Added thirdparty: boost library

thirdparty/include/boost/mysql/detail/writable_field_traits.hpp

@@ -0,0 +1,146 @@
+//
+// Copyright (c) 2019-2023 Ruben Perez Hidalgo (rubenperez038 at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_MYSQL_DETAIL_WRITABLE_FIELD_TRAITS_HPP
+#define BOOST_MYSQL_DETAIL_WRITABLE_FIELD_TRAITS_HPP
+
+#include <boost/mysql/field_view.hpp>
+
+#include <boost/mysql/detail/config.hpp>
+
+#include <type_traits>
+
+namespace boost {
+namespace mysql {
+namespace detail {
+
+template <class T, class En1 = void, class En2 = void>
+struct writable_field_traits
+{
+    static constexpr bool is_supported = false;
+};
+
+template <>
+struct writable_field_traits<bool, void, void>
+{
+    static constexpr bool is_supported = true;
+    static field_view to_field(bool value) noexcept { return field_view(value ? 1 : 0); }
+};
+
+template <class T>
+struct writable_field_traits<
+    T,
+    typename std::enable_if<std::is_constructible<field_view, const T&>::value>::type,
+    void>
+{
+    static constexpr bool is_supported = true;
+    static field_view to_field(const T& value) noexcept { return field_view(value); }
+};
+
+// Optionals. To avoid dependencies, we use a "concept".
+// We consider a type an optional if has a `bool has_value() const` and
+// `const value_type& value() const`
+template <class T>
+struct writable_field_traits<
+    T,
+    void,
+    typename std::enable_if<
+        std::is_same<decltype(std::declval<const T&>().has_value()), bool>::value &&
+        std::is_same<decltype(std::declval<const T&>().value()), const typename T::value_type&>::value>::type>
+{
+    using value_traits = writable_field_traits<typename T::value_type>;
+    static constexpr bool is_supported = value_traits::is_supported;
+    static field_view to_field(const T& value) noexcept
+    {
+        return value.has_value() ? value_traits::to_field(value.value()) : field_view();
+    }
+};
+
+template <class T>
+field_view to_field(const T& value) noexcept
+{
+    return writable_field_traits<T>::to_field(value);
+}
+
+template <class T>
+struct is_writable_field
+{
+    static constexpr bool value = writable_field_traits<T>::is_supported;
+};
+
+// field_view_forward_iterator
+template <typename T, typename = void>
+struct is_field_view_forward_iterator : std::false_type
+{
+};
+
+// clang-format off
+template <typename T>
+struct is_field_view_forward_iterator<
+    T,
+    typename std::enable_if<
+        std::is_convertible<
+            typename std::iterator_traits<T>::reference,
+            field_view
+        >::value
+        &&
+        std::is_base_of<
+            std::forward_iterator_tag, 
+            typename std::iterator_traits<T>::iterator_category
+        >::value
+    >::type
+> : std::true_type { };
+// clang-format on
+
+#ifdef BOOST_MYSQL_HAS_CONCEPTS
+
+template <class T>
+concept field_view_forward_iterator = is_field_view_forward_iterator<T>::value;
+
+#define BOOST_MYSQL_FIELD_VIEW_FORWARD_ITERATOR ::boost::mysql::detail::field_view_forward_iterator
+
+#else  // BOOST_MYSQL_HAS_CONCEPTS
+
+#define BOOST_MYSQL_FIELD_VIEW_FORWARD_ITERATOR class
+
+#endif  // BOOST_MYSQL_HAS_CONCEPTS
+
+// writable_field_tuple
+template <class... T>
+struct is_writable_field_tuple_impl : std::false_type
+{
+};
+
+template <class... T>
+struct is_writable_field_tuple_impl<std::tuple<T...>>
+    : mp11::mp_all_of<mp11::mp_list<T...>, is_writable_field>
+{
+};
+
+template <class Tuple>
+struct is_writable_field_tuple : is_writable_field_tuple_impl<typename std::decay<Tuple>::type>
+{
+};
+
+#ifdef BOOST_MYSQL_HAS_CONCEPTS
+
+template <class T>
+concept writable_field_tuple = is_writable_field_tuple<T>::value;
+
+#define BOOST_MYSQL_WRITABLE_FIELD_TUPLE ::boost::mysql::detail::writable_field_tuple
+
+#else  // BOOST_MYSQL_HAS_CONCEPTS
+
+#define BOOST_MYSQL_WRITABLE_FIELD_TUPLE class
+
+#endif  // BOOST_MYSQL_HAS_CONCEPTS
+
+}  // namespace detail
+}  // namespace mysql
+}  // namespace boost
+
+#endif