stream.h

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/////////////////////////////////////////////////////////////////////////////
// Name:        wx/stream.h
// Purpose:     stream classes
// Author:      Guilhem Lavaux, Guillermo Rodriguez Garcia, Vadim Zeitlin
// Modified by:
// Created:     11/07/98
// RCS-ID:      $Id: stream.h,v 1.71 2005/06/26 15:46:08 RR Exp $
// Copyright:   (c) Guilhem Lavaux
// Licence:     wxWindows licence
/////////////////////////////////////////////////////////////////////////////

#ifndef _WX_WXSTREAM_H__
#define _WX_WXSTREAM_H__

#if defined(__GNUG__) && !defined(NO_GCC_PRAGMA)
#pragma interface "stream.h"
#endif

#include "wx/defs.h"

#if wxUSE_STREAMS

#include <stdio.h>
#include "wx/object.h"
#include "wx/string.h"
#include "wx/filefn.h"  // for wxFileOffset, wxInvalidOffset and wxSeekMode

class WXDLLIMPEXP_BASE wxStreamBase;
class WXDLLIMPEXP_BASE wxInputStream;
class WXDLLIMPEXP_BASE wxOutputStream;

typedef wxInputStream& (*__wxInputManip)(wxInputStream&);
typedef wxOutputStream& (*__wxOutputManip)(wxOutputStream&);

WXDLLIMPEXP_BASE wxOutputStream& wxEndL(wxOutputStream& o_stream);

// ----------------------------------------------------------------------------
// constants
// ----------------------------------------------------------------------------

enum wxStreamError
{
    wxSTREAM_NO_ERROR = 0,      // stream is in good state
    wxSTREAM_EOF,               // EOF reached in Read() or similar
    wxSTREAM_WRITE_ERROR,       // generic write error
    wxSTREAM_READ_ERROR         // generic read error
};

// compatibility
#if WXWIN_COMPATIBILITY_2_2
    #define wxStream_NOERROR    wxSTREAM_NOERROR
    #define wxStream_EOF        wxSTREAM_EOF
    #define wxStream_WRITE_ERR  wxSTREAM_WRITE_ERROR
    #define wxStream_READ_ERR   wxSTREAM_READ_ERROR

    #define wxSTREAM_NO_ERR     wxSTREAM_NO_ERROR
    #define wxSTREAM_NOERROR    wxSTREAM_NO_ERROR
    #define wxSTREAM_WRITE_ERR  wxSTREAM_WRITE_ERROR
    #define wxSTREAM_READ_ERR   wxSTREAM_READ_ERROR
#endif // WXWIN_COMPATIBILITY_2_2

// ============================================================================
// base stream classes: wxInputStream and wxOutputStream
// ============================================================================

// ---------------------------------------------------------------------------
// wxStreamBase: common (but non virtual!) base for all stream classes
// ---------------------------------------------------------------------------

class WXDLLIMPEXP_BASE wxStreamBase
{
public:
    wxStreamBase();
    virtual ~wxStreamBase();

    // error testing
    wxStreamError GetLastError() const { return m_lasterror; }
    bool IsOk() const { return GetLastError() == wxSTREAM_NO_ERROR; }
    bool operator!() const { return !IsOk(); }

    // reset the stream state
    void Reset() { m_lasterror = wxSTREAM_NO_ERROR; }

    // this doesn't make sense for all streams, always test its return value
    virtual size_t GetSize() const;
    virtual wxFileOffset GetLength() const { return wxInvalidOffset; }

    // returns true if the streams supports seeking to arbitrary offsets
    virtual bool IsSeekable() const { return false; }

#if WXWIN_COMPATIBILITY_2_2
    // deprecated, for compatibility only
    wxDEPRECATED( wxStreamError LastError() const );
    wxDEPRECATED( size_t StreamSize() const );
#endif // WXWIN_COMPATIBILITY_2_2


    // Reserved for future use
    virtual void ReservedStreamFunc1() {}
    virtual void ReservedStreamFunc2() {}
    virtual void ReservedStreamFunc3() {}
    virtual void ReservedStreamFunc4() {}
    virtual void ReservedStreamFunc5() {}
    virtual void ReservedStreamFunc6() {}
    virtual void ReservedStreamFunc7() {}
    virtual void ReservedStreamFunc8() {}
    virtual void ReservedStreamFunc9() {}

protected:
    virtual wxFileOffset OnSysSeek(wxFileOffset seek, wxSeekMode mode);
    virtual wxFileOffset OnSysTell() const;

    size_t m_lastcount;
    wxStreamError m_lasterror;

    friend class wxStreamBuffer;

    DECLARE_NO_COPY_CLASS(wxStreamBase)
};

// ----------------------------------------------------------------------------
// wxInputStream: base class for the input streams
// ----------------------------------------------------------------------------

class WXDLLIMPEXP_BASE wxInputStream : public wxStreamBase
{
public:
    // ctor and dtor, nothing exciting
    wxInputStream();
    virtual ~wxInputStream();


    // IO functions
    // ------------

    // return a character from the stream without removing it, i.e. it will
    // still be returned by the next call to GetC()
    //
    // blocks until something appears in the stream if necessary, if nothing
    // ever does (i.e. EOF) LastRead() will return 0 (and the return value is
    // undefined), otherwise 1
    virtual char Peek();

    // return one character from the stream, blocking until it appears if
    // necessary
    //
    // if EOF, return value is undefined and LastRead() will return 0 and not 1
    char GetC();

    // read at most the given number of bytes from the stream
    //
    // there are 2 possible situations here: either there is nothing at all in
    // the stream right now in which case Read() blocks until something appears
    // (use CanRead() to avoid this) or there is already some data available in
    // the stream and then Read() doesn't block but returns just the data it
    // can read without waiting for more
    //
    // in any case, if there are not enough bytes in the stream right now,
    // LastRead() value will be less than size but greater than 0. If it is 0,
    // it means that EOF has been reached.
    virtual wxInputStream& Read(void *buffer, size_t size);

    // copy the entire contents of this stream into streamOut, stopping only
    // when EOF is reached or an error occurs
    wxInputStream& Read(wxOutputStream& streamOut);


    // status functions
    // ----------------

    // returns the number of bytes read by the last call to Read(), GetC() or
    // Peek()
    //
    // this should be used to discover whether that call succeeded in reading
    // all the requested data or not
    virtual size_t LastRead() const { return wxStreamBase::m_lastcount; }

    // returns true if some data is available in the stream right now, so that
    // calling Read() wouldn't block
    virtual bool CanRead() const;

    // is the stream at EOF?
    //
    // note that this cannot be really implemented for all streams and
    // CanRead() is more reliable than Eof()
    virtual bool Eof() const;


    // write back buffer
    // -----------------

    // put back the specified number of bytes into the stream, they will be
    // fetched by the next call to the read functions
    //
    // returns the number of bytes really stuffed back
    size_t Ungetch(const void *buffer, size_t size);

    // put back the specified character in the stream
    //
    // returns true if ok, false on error
    bool Ungetch(char c);


    // position functions
    // ------------------

    // move the stream pointer to the given position (if the stream supports
    // it)
    //
    // returns wxInvalidOffset on error
    virtual wxFileOffset SeekI(wxFileOffset pos, wxSeekMode mode = wxFromStart);

    // return the current position of the stream pointer or wxInvalidOffset
    virtual wxFileOffset TellI() const;


    // stream-like operators
    // ---------------------

    wxInputStream& operator>>(wxOutputStream& out) { return Read(out); }
    wxInputStream& operator>>(__wxInputManip func) { return func(*this); }

protected:
    // do read up to size bytes of data into the provided buffer
    //
    // this method should return 0 if EOF has been reached or an error occurred
    // (m_lasterror should be set accordingly as well) or the number of bytes
    // read
    virtual size_t OnSysRead(void *buffer, size_t size) = 0;

    // write-back buffer support
    // -------------------------

    // return the pointer to a buffer big enough to hold sizeNeeded bytes
    char *AllocSpaceWBack(size_t sizeNeeded);

    // read up to size data from the write back buffer, return the number of
    // bytes read
    size_t GetWBack(void *buf, size_t size);

    // write back buffer or NULL if none
    char *m_wback;

    // the size of the buffer
    size_t m_wbacksize;

    // the current position in the buffer
    size_t m_wbackcur;

    friend class wxStreamBuffer;

    DECLARE_NO_COPY_CLASS(wxInputStream)
};

// ----------------------------------------------------------------------------
// wxOutputStream: base for the output streams
// ----------------------------------------------------------------------------

class WXDLLIMPEXP_BASE wxOutputStream : public wxStreamBase
{
public:
    wxOutputStream();
    virtual ~wxOutputStream();

    void PutC(char c);
    virtual wxOutputStream& Write(const void *buffer, size_t size);
    wxOutputStream& Write(wxInputStream& stream_in);

    virtual wxFileOffset SeekO(wxFileOffset pos, wxSeekMode mode = wxFromStart);
    virtual wxFileOffset TellO() const;

    virtual size_t LastWrite() const { return wxStreamBase::m_lastcount; }

    virtual void Sync();
    virtual bool Close() { return true; }

    wxOutputStream& operator<<(wxInputStream& out) { return Write(out); }
    wxOutputStream& operator<<( __wxOutputManip func) { return func(*this); }

protected:
    // to be implemented in the derived classes (it should have been pure