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Diffstat (limited to 'src/boost/libs/hana/example/hash.cpp')
-rw-r--r-- | src/boost/libs/hana/example/hash.cpp | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/src/boost/libs/hana/example/hash.cpp b/src/boost/libs/hana/example/hash.cpp new file mode 100644 index 000000000..dcbdd7afa --- /dev/null +++ b/src/boost/libs/hana/example/hash.cpp @@ -0,0 +1,44 @@ +// Copyright Louis Dionne 2013-2017 +// Distributed under the Boost Software License, Version 1.0. +// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt) + +#include <boost/hana/assert.hpp> +#include <boost/hana/equal.hpp> +#include <boost/hana/hash.hpp> +#include <boost/hana/integral_constant.hpp> +#include <boost/hana/type.hpp> + +#include <type_traits> +#include <utility> +namespace hana = boost::hana; + + +// Sample implementation of a compile-time set data structure. Of course, +// this naive implementation only works when no two elements of the same +// set have the same hash. +template <typename T> +struct bucket { }; + +template <typename ...T> +struct set + : bucket<typename decltype(hana::hash(std::declval<T>()))::type>... +{ }; + +template <typename Set, typename T> +struct contains + : std::is_base_of< + bucket<typename decltype(hana::hash(std::declval<T>()))::type>, + Set + > +{ }; + +using Set = set<hana::int_<1>, hana::ulong<2>, hana::type<char>>; + +static_assert(contains<Set, hana::int_<1>>{}, ""); +static_assert(contains<Set, hana::ulong<2>>{}, ""); +static_assert(contains<Set, hana::type<char>>{}, ""); + +static_assert(!contains<Set, hana::int_<3>>{}, ""); +static_assert(!contains<Set, hana::type<float>>{}, ""); + +int main() { } |