update sources to v12.2.3

[ceph.git] / ceph / src / boost / libs / hana / example / zip_with.cpp

diff --git a/ceph/src/boost/libs/hana/example/zip_with.cpp b/ceph/src/boost/libs/hana/example/zip_with.cpp
index 47ce98eb7ff701d5301a9b62cc11394219dc20bc..55ae01026f7556012e93fde5d5d12a6f15da0cc5 100644 (file)
--- a/ceph/src/boost/libs/hana/example/zip_with.cpp
+++ b/ceph/src/boost/libs/hana/example/zip_with.cpp
@@ -1,18 +1,51 @@
-// Copyright Louis Dionne 2013-2016
+// 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/equal.hpp>
+#include <boost/hana/ext/std/tuple.hpp>
 #include <boost/hana/mult.hpp>
+#include <boost/hana/transform.hpp>
 #include <boost/hana/tuple.hpp>
+#include <boost/hana/type.hpp>
+#include <boost/hana/unpack.hpp>
 #include <boost/hana/zip_with.hpp>
+
+#include <tuple>
+#include <type_traits>
+#include <utility>
 namespace hana = boost::hana;
 
 
+// Basic usage:
 static_assert(
     hana::zip_with(hana::mult, hana::make_tuple(1, 2, 3, 4), hana::make_tuple(5, 6, 7, 8))
     ==
     hana::make_tuple(5, 12, 21, 32)
 , "");
 
+
+
+// Example of computing a tuple of all the common types of several tuples:
+template<typename... Ts>
+using common_tuple_t = typename decltype(
+    hana::unpack(
+        hana::zip_with(
+            hana::metafunction<std::common_type>,
+            hana::transform(std::declval<Ts>(), hana::decltype_)...
+        ),
+        hana::template_<std::tuple>
+    )
+)::type;
+
+
+static_assert(std::is_same<
+    common_tuple_t<
+        std::tuple<bool, int, unsigned>,
+        std::tuple<char, long, long>,
+        std::tuple<int, long long, double>
+    >,
+    std::tuple<int, long long, double>
+>::value, "");
+
 int main() { }