proc/control/command-impl-clone-builder.hpp

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/*
  COMMAND-IMPL-CLONE-BUILDER.hpp  -  Cloning command implementation without disclosing concrete type
 
  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 CONTROL_COMMAND_IMPL_CLONE_BUILDER_H
#define CONTROL_COMMAND_IMPL_CLONE_BUILDER_H

//#include "proc/control/command.hpp"
//#include "proc/control/command-closure.hpp"
#include "proc/control/command-mutation.hpp"
#include "lib/typed-allocation-manager.hpp"
#include "lib/opaque-holder.hpp"
//#include "lib/bool-checkable.hpp"

#include <boost/noncopyable.hpp>
//#include <boost/operators.hpp>

//#include <tr1/memory>
//#include <tr1/functional>


namespace control {
  
  using lib::TypedAllocationManager;
//  using std::tr1::function;
//  using std::tr1::shared_ptr;
  using lib::InPlaceBuffer;
  
  
  namespace impl { // Helper: type erased context for creating command clones
    
    struct CloneContext  
      {
        virtual ~CloneContext() {}
        
        virtual UndoMutation const& getUndoFunc() { NOTREACHED(); }
        virtual PClo         const& getClosure()  { NOTREACHED(); }
        virtual bool                isValid()     { return false; }
      };
    
    class ClonedContext
      : public CloneContext
      {
        PClo newClosure_;
        UndoMutation newUndoFunctor_;
        
        virtual UndoMutation const& getUndoFunc() { return newUndoFunctor_; }
        virtual PClo         const& getClosure()  { return newClosure_; }
        virtual bool                isValid()     { return true; }
        
        
        template<typename ARG>
        ARG&
        downcast()
          {
            REQUIRE (INSTANCEOF (ARG, newClosure_.get()));
            
            return static_cast<ARG&> (*newClosure_);
          }
        
        
      public:
        
        template<typename ARG>
        ClonedContext ( ARG const& origArgHolder
                      , TypedAllocationManager& allocator
                      )
          : newClosure_(allocator.create<ARG> (origArgHolder))
          , newUndoFunctor_(downcast<ARG>().getMementoWiring())
          { }
      };
    
  }//(End) impl namespace
  
  
  
  
  
  class CommandImplCloneBuilder
    : public boost::noncopyable
    {
      typedef InPlaceBuffer<impl::CloneContext, sizeof(impl::ClonedContext)> ContextHolder;
      
      TypedAllocationManager& allocator_;
      ContextHolder newContext_;
      
    public:
      CommandImplCloneBuilder (TypedAllocationManager& allo)
        : allocator_(allo)
        { }
      
      
      template<typename ARG>
      void
      buildCloneContext (ARG const& origArgHolder)
        {
          REQUIRE (!newContext_->isValid(), "Lifecycle-Error");
          
          newContext_.create<impl::ClonedContext> (origArgHolder, allocator_); 
        }
      
      
      
      UndoMutation const&
      clonedUndoMutation ()
        {
          REQUIRE (newContext_->isValid());
          return newContext_->getUndoFunc();
        }
      
      
      PClo const&
      clonedClosuere ()
        {
          REQUIRE (newContext_->isValid());
          return newContext_->getClosure();
        }
      
    };
  
  
  
  
  
} // namespace control
#endif

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