Added thirdparty: boost library

thirdparty/include/boost/hana/detail/has_common_embedding.hpp

@@ -0,0 +1,69 @@
+/*!
+@file
+Defines `boost::hana::detail::has_[nontrivial_]common_embedding`.
+
+Copyright Louis Dionne 2013-2022
+Distributed under the Boost Software License, Version 1.0.
+(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
+ */
+
+#ifndef BOOST_HANA_DETAIL_HAS_COMMON_EMBEDDING_HPP
+#define BOOST_HANA_DETAIL_HAS_COMMON_EMBEDDING_HPP
+
+#include <boost/hana/config.hpp>
+#include <boost/hana/core/common.hpp>
+#include <boost/hana/core/to.hpp>
+#include <boost/hana/detail/void_t.hpp>
+
+#include <type_traits>
+
+
+namespace boost { namespace hana { namespace detail {
+    template <template <typename...> class Concept, typename T, typename U, typename = void>
+    struct has_common_embedding_impl : std::false_type { };
+
+    template <template <typename...> class Concept, typename T, typename U>
+    struct has_common_embedding_impl<Concept, T, U, detail::void_t<
+        typename common<T, U>::type
+    >> {
+        using Common = typename common<T, U>::type;
+        using type = std::integral_constant<bool,
+            Concept<T>::value &&
+            Concept<U>::value &&
+            Concept<Common>::value &&
+            is_embedded<T, Common>::value &&
+            is_embedded<U, Common>::value
+        >;
+    };
+
+    //! @ingroup group-details
+    //! Returns whether `T` and `U` both have an embedding into a
+    //! common type.
+    //!
+    //! If `T` and `U` do not have a common-type, this metafunction returns
+    //! false.
+    template <template <typename...> class Concept, typename T, typename U>
+    using has_common_embedding = typename has_common_embedding_impl<Concept, T, U>::type;
+
+    template <template <typename...> class Concept, typename T, typename U>
+    struct has_nontrivial_common_embedding_impl
+        : has_common_embedding_impl<Concept, T, U>
+    { };
+
+    template <template <typename...> class Concept, typename T>
+    struct has_nontrivial_common_embedding_impl<Concept, T, T>
+        : std::false_type
+    { };
+
+    //! @ingroup group-details
+    //! Returns whether `T` and `U` are distinct and both have an embedding
+    //! into a common type.
+    //!
+    //! If `T` and `U` do not have a common-type, this metafunction returns
+    //! false.
+    template <template <typename...> class Concept, typename T, typename U>
+    using has_nontrivial_common_embedding =
+        typename has_nontrivial_common_embedding_impl<Concept, T, U>::type;
+} }} // end namespace boost::hana
+
+#endif // !BOOST_HANA_DETAIL_HAS_COMMON_EMBEDDING_HPP