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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/core/to.hpp>
- #include <boost/hana/assert.hpp>
- #include <boost/hana/core/tag_of.hpp>
- #include <string>
- #include <type_traits>
- namespace hana = boost::hana;
- template <typename X, typename Y>
- constexpr auto operator==(X x, Y y)
- { return x.value == y.value; }
- struct Datatype {
- int value;
- using hana_tag = Datatype;
- };
- struct Other {
- int value;
- using hana_tag = Datatype;
- };
- struct SpecializedFrom;
- struct specialized_from {
- int value;
- using hana_tag = SpecializedFrom;
- };
- struct SpecializedTo;
- struct specialized_to {
- int value;
- using hana_tag = SpecializedTo;
- };
- namespace boost { namespace hana {
- template <>
- struct to_impl<SpecializedTo, SpecializedFrom> {
- template <typename T>
- static constexpr auto apply(T t)
- { return specialized_to{t.value}; }
- };
- }}
- template <typename F, typename T>
- void check_convert(F f, T t) {
- using From = hana::tag_of_t<F>;
- using To = hana::tag_of_t<T>;
- // Check From -> To conversion
- BOOST_HANA_RUNTIME_CHECK(hana::to<To>(f) == t);
- static_assert(std::is_same<
- hana::tag_of_t<decltype(hana::to<To>(f))>, To
- >{}, "");
- static_assert(hana::is_convertible<From, To>{}, "");
- // Make sure From -> From and To -> To are the identity.
- BOOST_HANA_RUNTIME_CHECK(hana::to<From>(f) == f);
- static_assert(std::is_same<
- hana::tag_of_t<decltype(hana::to<From>(f))>, From
- >{}, "");
- BOOST_HANA_RUNTIME_CHECK(hana::to<To>(t) == t);
- static_assert(std::is_same<
- hana::tag_of_t<decltype(hana::to<To>(t))>, To
- >{}, "");
- static_assert(hana::is_convertible<From, From>{}, "");
- static_assert(hana::is_convertible<To, To>{}, "");
- static_assert(hana::is_embedded<From, From>{}, "");
- static_assert(hana::is_embedded<To, To>{}, "");
- }
- template <typename X>
- void check_variable_template_in_dependent_context(X x) {
- hana::to<int>(x);
- }
- int main() {
- // Clang used to assert in the code generation when we used variable
- // templates inside a lambda; this is to catch this.
- check_variable_template_in_dependent_context(3);
- check_convert("abcdef", std::string{"abcdef"});
- check_convert(int{1}, double{1});
- check_convert(double{1}, int{1});
- check_convert(std::true_type{}, int{1});
- check_convert(std::false_type{}, int{0});
- check_convert(Datatype{1}, Datatype{1});
- check_convert(Other{1}, Other{1});
- check_convert(specialized_from{1}, specialized_to{1});
- static_assert(!hana::is_convertible<void, int>{}, "");
- static_assert(!hana::is_embedded<void, int>{}, "");
- static_assert(hana::is_convertible<int, void>{}, "");
- static_assert(!hana::is_embedded<int, void>{}, "");
- }
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