ceph/src/boost/boost/beast/core/type_traits.hpp

   1 //
   2 // Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
   3 //
   4 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   5 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6 //
   7 // Official repository: https://github.com/boostorg/beast
   8 //
   9
  10 #ifndef BOOST_BEAST_TYPE_TRAITS_HPP
  11 #define BOOST_BEAST_TYPE_TRAITS_HPP
  12
  13 #ifndef BOOST_BEAST_DOXYGEN
  14
  15 #include <boost/beast/core/detail/config.hpp>
  16 #include <boost/beast/core/detail/is_invocable.hpp>
  17 #include <boost/config/pragma_message.hpp>
  18 #include <type_traits.hpp>
  19
  20 BOOST_PRAGMA_MESSAGE("<boost/beast/core/type_traits.hpp> is DEPRECATED and will be removed in a future release.")
  21
  22 namespace boost {
  23 namespace beast {
  24
  25 /** Determine if `T` meets the requirements of <em>CompletionHandler</em>.
  26
  27     This trait checks whether a type meets the requirements for a completion
  28     handler, and is also callable with the specified signature.
  29     Metafunctions are used to perform compile time checking of template
  30     types. This type will be `std::true_type` if `T` meets the requirements,
  31     else the type will be `std::false_type`.
  32
  33     @par Example
  34     Use with `static_assert`:
  35     @code
  36     struct handler
  37     {
  38         void operator()(error_code&);
  39     };
  40     static_assert(is_completion_handler<handler, void(error_code&)>::value,
  41         "Not a completion handler");
  42     @endcode
  43 */
  44 template<class T, class Signature>
  45 #if BOOST_BEAST_DOXYGEN
  46 using is_completion_handler = __see_below__
  47 #else
  48 using is_completion_handler = std::integral_constant<bool,
  49     std::is_move_constructible<typename std::decay<T>::type>::value &&
  50     detail::is_invocable<T, Signature>::value>;
  51 #endif
  52
  53 } // beast
  54 } // boost
  55
  56 #endif
  57
  58 #endif