1 files changed, 55 insertions, 0 deletions
diff --git a/src/boost/libs/hana/example/tutorial/integral-branching.cpp b/src/boost/libs/hana/example/tutorial/integral-branching.cpp
new file mode 100644
index 000000000..7e93f9402
--- /dev/null
+++ b/src/boost/libs/hana/example/tutorial/integral-branching.cpp
@@ -0,0 +1,55 @@
+// 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.hpp>
+#include <boost/hana/ext/std/integral_constant.hpp>
+
+#include <memory>
+#include <string>
+#include <type_traits>
+#include <utility>
+namespace hana = boost::hana;
+
+
+
+namespace ns1 {
+//! [make_unique.if_]
+template <typename T, typename ...Args>
+std::unique_ptr<T> make_unique(Args&&... args) {
+  return hana::if_(std::is_constructible<T, Args...>{},
+    [](auto&& ...x) { return std::unique_ptr<T>(new T(std::forward<Args>(x)...)); },
+    [](auto&& ...x) { return std::unique_ptr<T>(new T{std::forward<Args>(x)...}); }
+  )(std::forward<Args>(args)...);
+}
+//! [make_unique.if_]
+}
+
+
+namespace ns2 {
+//! [make_unique.eval_if]
+template <typename T, typename ...Args>
+std::unique_ptr<T> make_unique(Args&&... args) {
+  return hana::eval_if(std::is_constructible<T, Args...>{},
+    [&](auto _) { return std::unique_ptr<T>(new T(std::forward<Args>(_(args))...)); },
+    [&](auto _) { return std::unique_ptr<T>(new T{std::forward<Args>(_(args))...}); }
+  );
+}
+//! [make_unique.eval_if]
+}
+
+struct Student {
+  std::string name;
+  int age;
+};
+
+int main() {
+  {
+    std::unique_ptr<int> a = ns1::make_unique<int>(3);
+    std::unique_ptr<Student> b = ns1::make_unique<Student>("Bob", 25);
+  }
+  {
+    std::unique_ptr<int> a = ns2::make_unique<int>(3);
+    std::unique_ptr<Student> b = ns2::make_unique<Student>("Bob", 25);
+  }
+}