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

** 

**

** Implementation of QBuffer class

**

** Created : 930812

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#include "qbuffer.h"

#include <stdlib.h>

// REVISED: paul

/*!

  \class QBuffer qbuffer.h

  \brief The QBuffer class is an I/O device that operates on a QByteArray

  \ingroup io

  QBuffer allows reading and writing a memory buffer. It is normally

  used together with a QTextStream or a QDataStream.  QBuffer has an

  associated QByteArray which holds the buffer data. The size() of the

  buffer is automatically adjusted as data is written.

  The constructor \c QBuffer(QByteArray) creates a QBuffer with an

  existing byte array.  The byte array can also be set with setBuffer().

  Writing to the QBuffer will modify the original byte array, since

  QByteArray is \link shclass.html explicitly shared.\endlink

  Use open() to open the buffer before use, and to set the mode

  (read-only,write-only, etc.).  close() closes the buffer. The buffer

  must be closed before reopening or calling setBuffer().

  The common way to use QBuffer is through \l QDataStream or \l QTextStream

  which have constructors that take a QBuffer parameter. For

  convenience, there are also QDataStream and QTextStream constructors

  that take a QByteArray parameter.  These constructors create and open

  an internal QBuffer.

  Note that QTextStream can also operate on a QString (a Unicode

  string); a QBuffer cannot.

  You can also use QBuffer directly through the standard QIODevice

  functions readBlock(), writeBlock() readLine(), at(), getch(), putch() and

  ungetch().

  \sa QFile, QDataStream, QTextStream, QByteArray, \link shclass.html Shared Classes\endlink

*/

/*!

  Constructs an empty buffer.

*/

QBuffer::QBuffer()

{

    setFlags( IO_Direct );

    a_inc = 16;					// initial increment

    a_len = 0;

    ioIndex = 0;

}

/*!

  Constructs a buffer that operates on \a buf.

  If you open the buffer in write mode (\c IO_WriteOnly or

  \c IO_ReadWrite) and write something into the buffer, \a buf

  will be modified.

  Example:

  \code

    QCString str = "abc";

    QBuffer b( str );

    b.open( IO_WriteOnly );

    b.at( 3 );					// position at \0

    b.writeBlock( "def", 4 );			// write including \0

    b.close();

      // Now, str == "abcdef"

  \endcode

  \sa setBuffer()

*/

QBuffer::QBuffer( QByteArray buf ) : a(buf)

{

    setFlags( IO_Direct );

    a_len = a.size();

    a_inc = (a_len > 512) ? 512 : a_len;	// initial increment

    if ( a_inc < 16 )

	a_inc = 16;

    ioIndex = 0;

}

/*!

  Destructs the buffer.

*/

QBuffer::~QBuffer()

{

}

/*!

  Replaces the buffer's contents with \a buf.

  This may not be done when isOpen() is TRUE.

  Note that if you open the buffer in write mode (\c IO_WriteOnly or

  IO_ReadWrite) and write something into the buffer, \a buf is also

  modified because QByteArray is an explicitly shared class.

  \sa buffer(), open(), close()

*/

bool QBuffer::setBuffer( QByteArray buf )

{

    if ( isOpen() ) {

#if defined(CHECK_STATE)

	qWarning( "QBuffer::setBuffer: Buffer is open");

#endif

	return FALSE;

    }

    a = buf;

    a_len = a.size();

    a_inc = (a_len > 512) ? 512 : a_len;	// initial increment

    if ( a_inc < 16 )

	a_inc = 16;

    ioIndex = 0;

    return TRUE;

}

/*!

  \fn QByteArray QBuffer::buffer() const

  Returns this buffer's byte array.

  \sa setBuffer()

*/

/*!

  \reimp

  Opens the buffer in the mode \a m.  Returns TRUE if successful,

  otherwise FALSE. The buffer must be opened before use.

  The mode parameter \a m must be a combination of the following flags.

  
\c IO_ReadOnly opens a buffer in read-only mode.

  
\c IO_WriteOnly opens a buffer in write-only mode.

  
\c IO_ReadWrite opens a buffer in read/write mode.

  
\c IO_Append sets the buffer index to the end of the buffer.

  
\c IO_Truncate truncates the buffer.

  \sa close(), isOpen()

*/

bool QBuffer::open( int m  )

{

    if ( isOpen() ) {				// buffer already open

#if defined(CHECK_STATE)

	qWarning( "QBuffer::open: Buffer already open" );

#endif

	return FALSE;

    }

    setMode( m );

    if ( m & IO_Truncate ) {			// truncate buffer

	a.resize( 0 );

	a_len = 0;

    }

    if ( m & IO_Append ) {			// append to end of buffer

	ioIndex = a.size();

    } else {

	ioIndex = 0;

    }

    a_inc = 16;

    setState( IO_Open );

    setStatus( 0 );

    return TRUE;

}

/*!

  \reimp

  Closes an open buffer.

  \sa open()

*/

void QBuffer::close()

{

    if ( isOpen() ) {

	setFlags( IO_Direct );

	ioIndex = 0;

	a_inc = 16;

    }

}

/*!

  \reimp

  The flush function does nothing for a QBuffer.

*/

void QBuffer::flush()

{

    return;

}

/*!

  \fn int QBuffer::at() const

  \reimp

*/

/*!

  \fn uint QBuffer::size() const

  \reimp

*/

/*!

  \reimp

*/

bool QBuffer::at( int pos )

{

#if defined(CHECK_STATE)

    if ( !isOpen() ) {

	qWarning( "QBuffer::at: Buffer is not open" );

	return FALSE;

    }

#endif

    if ( (uint)pos > a_len ) {

#if defined(CHECK_RANGE)

	qWarning( "QBuffer::at: Index %d out of range", pos );

#endif

	return FALSE;

    }

    ioIndex = pos;

    return TRUE;

}

/*!

  \reimp

*/

int QBuffer::readBlock( char *p, uint len )

{

#if defined(CHECK_STATE)

    CHECK_PTR( p );

    if ( !isOpen() ) {				// buffer not open

	qWarning( "QBuffer::readBlock: Buffer not open" );

	return -1;

    }

    if ( !isReadable() ) {			// reading not permitted

	qWarning( "QBuffer::readBlock: Read operation not permitted" );

	return -1;

    }

#endif

    if ( (uint)ioIndex + len > a.size() ) {	// overflow

	if ( (uint)ioIndex >= a.size() ) {

	    setStatus( IO_ReadError );

	    return -1;

	} else {

	    len = a.size() - (uint)ioIndex;

	}

    }

    memcpy( p, a.data()+ioIndex, len );

    ioIndex += len;

    return len;

}

/*!

  \reimp

  Writes \a len bytes from \a p into the buffer at the current index,

  overwriting any characters there and extending the buffer if necessary.

  Returns the number of bytes actually written.

  Returns -1 if a serious error occurred.

  \sa readBlock()

*/

int QBuffer::writeBlock( const char *p, uint len )

{

#if defined(CHECK_NULL)

    if ( p == 0 && len != 0 )

	qWarning( "QBuffer::writeBlock: Null pointer error" );

#endif

#if defined(CHECK_STATE)

    if ( !isOpen() ) {				// buffer not open

	qWarning( "QBuffer::writeBlock: Buffer not open" );

	return -1;

    }

    if ( !isWritable() ) {			// writing not permitted

	qWarning( "QBuffer::writeBlock: Write operation not permitted" );

	return -1;

    }

#endif

    if ( (uint)ioIndex + len >= a_len ) {		// overflow

	uint new_len = a_len + a_inc*(((uint)ioIndex+len-a_len)/a_inc+1);

	if ( !a.resize( new_len ) ) {		// could not resize

#if defined(CHECK_NULL)

	    qWarning( "QBuffer::writeBlock: Memory allocation error" );

#endif

	    setStatus( IO_ResourceError );

	    return -1;

	}

	a_inc *= 2;				// double increment

	a_len = new_len;

	a.shd->len = (uint)ioIndex + len;

    }

    memcpy( a.data()+ioIndex, p, len );

    ioIndex += len;

    if ( a.shd->len < (uint)ioIndex )

	a.shd->len = (uint)ioIndex;		// fake (not alloc'd) length

    return len;

}

/*!

  \reimp

*/

int QBuffer::readLine( char *p, uint maxlen )

{

#if defined(CHECK_STATE)

    CHECK_PTR( p );

    if ( !isOpen() ) {				// buffer not open

	qWarning( "QBuffer::readLine: Buffer not open" );

	return -1;

    }

    if ( !isReadable() ) {			// reading not permitted

	qWarning( "QBuffer::readLine: Read operation not permitted" );

	return -1;

    }

#endif

    if ( maxlen == 0 )

	return 0;

    uint start = (uint)ioIndex;

    char *d = a.data() + ioIndex;

    maxlen--;					// make room for 0-terminator

    if ( a.size() - (uint)ioIndex < maxlen )

	maxlen = a.size() - (uint)ioIndex;

    while ( maxlen-- ) {

	if ( (*p++ = *d++) == '\n' )

	    break;

    }

    *p = '\0';

    ioIndex = (int)(d - a.data());

    return (uint)ioIndex - start;

}

/*!

  \reimp

*/

int QBuffer::getch()

{

#if defined(CHECK_STATE)

    if ( !isOpen() ) {				// buffer not open

	qWarning( "QBuffer::getch: Buffer not open" );

	return -1;

    }

    if ( !isReadable() ) {			// reading not permitted

	qWarning( "QBuffer::getch: Read operation not permitted" );

	return -1;

    }

#endif

    if ( (uint)ioIndex+1 > a.size() ) {		// overflow

	setStatus( IO_ReadError );

	return -1;

    }

    return uchar(*(a.data()+ioIndex++));

}

/*!

  \reimp

  Writes the character \a ch into the buffer, overwriting

  the character at the current index, extending the buffer

  if necessary.

  Returns \a ch, or -1 if some error occurred.

  \sa getch(), ungetch()

*/

int QBuffer::putch( int ch )

{

#if defined(CHECK_STATE)

    if ( !isOpen() ) {				// buffer not open

	qWarning( "QBuffer::putch: Buffer not open" );

	return -1;

    }

    if ( !isWritable() ) {			// writing not permitted

	qWarning( "QBuffer::putch: Write operation not permitted" );

	return -1;

    }

#endif

    if ( (uint)ioIndex + 1 >= a_len ) {		// overflow

	char buf[1];

	buf[0] = (char)ch;

	if ( writeBlock(buf,1) != 1 )

	    return -1;				// write error

    } else {

	*(a.data() + ioIndex++) = (char)ch;

	if ( a.shd->len < (uint)ioIndex )

	    a.shd->len = (uint)ioIndex;

    }

    return ch;

}

/*!

  \reimp

*/

int QBuffer::ungetch( int ch )

{

#if defined(CHECK_STATE)

    if ( !isOpen() ) {				// buffer not open

	qWarning( "QBuffer::ungetch: Buffer not open" );

	return -1;

    }

    if ( !isReadable() ) {			// reading not permitted

	qWarning( "QBuffer::ungetch: Read operation not permitted" );

	return -1;

    }

#endif

    if ( ch != -1 ) {

	if ( ioIndex )

	    ioIndex--;

	else

	    ch = -1;

    }

    return ch;

}