transmitter.h

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/*
    Copyright (C) 1998-99 Paul Barton-Davis 

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

    This program 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 General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

#ifndef __libmisc_transmitter_h__
#define __libmisc_transmitter_h__

#include <sstream>
#include <iostream>

#include <sigc++/sigc++.h>

#include "pbd/libpbd_visibility.h"

class LIBPBD_API Transmitter : public std::stringstream

{
  public:
        enum Channel {
                Info,
                Error,
                Warning,
                Fatal,
                Throw
        };

        Transmitter (Channel);

        sigc::signal<void,Channel, const char *> &sender() { 
                return *send;
        }

        bool does_not_return ();

  protected:
        virtual void deliver ();
        friend std::ostream& endmsg (std::ostream &);

  private:
        Channel channel;
        sigc::signal<void, Channel, const char *> *send;

        sigc::signal<void, Channel, const char *> info;
        sigc::signal<void, Channel, const char *> warning;
        sigc::signal<void, Channel, const char *> error;
        sigc::signal<void, Channel, const char *> fatal;
};

/* for EGCS 2.91.66, if this function is not compiled within the same
   compilation unit as the one where a ThrownError is thrown, then 
   nothing will catch the error. This is a pretty small function, so
   inlining it here seems like a reasonable workaround.
*/

inline std::ostream &
endmsg (std::ostream &ostr)

{
        Transmitter *t;

        /* There is a serious bug in the Cygnus/GCC libstdc++ library:
           cout is not actually an ostream, but a trick was played
           to make the compiler think that it is. This will cause
           the dynamic_cast<> to fail with SEGV. So, first check to
           see if ostr == cout, and handle it specially.
        */

        if (&ostr == &std::cout) {
                std::cout << std::endl;
                return ostr;
        } else if (&ostr == &std::cerr) {
                std::cerr << std::endl;
                return ostr;
        }

        if ((t = dynamic_cast<Transmitter *> (&ostr)) != 0) {
                t->deliver ();
        } else {
                /* hmm. not a Transmitter, so just put a newline on
                   it and assume that that will be enough.
                */
                
                ostr << std::endl;
        }

        return ostr;
}


extern "C" { LIBPBD_API void pbd_c_error (const char *); }

#endif // __libmisc_transmitter_h__