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# out_display.hxx

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    00001 // out_display.hxx: this file is part of the Vaucanson project.
    00002 //
    00003 // Vaucanson, a generic library for finite state machines.
    00004 //
    00005 // Copyright (C) 2005, 2006, 2007 The Vaucanson Group.
    00006 //
    00007 // This program is free software; you can redistribute it and/or
    00008 // modify it under the terms of the GNU General Public License
    00009 // as published by the Free Software Foundation; either version 2
    00010 // of the License, or (at your option) any later version.
    00011 //
    00012 // The complete GNU General Public Licence Notice can be found as the
    00013 // `COPYING' file in the root directory.
    00014 //
    00015 // The Vaucanson Group consists of people listed in the `AUTHORS' file.
    00016 //
    00017
    00026 #ifndef VCSN_TOOLS_OUT_DISPLAY_HXX
    00027 # define VCSN_TOOLS_OUT_DISPLAY_HXX
    00028
    00029 # include <vaucanson/tools/out_display.hh>
    00030 # include <sys/types.h>
    00031 # include <sys/wait.h>
    00032 # include <unistd.h>
    00033
    00034 namespace vcsn {
    00035
    00036   namespace tools {
    00037
    00038     template <class S, class T>
    00039     bool
    00040     out_display(const AutomataBase<S>&,
    00041                 const T&,
    00042                 const Element<S, T>& a,
    00043                 const std::string& name,
    00044                 const bool bg,
    00045                 const char *const argv[],
    00046                 void (*function)(std::ostream& o,
    00047                                  const Element<S, T>& a,
    00048                                  const std::string& name))
    00049
    00050     {
    00051       int filedes[2];
    00052       if (pipe(filedes))
    00053         return false;
    00054
    00055       pid_t child_pid = fork();
    00056       if (child_pid)
    00057         {
    00058           close(filedes[0]);
    00059           if (child_pid == -1)
    00060             {
    00061               close(filedes[1]);
    00062               return false;
    00063             }
    00064           else
    00065             {
    00066               // FIXME: That trick is dirty!
    00067               {
    00068                 std::cout.flush();
    00069                 int old = dup(STDOUT_FILENO);
    00070                 if (old != -1)
    00071                   dup2(filedes[1], STDOUT_FILENO);
    00072                 close(filedes[1]);
    00073
    00074                 function(std::cout, a, name);
    00075
    00076                 if (old != -1)
    00077                   {
    00078                     dup2(old, STDOUT_FILENO);
    00079                     close(old);
    00080                   }
    00081               }
    00082               return bg or waitpid(child_pid, NULL, 0) == child_pid;
    00083             }
    00084         }
    00085       else
    00086         {
    00087           close(filedes[1]);
    00088           dup2(filedes[0], STDIN_FILENO);
    00089           close(filedes[0]);
    00090           // execvp will treat its second argument as if it was
    00091           // "const char* const*".  See the following page for an
    00092           // explanation of why it is only declared as "char* const*".
    00093           // http://www.opengroup.org/onlinepubs/000095399/functions/exec.html
    00094           execvp(argv[0], const_cast<char *const *>(argv));
    00095           return false;
    00096         }
    00097     }
    00098
    00099   } // End of namespace tools.
    00100
    00101 } // End of namespace vcsn.
    00102
    00103 #endif // ! VCSN_TOOLS_OUT_DISPLAY_HXX