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// -*- C++ -*-
//=============================================================================
/**
* @file Cascadable_DocHandler.h
*
* $Id$
*
* @author Nanbor Wang <nanbor@cs.wustl.edu>
*/
//=============================================================================
#ifndef CIAO_XMLHELPERS_CASCADABLE_DOCHANDLER_H
#define CIAO_XMLHELPERS_CASCADABLE_DOCHANDLER_H
#include /**/ "ace/pre.h"
#include "ACEXML/common/DefaultHandler.h"
#include "ACEXML/common/XMLReader.h"
#include "XML_Helpers_Export.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
#pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
namespace CIAO
{
namespace XMLHelpers
{
/**
* @class Cascadable_DocHandler
*
* @brief A helper class for implementing cascadable XML Document Handler.
*
* This class is available as a convenience base class for writing
* cascadable XML Document DefaultHandler. This class implement
* the basic functionality for DocHandlers that can be cascaded
* together to handling nested XML tags. Users can write specific
* handlers to handle specific XML elements so they can be
* composed together to handle complex XML definitions. This
* class utilize the "Interpreter" design pattern as described in
* GoF.
*
* Application writers should extend this class to implement a
* handler that interpret a specific XML element. There are just
* a few rules to use the Cascadable_DocHandler.
*
* 1. A Cascadable_DocHandler determines whether a new
* Cascadable_DocHandler should be used to handle a subelement
* in its startElement method. When it encounter a subelement
* that requires a different implementation of
* Cascadable_DocHandler, it should create the new
* Cascadable_DocHandler, and then invoke the @c push_handler
* method to inform the @c parser to use the new handler (this
* in effect switches all four handlers the parse uses to the
* new handler.)
*
* 2. A Cascadable_DocHandler determines whether it has done
* handling an element structure in @a endElement method, it
* invoke the pop_handler method of its parent handler. The
* pop_handler in turn invokes the endElement eventhandler of
* the parent handler so it has a chance to harvest the parse
* result from the child handler.
*
* See the Handler-Interaction.png for how handlers interact with
* each other.
*
* @sa ACEXML_DefaultHandler
* @sa DocHandler_Context
*/
class CIAO_XML_HELPERS_Export Cascadable_DocHandler : public ACEXML_DefaultHandler
{
public:
/**
* Constructor.
*/
Cascadable_DocHandler (ACEXML_XMLReader *parser,
Cascadable_DocHandler *parent,
const ACEXML_Char *namespaceURI,
const ACEXML_Char *localName,
const ACEXML_Char *qName,
ACEXML_Attributes *atts
ACEXML_ENV_ARG_DECL)
ACE_THROW_SPEC ((ACEXML_SAXException)) ;
/**
* destructor.
*/
virtual ~Cascadable_DocHandler (void);
/**
* Destroy method.
*/
virtual void destroy ();
/**
* THIS function should be called by the @c startElement method
* of the parent Handler to replace it (the current *Handlers)
* the parser is using with the this Handler. This method will
* also invoke the startElement operations of this Handler.
*
* @@ I haven't figured out what should happen if an exception
* occurs in push_handler. It can either restore the original
* handler, or let the user decide what to do.
*/
void push_handler (Cascadable_DocHandler *new_handler,
ACEXML_Attributes *atts
ACEXML_ENV_ARG_DECL)
ACE_THROW_SPEC ((ACEXML_SAXException)) ;
/**
* This function should be called at the end of @c endElement
* method of this Handler to restore the Handler's used by the
* parser. This method aldo invokes the @c endElement method of
* the parent Handler before restoring the parser Handlers.
* This allows the parent handler to have a chance to harvest
* the parse result from this Handler. @c pop_handler will
* eventually invoke the @c destroy method of child handler.
* Since @c pop_handler should be invoked from child handler's
* @c endElement method, care should be taken to avoid accessing
* free'ed memory after calling parent's @c pop_handler method.
*/
void pop_handler (const ACEXML_Char *namespaceURI,
const ACEXML_Char *localName,
const ACEXML_Char *qName
ACEXML_ENV_ARG_DECL)
ACE_THROW_SPEC ((ACEXML_SAXException)) ;
/**
* Accessors for the element Context we are in. Make copy if
* you need to store the return strings for later use.
*/
const ACEXML_Char *namespaceURI (void) const;
const ACEXML_Char *localName (void) const;
const ACEXML_Char *qName (void) const;
/**
* Receive an object for locating the origin of SAX document events.
*/
virtual void setDocumentLocator (ACEXML_Locator *locator) ;
// Methods inherit from ACEXML_ErrorHandler.
/**
* Receive notification of a recoverable error.
*/
virtual void error (ACEXML_SAXParseException &exception
ACEXML_ENV_ARG_DECL)
ACE_THROW_SPEC ((ACEXML_SAXException))
;
/**
* Receive notification of a non-recoverable error.
*/
virtual void fatalError (ACEXML_SAXParseException &exception
ACEXML_ENV_ARG_DECL)
ACE_THROW_SPEC ((ACEXML_SAXException))
;
/**
* Receive notification of a warning.
*/
virtual void warning (ACEXML_SAXParseException &exception
ACEXML_ENV_ARG_DECL)
ACE_THROW_SPEC ((ACEXML_SAXException))
;
protected:
/**
* Print out an error/warning message
*/
virtual void print_warning (const ACEXML_Char *level,
ACEXML_SAXParseException &exception
ACEXML_ENV_ARG_DECL)
ACE_THROW_SPEC ((ACEXML_SAXException))
;
/**
* Element tag information.
*/
ACEXML_Char *namespaceURI_;
ACEXML_Char *localName_;
ACEXML_Char *qName_;
/// Pointer to the parser that send us events.
ACEXML_XMLReader *parser_;
/// Pointer to the parent event handler that handles the parent
/// element.
Cascadable_DocHandler *parent_;
/// Pointer to the child event handler that handles a sub-element.
Cascadable_DocHandler *child_;
private:
/// No implement
Cascadable_DocHandler ();
/// Pointer to Locator.
ACEXML_Locator* locator_;
};
/**
* @class Skip_DocHandler
*
* @brief This DocHandler ignore and skip over a specific tag.
*/
class CIAO_XML_HELPERS_Export Skip_DocHandler : public Cascadable_DocHandler
{
public:
/// Constructor.
Skip_DocHandler (ACEXML_XMLReader *parser,
Cascadable_DocHandler *parent,
const ACEXML_Char *namespaceURI,
const ACEXML_Char *localName,
const ACEXML_Char *qName,
ACEXML_Attributes *atts
ACEXML_ENV_ARG_DECL)
ACE_THROW_SPEC ((ACEXML_SAXException));
/// Destructor
virtual ~Skip_DocHandler ();
/**
* Receive notification of the end of an element.
*/
virtual void endElement (const ACEXML_Char *namespaceURI,
const ACEXML_Char *localName,
const ACEXML_Char *qName
ACEXML_ENV_ARG_DECL)
ACE_THROW_SPEC ((ACEXML_SAXException)) ;
/**
* Receive notification of the beginning of an element.
*/
virtual void startElement (const ACEXML_Char *namespaceURI,
const ACEXML_Char *localName,
const ACEXML_Char *qName,
ACEXML_Attributes *atts
ACEXML_ENV_ARG_DECL)
ACE_THROW_SPEC ((ACEXML_SAXException)) ;
protected:
long element_count_;
};
}
}
#if defined (__ACE_INLINE__)
# include "Cascadable_DocHandler.i"
#endif /* __ACE_INLINE__ */
#include /**/ "ace/post.h"
#endif /* CIAO_XMLHELPERS_CASCADABLE_DOCHANDLER_H */
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