json/detail/shared_resource.hpp

0001 //
0002 // Copyright (c) 2019 Vinnie Falco (vinnie.falco@gmail.com)
0003 //
0004 // Distributed under the Boost Software License, Version 1.0. (See accompanying
0005 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0006 //
0007 // Official repository: https://github.com/boostorg/json
0008 //
0009
0010 #ifndef BOOST_JSON_DETAIL_SHARED_RESOURCE_HPP
0011 #define BOOST_JSON_DETAIL_SHARED_RESOURCE_HPP
0012
0013 #include <boost/json/memory_resource.hpp>
0014 #include <atomic>
0015 #include <utility>
0016
0017 namespace boost {
0018 namespace json {
0019 namespace detail {
0020
0021 #ifdef _MSC_VER
0022 #pragma warning(push)
0023 #pragma warning(disable: 4275) // non dll-interface class used as base for dll-interface class
0024 #endif
0025
0026 struct BOOST_SYMBOL_VISIBLE
0027     shared_resource
0028     : memory_resource
0029 {
0030     BOOST_JSON_DECL
0031     shared_resource();
0032
0033     BOOST_JSON_DECL
0034     ~shared_resource();
0035
0036     std::atomic<std::size_t> refs{ 1 };
0037 };
0038
0039 template<class T>
0040 class shared_resource_impl final
0041     : public shared_resource
0042 {
0043     T t;
0044
0045 public:
0046     template<class... Args>
0047     shared_resource_impl(
0048         Args&&... args)
0049         : t(std::forward<Args>(args)...)
0050     {
0051     }
0052
0053     void*
0054     do_allocate(
0055         std::size_t n,
0056         std::size_t align) override
0057     {
0058         return t.allocate(n, align);
0059     }
0060
0061     void
0062     do_deallocate(
0063         void* p,
0064         std::size_t n,
0065         std::size_t align) override
0066     {
0067         return t.deallocate(p, n, align);
0068     }
0069
0070     bool
0071     do_is_equal(
0072         memory_resource const&) const noexcept override
0073     {
0074         // VFALCO Is always false ok?
0075         return false;
0076     }
0077 };
0078
0079 #ifdef _MSC_VER
0080 #pragma warning(pop)
0081 #endif
0082
0083 } // detail
0084 } // namespace json
0085 } // namespace boost
0086
0087 #endif