Initial import of hash function headers - so that they can be used by

Boost.MultiIndex.


[SVN r27819]

include/boost/functional/hash/pair.hpp

@@ -0,0 +1,47 @@
+
+//  (C) Copyright Daniel James 2005.
+//  Use, modification and distribution are subject to 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)
+//
+//  Based on Peter Dimov's proposal
+//  http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2005/n1756.pdf
+//  issue 6.18. 
+
+#if !defined(BOOST_FUNCTIONAL_HASH_PAIR_HPP)
+#define BOOST_FUNCTIONAL_HASH_PAIR_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+#include <utility>
+#include <boost/functional/hash/hash.hpp>
+
+namespace boost
+{
+    template <class A, class B>
+    std::size_t hash_value(std::pair<A, B> const& v)
+    {
+        std::size_t seed = 0;
+        hash_combine(seed, v.first);
+        hash_combine(seed, v.second);
+        return seed;
+    }
+
+#if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
+    namespace hash_detail
+    {
+        template <class A, class B>
+        struct call_hash<std::pair<A, B> >
+        {
+            static std::size_t call(std::pair<A, B> const& val)
+            {
+                return boost::hash_value(val);
+            }
+        };
+    }
+#endif
+}
+
+#endif