resource to be resolved and the associated data members
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* corresponding to this type.
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* @return An InputSource object describing the new input source,
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* or null to request that the parser open a regular
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* URI connection to the system identifier.
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* The returned InputSource is owned by the parser which is
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* responsible to clean up the memory.
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* @exception SAXException Any SAX exception, possibly
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* wrapping another exception.
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* @exception IOException An IO exception,
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* possibly the result of creating a new InputStream
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* or Reader for the InputSource.
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*
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* @see InputSource#InputSource
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* @see XMLResourceIdentifier
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*/
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virtual InputSource* resolveEntity
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(
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XMLResourceIdentifier* resourceIdentifier
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) = 0;
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//@}
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protected:
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/** Default Constructor */
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XMLEntityResolver()
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{
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}
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private :
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/* Unimplemented constructors and operators */
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/* Copy constructor */
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XMLEntityResolver(const XMLEntityResolver&);
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/* Assignment operator */
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XMLEntityResolver& operator=(const XMLEntityResolver&);
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};
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XERCES_CPP_NAMESPACE_END
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#endif
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