robot/include/rttr/detail/impl/wrapper_mapper_impl.h

/************************************************************************************
*                                                                                   *
*   Copyright (c) 2014 - 2018 Axel Menzel <info@rttr.org>                           *
*                                                                                   *
*   This file is part of RTTR (Run Time Type Reflection)                            *
*   License: MIT License                                                            *
*                                                                                   *
*   Permission is hereby granted, free of charge, to any person obtaining           *
*   a copy of this software and associated documentation files (the "Software"),    *
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*   and/or sell copies of the Software, and to permit persons to whom the           *
*   Software is furnished to do so, subject to the following conditions:            *
*                                                                                   *
*   The above copyright notice and this permission notice shall be included in      *
*   all copies or substantial portions of the Software.                             *
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*   SOFTWARE.                                                                       *
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*************************************************************************************/

#ifndef RTTR_WRAPPER_MAPPER_IMPL_H_
#define RTTR_WRAPPER_MAPPER_IMPL_H_

#include "rttr/detail/base/core_prerequisites.h"
#include "rttr/detail/misc/std_type_traits.h"
#include "rttr/detail/misc/utility.h"
#include <type_traits>

#include <memory>

namespace rttr
{

class type;

//////////////////////////////////////////////////////////////////////////////////////

template<typename T>
struct wrapper_mapper<std::shared_ptr<T>>
{
    using wrapped_type = decltype(std::shared_ptr<T>().get());
    using type = std::shared_ptr<T>;

    static RTTR_INLINE wrapped_type get(const type& obj)
    {
        return obj.get();
    }

    static RTTR_INLINE type create(const wrapped_type& t)
    {
        return type(t);
    }

    template<typename U>
    static std::shared_ptr<U> convert(const type& source, bool& ok)
    {
        if (auto p = rttr_cast<typename std::shared_ptr<U>::element_type*>(source.get()))
        {
            ok = true;
            return std::shared_ptr<U>(source, p);
        }
        else
        {
            ok = false;
            return std::shared_ptr<U>();
        }
    }
};

//////////////////////////////////////////////////////////////////////////////////////

template<typename T>
struct wrapper_mapper<std::reference_wrapper<T>>
{
    using wrapped_type  = decltype(std::declval<std::reference_wrapper<T>>().get());
    using type          = std::reference_wrapper<T>;

    static RTTR_INLINE wrapped_type get(const type& obj)
    {
        return obj.get();
    }

    static RTTR_INLINE type create(const wrapped_type& t)
    {
        return type(t);
    }
};

//////////////////////////////////////////////////////////////////////////////////////

template<typename T>
struct wrapper_mapper<std::unique_ptr<T>>
{
    using wrapped_type  = decltype(std::declval<std::unique_ptr<T>>().get());
    using type          = std::unique_ptr<T>;

    static RTTR_INLINE wrapped_type get(const type& obj)
    {
        return obj.get();
    }

    static RTTR_INLINE type create(const wrapped_type& t)
    {
        return type(t);
    }
};

//////////////////////////////////////////////////////////////////////////////////////

template<typename T>
struct wrapper_mapper<std::weak_ptr<T>>
{
    using wrapped_type  = decltype(std::declval<std::weak_ptr<T>>().lock().get());
    using type          = std::weak_ptr<T>;

    static RTTR_INLINE wrapped_type get(const type& obj)
    {
        return obj.lock().get();
    }

    // there is no create method because, weak pointer can only be created by a referencing a shared_ptr.
    // And a tmp shared_ptr which goes out of scope immediately, result always in an empty weak_ptr.

};

namespace detail
{

//////////////////////////////////////////////////////////////////////////////////////

template<typename T>
using wrapper_mapper_t = typename wrapper_mapper<typename std::remove_cv<typename std::remove_reference<T>::type
                                                                   >::type>::wrapped_type;

//////////////////////////////////////////////////////////////////////////////////////

template<typename T>
using is_wrapper = std::integral_constant<bool, !std::is_same<invalid_wrapper_type, wrapper_mapper_t<T>>::value >;

//////////////////////////////////////////////////////////////////////////////////////

template<typename T>
using wrapper_address_return_type_t = conditional_t<is_wrapper<T>::value,
                                                    raw_addressof_return_type_t< wrapper_mapper_t< T > >,
                                                    raw_addressof_return_type_t<T>>;

//////////////////////////////////////////////////////////////////////////////////////

template<typename T>
typename std::enable_if<is_wrapper<T>::value, raw_addressof_return_type_t< wrapper_mapper_t<T>> >::type wrapped_raw_addressof(T& obj)
{
    using raw_wrapper_type = remove_cv_t<remove_reference_t<T>>;
    wrapper_mapper_t<T> value = wrapper_mapper<raw_wrapper_type>::get(obj);
    return raw_addressof(value);
}

//////////////////////////////////////////////////////////////////////////////////////

template<typename T>
typename std::enable_if<!is_wrapper<T>::value, raw_addressof_return_type_t<T>>::type wrapped_raw_addressof(T& obj)
{
    return raw_addressof(obj);
}

//////////////////////////////////////////////////////////////////////////////////////

/*!
 * Determine if the given type \a T is a wrapper and has the member method
 * 'wrapper create(const wrapper_type&)' declared.
 */
template <typename T, typename Tp = typename std::remove_cv<typename std::remove_reference<T>::type>::type>
class has_create_wrapper_func_impl
{
    using YesType = char[1];
    using NoType  = char[2];

    template <typename U, typename V, U (*)(const V&)>
    class check { };

    template <typename C>
    static YesType& f(check<C, wrapper_mapper_t<C>, &wrapper_mapper<C>::create>*);

    template <typename C>
    static NoType& f(...);

public:
    static RTTR_CONSTEXPR_OR_CONST bool value = (sizeof(f<Tp>(0)) == sizeof(YesType));
};

template<typename T>
using has_create_wrapper_func = std::integral_constant<bool, has_create_wrapper_func_impl<T>::value>;

//////////////////////////////////////////////////////////////////////////////////////

} // end namespace detail
} // end namespace rttr

#endif // RTTR_WRAPPER_MAPPER_IMPL_H_