buffhandle-attach.hpp

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/*
  BUFFHANDLE-ATTACH.hpp  -  Buffer handle extension to attach objects into the buffer

  Copyright (C)         Lumiera.org
    2008,               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 ENGINE_BUFFHANDLE_ATTACH_H
#define ENGINE_BUFFHANDLE_ATTACH_H


#include "lib/error.hpp"
#include "steam/engine/buffer-provider.hpp"
#include "steam/engine/buffhandle.hpp"


namespace steam {
namespace engine {
  
  
  
  
  /* === BuffHandle Implementation === */
  
  
#define _EXCEPTION_SAFE_INVOKE(_CTOR_)  \
    try                                  \
      {                                   \
        return *new(pBuffer_) _CTOR_;     \
      }                                   \
    catch(...)                            \
      {                                   \
        emergencyCleanup(); /* EX_FREE */ \
        pBuffer_ = 0;                     \
        throw;                            \
      }
  
  template<typename BU>
  inline BU&
  BuffHandle::create()
  {
    takeOwnershipFor<BU>();
    _EXCEPTION_SAFE_INVOKE (BU());
  }
  
#undef _EXCEPTION_SAFE_INVOKE
  
  
  
  template<typename BU>
  inline void
  BuffHandle::takeOwnershipFor()
  {
    BufferDescriptor howto_attach_object_automatically
      = descriptor_.provider_->getDescriptor<BU>();
    takeOwnershipFor (howto_attach_object_automatically); // EX_STRONG
  }
  
  
  template<typename BU>
  inline BU&
  BuffHandle::accessAs()
  {
    if (!pBuffer_)
      throw error::Logic ("buffer not (yet) locked for access by clients"
                         , LERR_(LIFECYCLE));
    return *reinterpret_cast<BU*> (pBuffer_);
  }
  
  
  
}} // namespace steam::engine
#endif