ceph/src/boost/boost/json/detail/default_resource.hpp

   1 //
   2 // Copyright (c) 2019 Vinnie Falco (vinnie.falco@gmail.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/json
   8 //
   9
  10 #ifndef BOOST_JSON_DEFAULT_RESOURCE_HPP
  11 #define BOOST_JSON_DEFAULT_RESOURCE_HPP
  12
  13 #include <boost/json/detail/config.hpp>
  14 #include <new>
  15
  16 BOOST_JSON_NS_BEGIN
  17 namespace detail {
  18
  19 #ifdef _MSC_VER
  20 #pragma warning(push)
  21 #pragma warning(disable: 4251) // class needs to have dll-interface to be used by clients of class
  22 #pragma warning(disable: 4275) // non dll-interface class used as base for dll-interface class
  23 #endif
  24
  25 // A simple memory resource that uses operator new and delete.
  26 class
  27     BOOST_SYMBOL_VISIBLE
  28     BOOST_JSON_CLASS_DECL
  29     default_resource final
  30     : public memory_resource
  31 {
  32     union holder;
  33
  34 #ifndef BOOST_JSON_WEAK_CONSTINIT
  35 # ifndef BOOST_JSON_NO_DESTROY
  36     static holder instance_;
  37 # else
  38     BOOST_JSON_NO_DESTROY
  39     static default_resource instance_;
  40 # endif
  41 #endif
  42
  43 public:
  44     static
  45     memory_resource*
  46     get() noexcept
  47     {
  48     #ifdef BOOST_JSON_WEAK_CONSTINIT
  49         static default_resource instance_;
  50     #endif
  51         return reinterpret_cast<memory_resource*>(
  52             reinterpret_cast<std::uintptr_t*>(
  53                 &instance_));
  54     }
  55
  56     ~default_resource();
  57
  58     void*
  59     do_allocate(
  60         std::size_t n,
  61         std::size_t) override;
  62
  63     void
  64     do_deallocate(
  65         void* p,
  66         std::size_t,
  67         std::size_t) override;
  68
  69     bool
  70     do_is_equal(
  71         memory_resource const& mr) const noexcept override;
  72 };
  73
  74 #ifdef _MSC_VER
  75 #pragma warning(pop)
  76 #endif
  77
  78 union default_resource::
  79     holder
  80 {
  81 #ifndef BOOST_JSON_WEAK_CONSTINIT
  82     constexpr
  83 #endif
  84     holder()
  85         : mr()
  86     {
  87     }
  88
  89     ~holder()
  90     {
  91     }
  92
  93     default_resource mr;
  94 };
  95
  96 } // detail
  97 BOOST_JSON_NS_END
  98
  99 #endif