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OpenBoard/thirdparty/mera/pdf-merger/PageElementHandler.h

84 lines
2.2 KiB

#if !defined PageElementHandler_h
#define PageElementHandler_h
#include <string>
#include <set>
#include "Object.h"
#include "Parser.h"
namespace merge_lib
{
//base class for all elements handlers
//Handlers are needed to process Page fields during the merge
//this is the chain of responsibility pattern
class PageElementHandler
{
public:
PageElementHandler(Object * page): _page(page), _pageContent(page->_content), _nextHandler(0)
{
_createAllPageFieldsSet();
}
virtual ~PageElementHandler()
{
delete _nextHandler;
}
void addNextHandler(PageElementHandler * nextHandler)
{
_nextHandler = nextHandler;
}
void processObjectContent()
{
unsigned int startOfPageElement = _findStartOfPageElement();
if(startOfPageElement != std::string::npos)
_processObjectContent(startOfPageElement);
if(_nextHandler)
_nextHandler->processObjectContent();
}
void changeObjectContent()
{
unsigned int startOfPageElement = _findStartOfPageElement();
if(startOfPageElement != std::string::npos)
_changeObjectContent(startOfPageElement);
else
_pageElementNotFound();
if(_nextHandler)
_nextHandler->changeObjectContent();
}
protected:
//methods
void _setHandlerName(const std::string & handlerName)
{
_handlerName = handlerName;
}
unsigned int _findEndOfElementContent(unsigned int startOfPageElement);
void _createAllPageFieldsSet();
//members
std::string & _pageContent;
Object * _page;
std::string _handlerName;
PageElementHandler * _nextHandler;
private:
//methods
virtual void _processObjectContent(unsigned int startOfPageElement){};
virtual void _changeObjectContent(unsigned int startOfPageElement) = 0;
virtual void _pageElementNotFound() {};
unsigned int _findStartOfPageElement()
{
return Parser::findToken(_pageContent,_handlerName);
}
//members
static std::set<std::string> _allPageFields;
};
}
#endif