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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/not.hpp>
#include <boost/hana/traits.hpp>
#include <boost/hana/type.hpp>
#include <support/tracked.hpp>
#include <type_traits>
namespace hana = boost::hana;
struct undefined { };
struct static_nested_member { static const int member = 1; };
struct static_nested_member_array { static int member[3]; };
struct nested_template_struct { template <typename ...> struct nested; };
struct nested_template_alias { template <typename ...> using nested = void; };
int main() {
// Check for a non-static member
{
struct yes { int member; };
struct no { };
auto from_type = hana::is_valid([](auto t) -> decltype(
hana::traits::declval(t).member
) { });
BOOST_HANA_CONSTANT_CHECK(from_type(hana::type_c<yes>));
BOOST_HANA_CONSTANT_CHECK(hana::not_(from_type(hana::type_c<no>)));
auto from_object = hana::is_valid([](auto&& t) -> decltype(
t.member
) { });
BOOST_HANA_CONSTANT_CHECK(from_object(yes{}));
BOOST_HANA_CONSTANT_CHECK(hana::not_(from_object(no{})));
}
// Check for a non-static member function
{
struct yes { int member() const; };
struct no { };
auto from_type = hana::is_valid([](auto t) -> decltype(
hana::traits::declval(t).member()
) { });
BOOST_HANA_CONSTANT_CHECK(from_type(hana::type_c<yes>));
BOOST_HANA_CONSTANT_CHECK(hana::not_(from_type(hana::type_c<no>)));
auto from_object = hana::is_valid([](auto&& t) -> decltype(
t.member()
) { });
BOOST_HANA_CONSTANT_CHECK(from_object(yes{}));
BOOST_HANA_CONSTANT_CHECK(hana::not_(from_object(no{})));
}
// Check for a static member
{
using yes = static_nested_member;
struct no { };
auto from_type = hana::is_valid([](auto t) -> decltype(
decltype(t)::type::member
) { });
BOOST_HANA_CONSTANT_CHECK(from_type(hana::type_c<yes>));
BOOST_HANA_CONSTANT_CHECK(hana::not_(from_type(hana::type_c<no>)));
auto from_object = hana::is_valid([](auto&& t) -> decltype(
std::remove_reference_t<decltype(t)>::member
) { });
BOOST_HANA_CONSTANT_CHECK(from_object(yes{}));
BOOST_HANA_CONSTANT_CHECK(hana::not_(from_object(no{})));
}
// Check for a nested type
{
struct yes { using nested = void; };
struct no { };
auto from_type = hana::is_valid([](auto t) -> decltype(hana::type_c<
typename decltype(t)::type::nested
>) { });
BOOST_HANA_CONSTANT_CHECK(from_type(hana::type_c<yes>));
BOOST_HANA_CONSTANT_CHECK(hana::not_(from_type(hana::type_c<no>)));
auto from_object = hana::is_valid([](auto&& t) -> decltype(hana::type_c<
typename std::remove_reference_t<decltype(t)>::nested
>) { });
BOOST_HANA_CONSTANT_CHECK(from_object(yes{}));
BOOST_HANA_CONSTANT_CHECK(hana::not_(from_object(no{})));
}
// Check for a nested template
{
{ // template struct
using yes = nested_template_struct;
struct no { };
auto from_type = hana::is_valid([](auto t) -> decltype(hana::template_<
decltype(t)::type::template nested
>) { });
BOOST_HANA_CONSTANT_CHECK(from_type(hana::type_c<yes>));
BOOST_HANA_CONSTANT_CHECK(hana::not_(from_type(hana::type_c<no>)));
auto from_object = hana::is_valid([](auto&& t) -> decltype(hana::template_<
std::remove_reference_t<decltype(t)>::template nested
>) { });
BOOST_HANA_CONSTANT_CHECK(from_object(yes{}));
BOOST_HANA_CONSTANT_CHECK(hana::not_(from_object(no{})));
}
{ // template alias
using yes = nested_template_alias;
struct no { };
auto from_type = hana::is_valid([](auto t) -> decltype(hana::template_<
decltype(t)::type::template nested
>) { });
BOOST_HANA_CONSTANT_CHECK(from_type(hana::type_c<yes>));
BOOST_HANA_CONSTANT_CHECK(hana::not_(from_type(hana::type_c<no>)));
auto from_object = hana::is_valid([](auto&& t) -> decltype(hana::template_<
std::remove_reference_t<decltype(t)>::template nested
>) { });
BOOST_HANA_CONSTANT_CHECK(from_object(yes{}));
BOOST_HANA_CONSTANT_CHECK(hana::not_(from_object(no{})));
}
}
// Make sure that checking for a nested static or non-static member
// works even when the type of that member is an array type or
// something that can't be returned from a function.
{
{ // non-static member
struct yes { int member[3]; };
struct no { };
auto from_type = hana::is_valid([](auto t) -> decltype(
(void)hana::traits::declval(t).member
) { });
BOOST_HANA_CONSTANT_CHECK(from_type(hana::type_c<yes>));
BOOST_HANA_CONSTANT_CHECK(hana::not_(from_type(hana::type_c<no>)));
auto from_object = hana::is_valid([](auto&& t) -> decltype(
(void)t.member
) { });
BOOST_HANA_CONSTANT_CHECK(from_object(yes{}));
BOOST_HANA_CONSTANT_CHECK(hana::not_(from_object(no{})));
}
{ // static member
using yes = static_nested_member_array;
struct no { };
auto from_type = hana::is_valid([](auto t) -> decltype(
(void)decltype(t)::type::member
) { });
BOOST_HANA_CONSTANT_CHECK(from_type(hana::type_c<yes>));
BOOST_HANA_CONSTANT_CHECK(hana::not_(from_type(hana::type_c<no>)));
auto from_object = hana::is_valid([](auto&& t) -> decltype(
(void)std::remove_reference_t<decltype(t)>::member
) { });
BOOST_HANA_CONSTANT_CHECK(from_object(yes{}));
BOOST_HANA_CONSTANT_CHECK(hana::not_(from_object(no{})));
}
}
// Make sure the result of a `is_valid` function is constexpr
// even when called on non-constexpr arguments.
{
int i;
auto f = hana::is_valid([](auto) { });
constexpr auto result = f(i);
(void)result;
}
// Make sure `is_valid` works with non-PODs.
{
hana::is_valid(undefined{})(Tracked{1});
hana::is_valid([t = Tracked{1}](auto) { return 1; })(Tracked{1});
}
// Check `is_valid` with a nullary function.
{
auto f = [](auto ...x) { (void)sizeof...(x); /* -Wunused-param */ };
auto g = [](auto ...x) -> char(*)[sizeof...(x)] { };
BOOST_HANA_CONSTANT_CHECK(hana::is_valid(f)());
BOOST_HANA_CONSTANT_CHECK(hana::not_(hana::is_valid(g)()));
}
// Call `is_valid` in the non-curried form.
{
struct yes { int member; };
struct no { };
auto f = [](auto&& t) -> decltype(t.member) { };
BOOST_HANA_CONSTANT_CHECK(hana::is_valid(f, yes{}));
BOOST_HANA_CONSTANT_CHECK(hana::not_(hana::is_valid(f, no{})));
}
}
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