| class TBufBuf : public TStreamBuf |
A stream buffer that uses a dynamic buffer for its implementation.
A stream of this type is used by RBufWriteStream and RBufReadStream objects. It also has intermediate buffering capabilities.
This is a seekable stream buffer.
There are three write modes:
insert mode - inserts new data into the buffer at the offset passed to Set()
overwrite mode - replaces the data in the buffer starting at the offset passed to Set() . Once the end of the buffer is reached, it is automatically extended as more data is written. This is the default mode.
truncate mode - truncates the buffer to the offset passed to Set() before data is written, extending the buffer. When writing, the buffer size as reported by CBufBase::Size() may be larger than the data written to the stream. To synchronise the buffer's reported size with the stream, call the MStreamBuf::SynchL() function.
Note that this object never takes ownership of the dynamic buffer, the CBufBase type object.
RBufWriteStream RBufReadStream CBufBase::Size() MStreamBuf::SynchL()
| Public Member Functions | |
|---|---|
| TBufBuf () | |
| IMPORT_C void | Set ( CBufBase &, TInt , TInt ) |
| Protected Member Functions | |
|---|---|
| IMPORT_C TStreamPos | DoSeekL ( TMark , TStreamLocation , TInt ) |
| IMPORT_C void | DoSynchL () |
| IMPORT_C void | DoWriteL (const TAny *, TInt ) |
| IMPORT_C void | OverflowL () |
| IMPORT_C TInt | UnderflowL ( TInt ) |
| Private Member Functions | |
|---|---|
| CBufBase & | Buf () |
| void | Consolidate () |
| TInt | Mark ( TRead ) |
| TInt | Mark ( TWrite ) |
| TInt | MovePos ( TRead , TInt ) |
| TInt | MovePos ( TWrite , TInt ) |
| TInt | Pos ( TMark ) |
| TInt | Pos ( TRead ) |
| TInt | Pos ( TWrite ) |
| void | SetPos ( TMark , TInt ) |
| void | SetPos ( TRead , TInt ) |
| void | SetPos ( TWrite , TInt ) |
| Inherited Enumerations | |
|---|---|
| MStreamBuf:TRead | |
| MStreamBuf:TWrite | |
| Private Attributes | |
|---|---|
| CBufBase * | iBuf |
| TInt | iMode |
| TInt | iRPos |
| TInt | iWPos |
| IMPORT_C TStreamPos | DoSeekL | ( | TMark | aMark, |
| TStreamLocation | aLocation, | |||
| TInt | anOffset | |||
| ) | [protected, virtual] | |||
| IMPORT_C void | DoSynchL | ( | ) | [protected, virtual] |
Synchronises the stream buffer with the stream, leaving if any error occurs.
In effect, this ensures that buffered data is delivered to the stream.
It is called by SynchL() .
This implementation is empty, but classes derived from MStreamBuf can provide their own implementation, if necessary.
| IMPORT_C void | DoWriteL | ( | const TAny * | aPtr, |
| TInt | aLength | |||
| ) | [protected, virtual] | |||
Writes data from the specified memory location into the intermediate buffer.
The function calls the virtual function OverfLowL() to give concrete implementations the chance to forward the intermediate buffer content to its destination.
This implementation overrides the one supplied by the base class MStreamBuf , and is called by MStreamBuf::WriteL(const TAny*,TInt) .
| IMPORT_C void | OverflowL | ( | ) | [protected, virtual] |
Empties the intermediate buffer and resets the start and end points of the write area.
The implementation of this function depends on the way the stream itself is implemented. For example, the in-memory streams have simple implementations.
| IMPORT_C void | Set | ( | CBufBase & | aBuf, |
| TInt | aPos, | |||
| TInt | aMode = ERead|EWrite | |||
| ) | ||||
Sets up the stream to use the specified dynamic buffer.
| CBufBase & aBuf | The dynamic buffer that hosts the stream and that also acts as the intermediate buffer. |
| TInt aPos | The offset within the dynamic buffer where the stream starts. |
| TInt aMode = ERead|EWrite | The mode in which the stream is to be used. It can be used in either or both read and write modes, represented by ERead and EWrite. In addition, specify TBufBuf::EInsert to imply insert mode; specify TBufBuf::ETruncate to imply truncate mode. If neither TBufBuf::EInsert nor TBufBuf::ETruncate are specified, then overwrite mode is implied. Both TBufBuf::EInsert and TBufBuf::ETruncate imply EWrite. |
| IMPORT_C TInt | UnderflowL | ( | TInt | aMaxLength | ) | [protected, virtual] |
Re-fills the intermediate buffer and resets the start and end points of the read area.
The implementation of this function depends on the way the stream itself is implemented. For example, the in-memory streams have simple implementations.
| TInt aMaxLength | The maximum amount of data required for the intermediate buffer. |
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