Line data    Source code

       1              : /***************************************************************************\
       2              : * Name        : function_ref                                                *
       3              : * Description : non-owning reference to a callable                          *
       4              : * Author      : LLVM                                                        *
       5              : * Reference   : https://llvm.org/doxygen/classllvm_1_1function__ref_3_01Ret_07Params_8_8_8_08_4.html
       6              : *
       7              : * ------------------------------------------------------------------------- *
       8              : * This is free software; you can redistribute it and/or modify it under the *
       9              : * terms of the MIT license. A copy of the license can be found in the file  *
      10              : * "LICENSE" at the root of this distribution.                               *
      11              : \***************************************************************************/
      12              : #pragma once
      13              : #pragma once
      14              : 
      15              : #include <cstdint>
      16              : #include <type_traits>
      17              : #include <utility>
      18              : 
      19              : namespace spb::detail
      20              : {
      21              : 
      22              : template <typename Fn> class function_ref;
      23              : 
      24              : template <typename Ret, typename... Params> class function_ref<Ret(Params...)>
      25              : {
      26              :     Ret (*callback)(intptr_t callable, Params... params) = nullptr;
      27              :     intptr_t callable;
      28              : 
      29      4414531 :     template <typename Callable> static Ret callback_fn(intptr_t callable, Params... params)
      30              :     {
      31      4414531 :         return (*reinterpret_cast<Callable *>(callable))(std::forward<Params>(params)...);
      32              :     }
      33              : 
      34              :   public:
      35              :     function_ref() = default;
      36         5355 :     function_ref(std::nullptr_t)
      37         5355 :     {
      38         5355 :     }
      39              : 
      40              :     template <typename Callable>
      41         9306 :     function_ref(
      42              :         Callable &&callable,
      43              :         // This is not the copy-constructor.
      44              :         std::enable_if_t<!std::is_same<std::remove_cvref_t<Callable>, function_ref>::value> * = nullptr,
      45              :         // Functor must be callable and return a suitable type.
      46              :         std::enable_if_t<std::is_void<Ret>::value ||
      47              :                          std::is_convertible<decltype(std::declval<Callable>()(std::declval<Params>()...)),
      48              :                                              Ret>::value> * = nullptr)
      49         9306 :         : callback(callback_fn<std::remove_reference_t<Callable>>),
      50         9306 :           callable(reinterpret_cast<intptr_t>(&callable))
      51              :     {
      52         9306 :     }
      53              : 
      54      4414531 :     Ret operator()(Params... params) const
      55              :     {
      56      4414531 :         return callback(callable, std::forward<Params>(params)...);
      57              :     }
      58              : 
      59      8771905 :     explicit operator bool() const
      60              :     {
      61      8771905 :         return callback;
      62              :     }
      63              : };
      64              : } // namespace spb::detail