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
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+++ b/src/boost/libs/hana/example/hash.cpp
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+// 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() { }