TStreamMark Class Reference

class TStreamMark

Manages the position of a read mark or a write mark within a shared stream.

A shared stream is one that shares its host with other streams. In practice, the host is a stream buffer that is, itself, hosted by a file, an RFileBuf object.

TStreamMark objects are owned by RShareBuf, one for reading and one for writing. They re-direct read/write operations through a TStreamExchange object to the RFileBuf object, which handles the actual file read and write operations.

RFileBuf

RShareBuf

TStreamExchange

Public Member Functions
	TStreamMark()
	TStreamMark(TStreamPos)
void	Clear()
void	ExtractL(TStreamExchange &)
TBool	IsEmpty()
TBool	IsWith(TStreamExchange &)
TStreamPos	Position()
TInt	ReadL(TStreamExchange &, TAny *, TInt)
IMPORT_C TInt	ReadL(TStreamExchange &, TDes8 &, TRequestStatus &)
TInt	ReadL(TStreamExchange &, TDes8 &, TInt, TRequestStatus &)
TStreamTransfer	ReadL(TStreamExchange &, MStreamInput &, TStreamTransfer)
TInt	ReadL(TStreamExchange &, MStreamInput &, TInt)
void	ReadL(TStreamExchange &, MStreamInput &)
TBool	RelatesTo(TStreamExchange &)
void	SeekL(TStreamExchange &, TStreamPos)
TStreamPos	SeekL(TStreamExchange &, TStreamLocation, TInt)
TStreamPos	SeekL(TStreamExchange &, TInt)
TStreamPos	TellL(TStreamExchange &)
void	Withdraw(TStreamExchange &)
void	WriteL(TStreamExchange &, const TAny *, TInt)
IMPORT_C TInt	WriteL(TStreamExchange &, const TDesC8 &, TRequestStatus &)
TInt	WriteL(TStreamExchange &, const TDesC8 &, TInt, TRequestStatus &)
TStreamTransfer	WriteL(TStreamExchange &, MStreamOutput &, TStreamTransfer)
TInt	WriteL(TStreamExchange &, MStreamOutput &, TInt)
void	WriteL(TStreamExchange &, MStreamOutput &)
	operator TStreamMark *()
	operator const TStreamMark *()
TBool	operator!=(const TStreamMark &)
TBool	operator!=(const TStreamMark *)
TStreamMark &	operator=(TStreamPos)
TBool	operator==(const TStreamMark &)
TBool	operator==(const TStreamMark *)

Private Member Functions
	TStreamMark(const TStreamMark &)
TBool	IsTracking(TStreamMark *const &)
void	Track(TStreamMark *const &)
IMPORT_C void	__DbgChkPos(TStreamPos)
TStreamMark &	operator=(const TStreamMark &)

Private Attributes
TStreamPos	iPos

Constructor & Destructor Documentation

TStreamMark()

TStreamMark

(

)

[inline]

Constructs a default shared stream mark object.

The position for the mark is uninitialised.

An uninitialised mark means that a call to IsEmpty() returns true.

IsEmpty()

TStreamMark(TStreamPos)

TStreamMark

(

TStreamPos

aPos

)

[inline]

Constructs the shared stream mark object, setting the mark to the specified stream position.

An initialised mark means that a call to IsEmpty() returns false.

IsEmpty()

Parameters

TStreamPos aPos

The stream position

TStreamMark(const TStreamMark &)

TStreamMark

(

const TStreamMark &

)

[private]

Constructs a default shared stream mark object.

The position for the mark is uninitialised.

An uninitialised mark means that a call to IsEmpty() returns true.

IsEmpty()

Parameters

const TStreamMark &

Member Functions Documentation

Clear()

void

Clear

(

)

[inline]

Resets the mark object to its default state.

On return from this function, the mark is uninitialised and a call to IsEmpty() returns true.

Empties the object/makes it empty so that IsEmpty() returns false

ExtractL(TStreamExchange &)

void

ExtractL

(

TStreamExchange &

aHost

)

[inline]

Refreshes this mark from the mark in the host stream buffer and tells the shared streaming manager to drop any reference it has to to this mark object.

Parameters

TStreamExchange & aHost

The object that manages shared streaming.

IsEmpty()

TBool

IsEmpty

(

)

const [inline]

Tests whether this mark object is uninitialised.

True, if this mark object is uninitialised; false, otherwise.

IsTracking(TStreamMark *const &)

TBool

IsTracking

(

TStreamMark *const &

aRef

)

const [private, inline]

Parameters

TStreamMark *const & aRef

IsWith(TStreamExchange &)

TBool

IsWith

(

TStreamExchange &

aHost

)

const [inline]

Tests whether the specified shared streaming manager currently refers to this mark object.

True, if the shared stream manager refers to this mark; false, otherwise.

Parameters

TStreamExchange & aHost

The object that manages shared streaming.

Position()

TStreamPos

Position

(

)

const [inline]

Gets the position of the mark.

The stream position.

ReadL(TStreamExchange &, TAny *, TInt)

TInt	ReadL	(	TStreamExchange &	aHost,
			TAny *	aPtr,
			TInt	aMaxLength
		)	[inline]

Reads data from the shared stream into the specified memory location.

The number of bytes read.

Parameters

TStreamExchange & aHost	The object that manages shared streaming.
TAny * aPtr	A pointer to the target memory location for the data read from the shared stream.
TInt aMaxLength	The maximum number of bytes to be read.

ReadL(TStreamExchange &, TDes8 &, TRequestStatus &)

IMPORT_C TInt	ReadL	(	TStreamExchange &	aHost,
			TDes8 &	aDes,
			TRequestStatus &	aStatus
		)

Parameters

TStreamExchange & aHost
TDes8 & aDes
TRequestStatus & aStatus

ReadL(TStreamExchange &, TDes8 &, TInt, TRequestStatus &)

TInt	ReadL	(	TStreamExchange &	aHost,
			TDes8 &	aDes,
			TInt	aMaxLength,
			TRequestStatus &	aStatus
		)	[inline]

Reads data, asynchronously, from the shared stream into the specified descriptor.

If the function leaves, then no read request will have been initiated.

The maximum number of bytes to be read, as used in this request. This can be different to the value supplied in aMaxLength; this is dependent on the implementation of the underlying stream.

Parameters

TStreamExchange & aHost	The object that manages shared streaming.
TDes8 & aDes	The target descriptor for the data read from the shared stream.
TInt aMaxLength	The maximum number of bytes to be read.
TRequestStatus & aStatus	The request status that indicates the completion status of this asynchronous request.

ReadL(TStreamExchange &, MStreamInput &, TStreamTransfer)

TStreamTransfer	ReadL	(	TStreamExchange &	aHost,
			MStreamInput &	anInput,
			TStreamTransfer	aTransfer
		)	[inline]

Reads data from the shared stream into the specified data sink.

The amount of data that was not consumed.

Parameters

TStreamExchange & aHost	The object that manages shared streaming.
MStreamInput & anInput	The sink which is the target for the read operation.
TStreamTransfer aTransfer	Defines the amount of data available to be read from the shared stream.

ReadL(TStreamExchange &, MStreamInput &, TInt)

TInt	ReadL	(	TStreamExchange &	aHost,
			MStreamInput &	anInput,
			TInt	aMaxLength
		)	[inline]

Reads data from the shared stream into the specified data sink.

The amount of data that was not consumed.

Parameters

TStreamExchange & aHost	The object that manages shared streaming.
MStreamInput & anInput	The sink which is the target for the read operation.
TInt aMaxLength	The maximum amount of data available to be read from the shared stream.

ReadL(TStreamExchange &, MStreamInput &)

void	ReadL	(	TStreamExchange &	aHost,
			MStreamInput &	anInput
		)	[inline]

Reads data from the shared stream into the specified data sink.

No explicit limit is placed on the amount of data that can be read.

Parameters

TStreamExchange & aHost	The object that manages shared streaming.
MStreamInput & anInput	The sink which is the target for the read operation.

RelatesTo(TStreamExchange &)

TBool

RelatesTo

(

TStreamExchange &

aHost

)

const [inline]

Tests whether the specified shared streaming manager currently refers to this mark object OR whether this mark object is initialised.

True, if the shared stream manager refers to this mark OR if this mark object is initialised; false, otherwise.

IsWith()

TStreamExchange::IsActive()

Parameters

TStreamExchange & aHost

The object that manages shared streaming.

SeekL(TStreamExchange &, TStreamPos)

void	SeekL	(	TStreamExchange &	aHost,
			TStreamPos	aPos
		)	[inline]

Parameters

TStreamExchange & aHost
TStreamPos aPos

SeekL(TStreamExchange &, TStreamLocation, TInt)

TStreamPos	SeekL	(	TStreamExchange &	aHost,
			TStreamLocation	aLocation,
			TInt	anOffset = 0
		)	[inline]

Moves the position of the mark in the host stream.

The new position is calculated by adding the specified offset to one of:

the position of the beginning of the host stream

the position of the end of the host stream

the position of the current mark.

The new position of the mark.

Parameters

TStreamExchange & aHost	The object that manages shared streaming.
TStreamLocation aLocation	The location in the host stream on which the calculation of the new position is based.
TInt anOffset = 0	The offset value.

SeekL(TStreamExchange &, TInt)

TStreamPos	SeekL	(	TStreamExchange &	aHost,
			TInt	anOffset
		)	[inline]

Moves the position of the mark in the host stream.

The new position of the mark.

Parameters

TStreamExchange & aHost	The object that manages shared streaming.
TInt anOffset	The amount by which the position of the mark is to be moved relative to the existing position of the mark.

TellL(TStreamExchange &)

TStreamPos

TellL

(

TStreamExchange &

aHost

)

const [inline]

Gets the position of the mark within the host stream.

The stream position.

Parameters

TStreamExchange & aHost

The object that manages shared streaming.

Track(TStreamMark *const &)

void

Track

(

TStreamMark *const &

aRef

)

[private, inline]

Parameters

TStreamMark *const & aRef

Withdraw(TStreamExchange &)

void

Withdraw

(

TStreamExchange &

aHost

)

[inline]

Instructs the shared streaming manager to remove any reference it has to this mark object.

Parameters

TStreamExchange & aHost

The object that manages shared streaming.

WriteL(TStreamExchange &, const TAny *, TInt)

void	WriteL	(	TStreamExchange &	aHost,
			const TAny *	aPtr,
			TInt	aLength
		)	[inline]

Writes data from the specified memory location into the shared stream.

Parameters

TStreamExchange & aHost	The object that manages shared streaming.
const TAny * aPtr	A pointer to the memory location from which data is to be written to the shared stream.
TInt aLength	The number of bytes to be written.

WriteL(TStreamExchange &, const TDesC8 &, TRequestStatus &)

IMPORT_C TInt	WriteL	(	TStreamExchange &	aHost,
			const TDesC8 &	aDes,
			TRequestStatus &	aStatus
		)

Parameters

TStreamExchange & aHost
const TDesC8 & aDes
TRequestStatus & aStatus

WriteL(TStreamExchange &, const TDesC8 &, TInt, TRequestStatus &)

TInt	WriteL	(	TStreamExchange &	aHost,
			const TDesC8 &	aDes,
			TInt	aMaxLength,
			TRequestStatus &	aStatus
		)	[inline]

Writes data, asynchronously, from the specified descriptor into the shared stream.

If the function leaves, then no write request will have been initiated.

The maximum number of bytes to be written, as used in this request. This can be different to the value supplied in aMaxLength; this is dependent on the implementation.

Parameters

TStreamExchange & aHost	The object that manages shared streaming.
const TDesC8 & aDes	The source descriptor for the data to be written into the shared stream.
TInt aMaxLength	The maximum number of bytes to be written.
TRequestStatus & aStatus	The request status that indicates the completion status of this asynchronous request.

WriteL(TStreamExchange &, MStreamOutput &, TStreamTransfer)

TStreamTransfer	WriteL	(	TStreamExchange &	aHost,
			MStreamOutput &	anOutput,
			TStreamTransfer	aTransfer
		)	[inline]

Writes data into the shared stream from the specified data source.

A stream transfer object defining the amount of data that was not consumed.

Parameters

TStreamExchange & aHost	The object that manages shared streaming.
MStreamOutput & anOutput	The data source for the write operation.
TStreamTransfer aTransfer	Defines the amount of data to be pulled from the output stream object.

WriteL(TStreamExchange &, MStreamOutput &, TInt)

TInt	WriteL	(	TStreamExchange &	aHost,
			MStreamOutput &	anOutput,
			TInt	aMaxLength
		)	[inline]

Writes data into the shared stream from the specified data source

The amount of data that was not consumed.

Parameters

TStreamExchange & aHost	The object that manages shared streaming.
MStreamOutput & anOutput	The data source for the write operation.
TInt aMaxLength	The maximum amount of data available to be written.

WriteL(TStreamExchange &, MStreamOutput &)

void	WriteL	(	TStreamExchange &	aHost,
			MStreamOutput &	anOutput
		)	[inline]

Writes data into the shared stream from the specified data source.

No explicit limit is placed on the amount of data that can be written.

Parameters

TStreamExchange & aHost	The object that manages shared streaming.
MStreamOutput & anOutput	The data source for the write operation.

__DbgChkPos(TStreamPos)

IMPORT_C void

__DbgChkPos

(

TStreamPos

aPos

)

[private, static]

Parameters

TStreamPos aPos

operator TStreamMark *()

operator TStreamMark *

(

)

[inline]

operator const TStreamMark *()

operator const TStreamMark *

(

)

const [inline]

operator!=(const TStreamMark &)

TBool

operator!=

(

const TStreamMark &

aMark

)

const [inline]

Tests whether this object and the specified shared stream mark object are different objects.

True, if the two objects are different objects; false, otherwise.

Parameters

const TStreamMark & aMark

A pointer to a shared stream mark object.

operator!=(const TStreamMark *)

TBool

operator!=

(

const TStreamMark *

aPtr

)

const [inline]

Parameters

const TStreamMark * aPtr

operator=(TStreamPos)

TStreamMark &

operator=

(

TStreamPos

aPos

)

[inline]

Assigns the specified stream position value to this shared stream mark object.

A reference to this shared stream mark object.

Parameters

TStreamPos aPos

The stream position value to be assigned.

operator=(const TStreamMark &)

TStreamMark &

operator=

(

const TStreamMark &

)

[private]

Parameters

const TStreamMark &

operator==(const TStreamMark &)

TBool

operator==

(

const TStreamMark &

aMark

)

const [inline]

Tests whether this object and the specified referenced shared stream mark object are the same object.

True, if the two objects are the same object; false, otherwise.

Parameters

const TStreamMark & aMark

A reference to a shared stream mark object.

operator==(const TStreamMark *)

TBool

operator==

(

const TStreamMark *

aPtr

)

const [inline]

Parameters

const TStreamMark * aPtr

Member Data Documentation

TStreamPos iPos

TStreamPos

iPos

[private]