test2/source/blender/freestyle/intern/system/PointerSequence.h

/* SPDX-FileCopyrightText: 2023 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

#pragma once

/** \file
 * \ingroup freestyle
 * \brief Simple RAII wrappers for std:: sequential containers
 *
 *  PointerSequence
 *
 *  Produces a wrapped version of a sequence type (std::vector, std::deque, std::list) that will
 * take ownership of pointers that it stores.  Those pointers will be deleted in its destructor.
 *
 *  Because the contained pointers are wholly owned by the sequence, you cannot make a copy of the
 * sequence. Making a copy would result in a double free.
 *
 *  This is a no-frills class that provides no additional facilities.  The user is responsible for
 * managing any pointers that are removed from the list, and for making sure that any pointers
 * contained in the class are not deleted elsewhere.  Because this class does no reference
 * counting, the user must also make sure that any pointer appears only once in the sequence.
 *
 *  If more sophisticated facilities are needed, use tr1::shared_ptr or boost::shared_ptr.
 *  This class is only intended to allow one to eke by in projects where tr1 or boost are not
 * available.
 *
 *  Usage: The template takes two parameters, the standard container, and the class held in the
 * container. This is a limitation of C++ templates, where T::iterator is not a type when T is a
 * template parameter. If anyone knows a way around this limitation, then the second parameter can
 * be eliminated.
 *
 * Example:
 * \code{.cc}
 * PointerSequence<vector<Widget*>, Widget*> v;
 * v.push_back(new Widget);
 * cout << v[0] << endl; // operator[] is provided by std::vector, not by PointerSequence
 * v.destroy(); // Deletes all pointers in sequence and sets them to nullptr.
 * \endcode
 *
 * The idiom for removing a pointer from a sequence is:
 * \code{.cc}
 * Widget* w = v[3];
 * v.erase(v.begin() + 3); // or v[3] = 0;
 * \endcode
 *  The user is now responsible for disposing of `w` properly.
 */

#include <algorithm>

#include "MEM_guardedalloc.h"

namespace Freestyle {

template<typename C, typename T> class PointerSequence : public C {
  PointerSequence(PointerSequence &other);
  PointerSequence &operator=(PointerSequence &other);

  static void destroyer(T t)
  {
    delete t;
  }

 public:
  PointerSequence(){};

  ~PointerSequence()
  {
    destroy();
  }

  void destroy()
  {
    for_each(this->begin(), this->end(), destroyer);
  }

  MEM_CXX_CLASS_ALLOC_FUNCS("Freestyle:PointerSequence")
};

} /* namespace Freestyle */