kmime_codecs.h

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/*  -*- c++ -*-

    KMime, the KDE Internet mail/usenet news message library.
    Copyright (c) 2001-2002 Marc Mutz <mutz@kde.org>

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public License
    along with this library; see the file COPYING.LIB.  If not, write to
    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
    Boston, MA 02110-1301, USA.
*/
#ifndef __KMIME_CODECS__
#define __KMIME_CODECS__

#include <QtCore/QByteArray>

#include <kdebug.h> // for kFatal()

#include "kmime_export.h"

namespace KMime {

template <class Key, class T> class KAutoDeleteHash;

class Encoder;
class Decoder;

class KMIME_EXPORT Codec
{
  protected:
    //@cond PRIVATE
    static KAutoDeleteHash<QByteArray, Codec> *all;
    static void cleanupCodec();
    //@endcond
    Codec() {}

  public:
    static Codec *codecForName( const char *name );

    static Codec *codecForName( const QByteArray &name );

    virtual int maxEncodedSizeFor( int insize, bool withCRLF=false ) const = 0;

    virtual int maxDecodedSizeFor( int insize, bool withCRLF=false ) const = 0;

    virtual Encoder *makeEncoder( bool withCRLF=false ) const = 0;

    virtual Decoder *makeDecoder( bool withCRLF=false ) const = 0;

    virtual bool encode( const char* &scursor, const char * const send,
                         char* &dcursor, const char * const dend,
                         bool withCRLF=false ) const;

    virtual bool decode( const char* &scursor, const char * const send,
                         char* &dcursor, const char * const dend,
                         bool withCRLF=false ) const;

    virtual QByteArray encode( const QByteArray &src, bool withCRLF=false ) const;

    virtual QByteArray decode( const QByteArray &src, bool withCRLF=false ) const;

    virtual const char *name() const = 0;

    virtual ~Codec() {}

  private:
    static void fillDictionary();
};

class Decoder
{
  protected:
    friend class Codec;
    Decoder( bool withCRLF=false )
      : mWithCRLF( withCRLF ) {}

  public:
    virtual ~Decoder() {}

    virtual bool decode( const char* &scursor, const char * const send,
                         char* &dcursor, const char * const dend ) = 0;

    virtual bool finish( char* &dcursor, const char * const dend ) = 0;

  protected:
    //@cond PRIVATE
    const bool mWithCRLF;
    //@endcond
};

class Encoder
{
  protected:
    friend class Codec;
    explicit Encoder( bool withCRLF=false )
      : mOutputBufferCursor( 0 ), mWithCRLF( withCRLF ) {}

  public:
    virtual ~Encoder() {}

    virtual bool encode( const char* &scursor, const char * const send,
                         char* &dcursor, const char * const dend ) = 0;

    virtual bool finish( char* &dcursor, const char * const dend ) = 0;

  protected:
    enum {
      maxBufferedChars = 8  
    };

    bool write( char ch, char* &dcursor, const char * const dend )
      {
        if ( dcursor != dend ) {
          // if there's space in the output stream, write there:
          *dcursor++ = ch;
          return true;
        } else {
          // else buffer the output:
          kFatal( mOutputBufferCursor >= maxBufferedChars )
            << "KMime::Encoder: internal buffer overflow!";
          mOutputBuffer[ mOutputBufferCursor++ ] = ch;
          return false;
        }
      }

    bool flushOutputBuffer( char* &dcursor, const char * const dend );

    bool writeCRLF( char* &dcursor, const char * const dend )
      {
        if ( mWithCRLF ) {
          write( '\r', dcursor, dend );
        }
        return write( '\n', dcursor, dend );
      }

  private:
    //@cond PRIVATE
    char mOutputBuffer[ maxBufferedChars ];
    //@endcond

  protected:
    //@cond PRIVATE
    uchar mOutputBufferCursor;
    const bool mWithCRLF;
    //@endcond
};

} // namespace KMime

#endif // __KMIME_CODECS__