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🔀 Add variant implementation
This adds the variant implementation to Backport, complete with proper constexpr, trivial destructor, and unit tests! Currently absent is a proper implementation of 'visit' to work with multiple variants -- to be added at a later time. Closes #1
2 parents 4c91ed2 + 42788c2 commit 76980f9

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12 files changed

+4515
-3
lines changed

12 files changed

+4515
-3
lines changed

‎CMakeLists.txt‎

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@@ -41,6 +41,12 @@ set(CMAKE_CXX_STANDARD_REQUIRED ON)
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set(CMAKE_CXX_EXTENSIONS OFF)
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set(header_files
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"include/bpstd/detail/nth_type.hpp"
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"include/bpstd/detail/variant_fwds.hpp"
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"include/bpstd/detail/variant_union.hpp"
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"include/bpstd/detail/variant_base.hpp"
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"include/bpstd/detail/variant_traits.hpp"
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"include/bpstd/detail/variant_visitors.hpp"
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"include/bpstd/detail/move.hpp"
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"include/bpstd/detail/invoke.hpp"
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"include/bpstd/detail/proxy_iterator.hpp"
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"include/bpstd/span.hpp"
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"include/bpstd/chrono.hpp"
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"include/bpstd/string.hpp"
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"include/bpstd/variant.hpp"
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)
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add_library(${PROJECT_NAME} INTERFACE)
@@ -79,6 +86,9 @@ if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" AND
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# Disable the ridiculous compatibility warnings, since it fails on files not
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# ending in newlines
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add_compile_options(-Wno-c++98-compat -Wno-c++98-compat-pedantic)
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# This gives an unbelievable amount of false-positives spuriously. Ignore it.
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add_compile_options(-Wno-unneeded-member-function)
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elseif ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" OR
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"${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" )
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add_compile_options(-Wall -Werror -Wextra -pedantic -pedantic-errors)

‎README.md‎

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@@ -90,7 +90,7 @@ C++17, and C++20.
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| ✅ | `bpstd::apply` | [`N3915`][3915] |
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| ✅ | `bpstd::make_from_tuple` | [`P0209R2`][02092] |
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| ✅ | `bpstd::as_const` | [`P0007R1`][00071] |
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| 🚧 | `bpstd::variant` | [`P0088R3`][00883]<br> [`P0032R3`][00323]<br> [`P0393R3`][03933] |
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| ✅ | `bpstd::variant` | [`P0088R3`][00883]<br> [`P0032R3`][00323]<br> [`P0393R3`][03933] |
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| ✅ | `bpstd::uncaught_exceptions` | [`N4152`][4152]<br> [`N4259`][4259] |
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| ✅ | `bpstd::byte` | [`P0298R3`][02983] |
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| ✅ | `bpstd::not_fn` | [`P0005R4`][00054] |

‎include/bpstd/detail/config.hpp‎

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# define BPSTD_MAY_ALIAS
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#endif // defined __clang__ || defined __GNUC__
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#if defined(__clang__) || defined(__GNUC__)
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// When using 'clang-cl', don't forceinline -- since it results in code generation
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// failures in 'variant'
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#if defined(__clang__) && defined(_MSC_VER)
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# define BPSTD_INLINE_VISIBILITY __attribute__((visibility("hidden"), no_instrument_function))
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#elif defined(__clang__) || defined(__GNUC__)
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# define BPSTD_INLINE_VISIBILITY __attribute__((visibility("hidden"), always_inline, no_instrument_function))
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#elif defined(_MSC_VER)
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# define BPSTD_INLINE_VISIBILITY __forceinline
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#else
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# define inline
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# define BPSTD_INLINE_VISIBILITY
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#endif
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#endif /* BPSTD_DETAIL_CONFIG_HPP */

‎include/bpstd/detail/nth_type.hpp‎

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/*****************************************************************************
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* \file nth_type.hpp
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*
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* \brief This internal header provides the definition of the INVOKE overload
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*****************************************************************************/
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/*
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The MIT License (MIT)
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Copyright (c) 2020 Matthew Rodusek All rights reserved.
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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#ifndef BPSTD_DETAIL_NTH_TYPE_HPP
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#define BPSTD_DETAIL_NTH_TYPE_HPP
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#if defined(_MSC_VER) && (_MSC_VER >= 1200)
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# pragma once
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#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
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#include <cstddef> // std::size_t
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namespace bpstd {
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namespace detail {
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/// \brief Gets the nth type from a variadic pack of arguments
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///
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/// \tparam N the argument to retrieve
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/// \tparam Args the arguments to extract from
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template <std::size_t N, typename...Args>
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struct nth_type;
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template <std::size_t N, typename Arg0, typename...Args>
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struct nth_type<N,Arg0,Args...> : nth_type<N-1,Args...>{};
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template <typename Arg0, typename...Args>
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struct nth_type<0,Arg0,Args...>
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{
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using type = Arg0;
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};
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template <std::size_t N, typename...Args>
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using nth_type_t = typename nth_type<N,Args...>::type;
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} // namespace detail
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} // namespace bpstd
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#endif /* BPSTD_DETAIL_NTH_TYPE_HPP */

‎include/bpstd/detail/variant_base.hpp‎

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/*****************************************************************************
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* \file variant_base.hpp
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*
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* \brief This internal header provides the definition of a utility for
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* variant, variant_base
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*****************************************************************************/
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/*
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The MIT License (MIT)
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Copyright (c) 2020 Matthew Rodusek All rights reserved.
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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#ifndef BPSTD_DETAIL_VARIANT_BASE_HPP
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#define BPSTD_DETAIL_VARIANT_BASE_HPP
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#include "config.hpp" // BPSTD_CPP14_CONSTEXPR
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#include "variant_union.hpp" // detail::variant_union
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#include <cstddef> // std::size_t
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#include <utility> // std::forward
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namespace bpstd {
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namespace detail {
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//==========================================================================
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// class : variant_base
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//==========================================================================
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////////////////////////////////////////////////////////////////////////////
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/// \brief The base class used by variant
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////////////////////////////////////////////////////////////////////////////
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template <bool IsTrivial, typename...Types>
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class variant_base;
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//==========================================================================
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// class : variant_base<true, Types...>
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//==========================================================================
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template <typename...Types>
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class variant_base<true,Types...>
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{
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//------------------------------------------------------------------------
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// Constructors
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//------------------------------------------------------------------------
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public:
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constexpr variant_base();
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template <std::size_t N, typename...Args>
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constexpr variant_base(variant_index_tag<N>, Args&&...args);
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//------------------------------------------------------------------------
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// Protected Members
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//------------------------------------------------------------------------
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protected:
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variant_union<true,Types...> m_union;
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std::size_t m_index;
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//---------------------------------------------------------------------
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// Protected Member Functions
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//---------------------------------------------------------------------
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protected:
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void destroy_active_object();
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};
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//==========================================================================
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// class : variant_base<false, Types...>
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//==========================================================================
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template <typename...Types>
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class variant_base<false,Types...>
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{
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public:
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constexpr variant_base();
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template <std::size_t N, typename...Args>
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constexpr variant_base(variant_index_tag<N>, Args&&...args);
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~variant_base();
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//---------------------------------------------------------------------
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// Protected Members
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//---------------------------------------------------------------------
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protected:
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variant_union<false,Types...> m_union;
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std::size_t m_index;
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//---------------------------------------------------------------------
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// Protected Member Functions
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//---------------------------------------------------------------------
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protected:
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void destroy_active_object();
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//---------------------------------------------------------------------
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// Private Static Member Functions
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//---------------------------------------------------------------------
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private:
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struct destroy_visitor
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{
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template <typename T>
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inline BPSTD_INLINE_VISIBILITY
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void operator()(T& v) {
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v.~T();
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}
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};
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};
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} // namespace detail
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} // namespace bpstd
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//==============================================================================
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// class : variant_base<true, Types...>
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//==============================================================================
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//------------------------------------------------------------------------------
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// Constructors
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//------------------------------------------------------------------------------
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template <typename...Types>
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inline BPSTD_INLINE_VISIBILITY constexpr
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bpstd::detail::variant_base<true,Types...>::variant_base()
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: m_union{},
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m_index{static_cast<std::size_t>(-1)}
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{
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}
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template <typename...Types>
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template <std::size_t N, typename...Args>
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inline BPSTD_INLINE_VISIBILITY constexpr
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bpstd::detail::variant_base<true,Types...>::variant_base(variant_index_tag<N>,
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Args&&...args)
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: m_union{variant_index_tag<N>{}, std::forward<Args>(args)...},
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m_index{N}
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{
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}
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//------------------------------------------------------------------------------
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// Protected Members
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//------------------------------------------------------------------------------
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template <typename...Types>
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inline BPSTD_INLINE_VISIBILITY
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void bpstd::detail::variant_base<true,Types...>::destroy_active_object()
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{
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m_index = static_cast<std::size_t>(-1);
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}
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//==============================================================================
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// class : variant_base<false, Types...>
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//==============================================================================
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//------------------------------------------------------------------------------
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// Constructors / Destructor
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//------------------------------------------------------------------------------
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template <typename...Types>
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inline BPSTD_INLINE_VISIBILITY constexpr
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bpstd::detail::variant_base<false,Types...>::variant_base()
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: m_union{},
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m_index{static_cast<std::size_t>(-1)}
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{
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}
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template <typename...Types>
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template <std::size_t N, typename...Args>
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inline BPSTD_INLINE_VISIBILITY constexpr
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bpstd::detail::variant_base<false,Types...>::variant_base(variant_index_tag<N>,
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Args&&...args)
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: m_union{variant_index_tag<N>{}, std::forward<Args>(args)...},
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m_index{N}
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{
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}
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//------------------------------------------------------------------------------
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template <typename...Types>
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inline BPSTD_INLINE_VISIBILITY
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bpstd::detail::variant_base<false,Types...>::~variant_base()
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{
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destroy_active_object();
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}
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//------------------------------------------------------------------------------
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// Protected Members
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//------------------------------------------------------------------------------
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template <typename...Types>
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inline BPSTD_INLINE_VISIBILITY
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void bpstd::detail::variant_base<false,Types...>::destroy_active_object()
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{
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if (m_index == static_cast<std::size_t>(-1)) {
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return;
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}
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visit_union(m_index, destroy_visitor{}, m_union);
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m_index = static_cast<std::size_t>(-1);
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}
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#endif /* BPSTD_DETAIL_VARIANT_BASE_HPP */

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