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SubregionStream Class Reference

Wraps another input stream, and reads from a specific part of it. More...

Inherits InputStream.

Public Member Functions

 SubregionStream (InputStream *sourceStream, int64 startPositionInSourceStream, int64 lengthOfSourceStream, bool deleteSourceWhenDestroyed)
 Creates a SubregionStream from an input source.
 
 ~SubregionStream ()
 Destructor.
 
int64 getTotalLength () override
 Returns the total number of bytes available for reading in this stream.
 
int64 getPosition () override
 Returns the offset of the next byte that will be read from the stream.
 
bool setPosition (int64 newPosition) override
 Tries to move the current read position of the stream.
 
int read (void *destBuffer, int maxBytesToRead) override
 Reads some data from the stream into a memory buffer.
 
bool isExhausted () override
 Returns true if the stream has no more data to read.
 
- Public Member Functions inherited from InputStream
virtual ~InputStream ()
 Destructor.
 
int64 getNumBytesRemaining ()
 Returns the number of bytes available for reading, or a negative value if the remaining length is not known.
 
virtual char readByte ()
 Reads a byte from the stream.
 
virtual bool readBool ()
 Reads a boolean from the stream.
 
virtual short readShort ()
 Reads two bytes from the stream as a little-endian 16-bit value.
 
virtual short readShortBigEndian ()
 Reads two bytes from the stream as a little-endian 16-bit value.
 
virtual int readInt ()
 Reads four bytes from the stream as a little-endian 32-bit value.
 
virtual int readIntBigEndian ()
 Reads four bytes from the stream as a big-endian 32-bit value.
 
virtual int64 readInt64 ()
 Reads eight bytes from the stream as a little-endian 64-bit value.
 
virtual int64 readInt64BigEndian ()
 Reads eight bytes from the stream as a big-endian 64-bit value.
 
virtual float readFloat ()
 Reads four bytes as a 32-bit floating point value.
 
virtual float readFloatBigEndian ()
 Reads four bytes as a 32-bit floating point value.
 
virtual double readDouble ()
 Reads eight bytes as a 64-bit floating point value.
 
virtual double readDoubleBigEndian ()
 Reads eight bytes as a 64-bit floating point value.
 
virtual int readCompressedInt ()
 Reads an encoded 32-bit number from the stream using a space-saving compressed format.
 
virtual String readNextLine ()
 Reads a UTF-8 string from the stream, up to the next linefeed or carriage return.
 
virtual String readString ()
 Reads a zero-terminated UTF-8 string from the stream.
 
virtual String readEntireStreamAsString ()
 Tries to read the whole stream and turn it into a string.
 
virtual size_t readIntoMemoryBlock (MemoryBlock &destBlock, ssize_t maxNumBytesToRead=-1)
 Reads from the stream and appends the data to a MemoryBlock.
 
virtual void skipNextBytes (int64 numBytesToSkip)
 Reads and discards a number of bytes from the stream.
 

Additional Inherited Members

- Protected Member Functions inherited from InputStream
 InputStream () noexcept
 

Detailed Description

Wraps another input stream, and reads from a specific part of it.

This lets you take a subsection of a stream and present it as an entire stream in its own right.

Constructor & Destructor Documentation

SubregionStream::SubregionStream ( InputStream sourceStream,
int64  startPositionInSourceStream,
int64  lengthOfSourceStream,
bool  deleteSourceWhenDestroyed 
)

Creates a SubregionStream from an input source.

Parameters
sourceStreamthe source stream to read from
startPositionInSourceStreamthis is the position in the source stream that corresponds to position 0 in this stream
lengthOfSourceStreamthis specifies the maximum number of bytes from the source stream that will be passed through by this stream. When the position of this stream exceeds lengthOfSourceStream, it will cause an end-of-stream. If the length passed in here is greater than the length of the source stream (as returned by getTotalLength()), then the smaller value will be used. Passing a negative value for this parameter means it will keep reading until the source's end-of-stream.
deleteSourceWhenDestroyedwhether the sourceStream that is passed in should be deleted by this object when it is itself deleted.
SubregionStream::~SubregionStream ( )

Destructor.

This may also delete the source stream, if that option was chosen when the buffered stream was created.

Member Function Documentation

int64 SubregionStream::getTotalLength ( )
overridevirtual

Returns the total number of bytes available for reading in this stream.

Note that this is the number of bytes available from the start of the stream, not from the current position.

If the size of the stream isn't actually known, this will return -1.

See Also
getNumBytesRemaining

Implements InputStream.

int64 SubregionStream::getPosition ( )
overridevirtual

Returns the offset of the next byte that will be read from the stream.

See Also
setPosition

Implements InputStream.

bool SubregionStream::setPosition ( int64  newPosition)
overridevirtual

Tries to move the current read position of the stream.

The position is an absolute number of bytes from the stream's start.

Some streams might not be able to do this, in which case they should do nothing and return false. Others might be able to manage it by resetting themselves and skipping to the correct position, although this is obviously a bit slow.

Returns
true if the stream manages to reposition itself correctly
See Also
getPosition

Implements InputStream.

int SubregionStream::read ( void *  destBuffer,
int  maxBytesToRead 
)
overridevirtual

Reads some data from the stream into a memory buffer.

This is the only read method that subclasses actually need to implement, as the InputStream base class implements the other read methods in terms of this one (although it's often more efficient for subclasses to implement them directly).

Parameters
destBufferthe destination buffer for the data. This must not be null.
maxBytesToReadthe maximum number of bytes to read - make sure the memory block passed in is big enough to contain this many bytes. This value must not be negative.
Returns
the actual number of bytes that were read, which may be less than maxBytesToRead if the stream is exhausted before it gets that far

Implements InputStream.

bool SubregionStream::isExhausted ( )
overridevirtual

Returns true if the stream has no more data to read.

Implements InputStream.


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