lib/handle.hpp

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/*
  HANDLE.hpp  -  opaque handle to an implementation entity, automatically managing lifecycle
 
  Copyright (C)         Lumiera.org
    2009,               Hermann Vosseler <Ichthyostega@web.de>
 
  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 LIB_HANDLE_H
#define LIB_HANDLE_H

#include "lib/nobug-init.hpp"
#include "lib/bool-checkable.hpp"

#include <tr1/memory>


namespace lib {
  
  using std::tr1::shared_ptr;
  using std::tr1::weak_ptr;
  
  
  
  template<class IMP>
  class Handle 
    : public lib::BoolCheckable<Handle<IMP> >
    {
    protected:
      typedef std::tr1::shared_ptr<IMP> SmPtr;
      
      SmPtr smPtr_;
      
    public:
      
      Handle ( )
      : smPtr_()
      { }
      
                                 Handle (Handle const& r)          : smPtr_(r.smPtr_)   { }
      template<class Y> explicit Handle (shared_ptr<Y> const& r)   : smPtr_(r)          { }
      template<class Y> explicit Handle (weak_ptr<Y> const& wr)    : smPtr_(wr)         { }
      template<class Y> explicit Handle (std::auto_ptr<Y> & ar)    : smPtr_(ar)         { }
      
                        Handle& operator=(Handle const& r)         { smPtr_ = r.smPtr_; return *this; }
      template<class Y> Handle& operator=(shared_ptr<Y> const& sr) { smPtr_ = sr;       return *this; }
      template<class Y> Handle& operator=(std::auto_ptr<Y> & ar)   { smPtr_ = ar;       return *this; }
      
      
      template<typename DEL>
      Handle&
      activate (IMP* impl, DEL whenDead)
        {
          smPtr_.reset (impl, whenDead);
          return *this;
        }
      
      Handle&
      activate(shared_ptr<IMP> const& impl)
        {
          smPtr_ = impl;
          return *this;
        }
      
      void close ()  { smPtr_.reset(); }
      
      
      bool isValid()  const { return bool(smPtr_);}
      
      
      
      
    protected:
      IMP& 
      impl()  const
        {
          REQUIRE (smPtr_.get(), "Lifecycle-Error");
          return *(smPtr_.get());
        }
    };
  
  
} // namespace lib
#endif

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