iobuf_Seq Class Reference

Stream buffer. More...

#include <io_buffer.h>

Inheritance diagram for iobuf_Seq:

Collaboration diagram for iobuf_Seq:

Public Member Functions
	iobuf_Seq (uint16 clusterSize)
	Constructor.
virtual	~iobuf_Seq ()
	Destructor.
void	Reserve (size_t n, bool addAdditionalSpace=true)
	< Reserve space for a given number of elements. More...
void	Flush ()
	Free the whole memory.
void	HardFlush ()
	Free the unnecessary memory.
void	Adjust ()
	Add an element to the end of the array.
Cluster *	Add ()
	Add a given element to the end of the array.
Cluster *	Add (const Cluster &e)
	Get the number of elements in array.
Cluster &	operator[] (size_t loc) const
	Access by index operator. More...
int	gc ()
	Get the next byte from the buffer.
size_t	getn (void *, size_t)
	Get the next n bytes from the buffer elementwise.
size_t	getln (void *, size_t)
	Get the next n bytes from the buffer by copying the storage area.
int	pc (uint8 c)
	Get the next byte from the buffer but don't shift the pointer to the next one. More...
size_t	putn (const void *, size_t)
	Put the next n bytes to the buffer elementwise.
size_t	putln (const void *, size_t)
	Put the next n bytes to the buffer by copying the storage area.
void	advance ()
	If current buffer exhausted, advance pointer to the next one.
bool	good () const
	Whether the buffer state is correct.
bool	eof () const
	Is the end of file reached?
uint32	state () const
	Get the buffer state.
void	setState (io::state add)
	Add the buffer state.
void	clearState (io::state sub)
	Remove the buffer state.
io::pos	size () const
	Calculate the current file size.
io::pos	tell () const
	Returns the current position in the file.
void	lseek (size_t pos=SYS_MAX_T)
	Set current position in the buffer.
bool	attach (FileSpace &file, bool check=true)
	Attach the file to the buffer with or without checking.
virtual bool	open (FileSpace &file, uint8 om, const VersionContainer &, bool fullCheck=true)
	Open the file if it is one's own file. The flag fullCheck == false switches off excessive checks (for the sake of performance).
bool	openSys (uint8 om)
	Open the system file.
virtual void	close ()
	Close the file.
virtual void	closeBuff ()
	Close the buffer.
virtual FileSpace *	enterFileSpace (uint8)
	Set FileSpace with given index for writing (create if necessary).
virtual FileSpace *	enterFileSpace (const ClusterReference &, bool)
	Set position for for writing/reading by given ClusterReference. If saveCurr = true, save previous position.
virtual FileSpace *	enterFileSpace (const ClusterReference &, FileSpace *, bool)
	Set position for writing/reading by given FileSpace and ClusterReference. Warning: in this function, ClusterReference.clusterIndex should contain an index in array of cluster indices in FileSpace! If saveCurr = true, save previous position.
virtual FileSpace *	returnToPreviousFileSpace ()
	Set previous FileSpace for writing/reading.
ClusterReference	getCurrentClusterPos ()
	Get current position in the buffer.
FileSpace &	sysFile ()
	Get access to the system file.
FileSpace *	openedFile () const
	Get access to the open file.
virtual size_t	DOSFileLen () const
	The storage data size (of the file on the disk).
virtual const TCHAR *	DOSFileName () const
	Storage name (of file on the disk).
bool	fresh () const
	Is the buffer fresh?
void	fresh (bool f)
	Set the state of buffer freshness.
bool	modified () const
	Is the buffer modified?
void	modified (bool m)
	Set the state of modified buffer.
uint8	mode () const
	Get the buffer mode.
void	mode (uint8 m)
	Set the buffer mode.
bool	IsInMode () const
	Is in the reading mode?
bool	IsOutMode () const
	Is in the writing mode?
bool	IsInOrOutMode () const
	Is in the reading or writing mode?
bool	deleteIfEmpty () const
	Is the empty file to be deleted?
void	deleteIfEmpty (bool s)
	Set the flag of deleting the empty file.
bool	deleteOnClose () const
	Is the file to be deleted while closing the buffer?
void	deleteOnClose (bool s)
	Set the flag of deleting the file while closing the buffer.
void	SetVersionsByStorage ()
	Set the current version to be equal to the storage version.
VERSION	MathVersion () const
	Return the main version (of the mathematical kernel).
VERSION	AppVersion (size_t ind=-1) const
	Return the additional version (of the target application).
const VersionContainer &	GetVersionsContainer () const
	Get the buffer versions.
VERSION	GetStorageVersion ()
	Get the storage version.
VERSION	GetFormatVersion () const
	Get the format version.
void	SetFormatVersion (VERSION version)
	Set the format version.

Protected Member Functions
int	underflow ()
	Called when the whole buffer are read, but it is necessary to continue reading.
int	overflow (uint8 ch)
	Called when the buffer is full but it is necessary to continue writing.
virtual int	setup ()=0
	Set the next buffer.
virtual int	flush ()=0
	Flush the buffer.
void	checkEof ()
	Set the end of file if necessary.
size_t	avail () const
	Get the number of unprocessed bytes in the buffer.
size_t	waiting () const
	Get the number of processed bytes in the buffer.
bool	mine (FileSpace &)
	Check if the file is mine.
void	SetVersionsContainer (const VersionContainer &vers)
	Set the version of open file.
VERSION	SetStorageVersion (VERSION)
	Set the storage version.

Protected Attributes
uint8 *	base
	Pointer to the beginning of the buffer.
uint8 *	ptr
	Pointer to the next byte.
uint8 *	end
	Pointer to the end of the file.
VERSION	storageVers
	The storage version (must be before 'curFileVers').
VersionContainer	curFileVers
	Version of the current open file (stream).
VERSION	formatVersion
	The format version.
FileSpace	sys
	System file.
PArray< FileSpace >	files
	List of files contained in iobuf_Seq (the first element is the address of 'sys').
FileSpace *	curr
	Current open file (stream).
size_t	part
	Current cluster in the current open file.
uint16	clusterSize
	Cluster size.
uint8	bufferMode
	Buffer mode.
uint8	curFileMode
	Mode of opening the current file.
bool	modifiedFlag
	The buffer has been modified.
bool	freshFlag
	Is the buffer fresh.

Friends
class	tape

Detailed Description

Stream buffer.

Stream buffer - the base class.
Buffer iobuf_Seq and its descendants are used for read and write operations in the interest of the stream (class tape).
Classes iobuf_Seq, tape, Catalog and their descendants should be considered together.
Terminology:

• Storage - file on the disk or memory space.
  
• Catalog - catalog inside the storage.
  
• File - file inside the storage.
  Class iobuf_Seq contains a cluster array.
  Class Cluster is structured information about the cluster (its beginning and length). It is used for operations with disk, in this case the beginning is a shift, and for operations with memory, in this case the beginning is an address in memory. All the operations of reading and writing are performed clusterwise using the index in the array of clusters iobuf_Seq.
  Class FileSpace is a place allocated for the file, is an array of indices in the array of clusters. It is just what we call 'file' here.
  Attention: from this place the word 'cluster' should be read as index of cluster in the array iobuf_Seq of clusters.
  
  The most important data fields of iobuf_Seq:
  FileSpace sys - "system" file. It is opened in the constructor of the class tape.
  
  1. If the class iobuf_Seq is directly used by class tape (for instance: writer potok( "file.ext" ); or reader * potok = new reader( "file.ext" ), then the file sys contains the information which were written to file.ext.
     
  2. If the class iobuf_Seq is used by class Catalog, then file sys contains the structure of catalogs and files inside Catalog (it is read in the constructor of class Catalog).
     PArray<FileSpace> files - the list of files contained in iobuf_Seq. The first element is always the address of sys. While writing Catalog, the contents of files is written to sys, except the first element, naturally.
     uint32 stateFlag - the buffer state. It is considered that all the read-write operations set this flag when it is necessary and check its state before the real execution. The following functions work with this flag: iobuf_Seq::good, iobuf_Seq::eof, iobuf_Seq::state, iobuf_Seq::setState, iobuf_Seq::clearState; tape::good, tape::eof, tape::state; Catalog::good, Catalog::goodeof, Catalog::goodstate.
     VERSION storageVers - the storage version.
     VERSION curFileVers - version of the current open file (stream).
     In the common case the storage version and the version of any file in the storage can be different.
     uint8 bufferMode - A possible buffer mode.
     uint8 curFileMode - Mode of the current file opening.
     In the common case the storage mode and the mode of open file in this storage can be different. Constraint - if the buffer mode is io::in, then an attempt to open the file for writing (io::out) doesn't result in opening.
     uint8 * base - Pointer to the beginning of the buffer in memory.
     uint8 * ptr - Pointer to the next symbol in memory.
     uint8 * end - Pointer to the end of buffer in the memory.
     When working with the disk, pointers are set to a fixed memory block the sections of file are loaded to while reading. When working with the memory, 'membuf' set them to the memory allocated for the cluster.
     
     The most important functions of iobuf_Seq:
     Function setup() - set the next cluster to 'buffer' (variables 'base', 'ptr', 'end'). Called from functions 'overflow' (while writing) and 'underflow' (while reading) when the current buffer is over. These functions are in turn called from functions of reading-writing of symbols from the stream (gc(), getn(), getln(), pc(), putn(), putln()).

Function flush() - flush the buffer. Called before getting the next cluster. Do nothing while reading. When writing, when working with the disk, saves the previos cluster on the disk, and, when working with the memory, stores the size of the last filled cluster.
Read operations are performed inside the file which is open at the moment, no read after end of the file.

Member Function Documentation

Reserve()

void iobuf_Seq::Reserve	(	size_t	n,
		bool	addAdditionalSpace = true
	)

< Reserve space for a given number of elements.

Set the number of elements to null.

operator[]()

Cluster& iobuf_Seq::operator[]

(

size_t

loc

)

const

Access by index operator.

Reserve space for a given number of FileSpace.

pc()

int iobuf_Seq::pc

(

uint8

c

)

Get the next byte from the buffer but don't shift the pointer to the next one.

Put byte to the buffer.

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The documentation for this class was generated from the following file:

• io_buffer.h