pimpl.h

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          http://www.mrpt.org/                          |
   |                                                                        |
   | Copyright (c) 2005-2017, Individual contributors, see AUTHORS file     |
   | See: http://www.mrpt.org/Authors - All rights reserved.                |
   | Released under BSD License. See details in http://www.mrpt.org/License |
   +------------------------------------------------------------------------+ */

#pragma once

#include <mrpt/config.h>
#include <mrpt/utils/mrpt_macros.h>
#include <memory>

/** \file Macros to help implementing the PIMPL idiom and make all
 * declarations easier to read and less error-prone.
 */
namespace mrpt
{
namespace utils
{
/** Pointer to IMPLementation auxiliary structure to make raw pointers movable,
 *copiable and automatically deleted.
 *\ingroup mrpt_base_grp
 */
template <typename T>
struct pimpl
{
        std::unique_ptr<T> ptr;

        // All these must be defined in a .cpp file with PIMPL_DEFINE(_TYPE), after
        // including the
        // real definition of T, which is only forward-declared in the headers:
        pimpl();
        ~pimpl();
        pimpl(pimpl&& op) noexcept;  // movable
        pimpl& operator=(pimpl&& op) noexcept;  //
        pimpl(const pimpl& op);  // and copyable
        pimpl& operator=(const pimpl& op);  //
};
}
}

// ========== Header file ==============
#define PIMPL_FORWARD_DECLARATION(_TYPE) _TYPE

#define PIMPL_DECLARE_TYPE(_TYPE, _VAR_NAME) mrpt::utils::pimpl<_TYPE> _VAR_NAME

// ========== Implementation file ==============
#define PIMPL_IMPLEMENT(_TYPE)                                               \
        namespace mrpt                                                           \
        {                                                                        \
        namespace utils                                                          \
        {                                                                        \
        template <>                                                              \
        pimpl<_TYPE>::pimpl() : ptr()                                            \
        {                                                                        \
        }                                                                        \
        template <>                                                              \
        pimpl<_TYPE>::~pimpl()                                                   \
        {                                                                        \
        }                                                                        \
        /* Movable */                                                            \
        template <>                                                              \
        pimpl<_TYPE>::pimpl(pimpl<_TYPE>&& op) noexcept : ptr(std::move(op.ptr)) \
        {                                                                        \
        }                                                                        \
        template <>                                                              \
        pimpl<_TYPE>& pimpl<_TYPE>::operator=(pimpl<_TYPE>&& op) noexcept        \
        {                                                                        \
                ptr = std::move(op.ptr);                                             \
                return *this;                                                        \
        }                                                                        \
        /* Copyable: */                                                          \
        template <>                                                              \
        pimpl<_TYPE>::pimpl(const pimpl<_TYPE>& op)                              \
        {                                                                        \
                if (op.ptr.get() == ptr.get()) return;                               \
                ptr.reset(new _TYPE());                                              \
                *ptr = *op.ptr;                                                      \
        }                                                                        \
        template <>                                                              \
        pimpl<_TYPE>& pimpl<_TYPE>::operator=(const pimpl<_TYPE>& op)            \
        {                                                                        \
                if (op.ptr.get() == ptr.get()) return *this;                         \
                ptr.reset(new _TYPE());                                              \
                *ptr = *op.ptr;                                                      \
                return *this;                                                        \
        }                                                                        \
        }                                                                        \
        }

// Put in the constructor, initializer, etc.
#define PIMPL_CONSTRUCT(_TYPE, _VAR_NAME) _VAR_NAME.ptr.reset(new _TYPE())

#define PIMPL_GET_PTR(_TYPE, _VAR_NAME) _VAR_NAME.ptr.get()
#define PIMPL_GET_REF(_TYPE, _VAR_NAME) (*_VAR_NAME.ptr.get())
#define PIMPL_GET_CONSTREF(_TYPE, _VAR_NAME) (*_VAR_NAME.ptr.get())