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90 lines
3.5 KiB
C++
90 lines
3.5 KiB
C++
//
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// EntityResolver.h
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//
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// Library: XML
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// Package: SAX
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// Module: SAX
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//
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// SAX EntityResolver Interface.
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//
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// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
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// and Contributors.
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//
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// SPDX-License-Identifier: BSL-1.0
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//
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#ifndef SAX_EntityResolver_INCLUDED
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#define SAX_EntityResolver_INCLUDED
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#include "Poco/XML/XML.h"
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#include "Poco/XML/XMLString.h"
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namespace Poco
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{
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namespace XML
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{
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class InputSource;
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class XML_API EntityResolver
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/// If a SAX application needs to implement customized handling for external entities,
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/// it must implement this interface and register an instance with the SAX driver using
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/// the setEntityResolver method.
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///
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/// The XML reader will then allow the application to intercept any external entities
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/// (including the external DTD subset and external parameter entities, if any) before
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/// including them.
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///
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/// Many SAX applications will not need to implement this interface, but it will be
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/// especially useful for applications that build XML documents from databases or other
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/// specialised input sources, or for applications that use URI types other than URLs.
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///
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/// The application can also use this interface to redirect system identifiers to local
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/// URIs or to look up replacements in a catalog (possibly by using the public identifier).
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{
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public:
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virtual InputSource * resolveEntity(const XMLString * publicId, const XMLString & systemId) = 0;
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/// Allow the application to resolve external entities.
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///
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/// The parser will call this method before opening any external entity except the
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/// top-level document entity. Such entities include the external DTD subset and
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/// external parameter entities referenced within the DTD (in either case, only
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/// if the parser reads external parameter entities), and external general entities
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/// referenced within the document element (if the parser reads external general entities).
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/// The application may request that the parser locate the entity itself, that it use an
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/// alternative URI, or that it use data provided by the application (as a character or
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/// byte input stream).
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///
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/// Application writers can use this method to redirect external system identifiers to
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/// secure and/or local URIs, to look up public identifiers in a catalogue, or to read an
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/// entity from a database or other input source (including, for example, a dialog box).
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/// Neither XML nor SAX specifies a preferred policy for using public or system IDs to resolve
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/// resources. However, SAX specifies how to interpret any InputSource returned by this method,
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/// and that if none is returned, then the system ID will be dereferenced as a URL.
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///
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/// If the system identifier is a URL, the SAX parser must resolve it fully before reporting it to
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/// the application.
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///
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/// Note that publicId maybe null, therefore we pass a pointer rather than a reference.
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virtual void releaseInputSource(InputSource * pSource) = 0;
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/// This is a non-standard extension to SAX!
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/// Called by the parser when the input source returned by ResolveEntity is
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/// no longer needed. Should free any resources used by the input source.
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protected:
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virtual ~EntityResolver();
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};
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}
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} // namespace Poco::XML
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#endif // SAX_EntityResolver_INCLUDED
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