Add DISABLE_VARIADIC_VECTOR and SFINAE for c++11 tuple element construction

include/boost/fusion/support/detail/and.hpp

@@ -0,0 +1,35 @@
+/*=============================================================================
+    Copyright (c) 2016 Lee Clagett
+
+    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 FUSION_AND_07152016_1625
+#define FUSION_AND_07152016_1625
+
+#include <boost/config.hpp>
+#include <boost/type_traits/integral_constant.hpp>
+
+#if defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
+#error fusion::detail::and_ requires variadic templates
+#endif
+
+namespace boost { namespace fusion { namespace detail {
+    template<typename ...Cond>
+    struct and_impl : false_type {};
+
+    template<typename ...T>
+    struct and_impl<integral_constant<T, true>...> : true_type {};
+   
+    /* fusion::detail::and_ differs from mpl::and_ in the following ways:
+       - The empty set is valid and returns true
+       - A single element set is valid and returns the identity
+       - There is no upper bound on the set size
+       - The conditions are evaluated at once, and are not short-circuited. This
+         reduces instantations when returning true; the implementation is not
+         recursive. */
+    template<typename ...Cond>
+    struct and_ : and_impl<integral_constant<bool, Cond::value>...> {};
+}}}
+
+#endif // FUSION_AND_07152016_1625