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