libcxx/include/__functional/reference_wrapper.h

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP___FUNCTIONAL_REFERENCE_WRAPPER_H
#define _LIBCPP___FUNCTIONAL_REFERENCE_WRAPPER_H

#include <__config>
#include <__functional/weak_result_type.h>
#include <__memory/addressof.h>
#include <__utility/forward.h>
#include <type_traits>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
#endif

_LIBCPP_BEGIN_NAMESPACE_STD

template <class _Tp>
class _LIBCPP_TEMPLATE_VIS reference_wrapper
#if _LIBCPP_STD_VER <= 17 || !defined(_LIBCPP_ABI_NO_BINDER_BASES)
    : public __weak_result_type<_Tp>
#endif
{
public:
    // types
    typedef _Tp type;
private:
    type* __f_;

#ifndef _LIBCPP_CXX03_LANG
    static void __fun(_Tp&) _NOEXCEPT;
    static void __fun(_Tp&&) = delete;
#endif

public:
    // construct/copy/destroy
#ifdef _LIBCPP_CXX03_LANG
    _LIBCPP_INLINE_VISIBILITY
    reference_wrapper(type& __f) _NOEXCEPT
        : __f_(_VSTD::addressof(__f)) {}
#else
    template <class _Up, class = __enable_if_t<!__is_same_uncvref<_Up, reference_wrapper>::value, decltype(__fun(declval<_Up>())) >>
    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
    reference_wrapper(_Up&& __u) _NOEXCEPT_(noexcept(__fun(declval<_Up>()))) {
        type& __f = static_cast<_Up&&>(__u);
        __f_ = _VSTD::addressof(__f);
    }
#endif

    // access
    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
    operator type&() const _NOEXCEPT {return *__f_;}
    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
    type& get() const _NOEXCEPT {return *__f_;}

#ifndef _LIBCPP_CXX03_LANG
    // invoke
    template <class... _ArgTypes>
    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
    typename __invoke_of<type&, _ArgTypes...>::type
    operator() (_ArgTypes&&... __args) const {
        return _VSTD::__invoke(get(), _VSTD::forward<_ArgTypes>(__args)...);
    }
#else

    _LIBCPP_INLINE_VISIBILITY
    typename __invoke_return<type>::type
    operator() () const {
        return _VSTD::__invoke(get());
    }

    template <class _A0>
    _LIBCPP_INLINE_VISIBILITY
    typename __invoke_return0<type, _A0>::type
    operator() (_A0& __a0) const {
        return _VSTD::__invoke(get(), __a0);
    }

    template <class _A0>
    _LIBCPP_INLINE_VISIBILITY
    typename __invoke_return0<type, _A0 const>::type
    operator() (_A0 const& __a0) const {
        return _VSTD::__invoke(get(), __a0);
    }

    template <class _A0, class _A1>
    _LIBCPP_INLINE_VISIBILITY
    typename __invoke_return1<type, _A0, _A1>::type
    operator() (_A0& __a0, _A1& __a1) const {
        return _VSTD::__invoke(get(), __a0, __a1);
    }

    template <class _A0, class _A1>
    _LIBCPP_INLINE_VISIBILITY
    typename __invoke_return1<type, _A0 const, _A1>::type
    operator() (_A0 const& __a0, _A1& __a1) const {
        return _VSTD::__invoke(get(), __a0, __a1);
    }

    template <class _A0, class _A1>
    _LIBCPP_INLINE_VISIBILITY
    typename __invoke_return1<type, _A0, _A1 const>::type
    operator() (_A0& __a0, _A1 const& __a1) const {
        return _VSTD::__invoke(get(), __a0, __a1);
    }

    template <class _A0, class _A1>
    _LIBCPP_INLINE_VISIBILITY
    typename __invoke_return1<type, _A0 const, _A1 const>::type
    operator() (_A0 const& __a0, _A1 const& __a1) const {
        return _VSTD::__invoke(get(), __a0, __a1);
    }

    template <class _A0, class _A1, class _A2>
    _LIBCPP_INLINE_VISIBILITY
    typename __invoke_return2<type, _A0, _A1, _A2>::type
    operator() (_A0& __a0, _A1& __a1, _A2& __a2) const {
        return _VSTD::__invoke(get(), __a0, __a1, __a2);
    }

    template <class _A0, class _A1, class _A2>
    _LIBCPP_INLINE_VISIBILITY
    typename __invoke_return2<type, _A0 const, _A1, _A2>::type
    operator() (_A0 const& __a0, _A1& __a1, _A2& __a2) const {
        return _VSTD::__invoke(get(), __a0, __a1, __a2);
    }

    template <class _A0, class _A1, class _A2>
    _LIBCPP_INLINE_VISIBILITY
    typename __invoke_return2<type, _A0, _A1 const, _A2>::type
    operator() (_A0& __a0, _A1 const& __a1, _A2& __a2) const {
        return _VSTD::__invoke(get(), __a0, __a1, __a2);
    }

    template <class _A0, class _A1, class _A2>
    _LIBCPP_INLINE_VISIBILITY
    typename __invoke_return2<type, _A0, _A1, _A2 const>::type
    operator() (_A0& __a0, _A1& __a1, _A2 const& __a2) const {
        return _VSTD::__invoke(get(), __a0, __a1, __a2);
    }

    template <class _A0, class _A1, class _A2>
    _LIBCPP_INLINE_VISIBILITY
    typename __invoke_return2<type, _A0 const, _A1 const, _A2>::type
    operator() (_A0 const& __a0, _A1 const& __a1, _A2& __a2) const {
        return _VSTD::__invoke(get(), __a0, __a1, __a2);
    }

    template <class _A0, class _A1, class _A2>
    _LIBCPP_INLINE_VISIBILITY
    typename __invoke_return2<type, _A0 const, _A1, _A2 const>::type
    operator() (_A0 const& __a0, _A1& __a1, _A2 const& __a2) const {
        return _VSTD::__invoke(get(), __a0, __a1, __a2);
    }

    template <class _A0, class _A1, class _A2>
    _LIBCPP_INLINE_VISIBILITY
    typename __invoke_return2<type, _A0, _A1 const, _A2 const>::type
    operator() (_A0& __a0, _A1 const& __a1, _A2 const& __a2) const {
        return _VSTD::__invoke(get(), __a0, __a1, __a2);
    }

    template <class _A0, class _A1, class _A2>
    _LIBCPP_INLINE_VISIBILITY
    typename __invoke_return2<type, _A0 const, _A1 const, _A2 const>::type
    operator() (_A0 const& __a0, _A1 const& __a1, _A2 const& __a2) const {
        return _VSTD::__invoke(get(), __a0, __a1, __a2);
    }
#endif // _LIBCPP_CXX03_LANG
};

#if _LIBCPP_STD_VER >= 17
template <class _Tp>
reference_wrapper(_Tp&) -> reference_wrapper<_Tp>;
#endif

template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
reference_wrapper<_Tp>
ref(_Tp& __t) _NOEXCEPT
{
    return reference_wrapper<_Tp>(__t);
}

template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
reference_wrapper<_Tp>
ref(reference_wrapper<_Tp> __t) _NOEXCEPT
{
    return _VSTD::ref(__t.get());
}

template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
reference_wrapper<const _Tp>
cref(const _Tp& __t) _NOEXCEPT
{
    return reference_wrapper<const _Tp>(__t);
}

template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
reference_wrapper<const _Tp>
cref(reference_wrapper<_Tp> __t) _NOEXCEPT
{
    return _VSTD::cref(__t.get());
}

#ifndef _LIBCPP_CXX03_LANG
template <class _Tp> void ref(const _Tp&&) = delete;
template <class _Tp> void cref(const _Tp&&) = delete;
#endif

_LIBCPP_END_NAMESPACE_STD

#endif // _LIBCPP___FUNCTIONAL_REFERENCE_WRAPPER_H