35 lines
1.6 KiB
C++
35 lines
1.6 KiB
C++
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//
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// Copyright (c) 2019-2024 Ruben Perez Hidalgo (rubenperez038 at gmail dot com)
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//
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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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//
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#ifndef BOOST_MYSQL_IMPL_INTERNAL_COROUTINE_HPP
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#define BOOST_MYSQL_IMPL_INTERNAL_COROUTINE_HPP
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// asio::coroutine uses __COUNTER__ internally, which can trigger
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// ODR violations if we use them in header-only code. These manifest as
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// extremely hard-to-debug bugs only present in release builds
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// Coroutine state is represented as an integer (resume_point_var).
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// Every yield gets assigned a unique value (resume_point_id).
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// Yielding sets the next resume point, returns, and sets a case label for re-entering.
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// Coroutines need to switch on resume_point_var to re-enter.
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// Enclosing this in a scope allows placing the macro inside a brace-less for/while loop
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// The empty scope after the case label is required because labels can't be at the end of a compound statement
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#define BOOST_MYSQL_YIELD(resume_point_var, resume_point_id, ...) \
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{ \
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resume_point_var = resume_point_id; \
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return __VA_ARGS__; \
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case resume_point_id: \
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{ \
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} \
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}
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#define BOOST_MYSQL_YIELD_VOID(resume_point_var, resume_point_id) \
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BOOST_MYSQL_YIELD(resume_point_var, resume_point_id, static_cast<void>(0))
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#endif
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