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#include "qdatastream.h"

#include "qdatastream_p.h"

#ifndef QT_NO_DATASTREAM

#include "qbuffer.h"

#include "qstring.h"

#include <stdio.h>

#include <ctype.h>

#include <stdlib.h>

QT_BEGIN_NAMESPACE

/*!

    \class QDataStream

    \reentrant

    \brief The QDataStream class provides serialization of binary data

    to a QIODevice.

    \ingroup io

    A data stream is a binary stream of encoded information which is

    100% independent of the host computer's operating system, CPU or

    byte order. For example, a data stream that is written by a PC

    under Windows can be read by a Sun SPARC running Solaris.

    You can also use a data stream to read/write \l{raw}{raw

    unencoded binary data}. If you want a "parsing" input stream, see

    QTextStream.

    The QDataStream class implements the serialization of C++'s basic

    data types, like \c char, \c short, \c int, \c{char *}, etc.

    Serialization of more complex data is accomplished by breaking up

    the data into primitive units.

    A data stream cooperates closely with a QIODevice. A QIODevice

    represents an input/output medium one can read data from and write

    data to. The QFile class is an example of an I/O device.

    Example (write binary data to a stream):

    \snippet doc/src/snippets/code/src_corelib_io_qdatastream.cpp 0

    Example (read binary data from a stream):

    \snippet doc/src/snippets/code/src_corelib_io_qdatastream.cpp 1

    Each item written to the stream is written in a predefined binary

    format that varies depending on the item's type. Supported Qt

    types include QBrush, QColor, QDateTime, QFont, QPixmap, QString,

    QVariant and many others. For the complete list of all Qt types

    supporting data streaming see the \l{Format of the QDataStream

    operators}.

    For integers it is best to always cast to a Qt integer type for

    writing, and to read back into the same Qt integer type. This

    ensures that you get integers of the size you want and insulates

    you from compiler and platform differences.

    To take one example, a \c{char *} string is written as a 32-bit

    integer equal to the length of the string including the '\\0' byte,

    followed by all the characters of the string including the

    '\\0' byte. When reading a \c{char *} string, 4 bytes are read to

    create the 32-bit length value, then that many characters for the

    \c {char *} string including the '\\0' terminator are read.

    The initial I/O device is usually set in the constructor, but can be

    changed with setDevice(). If you've reached the end of the data

    (or if there is no I/O device set) atEnd() will return true.

    \section1 Versioning

    QDataStream's binary format has evolved since Qt 1.0, and is

    likely to continue evolving to reflect changes done in Qt. When

    inputting or outputting complex types, it's very important to

    make sure that the same version of the stream (version()) is used

    for reading and writing. If you need both forward and backward

    compatibility, you can hardcode the version number in the

    application:

    \snippet doc/src/snippets/code/src_corelib_io_qdatastream.cpp 2

    If you are producing a new binary data format, such as a file

    format for documents created by your application, you could use a

    QDataStream to write the data in a portable format. Typically, you

    would write a brief header containing a magic string and a version

    number to give yourself room for future expansion. For example:

    \snippet doc/src/snippets/code/src_corelib_io_qdatastream.cpp 3

    Then read it in with:

    \snippet doc/src/snippets/code/src_corelib_io_qdatastream.cpp 4

    You can select which byte order to use when serializing data. The

    default setting is big endian (MSB first). Changing it to little

    endian breaks the portability (unless the reader also changes to

    little endian). We recommend keeping this setting unless you have

    special requirements.

    \target raw

    \section1 Reading and writing raw binary data

    You may wish to read/write your own raw binary data to/from the

    data stream directly. Data may be read from the stream into a

    preallocated \c{char *} using readRawData(). Similarly data can be

    written to the stream using writeRawData(). Note that any

    encoding/decoding of the data must be done by you.

    A similar pair of functions is readBytes() and writeBytes(). These

    differ from their \e raw counterparts as follows: readBytes()

    reads a quint32 which is taken to be the length of the data to be

    read, then that number of bytes is read into the preallocated

    \c{char *}; writeBytes() writes a quint32 containing the length of the

    data, followed by the data. Note that any encoding/decoding of

    the data (apart from the length quint32) must be done by you.

    \target Serializing Qt Classes

    \section1 Reading and writing other Qt classes.

    In addition to the overloaded stream operators documented here,

    any Qt classes that you might want to serialize to a QDataStream

    will have appropriate stream operators declared as non-member of

    the class:

    \code

    QDataStream &operator<<(QDataStream &, const QXxx &);

    QDataStream &operator>>(QDataStream &, QXxx &);

    \endcode

    For example, here are the stream operators declared as non-members

    of the QImage class:

    \code

    QDataStream & operator<< (QDataStream& stream, const QImage& image);

    QDataStream & operator>> (QDataStream& stream, QImage& image);

    \endcode

    To see if your favorite Qt class has similar stream operators

    defined, check the \bold {Related Non-Members} section of the

    class's documentation page.

    \sa QTextStream QVariant

*/

/*!

    \enum QDataStream::ByteOrder

    The byte order used for reading/writing the data.

    \value BigEndian Most significant byte first (the default)

    \value LittleEndian Least significant byte first

*/

/*!

  \enum QDataStream::FloatingPointPrecision

  The precision of floating point numbers used for reading/writing the data. This will only have

  an effect if the version of the data stream is Qt_4_6 or higher.

  \warning The floating point precision must be set to the same value on the object that writes

  and the object that reads the data stream.

  \value SinglePrecision All floating point numbers in the data stream have 32-bit precision.

  \value DoublePrecision All floating point numbers in the data stream have 64-bit precision.

  \sa setFloatingPointPrecision(), floatingPointPrecision()

*/

/*!

    \enum QDataStream::Status

    This enum describes the current status of the data stream.

    \value Ok               The data stream is operating normally.

    \value ReadPastEnd      The data stream has read past the end of the

                            data in the underlying device.

    \value ReadCorruptData  The data stream has read corrupt data.

*/

/*****************************************************************************

  QDataStream member functions

 *****************************************************************************/

#undef  CHECK_STREAM_PRECOND

#ifndef QT_NO_DEBUG

#define CHECK_STREAM_PRECOND(retVal) \

    if (!dev) { \

        qWarning("QDataStream: No device"); \

        return retVal; \

    }

#else

#define CHECK_STREAM_PRECOND(retVal) \

    if (!dev) { \

        return retVal; \

    }

#endif

enum {

    DefaultStreamVersion = QDataStream::Qt_4_6

};

// ### 5.0: when streaming invalid QVariants, just the type should

// be written, no "data" after it

/*!

    Constructs a data stream that has no I/O device.

    \sa setDevice()

*/

QDataStream::QDataStream()

{

    dev = 0;

    owndev = false;

    byteorder = BigEndian;

    ver = DefaultStreamVersion;

    noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian;

    q_status = Ok;

}

/*!

    Constructs a data stream that uses the I/O device \a d.

    \warning If you use QSocket or QSocketDevice as the I/O device \a d

    for reading data, you must make sure that enough data is available

    on the socket for the operation to successfully proceed;

    QDataStream does not have any means to handle or recover from

    short-reads.

    \sa setDevice(), device()

*/

QDataStream::QDataStream(QIODevice *d)

{

    dev = d;                                // set device

    owndev = false;

    byteorder = BigEndian;                        // default byte order

    ver = DefaultStreamVersion;

    noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian;

    q_status = Ok;

}

#ifdef QT3_SUPPORT

/*!

    \fn QDataStream::QDataStream(QByteArray *array, int mode)

    \compat

    Constructs a data stream that operates on the given \a array. The

    \a mode specifies how the byte array is to be used, and is

    usually either QIODevice::ReadOnly or QIODevice::WriteOnly.

*/

QDataStream::QDataStream(QByteArray *a, int mode)

{

    QBuffer *buf = new QBuffer(a);

#ifndef QT_NO_QOBJECT

    buf->blockSignals(true);

#endif

    buf->open(QIODevice::OpenMode(mode));

    dev = buf;

    owndev = true;

    byteorder = BigEndian;

    ver = DefaultStreamVersion;

    noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian;

    q_status = Ok;

}

#endif

/*!

    \fn QDataStream::QDataStream(QByteArray *a, QIODevice::OpenMode mode)

    Constructs a data stream that operates on a byte array, \a a. The

    \a mode describes how the device is to be used.

    Alternatively, you can use QDataStream(const QByteArray &) if you

    just want to read from a byte array.

    Since QByteArray is not a QIODevice subclass, internally a QBuffer

    is created to wrap the byte array.

*/

QDataStream::QDataStream(QByteArray *a, QIODevice::OpenMode flags)

{

    QBuffer *buf = new QBuffer(a);

#ifndef QT_NO_QOBJECT

    buf->blockSignals(true);

#endif

    buf->open(flags);

    dev = buf;

    owndev = true;

    byteorder = BigEndian;

    ver = DefaultStreamVersion;

    noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian;

    q_status = Ok;

}

/*!

    Constructs a read-only data stream that operates on byte array \a a.

    Use QDataStream(QByteArray*, int) if you want to write to a byte

    array.

    Since QByteArray is not a QIODevice subclass, internally a QBuffer

    is created to wrap the byte array.

*/

QDataStream::QDataStream(const QByteArray &a)

{

    QBuffer *buf = new QBuffer;

#ifndef QT_NO_QOBJECT

    buf->blockSignals(true);

#endif

    buf->setData(a);

    buf->open(QIODevice::ReadOnly);

    dev = buf;

    owndev = true;

    byteorder = BigEndian;

    ver = DefaultStreamVersion;

    noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian;

    q_status = Ok;

}

/*!

    Destroys the data stream.

    The destructor will not affect the current I/O device, unless it is

    an internal I/O device (e.g. a QBuffer) processing a QByteArray

    passed in the \e constructor, in which case the internal I/O device

    is destroyed.

*/

QDataStream::~QDataStream()

{

    if (owndev)

        delete dev;

}

/*!

    \fn QIODevice *QDataStream::device() const

    Returns the I/O device currently set, or 0 if no

    device is currently set.

    \sa setDevice()

*/

/*!

    void QDataStream::setDevice(QIODevice *d)

    Sets the I/O device to \a d, which can be 0

    to unset to current I/O device.

    \sa device()

*/

void QDataStream::setDevice(QIODevice *d)

{

    if (owndev) {

        delete dev;

        owndev = false;

    }

    dev = d;

}

/*!

    \obsolete

    Unsets the I/O device.

    Use setDevice(0) instead.

*/

void QDataStream::unsetDevice()

{

    setDevice(0);

}

/*!

    \fn bool QDataStream::atEnd() const

    Returns true if the I/O device has reached the end position (end of

    the stream or file) or if there is no I/O device set; otherwise

    returns false.

    \sa QIODevice::atEnd()

*/

bool QDataStream::atEnd() const

{

    return dev ? dev->atEnd() : true;

}

/*!

    Returns the floating point precision of the data stream.

    \since 4.6

    \sa FloatingPointPrecision setFloatingPointPrecision()

*/

QDataStream::FloatingPointPrecision QDataStream::floatingPointPrecision() const

{

    return d == 0 ? QDataStream::DoublePrecision : d->floatingPointPrecision;

}

/*!

    Sets the floating point precision of the data stream to \a precision. If the floating point precision is

    DoublePrecision and the version of the data stream is Qt_4_6 or higher, all floating point

    numbers will be written and read with 64-bit precision. If the floating point precision is

    SinglePrecision and the version is Qt_4_6 or higher, all floating point numbers will be written

    and read with 32-bit precision.

    For versions prior to Qt_4_6, the precision of floating point numbers in the data stream depends

    on the stream operator called.

    The default is DoublePrecision.

    \warning This property must be set to the same value on the object that writes and the object

    that reads the data stream.

    \since 4.6

*/

void QDataStream::setFloatingPointPrecision(QDataStream::FloatingPointPrecision precision)

{

    if (d == 0)

        d.reset(new QDataStreamPrivate());

    d->floatingPointPrecision = precision;

}

/*!

    Returns the status of the data stream.

    \sa Status setStatus() resetStatus()

*/

QDataStream::Status QDataStream::status() const

{

    return q_status;

}

/*!

    Resets the status of the data stream.

    \sa Status status() setStatus()

*/

void QDataStream::resetStatus()

{

    q_status = Ok;

}

/*!

    Sets the status of the data stream to the \a status given.

    \sa Status status() resetStatus()

*/

void QDataStream::setStatus(Status status)

{

    if (q_status == Ok)

        q_status = status;

}

/*!\fn bool QDataStream::eof() const

    Use atEnd() instead.

*/

/*!

    \fn int QDataStream::byteOrder() const

    Returns the current byte order setting -- either BigEndian or

    LittleEndian.

    \sa setByteOrder()

*/

/*!

    Sets the serialization byte order to \a bo.

    The \a bo parameter can be QDataStream::BigEndian or

    QDataStream::LittleEndian.

    The default setting is big endian. We recommend leaving this

    setting unless you have special requirements.

    \sa byteOrder()

*/

void QDataStream::setByteOrder(ByteOrder bo)

{

    byteorder = bo;