StreamRedirect.h

#ifndef _theplu_yat_utility_stream_readirect_ 
#define _theplu_yat_utility_stream_readirect_ 

// $Id: StreamRedirect.h 2061 2009-09-11 17:54:01Z peter $

/*
  Copyright (C) 2009 Peter Johansson

  This file is part of the yat library, http://dev.thep.lu.se/yat

  The yat library 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 3 of the
  License, or (at your option) any later version.

  The yat 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
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with yat. If not, see <http://www.gnu.org/licenses/>.
*/

#include <fstream>
#include <istream>
#include <ostream>
#include <streambuf>
#include <string>

namespace theplu {
namespace yat {
namespace utility {

  template<class charT, class traits = std::char_traits<charT> >
  class BasicStreamRedirect
  {
  public:
    BasicStreamRedirect(std::basic_istream<charT, traits>& is1, 
                        std::basic_istream<charT, traits>& is2,
                        bool active=true);
    
    BasicStreamRedirect(std::basic_istream<charT, traits>& is, 
                        const std::string& file, bool active=true);
    
    BasicStreamRedirect(std::basic_ostream<charT, traits>& os1, 
                        std::basic_ostream<charT, traits>& os2,
                        bool active=true);
    
    BasicStreamRedirect(std::basic_ostream<charT, traits>& os, 
                        const std::string& file, bool active=true);
    
    ~BasicStreamRedirect(void);
    
  private:
    // no copying
    BasicStreamRedirect(const BasicStreamRedirect&);
    BasicStreamRedirect& operator=(const BasicStreamRedirect&);
    
    void init(std::basic_ios<charT, traits>& ios1, 
              std::basic_ios<charT, traits>& ios2,
              bool active);
    
    std::basic_streambuf<charT, traits>* buf_;
    std::basic_ifstream<charT, traits>* ifs_;
    std::basic_ios<charT, traits>* ios_;
    std::basic_ofstream<charT, traits>* ofs_;
  };
  
  typedef BasicStreamRedirect<char> StreamRedirect;
  
  typedef BasicStreamRedirect<wchar_t> wStreamRedirect;
  
  
  // template implementations
  
  template<class charT, class traits>
  BasicStreamRedirect<charT, traits>::
	BasicStreamRedirect(std::basic_istream<charT, traits>& is1, 
                      std::basic_istream<charT, traits>& is2, bool active)
    : buf_(NULL), ifs_(NULL), ios_(NULL), ofs_(NULL)
  {
    init(is1, is2, active);
  }
  
  
  template<class charT, class traits>
  BasicStreamRedirect<charT, traits>::
	BasicStreamRedirect(std::basic_istream<charT, traits>& is, 
                      const std::string& file, bool active)
    : buf_(NULL), ifs_(NULL), ios_(NULL), ofs_(NULL)
  {
    if (active) {
      ifs_ = new std::basic_ifstream<charT, traits>(file.c_str());
      init(is, *ofs_, active);
    }
  }
  
  
  template<class charT, class traits>
  BasicStreamRedirect<charT, traits>::
	BasicStreamRedirect(std::basic_ostream<charT, traits>& os1, 
                      std::basic_ostream<charT, traits>& os2, bool active)
    : buf_(NULL), ifs_(NULL), ios_(NULL), ofs_(NULL)
  {
    init(os1, os2, active);
  }
  
  
  template<class charT, class traits>
  BasicStreamRedirect<charT, traits>::
	BasicStreamRedirect(std::basic_ostream<charT, traits>& os, 
                      const std::string& file, bool active)
    : buf_(NULL), ifs_(NULL), ios_(NULL), ofs_(NULL)
  {
    if (active) {
      ofs_ = new std::basic_ofstream<charT, traits>(file.c_str());
      init(os, *ofs_, active);
    }
  }
  
  
  template<class charT, class traits>
  BasicStreamRedirect<charT, traits>::
	~BasicStreamRedirect(void)
  {
    // only restore stream if active is true
    if (ios_) {
      ios_->rdbuf(buf_);
    }
    delete ifs_;
    delete ofs_;
  }
  
  
  template<class charT, class traits>
  void 
  BasicStreamRedirect<charT, traits>::init(std::basic_ios<charT, traits>& s1, 
                                           std::basic_ios<charT, traits>& s2,
                                           bool active)
  {
    if (active) {
      ios_ = &s1;
      // save the buffer 
      buf_ = s1.rdbuf();
      // redirect os1 to os2
      s1.rdbuf(s2.rdbuf());
    }
  }
  
}}} // of namespace utility, yat, and theplu

#endif