Added thirdparty: boost library

thirdparty/include/boost/hana/product.hpp

@@ -0,0 +1,56 @@
+/*!
+@file
+Defines `boost::hana::product`.
+
+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_PRODUCT_HPP
+#define BOOST_HANA_PRODUCT_HPP
+
+#include <boost/hana/fwd/product.hpp>
+
+#include <boost/hana/concept/foldable.hpp>
+#include <boost/hana/concept/ring.hpp>
+#include <boost/hana/config.hpp>
+#include <boost/hana/core/dispatch.hpp>
+#include <boost/hana/fold_left.hpp>
+#include <boost/hana/integral_constant.hpp> // required by fwd decl
+#include <boost/hana/mult.hpp>
+#include <boost/hana/one.hpp>
+
+
+namespace boost { namespace hana {
+    //! @cond
+    template <typename R>
+    template <typename Xs>
+    constexpr decltype(auto) product_t<R>::operator()(Xs&& xs) const {
+        using S = typename hana::tag_of<Xs>::type;
+        using Product = BOOST_HANA_DISPATCH_IF(product_impl<S>,
+            hana::Foldable<S>::value
+        );
+
+    #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
+        static_assert(hana::Ring<R>::value,
+        "hana::product<R> requires 'R' to be a Ring");
+
+        static_assert(hana::Foldable<S>::value,
+        "hana::product<R>(xs) requires 'xs' to be Foldable");
+    #endif
+
+        return Product::template apply<R>(static_cast<Xs&&>(xs));
+    }
+    //! @endcond
+
+    template <typename T, bool condition>
+    struct product_impl<T, when<condition>> : default_ {
+        template <typename R, typename Xs>
+        static constexpr decltype(auto) apply(Xs&& xs) {
+            return hana::fold_left(static_cast<Xs&&>(xs), hana::one<R>(), hana::mult);
+        }
+    };
+}} // end namespace boost::hana
+
+#endif // !BOOST_HANA_PRODUCT_HPP