1 files changed, 45 insertions, 0 deletions
diff --git a/src/boost/libs/hana/example/while.cpp b/src/boost/libs/hana/example/while.cpp
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+++ b/src/boost/libs/hana/example/while.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/integral_constant.hpp>
+#include <boost/hana/less.hpp>
+#include <boost/hana/plus.hpp>
+#include <boost/hana/while.hpp>
+
+#include <vector>
+namespace hana = boost::hana;
+using namespace hana::literals;
+
+
+int main() {
+    // while_ with a Constant condition (loop is unrolled at compile-time)
+    {
+        std::vector<int> ints;
+        auto final_state = hana::while_(hana::less.than(10_c), 0_c, [&](auto i) {
+            ints.push_back(i);
+            return i + 1_c;
+        });
+
+        // The state is known at compile-time
+        BOOST_HANA_CONSTANT_CHECK(final_state == 10_c);
+
+        BOOST_HANA_RUNTIME_CHECK(ints == std::vector<int>{0, 1, 2, 3, 4, 5, 6, 7, 8, 9});
+    }
+
+    // while_ with a constexpr or runtime condition (loop is not unrolled)
+    {
+        std::vector<int> ints;
+        int final_state = hana::while_(hana::less.than(10), 0, [&](int i) {
+            ints.push_back(i);
+            return i + 1;
+        });
+
+        // The state is known only at runtime, or at compile-time if constexpr
+        BOOST_HANA_RUNTIME_CHECK(final_state == 10);
+
+        BOOST_HANA_RUNTIME_CHECK(ints == std::vector<int>{0, 1, 2, 3, 4, 5, 6, 7, 8, 9});
+    }
+}