1 files changed, 27 insertions, 0 deletions
diff --git a/boost/histogram/detail/make_default.hpp b/boost/histogram/detail/make_default.hpp
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+++ b/boost/histogram/detail/make_default.hpp
@@ -0,0 +1,27 @@
+// Copyright 2015-2019 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_DETAIL_MAKE_DEFAULT_HPP
+#define BOOST_HISTOGRAM_DETAIL_MAKE_DEFAULT_HPP
+
+#include <boost/histogram/detail/detect.hpp>
+#include <boost/histogram/detail/static_if.hpp>
+
+namespace boost {
+namespace histogram {
+namespace detail {
+
+template <class T>
+auto make_default(const T& t) {
+  return static_if<has_allocator<T>>([](const auto& t) { return T(t.get_allocator()); },
+                                     [](const auto&) { return T{}; }, t);
+}
+
+} // namespace detail
+} // namespace histogram
+} // namespace boost
+
+#endif