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Diffstat (limited to 'boost/fusion/support/detail/and.hpp')
| -rw-r--r-- | boost/fusion/support/detail/and.hpp | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/boost/fusion/support/detail/and.hpp b/boost/fusion/support/detail/and.hpp new file mode 100644 index 0000000000..1b310dda36 --- /dev/null +++ b/boost/fusion/support/detail/and.hpp @@ -0,0 +1,39 @@ +/*============================================================================= + 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 {}; + + // This specialization is necessary to avoid MSVC-12 variadics bug. + template<bool ...Cond> + struct and_impl1 : and_impl<integral_constant<bool, Cond>...> {}; + + /* 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_impl1<Cond::value...> {}; +}}} + +#endif // FUSION_AND_07152016_1625 |