core/ASCOfficeXlsFile2/source/XlsFormat/Binary/CFStreamCacheReader.h

#pragma once

#include "CFRecordType.h"
#include "BinSmartPointers.h"
#include <Logic/GlobalWorkbookInfo.h>
#include <Logic/Biff_structures/ODRAW/OfficeArtRecordHeader.h>

namespace XLS
{

// The only purpose of the reader is to avoid seeking back through IStream when, for example, 
// we have read a record from a binary stream to the CFRecord, but the record of this type is
// not waitable right at the moment and shall be read a little bit later.
// Example of a construction: 
// PIVOTTH = SXTH *ContinueFrt
// ContinueFrt may appear in the stream and may not. So, this class will increase performance much

class CFStreamCacheReader
{
public:
	CFStreamCacheReader(CFStreamPtr stream, const GlobalWorkbookInfoPtr global_info);
	~CFStreamCacheReader();

	// Reads the next CFRecord from the CFStream and if it's type is not the desired one, caches it for the next call
	CFRecordPtr getNextRecord(const CFRecordType::TypeId desirable_type, const bool gen_except = false);
	// Check if the next read record would be of desired type
	const bool checkNextRecord(const CFRecordType::TypeId desirable_type, const size_t num_records_to_check = 1);
	// Checks whether the next record is Continue and append its data to the real record if so
	void checkAndAppendContinueData();

	const bool isEOF() const;
	// Skip the specified number of unsigned chars without processing
	void skipNunBytes(const size_t n);
	// Seek to the next substream (Read all records till EOF then skip EOF)
	// Doesn't generate EndOfStreamReached if the stream is the last one
	const bool SeekToEOF(); 
	// Extract the next record from the stream leaving it in the cache for future read.
	// Always call resetPointerToBegin for the extracted CFRecord after using it
	CFRecordPtr touchTheNextRecord();
	// Check the next record type
	const CFRecordType::TypeId getNextRecordType();

	GlobalWorkbookInfoPtr getGlobalWorkbookInfo() { return global_info_; }
private:
	// Make sure the internal buffer has concrete number of records. Returns number of records read
	const size_t readFromStream(const size_t num_of_records_min_necessary);

private:
	CFStreamPtr stream_;
	CFRecordPtrList records_cache;
	GlobalWorkbookInfoPtr global_info_;
	std::vector<std::string> skippable_records_names;	
};

} // namespace XLS