ObjectPtr.h

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/***************************************************************************
 *
 * Copyright (C) 2009-2011 Cassio Neri Moreira
 *
 * This file is part of the KeyValue library.
 *
 * The KeyValue 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 KeyValue 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 KeyValue. If not, see <http://www.gnu.org/licenses/>.
 *
 * If you modify this library, or any covered work, by linking or combining
 * it with Excel (or a modified version of that program), containing parts
 * covered by the terms of End-User License Agreement for Microsoft
 * Software, the licensors of KeyValue grant you additional permission to
 * convey the resulting work.
 *
 **************************************************************************/

#ifndef KEYVALUE_VALUE_OBJECTPTR_H_
#define KEYVALUE_VALUE_OBJECTPTR_H_

#include <boost/type_traits/is_base_of.hpp>
#include <boost/utility/enable_if.hpp>

#include "keyvalue/extern/SharedPtr.h"
#include "keyvalue/value/Object.h"
#include "keyvalue/value/PtrTraits.h"

namespace keyvalue {
namespace value {

class ObjectPtr {

public:

  ObjectPtr();

  template <typename ObjectType>
  ObjectPtr(const shared_ptr<ObjectType>& ptr, typename
    ::boost::enable_if< ::boost::is_base_of<Object, ObjectType> >::type*
    dummy = 0);

  template <typename ObjectType, template <typename> class SmartPtr>
  ObjectPtr(const SmartPtr<ObjectType>& ptr, typename
    ::boost::disable_if< ::boost::is_base_of<Object, ObjectType> >::type*
    dummy = 0);

  template <typename Rhs>
  ObjectPtr(const Rhs& rhs);

  template <typename Rhs>
  ObjectPtr&
  operator =(const Rhs& rhs);

  operator bool() const;

  template <typename ObjectType>
  shared_ptr<ObjectType>
  cast(typename
    ::boost::enable_if< ::boost::is_base_of<Object, ObjectType> >::type*
    dummy = 0) const;

  template <typename ObjectType>
  typename PtrTraits<ObjectType>::Type_
  cast(typename 
    ::boost::disable_if< ::boost::is_base_of<Object, ObjectType> >::type*
    dummy = 0) const;

private:

  void
  swap(ObjectPtr& other);

  shared_ptr<Object>     kvPtr_; // Pointer to KeyValue objects.
  PtrTraits<void>::Type_ ptr_;   // Pointer to users objects.

}; // class ObjectPtr

/*
 * ATTENTION: If you make changes here, please, update doc in Parent.h
 *
 * In value hierarchy:
 *
 *  ObjectPtr
 *  +- shared_ptr<Object>
 *  |  `- Object*
 *  `- PtrTraits<ObjectType>::Type_
 *     `- ObjectType*
 */

template <typename Rhs>
struct Parent;

template <typename ObjectType, template <typename> class SmartPtr>
struct Parent<SmartPtr<ObjectType> > {
  typedef ObjectPtr Type_;
};

template <typename ObjectType,
  bool isObject = ::boost::is_base_of<Object, ObjectType>::value>
struct PointerParent;

template <typename ObjectType>
struct PointerParent<ObjectType, true> {
  typedef shared_ptr<Object> Type_;
};

template <typename ObjectType>
struct PointerParent<ObjectType, false> {
  typedef typename PtrTraits<ObjectType>::Type_ Type_;
};

template <typename ObjectType>
struct Parent<ObjectType*> {
  typedef typename PointerParent<ObjectType>::Type_ Type_;
};

/*--------------------------------------------------------------------------
 * ObjectPtr::ObjectPtr()
 *------------------------------------------------------------------------*/

template <typename ObjectType>
ObjectPtr::ObjectPtr(const shared_ptr<ObjectType>& ptr, typename
  ::boost::enable_if< ::boost::is_base_of<Object, ObjectType> >::type*) :
  kvPtr_(ptr) {
}

template <typename ObjectType, template <typename> class SmartPtr>
ObjectPtr::ObjectPtr(const SmartPtr<ObjectType>& ptr, typename 
  ::boost::disable_if< ::boost::is_base_of<Object, ObjectType> >::type*) :
  ptr_(ptr) {
}

template <typename Rhs>
ObjectPtr::ObjectPtr(const Rhs& rhs) {

  /*
   * If you get an error here about 'keyvalue::value::Parent<Rhs>', this
   * means that Rhs isn't in a lower level in the hierarchy.
   */

  typename Parent<Rhs>::Type_ tmp(rhs);
  ObjectPtr other(tmp);
  swap(other);
}

/*--------------------------------------------------------------------------
 * operator =()
 *------------------------------------------------------------------------*/

template <typename Rhs>
ObjectPtr&
ObjectPtr::operator =(const Rhs& rhs) {

  /*
   * If you get an error here about 'keyvalue::value::Parent<P>', this
   * means that Rhs isn't in a lower level in the hierarchy.
   */

  return *this = typename Parent<Rhs>::Type_(rhs);
}

/*--------------------------------------------------------------------------
 * cast()
 *------------------------------------------------------------------------*/

template <typename ObjectType>
shared_ptr<ObjectType>
ObjectPtr::cast(typename
  ::boost::enable_if< ::boost::is_base_of<Object, ObjectType> >::type*)
  const {
  return dynamic_pointer_cast<ObjectType>(kvPtr_);
}

template <typename ObjectType>
typename PtrTraits<ObjectType>::Type_
ObjectPtr::cast(typename
  ::boost::disable_if< ::boost::is_base_of<Object, ObjectType> >::type*)
  const {
  return dynamic_pointer_cast<ObjectType>(ptr_);
}

} // namespace value
} // namespace keyvalue

#endif // KEYVALUE_VALUE_OBJECTPTR_H_