ceph/src/boost/boost/json/impl/null_resource.ipp

   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_IMPL_NULL_RESOURCE_IPP
  11 #define BOOST_JSON_IMPL_NULL_RESOURCE_IPP
  12
  13 #include <boost/json/null_resource.hpp>
  14 #include <boost/json/detail/except.hpp>
  15
  16 BOOST_JSON_NS_BEGIN
  17
  18 namespace detail {
  19
  20 /** A resource which always fails.
  21
  22     This memory resource always throws the exception
  23     `std::bad_alloc` in calls to `allocate`.
  24 */
  25 class null_resource final
  26     : public memory_resource
  27 {
  28 public:
  29     /// Copy constructor (deleted)
  30     null_resource(
  31         null_resource const&) = delete;
  32
  33     /// Copy assignment (deleted)
  34     null_resource& operator=(
  35         null_resource const&) = delete;
  36
  37     /** Destructor
  38
  39         This destroys the resource.
  40
  41         @par Complexity
  42         Constant.
  43
  44         @part Exception Safety
  45         No-throw guarantee.
  46     */
  47     ~null_resource() noexcept = default;
  48
  49     /** Constructor
  50
  51         This constructs the resource.
  52
  53         @par Complexity
  54         Constant.
  55
  56         @par Exception Safety
  57         No-throw guarantee.
  58     */
  59     /** @{ */
  60     null_resource() noexcept = default;
  61
  62 protected:
  63     void*
  64     do_allocate(
  65         std::size_t,
  66         std::size_t) override
  67     {
  68         detail::throw_bad_alloc(
  69             BOOST_CURRENT_LOCATION);
  70     }
  71
  72     void
  73     do_deallocate(
  74         void*,
  75         std::size_t,
  76         std::size_t) override
  77     {
  78         // do nothing
  79     }
  80
  81     bool
  82     do_is_equal(
  83         memory_resource const& mr
  84             ) const noexcept override
  85     {
  86         return this == &mr;
  87     }
  88 };
  89
  90 } // detail
  91
  92 memory_resource*
  93 get_null_resource() noexcept
  94 {
  95     static detail::null_resource mr;
  96     return &mr;
  97 }
  98
  99 BOOST_JSON_NS_END
 100
 101 #endif