Add an implementation of or_ using is_same.

include/boost/mpl11/detail/logical_or/strict_is_same.hpp

@@ -0,0 +1,39 @@
+/*!
+ * @file
+ * Defines `boost::mpl11::detail::logical_or::strict_is_same`.
+ *
+ *
+ * @copyright Louis Dionne 2014
+ * Distributed under the Boost Software License, Version 1.0.
+ *         (See accompanying file LICENSE.md or copy at
+ *             http://www.boost.org/LICENSE_1_0.txt)
+ */
+
+#ifndef BOOST_MPL11_DETAIL_LOGICAL_OR_STRICT_IS_SAME_HPP
+#define BOOST_MPL11_DETAIL_LOGICAL_OR_STRICT_IS_SAME_HPP
+
+#include <boost/mpl11/bool.hpp>
+#include <boost/mpl11/detail/std_is_same.hpp>
+
+
+namespace boost { namespace mpl11 { namespace detail { namespace logical_or {
+    template <bool ...>
+    struct strict_is_same_impl;
+
+    /*!
+     * @ingroup details
+     *
+     * Strict (non short-circuiting) logical or implemented with `is_same`.
+     *
+     * All credit goes to Roland Bock for the technique.
+     */
+    template <typename ...xs>
+    using strict_is_same = bool_<
+        !std_is_same<
+            strict_is_same_impl<(bool)xs::type::value...>,
+            strict_is_same_impl<(xs::type::value, false)...>
+        >::value
+    >;
+}}}} // end namespace boost::mpl11::detail::logical_or
+
+#endif // !BOOST_MPL11_DETAIL_LOGICAL_OR_STRICT_IS_SAME_HPP

test/detail/logical_or.cpp

@@ -10,6 +10,7 @@
  */
 
 #include <boost/mpl11/detail/logical_or/lazy_naive_struct.hpp>
+#include <boost/mpl11/detail/logical_or/strict_is_same.hpp>
 #include <boost/mpl11/detail/logical_or/strict_noexcept.hpp>
 #include <boost/mpl11/detail/logical_or/strict_overload.hpp>
 #include <boost/mpl11/detail/logical_or/strict_specialization.hpp>
@@ -23,6 +24,7 @@ struct tests
     : detail::test_logical_or_strict<detail::logical_or::strict_overload>
     , detail::test_logical_or_strict<detail::logical_or::strict_noexcept>
     , detail::test_logical_or_strict<detail::logical_or::strict_specialization>
+    , detail::test_logical_or_strict<detail::logical_or::strict_is_same>
 
     , detail::test_logical_or_lazy<detail::logical_or::lazy_naive_struct>
 { };