AnyPtr.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_UTIL_ANY_PTR_H_
#define KEYVALUE_UTIL_ANY_PTR_H_

#include "keyvalue/extern/SharedPtr.h"
#include "keyvalue/util/Paparazzo.h"

namespace keyvalue {
namespace util {

class AnyPtr {

public:

  AnyPtr();

  template <typename T>
  explicit AnyPtr(T* ptr);
  template <typename T>
  explicit AnyPtr(shared_ptr<T> ptr);

  template <typename T>
  operator shared_ptr<T>() const;

  operator bool() const;

  void
  swap(AnyPtr& other);

private:

  template <typename T>
  void
  thrower() const;

  shared_ptr<void> ptr_;
  void (AnyPtr::*thr_)() const;

}; // class AnyPtr

template <typename T>
shared_ptr<T>
dynamic_pointer_cast(const AnyPtr& ptr);

//--------------------------------------------------------------------------
// AnyPtr()
//--------------------------------------------------------------------------

template <typename T>
AnyPtr::AnyPtr(T* ptr) : ptr_(ptr), thr_(&AnyPtr::thrower<T>) {
}

template <typename T>
AnyPtr::AnyPtr(shared_ptr<T> ptr) : ptr_(ptr), thr_(&AnyPtr::thrower<T>) {
}

//--------------------------------------------------------------------------
// operator shared_ptr<T>()
//--------------------------------------------------------------------------

template <typename T>
AnyPtr::operator shared_ptr<T>() const {

  if (ptr_) {

    try { (this->*thr_)(); }

    catch (T* p) {
      shared_ptr<T> result = static_pointer_cast<T>(ptr_);
      shared_ptr<Paparazzo>::change_px(result, p);
      return result;
    }

    catch (...) {}
  }

  return shared_ptr<T>();
}

//--------------------------------------------------------------------------
// thrower()
//--------------------------------------------------------------------------

template <typename T>
void
AnyPtr::thrower() const {
  throw static_cast<T*>(ptr_.get());
}

//--------------------------------------------------------------------------
// dynamic_pointer_cast()
//--------------------------------------------------------------------------

template <typename T>
shared_ptr<T>
dynamic_pointer_cast(const AnyPtr& ptr) {
  // The automatic conversion does the job.
  return ptr;
}

} // namespace util
} // namespace keyvalue

#endif // KEYVALUE_UTIL_ANY_PTR_H_