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boost_fusion/test/sequence/tuple_traits.cpp

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/*=============================================================================
Copyright (c) 2016 Lee Clagett
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
==============================================================================*/
#include <boost/detail/lightweight_test.hpp>
#include <boost/fusion/container/vector.hpp>
#include <boost/fusion/tuple/tuple.hpp>
#include <boost/config.hpp>
#include <boost/type_traits/is_constructible.hpp>
#include <boost/type_traits/is_convertible.hpp>
struct test_conversion
{
test_conversion(int) {}
};
struct test_no_conversion
{
explicit test_no_conversion(int) {}
};
/* Some construction differences in fusion::tuple from std::tuple:
- Construction from elements cannot call an explicit constructor.
- There is no implicit construction from elements.
- Construction from std::pair is _enabled_ when tuple is not of size 2.
- Construction from tuple is _enabled_ when destination tuple is of
different size.
- Implicit construction from std::pair can call explicit constructors on
elements.
- Implicit construction from tuple can call explicit constructors on
elements.
These differences are historical. Matching the behavior of std::tuple
could break existing code, however, switching to fusion::vector would
restore the historical behavior. */
int
main() {
{
using namespace boost;
using namespace boost::fusion;
BOOST_TEST(!(is_convertible<int, tuple<> >::value));
BOOST_TEST(!(is_convertible<int&, tuple<> >::value));
BOOST_TEST(!(is_convertible< int, tuple<int> >::value));
BOOST_TEST(!(is_convertible< int&, tuple<int> >::value));
BOOST_TEST(!(is_convertible< vector<int>, tuple<int> >::value));
BOOST_TEST(!(is_convertible< vector<int>&, tuple<int> >::value));
BOOST_TEST(!(is_convertible<int, tuple<int, int> >::value));
BOOST_TEST(!(is_convertible<int&, tuple<int, int> >::value));
}
// is_constructible has some restrictions ...
#if !(defined(BOOST_NO_CXX11_DECLTYPE) || defined(BOOST_NO_CXX11_TEMPLATES) || \
defined(BOOST_NO_SFINAE_EXPR))
{
using namespace boost;
using namespace boost::fusion;
BOOST_TEST((is_constructible< tuple<> >::value));
BOOST_TEST(!(is_constructible<tuple<>, int>::value));
BOOST_TEST(!(is_constructible<tuple<>, int&>::value));
BOOST_TEST((is_constructible< tuple<int> >::value));
BOOST_TEST((is_constructible<tuple<int>, int>::value));
BOOST_TEST((is_constructible<tuple<int>, int&>::value));
BOOST_TEST((is_constructible<tuple<test_conversion>, int>::value));
BOOST_TEST((is_constructible<tuple<test_conversion>, int&>::value));
BOOST_TEST(!(is_constructible<tuple<test_no_conversion>, int>::value));
BOOST_TEST(!(is_constructible<tuple<test_no_conversion>, int&>::value));
BOOST_TEST(!(is_constructible< tuple<int>, vector<int> >::value));
BOOST_TEST(!(is_constructible<tuple<int>, vector<int>&>::value));
BOOST_TEST(!(is_constructible<tuple<int>, int, int>::value));
BOOST_TEST(!(is_constructible<tuple<int>, int&, int&>::value));
BOOST_TEST((is_constructible< tuple<int, int> >::value));
BOOST_TEST((is_constructible<tuple<int, int>, int, int>::value));
BOOST_TEST((is_constructible<tuple<int, int>, int&, int&>::value));
BOOST_TEST((
is_constructible<
tuple<test_conversion, test_conversion>
, int
, int
>::value
));
BOOST_TEST((
is_constructible<
tuple<test_conversion, test_conversion>
, int&
, int&
>::value
));
BOOST_TEST(!(
is_constructible<
tuple<test_no_conversion, test_no_conversion>
, int
, int
>::value
));
BOOST_TEST(!(
is_constructible<
tuple<test_no_conversion, test_no_conversion>
, int&
, int&
>::value
));
#if defined(BOOST_FUSION_HAS_VARIADIC_VECTOR)
// C++03 fusion::tuple has constructors that can never be used
BOOST_TEST(!(is_constructible<tuple<int, int>, int>::value));
BOOST_TEST(!(is_constructible<tuple<int, int>, int&>::value));
#endif
BOOST_TEST(!(is_constructible<tuple<int, int>, int, int, int>::value));
BOOST_TEST(!(
is_constructible<tuple<int, int>, int&, int&, int&>::value
));
}
#endif
return boost::report_errors();
}