Added thirdparty: boost library

thirdparty/include/boost/multiprecision/detail/empty_value.hpp

@@ -0,0 +1,87 @@
+/////////////////////////////////////////////////////////////////////
+//  Copyright 2018 Glen Joseph Fernandes. 
+//  Copyright 2021 Matt Borland. Distributed under the Boost
+//  Software License, Version 1.0. (See accompanying file
+//  LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt
+
+#ifndef BOOST_MP_DETAIL_EMPTY_VALUE_HPP
+#define BOOST_MP_DETAIL_EMPTY_VALUE_HPP
+
+#include <utility>
+#include <boost/multiprecision/detail/standalone_config.hpp>
+
+#if defined(BOOST_GCC_VERSION) && (BOOST_GCC_VERSION >= 40700)
+#define BOOST_DETAIL_EMPTY_VALUE_BASE
+#elif defined(BOOST_INTEL) && defined(_MSC_VER) && (_MSC_VER >= 1800)
+#define BOOST_DETAIL_EMPTY_VALUE_BASE
+#elif defined(BOOST_MSVC) && (BOOST_MSVC >= 1800)
+#define BOOST_DETAIL_EMPTY_VALUE_BASE
+#elif defined(BOOST_CLANG) && !defined(__CUDACC__)
+#if __has_feature(is_empty) && __has_feature(is_final)
+#define BOOST_DETAIL_EMPTY_VALUE_BASE
+#endif
+#endif
+
+namespace boost { namespace multiprecision { namespace detail {
+
+template <typename T>
+struct use_empty_value_base 
+{
+#if defined(BOOST_DETAIL_EMPTY_VALUE_BASE)
+        static constexpr bool value = __is_empty(T) && !__is_final(T);
+#else
+        static constexpr bool value = false;
+#endif
+};
+
+struct empty_init_t {};
+
+namespace empty_impl {
+
+template <typename T, unsigned N = 0, 
+          bool E = boost::multiprecision::detail::use_empty_value_base<T>::value>
+class empty_value
+{
+private:
+    T value_;
+
+public:
+    using type = T;
+
+    empty_value() = default;
+    explicit empty_value(boost::multiprecision::detail::empty_init_t) : value_ {} {}
+
+    template <typename U, typename... Args>
+    empty_value(boost::multiprecision::detail::empty_init_t, U&& value, Args&&... args) :
+        value_ {std::forward<U>(value), std::forward<Args>(args)...} {}
+
+    const T& get() const noexcept { return value_; }
+    T& get() noexcept { return value_; }
+};
+
+template <typename T, unsigned N>
+class empty_value<T, N, true> : T
+{
+public:
+    using type = T;
+
+    empty_value() = default;
+    explicit empty_value(boost::multiprecision::detail::empty_init_t) : T{} {}
+
+    template <typename U, typename... Args>
+    empty_value(boost::multiprecision::detail::empty_init_t, U&& value, Args&&... args) :
+        T{std::forward<U>(value), std::forward<Args>(args)...} {}
+
+    const T& get() const noexcept { return *this; }
+    T& get() noexcept { return *this; }
+};
+
+} // Namespace empty impl
+
+using empty_impl::empty_value;
+
+BOOST_INLINE_CONSTEXPR empty_init_t empty_init = empty_init_t();
+
+}}} // Namespaces
+
+#endif // BOOST_MP_DETAIL_EMPTY_VALUE_HPP