ofconsol.h

/*
 *
 *  Copyright (C) 1999-2005, OFFIS
 *
 *  This software and supporting documentation were developed by
 *
 *    Kuratorium OFFIS e.V.
 *    Healthcare Information and Communication Systems
 *    Escherweg 2
 *    D-26121 Oldenburg, Germany
 *
 *  THIS SOFTWARE IS MADE AVAILABLE,  AS IS,  AND OFFIS MAKES NO  WARRANTY
 *  REGARDING  THE  SOFTWARE,  ITS  PERFORMANCE,  ITS  MERCHANTABILITY  OR
 *  FITNESS FOR ANY PARTICULAR USE, FREEDOM FROM ANY COMPUTER DISEASES  OR
 *  ITS CONFORMITY TO ANY SPECIFICATION. THE ENTIRE RISK AS TO QUALITY AND
 *  PERFORMANCE OF THE SOFTWARE IS WITH THE USER.
 *
 *  Module:  ofstd
 *
 *  Author:  Marco Eichelberg
 *
 *  Purpose: Define general purpose facility for console output
 *
 *  class OFConsole and its global instance, ofConsole,
 *  provide access to the standard console output and error streams
 *  in a way that allows multiple threads to concurrently create output
 *  even if that output is redirected, e. g. to file or memory.
 *  Protection is implemented if the module is compiled with -D_REENTRANT
 *  and is based on Mutexes.
 *
 *  In cases where DCMTK is used for GUI development, the fact that the
 *  libraries send many error messages to the standard or error streams
 *  are annoying since these streams are not present in a GUI environment.
 *  Either the messages just go lost or they even cause the GUI
 *  application to fail.  This file introduces aliases for the standard
 *  stream handles called COUT and CERR, which are normally only
 *  preprocessor macros for cout and cerr, respectively. If the
 *  toolkit is compiled with the flag DCMTK_GUI defined, however, these
 *  streams are created as OFOStringStream. This will allow a GUI based
 *  application to extract the messages and either present them to the
 *  user or store them in a log file.
 *
 *  GUI based applications making use of this feature should periodically
 *  check and clear these streams in order to avoid increasing consumption
 *  of heap memory.
 *
 *  Caveat 1: The DCMTK command line tools do not yet support the DCMTK_GUI
 *  flag, and will most likely exhibit all kinds of undesired behaviour
 *  if this flag is used.
 *
 *  Caveat 2: The direct use of the COUT and CERR macros is unsafe
 *  in multithread applications. Use ofConsole instead.
 *
 *  Last Update:      $Author: meichel $
 *  Update Date:      $Date: 2005/12/08 16:05:52 $
 *  CVS/RCS Revision: $Revision: 1.18 $
 *  Status:           $State: Exp $
 *
 *  CVS/RCS Log at end of file
 *
 */


#ifndef OFCONSOL_H
#define OFCONSOL_H

#include "dcmtk/config/osconfig.h"
#include "dcmtk/ofstd/ofstream.h"
#include "dcmtk/ofstd/ofthread.h"

#define INCLUDE_CSTDLIB
#include "dcmtk/ofstd/ofstdinc.h"


class OFConsole
{
public:

  virtual ~OFConsole(){ }

  ostream& lockCout()
  {
#ifdef _REENTRANT
    coutMutex.lock();
#endif
    return *currentCout;
  }

  void unlockCout()
  {
#ifdef _REENTRANT
    coutMutex.unlock();
#endif
  }

  ostream& getCout()
  {
    return *currentCout;
  }

  ostream *setCout(ostream *newCout=NULL);

  ostream& lockCerr()
  {
#ifdef _REENTRANT
    cerrMutex.lock();
#endif
    if (joined)
    {
#ifdef _REENTRANT
      coutMutex.lock();
#endif
      return *currentCout;
    }
    else return *currentCerr;
  }

  ostream& getCerr()
  {
    if (joined) return *currentCout;
    else return *currentCerr;
  }

  void unlockCerr()
  {
#ifdef _REENTRANT
    if (joined) coutMutex.unlock();
    cerrMutex.unlock();
#endif
  }

  ostream *setCerr(ostream *newCerr=NULL);

  void join();

  void split();

  OFBool isJoined();

  static OFConsole& instance();

private:

  OFConsole();

  OFConsole(const OFConsole &arg);

  OFConsole& operator=(const OFConsole &arg);

  ostream *currentCout;

  ostream *currentCerr;

  int joined;

#ifdef _REENTRANT

  OFMutex coutMutex;

  OFMutex cerrMutex;
#endif

  // dummy declaration to keep gcc quiet
  friend class OFConsoleDummyFriend;
};


#define ofConsole (OFConsole::instance())

/*
 * definitions for COUT, CERR, CLOG.
 *
 * NOTE: DIRECT USE OF THESE MACROS IS UNSAFE IN MULTITHREAD APPLICATIONS.
 */

#ifdef DCMTK_GUI

extern OFOStringStream COUT;
extern OFOStringStream CERR;

#else /* DCMTK_GUI */

#define COUT (ofConsole.getCout())
#define CERR (ofConsole.getCerr())

#endif /* DCMTK_GUI */

#endif /* OFCONSOL_H */


/*
 *
 * CVS/RCS Log:
 * $Log: ofconsol.h,v $
 * Revision 1.18  2005/12/08 16:05:52  meichel
 * Changed include path schema for all DCMTK header files
 *
 * Revision 1.17  2004/01/21 11:50:10  meichel
 * Fixed DOS CR/LF in preprocessor directives
 *
 * Revision 1.16  2004/01/16 10:30:12  joergr
 * Removed acknowledgements with e-mail addresses from CVS log.
 *
 * Revision 1.15  2003/12/17 17:38:39  meichel
 * Changed definition of COUT and CERR macros to allow redirection to file.
 *
 * Revision 1.14  2003/12/05 10:37:41  joergr
 * Removed leading underscore characters from preprocessor symbols (reserved
 * symbols). Updated copyright date where appropriate.
 *
 * Revision 1.13  2002/11/27 11:23:05  meichel
 * Adapted module ofstd to use of new header file ofstdinc.h
 *
 * Revision 1.12  2002/05/16 15:56:33  meichel
 * Changed ofConsole into singleton implementation that can safely
 *   be used prior to start of main, i.e. from global constructors
 *
 * Revision 1.11  2002/05/16 08:16:44  meichel
 * changed return type of OFConsole::setCout() and OFConsole::setCerr()
 *   to pointer instead of reference.
 *
 * Revision 1.10  2002/05/02 14:05:50  joergr
 * Added support for standard and non-standard string streams (which one is
 * supported is detected automatically via the configure mechanism).
 *
 * Revision 1.9  2002/04/16 13:36:02  joergr
 * Added configurable support for C++ ANSI standard includes (e.g. streams).
 *
 * Revision 1.8  2001/06/01 15:51:33  meichel
 * Updated copyright header
 *
 * Revision 1.7  2000/12/13 15:14:25  joergr
 * Introduced dummy parameter for "default" constructor of class OFConsole
 * to "convince" linker of gcc 2.5.8 (NeXTSTEP) to allocate memory for global
 * variable 'ofConsole'.
 *
 * Revision 1.6  2000/10/10 12:01:21  meichel
 * Created/updated doc++ comments
 *
 * Revision 1.5  2000/09/26 13:46:12  meichel
 * Simplified inline code in ofconsol.h, required by Sun CC 2.x
 *
 * Revision 1.4  2000/06/21 15:47:54  meichel
 * Including stdlib.h, required for Sun CC 4.2
 *
 * Revision 1.3  2000/04/14 15:41:40  meichel
 * Added unprotected get methods, required for the cmdata debug facility.
 *
 * Revision 1.2  2000/04/14 15:16:08  meichel
 * Added new class OFConsole and global instance ofConsole which provide
 *   access to standard output and error streams in a way that allows multiple
 *   threads to safely create output concurrently.
 *
 * Revision 1.1  2000/03/03 14:02:47  meichel
 * Implemented library support for redirecting error messages into memory
 *   instead of printing them to stdout/stderr for GUI applications.
 *
 *
 */

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