libcxx/include/__functional/reference_wrapper.h

   1 // -*- C++ -*-
   2 //===----------------------------------------------------------------------===//
   3 //
   4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5 // See https://llvm.org/LICENSE.txt for license information.
   6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #ifndef _LIBCPP___FUNCTIONAL_REFERENCE_WRAPPER_H
  11 #define _LIBCPP___FUNCTIONAL_REFERENCE_WRAPPER_H
  12
  13 #include <__config>
  14 #include <__functional/weak_result_type.h>
  15 #include <__memory/addressof.h>
  16 #include <__utility/forward.h>
  17 #include <type_traits>
  18
  19 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  20 #pragma GCC system_header
  21 #endif
  22
  23 _LIBCPP_BEGIN_NAMESPACE_STD
  24
  25 template <class _Tp>
  26 class _LIBCPP_TEMPLATE_VIS reference_wrapper
  27 #if _LIBCPP_STD_VER <= 17 || !defined(_LIBCPP_ABI_NO_BINDER_BASES)
  28     : public __weak_result_type<_Tp>
  29 #endif
  30 {
  31 public:
  32     // types
  33     typedef _Tp type;
  34 private:
  35     type* __f_;
  36
  37 #ifndef _LIBCPP_CXX03_LANG
  38     static void __fun(_Tp&) _NOEXCEPT;
  39     static void __fun(_Tp&&) = delete;
  40 #endif
  41
  42 public:
  43     // construct/copy/destroy
  44 #ifdef _LIBCPP_CXX03_LANG
  45     _LIBCPP_INLINE_VISIBILITY
  46     reference_wrapper(type& __f) _NOEXCEPT
  47         : __f_(_VSTD::addressof(__f)) {}
  48 #else
  49     template <class _Up, class = __enable_if_t<!__is_same_uncvref<_Up, reference_wrapper>::value, decltype(__fun(declval<_Up>())) >>
  50     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
  51     reference_wrapper(_Up&& __u) _NOEXCEPT_(noexcept(__fun(declval<_Up>()))) {
  52         type& __f = static_cast<_Up&&>(__u);
  53         __f_ = _VSTD::addressof(__f);
  54     }
  55 #endif
  56
  57     // access
  58     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
  59     operator type&() const _NOEXCEPT {return *__f_;}
  60     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
  61     type& get() const _NOEXCEPT {return *__f_;}
  62
  63 #ifndef _LIBCPP_CXX03_LANG
  64     // invoke
  65     template <class... _ArgTypes>
  66     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
  67     typename __invoke_of<type&, _ArgTypes...>::type
  68     operator() (_ArgTypes&&... __args) const {
  69         return _VSTD::__invoke(get(), _VSTD::forward<_ArgTypes>(__args)...);
  70     }
  71 #else
  72
  73     _LIBCPP_INLINE_VISIBILITY
  74     typename __invoke_return<type>::type
  75     operator() () const {
  76         return _VSTD::__invoke(get());
  77     }
  78
  79     template <class _A0>
  80     _LIBCPP_INLINE_VISIBILITY
  81     typename __invoke_return0<type, _A0>::type
  82     operator() (_A0& __a0) const {
  83         return _VSTD::__invoke(get(), __a0);
  84     }
  85
  86     template <class _A0>
  87     _LIBCPP_INLINE_VISIBILITY
  88     typename __invoke_return0<type, _A0 const>::type
  89     operator() (_A0 const& __a0) const {
  90         return _VSTD::__invoke(get(), __a0);
  91     }
  92
  93     template <class _A0, class _A1>
  94     _LIBCPP_INLINE_VISIBILITY
  95     typename __invoke_return1<type, _A0, _A1>::type
  96     operator() (_A0& __a0, _A1& __a1) const {
  97         return _VSTD::__invoke(get(), __a0, __a1);
  98     }
  99
 100     template <class _A0, class _A1>
 101     _LIBCPP_INLINE_VISIBILITY
 102     typename __invoke_return1<type, _A0 const, _A1>::type
 103     operator() (_A0 const& __a0, _A1& __a1) const {
 104         return _VSTD::__invoke(get(), __a0, __a1);
 105     }
 106
 107     template <class _A0, class _A1>
 108     _LIBCPP_INLINE_VISIBILITY
 109     typename __invoke_return1<type, _A0, _A1 const>::type
 110     operator() (_A0& __a0, _A1 const& __a1) const {
 111         return _VSTD::__invoke(get(), __a0, __a1);
 112     }
 113
 114     template <class _A0, class _A1>
 115     _LIBCPP_INLINE_VISIBILITY
 116     typename __invoke_return1<type, _A0 const, _A1 const>::type
 117     operator() (_A0 const& __a0, _A1 const& __a1) const {
 118         return _VSTD::__invoke(get(), __a0, __a1);
 119     }
 120
 121     template <class _A0, class _A1, class _A2>
 122     _LIBCPP_INLINE_VISIBILITY
 123     typename __invoke_return2<type, _A0, _A1, _A2>::type
 124     operator() (_A0& __a0, _A1& __a1, _A2& __a2) const {
 125         return _VSTD::__invoke(get(), __a0, __a1, __a2);
 126     }
 127
 128     template <class _A0, class _A1, class _A2>
 129     _LIBCPP_INLINE_VISIBILITY
 130     typename __invoke_return2<type, _A0 const, _A1, _A2>::type
 131     operator() (_A0 const& __a0, _A1& __a1, _A2& __a2) const {
 132         return _VSTD::__invoke(get(), __a0, __a1, __a2);
 133     }
 134
 135     template <class _A0, class _A1, class _A2>
 136     _LIBCPP_INLINE_VISIBILITY
 137     typename __invoke_return2<type, _A0, _A1 const, _A2>::type
 138     operator() (_A0& __a0, _A1 const& __a1, _A2& __a2) const {
 139         return _VSTD::__invoke(get(), __a0, __a1, __a2);
 140     }
 141
 142     template <class _A0, class _A1, class _A2>
 143     _LIBCPP_INLINE_VISIBILITY
 144     typename __invoke_return2<type, _A0, _A1, _A2 const>::type
 145     operator() (_A0& __a0, _A1& __a1, _A2 const& __a2) const {
 146         return _VSTD::__invoke(get(), __a0, __a1, __a2);
 147     }
 148
 149     template <class _A0, class _A1, class _A2>
 150     _LIBCPP_INLINE_VISIBILITY
 151     typename __invoke_return2<type, _A0 const, _A1 const, _A2>::type
 152     operator() (_A0 const& __a0, _A1 const& __a1, _A2& __a2) const {
 153         return _VSTD::__invoke(get(), __a0, __a1, __a2);
 154     }
 155
 156     template <class _A0, class _A1, class _A2>
 157     _LIBCPP_INLINE_VISIBILITY
 158     typename __invoke_return2<type, _A0 const, _A1, _A2 const>::type
 159     operator() (_A0 const& __a0, _A1& __a1, _A2 const& __a2) const {
 160         return _VSTD::__invoke(get(), __a0, __a1, __a2);
 161     }
 162
 163     template <class _A0, class _A1, class _A2>
 164     _LIBCPP_INLINE_VISIBILITY
 165     typename __invoke_return2<type, _A0, _A1 const, _A2 const>::type
 166     operator() (_A0& __a0, _A1 const& __a1, _A2 const& __a2) const {
 167         return _VSTD::__invoke(get(), __a0, __a1, __a2);
 168     }
 169
 170     template <class _A0, class _A1, class _A2>
 171     _LIBCPP_INLINE_VISIBILITY
 172     typename __invoke_return2<type, _A0 const, _A1 const, _A2 const>::type
 173     operator() (_A0 const& __a0, _A1 const& __a1, _A2 const& __a2) const {
 174         return _VSTD::__invoke(get(), __a0, __a1, __a2);
 175     }
 176 #endif // _LIBCPP_CXX03_LANG
 177 };
 178
 179 #if _LIBCPP_STD_VER >= 17
 180 template <class _Tp>
 181 reference_wrapper(_Tp&) -> reference_wrapper<_Tp>;
 182 #endif
 183
 184 template <class _Tp>
 185 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
 186 reference_wrapper<_Tp>
 187 ref(_Tp& __t) _NOEXCEPT
 188 {
 189     return reference_wrapper<_Tp>(__t);
 190 }
 191
 192 template <class _Tp>
 193 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
 194 reference_wrapper<_Tp>
 195 ref(reference_wrapper<_Tp> __t) _NOEXCEPT
 196 {
 197     return _VSTD::ref(__t.get());
 198 }
 199
 200 template <class _Tp>
 201 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
 202 reference_wrapper<const _Tp>
 203 cref(const _Tp& __t) _NOEXCEPT
 204 {
 205     return reference_wrapper<const _Tp>(__t);
 206 }
 207
 208 template <class _Tp>
 209 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
 210 reference_wrapper<const _Tp>
 211 cref(reference_wrapper<_Tp> __t) _NOEXCEPT
 212 {
 213     return _VSTD::cref(__t.get());
 214 }
 215
 216 #ifndef _LIBCPP_CXX03_LANG
 217 template <class _Tp> void ref(const _Tp&&) = delete;
 218 template <class _Tp> void cref(const _Tp&&) = delete;
 219 #endif
 220
 221 _LIBCPP_END_NAMESPACE_STD
 222
 223 #endif // _LIBCPP___FUNCTIONAL_REFERENCE_WRAPPER_H