160 lines
4.1 KiB
C++
160 lines
4.1 KiB
C++
//
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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_DETAIL_WRITABLE_FIELD_TRAITS_HPP
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#define BOOST_MYSQL_DETAIL_WRITABLE_FIELD_TRAITS_HPP
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#include <boost/mysql/field_view.hpp>
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#include <boost/mysql/detail/config.hpp>
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#include <type_traits>
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namespace boost {
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namespace mysql {
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namespace detail {
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template <class T, class En1 = void, class En2 = void>
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struct writable_field_traits
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{
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static constexpr bool is_supported = false;
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};
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template <>
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struct writable_field_traits<bool>
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{
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static constexpr bool is_supported = true;
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static field_view to_field(bool value) noexcept { return field_view(value ? 1 : 0); }
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};
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template <class T>
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struct writable_field_traits<
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T,
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typename std::enable_if<
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std::is_constructible<field_view, const T&>::value && std::is_object<T>::value>::type,
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void>
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{
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static constexpr bool is_supported = true;
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static field_view to_field(const T& value) noexcept { return field_view(value); }
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};
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// Optionals. To avoid dependencies, we use a "concept".
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// We consider a type an optional if has a `bool has_value() const` and
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// `const value_type& value() const`
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template <class T>
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struct writable_field_traits<
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T,
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void,
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typename std::enable_if<
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std::is_same<decltype(std::declval<const T&>().has_value()), bool>::value &&
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std::is_same<decltype(std::declval<const T&>().value()), const typename T::value_type&>::value>::type>
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{
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using value_traits = writable_field_traits<typename T::value_type>;
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static constexpr bool is_supported = value_traits::is_supported;
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static field_view to_field(const T& value) noexcept
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{
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return value.has_value() ? value_traits::to_field(value.value()) : field_view();
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}
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};
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template <class T>
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field_view to_field(const T& value) noexcept
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{
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return writable_field_traits<T>::to_field(value);
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}
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template <class T>
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struct is_writable_field : std::integral_constant<bool, writable_field_traits<T>::is_supported>
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{
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};
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#ifdef BOOST_MYSQL_HAS_CONCEPTS
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template <class T>
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concept writable_field = is_writable_field<T>::value;
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#define BOOST_MYSQL_WRITABLE_FIELD ::boost::mysql::detail::writable_field
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#else
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#define BOOST_MYSQL_WRITABLE_FIELD class
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#endif
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// field_view_forward_iterator
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template <typename T, typename = void>
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struct is_field_view_forward_iterator : std::false_type
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{
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};
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// clang-format off
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template <typename T>
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struct is_field_view_forward_iterator<
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T,
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typename std::enable_if<
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std::is_convertible<
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typename std::iterator_traits<T>::reference,
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field_view
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>::value
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&&
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std::is_base_of<
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std::forward_iterator_tag,
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typename std::iterator_traits<T>::iterator_category
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>::value
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>::type
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> : std::true_type { };
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// clang-format on
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#ifdef BOOST_MYSQL_HAS_CONCEPTS
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template <class T>
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concept field_view_forward_iterator = is_field_view_forward_iterator<T>::value;
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#define BOOST_MYSQL_FIELD_VIEW_FORWARD_ITERATOR ::boost::mysql::detail::field_view_forward_iterator
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#else // BOOST_MYSQL_HAS_CONCEPTS
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#define BOOST_MYSQL_FIELD_VIEW_FORWARD_ITERATOR class
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#endif // BOOST_MYSQL_HAS_CONCEPTS
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// writable_field_tuple
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template <class... T>
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struct is_writable_field_tuple_impl : std::false_type
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{
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};
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template <class... T>
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struct is_writable_field_tuple_impl<std::tuple<T...>>
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: mp11::mp_all_of<mp11::mp_list<typename std::remove_reference<T>::type...>, is_writable_field>
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{
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};
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template <class Tuple>
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struct is_writable_field_tuple : is_writable_field_tuple_impl<typename std::decay<Tuple>::type>
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{
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};
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#ifdef BOOST_MYSQL_HAS_CONCEPTS
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template <class T>
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concept writable_field_tuple = is_writable_field_tuple<T>::value;
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#define BOOST_MYSQL_WRITABLE_FIELD_TUPLE ::boost::mysql::detail::writable_field_tuple
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#else // BOOST_MYSQL_HAS_CONCEPTS
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#define BOOST_MYSQL_WRITABLE_FIELD_TUPLE class
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#endif // BOOST_MYSQL_HAS_CONCEPTS
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} // namespace detail
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} // namespace mysql
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} // namespace boost
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#endif
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