Added thirdparty: boost library

thirdparty/include/boost/histogram/accumulators/is_thread_safe.hpp

@@ -0,0 +1,41 @@
+// Copyright 2021 Hans Dembinski
+//
+// 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_HISTOGRAM_ACCUMULATORS_IS_THREAD_SAFE_HPP
+#define BOOST_HISTOGRAM_ACCUMULATORS_IS_THREAD_SAFE_HPP
+
+#include <boost/histogram/detail/priority.hpp>
+#include <boost/histogram/fwd.hpp>
+#include <type_traits>
+
+namespace boost {
+namespace histogram {
+namespace detail {
+
+template <class T>
+constexpr bool is_thread_safe_impl(priority<0>) {
+  return false;
+}
+
+template <class T>
+constexpr auto is_thread_safe_impl(priority<1>) -> decltype(T::thread_safe()) {
+  return T::thread_safe();
+}
+
+} // namespace detail
+
+namespace accumulators {
+
+template <class T>
+struct is_thread_safe
+    : std::integral_constant<bool,
+                             detail::is_thread_safe_impl<T>(detail::priority<1>{})> {};
+
+} // namespace accumulators
+} // namespace histogram
+} // namespace boost
+
+#endif