1 files changed, 46 insertions, 0 deletions
diff --git a/boost/variant/detail/std_hash.hpp b/boost/variant/detail/std_hash.hpp
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+++ b/boost/variant/detail/std_hash.hpp
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+//-----------------------------------------------------------------------------
+// boost variant/detail/std_hash.hpp header file
+// See http://www.boost.org for updates, documentation, and revision history.
+//-----------------------------------------------------------------------------
+//
+// Copyright (c) 2018-2019 Antony Polukhin
+//
+// 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_VARIANT_DETAIL_STD_HASH_HPP
+#define BOOST_VARIANT_DETAIL_STD_HASH_HPP
+
+#include <boost/config.hpp>
+#ifdef BOOST_HAS_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <boost/variant/variant_fwd.hpp>
+#include <boost/variant/detail/hash_variant.hpp>
+
+///////////////////////////////////////////////////////////////////////////////
+// macro BOOST_VARIANT_DO_NOT_SPECIALIZE_STD_HASH
+//
+// Define this macro if you do not with to have a std::hash specialization for
+// boost::variant.
+
+#if !defined(BOOST_VARIANT_DO_NOT_SPECIALIZE_STD_HASH) && !defined(BOOST_NO_CXX11_HDR_FUNCTIONAL)
+
+#include <functional> // for std::hash
+
+namespace std {
+    template < BOOST_VARIANT_ENUM_PARAMS(typename T) >
+    struct hash<boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) > > {
+        std::size_t operator()(const boost::variant< BOOST_VARIANT_ENUM_PARAMS(T) >& val) const {
+            return ::boost::hash_value(val);
+        }
+    };
+}
+
+#endif // #if !defined(BOOST_VARIANT_DO_NOT_SPECIALIZE_STD_HASH) && !defined(BOOST_NO_CXX11_HDR_FUNCTIONAL)
+
+#endif // BOOST_VARIANT_DETAIL_STD_HASH_HPP
+