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 >
      23              : class function_ref;
      24              : 
      25              : template < typename Ret, typename... Params >
      26              : class function_ref< Ret( Params... ) >
      27              : {
      28              :     Ret ( *callback )( intptr_t callable, Params... params ) = nullptr;
      29              :     intptr_t callable;
      30              : 
      31              :     template < typename Callable >
      32      4410217 :     static Ret callback_fn( intptr_t callable, Params... params )
      33              :     {
      34      4410217 :         return ( *reinterpret_cast< Callable * >( callable ) )(
      35      8820434 :             std::forward< Params >( params )... );
      36              :     }
      37              : 
      38              : public:
      39              :     function_ref( ) = default;
      40         4850 :     function_ref( std::nullptr_t )
      41         4850 :     {
      42         4850 :     }
      43              : 
      44              :     template < typename Callable >
      45         8814 :     function_ref( Callable && callable,
      46              :                   // This is not the copy-constructor.
      47              :                   std::enable_if_t< !std::is_same< std::remove_cvref_t< Callable >,
      48              :                                                    function_ref >::value > * = nullptr,
      49              :                   // Functor must be callable and return a suitable type.
      50              :                   std::enable_if_t< std::is_void< Ret >::value ||
      51              :                                     std::is_convertible< decltype( std::declval< Callable >( )(
      52              :                                                              std::declval< Params >( )... ) ),
      53              :                                                          Ret >::value > * = nullptr )
      54         8814 :         : callback( callback_fn< std::remove_reference_t< Callable > > )
      55         8814 :         , callable( reinterpret_cast< intptr_t >( &callable ) )
      56              :     {
      57         8814 :     }
      58              : 
      59      4410217 :     Ret operator( )( Params... params ) const
      60              :     {
      61      4410217 :         return callback( callable, std::forward< Params >( params )... );
      62              :     }
      63              : 
      64      8764606 :     explicit operator bool( ) const
      65              :     {
      66      8764606 :         return callback;
      67              :     }
      68              : };
      69              : }// namespace spb::detail