51 lines
1.6 KiB
C++
51 lines
1.6 KiB
C++
#ifndef BOOST_LEAF_TO_VARIANT_HPP_INCLUDED
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#define BOOST_LEAF_TO_VARIANT_HPP_INCLUDED
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// Copyright 2018-2022 Emil Dotchevski and Reverge Studios, Inc.
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#if __cplusplus >= 201703L
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#include <boost/leaf/config.hpp>
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#include <boost/leaf/handle_errors.hpp>
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#include <boost/leaf/result.hpp>
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#include <variant>
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#include <optional>
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#include <tuple>
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namespace boost { namespace leaf {
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template <class... E, class TryBlock>
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std::variant<typename std::decay<decltype(std::declval<TryBlock>()().value())>::type,std::tuple<std::optional<E>...>>
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to_variant( TryBlock && try_block )
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{
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static_assert(is_result_type<decltype(std::declval<TryBlock>()())>::value, "The return type of the try_block passed to a to_variant function must be registered with leaf::is_result_type");
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using T = typename std::decay<decltype(std::declval<TryBlock>()().value())>::type;
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using error_tuple_type = std::tuple<std::optional<E>...>;
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using variant_type = std::variant<T, error_tuple_type>;
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return try_handle_all(
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[&]() -> result<variant_type>
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{
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if( auto r = std::forward<TryBlock>(try_block)() )
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return *std::move(r);
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else
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return r.error();
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},
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[]( E const * ... e ) -> variant_type
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{
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return error_tuple_type { e ? std::optional<E>(*e) : std::optional<E>{}... };
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},
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[]() -> variant_type
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{
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return error_tuple_type { };
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} );
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}
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} }
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#endif
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#endif
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