1 files changed, 39 insertions, 0 deletions
diff --git a/src/boost/libs/hana/example/lexicographical_compare.cpp b/src/boost/libs/hana/example/lexicographical_compare.cpp
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index 000000000..5c70f59e8
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+++ b/src/boost/libs/hana/example/lexicographical_compare.cpp
@@ -0,0 +1,39 @@
+// 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/integral_constant.hpp>
+#include <boost/hana/less.hpp>
+#include <boost/hana/lexicographical_compare.hpp>
+#include <boost/hana/tuple.hpp>
+#include <boost/hana/type.hpp>
+namespace hana = boost::hana;
+
+
+int main() {
+    // works with elements whose `less` does not return a Constant
+    {
+        constexpr auto xs = hana::make_tuple(1, 2, 3, 4);
+        constexpr auto ys = hana::make_tuple(1, 6, 3, 4);
+        static_assert(hana::lexicographical_compare(xs, ys), "");
+    }
+
+    // and with those that do
+    {
+        auto xs = hana::make_tuple(hana::int_c<1>, hana::int_c<2>, hana::int_c<3>);
+        auto ys = hana::make_tuple(hana::int_c<1>, hana::int_c<5>, hana::int_c<3>);
+        BOOST_HANA_CONSTANT_CHECK(hana::lexicographical_compare(xs, ys));
+    }
+
+    // it also accepts a custom predicate
+    {
+        auto xs = hana::make_tuple(hana::type_c<int>, hana::type_c<char>, hana::type_c<void*>);
+        auto ys = hana::make_tuple(hana::type_c<int>, hana::type_c<long>, hana::type_c<void*>);
+        BOOST_HANA_CONSTANT_CHECK(
+            hana::lexicographical_compare(xs, ys, [](auto t, auto u) {
+                return hana::sizeof_(t) < hana::sizeof_(u);
+            })
+        );
+    }
+}