1// Copyright 2017 Peter Dimov.
2// Distributed under the Boost Software License, Version 1.0.
3
4#include <boost/tuple/tuple.hpp>
5#include <boost/core/lightweight_test_trait.hpp>
6#include <boost/type_traits/is_same.hpp>
7#include <boost/config.hpp>
8#include <boost/config/pragma_message.hpp>
9
10#if defined(BOOST_NO_CXX11_HDR_TUPLE)
11
12BOOST_PRAGMA_MESSAGE("Skipping std::tuple_element tests for lack of <tuple>")
13int main() {}
14
15#else
16
17#include <tuple>
18
19template<class Tp, std::size_t I, class E> void test()
20{
21 BOOST_TEST_TRAIT_TRUE((boost::is_same<typename std::tuple_element<I, Tp>::type, E>));
22
23 typedef typename Tp::inherited Tp2;
24 BOOST_TEST_TRAIT_TRUE((boost::is_same<typename std::tuple_element<I, Tp2>::type, E>));
25}
26
27template<int> struct X
28{
29};
30
31int main()
32{
33 test<boost::tuple<X<0> const>, 0, X<0> const>();
34
35 test<boost::tuple<X<0> const, X<1> const>, 0, X<0> const>();
36 test<boost::tuple<X<0> const, X<1> const>, 1, X<1> const>();
37
38 test<boost::tuple<X<0> const, X<1> const, X<2> const>, 0, X<0> const>();
39 test<boost::tuple<X<0> const, X<1> const, X<2> const>, 1, X<1> const>();
40 test<boost::tuple<X<0> const, X<1> const, X<2> const>, 2, X<2> const>();
41
42 test<boost::tuple<X<0> const, X<1> const, X<2> const, X<3> const>, 0, X<0> const>();
43 test<boost::tuple<X<0> const, X<1> const, X<2> const, X<3> const>, 1, X<1> const>();
44 test<boost::tuple<X<0> const, X<1> const, X<2> const, X<3> const>, 2, X<2> const>();
45 test<boost::tuple<X<0> const, X<1> const, X<2> const, X<3> const>, 3, X<3> const>();
46
47 test<boost::tuple<X<0> const, X<1> const, X<2> const, X<3> const, X<4> const>, 0, X<0> const>();
48 test<boost::tuple<X<0> const, X<1> const, X<2> const, X<3> const, X<4> const>, 1, X<1> const>();
49 test<boost::tuple<X<0> const, X<1> const, X<2> const, X<3> const, X<4> const>, 2, X<2> const>();
50 test<boost::tuple<X<0> const, X<1> const, X<2> const, X<3> const, X<4> const>, 3, X<3> const>();
51 test<boost::tuple<X<0> const, X<1> const, X<2> const, X<3> const, X<4> const>, 4, X<4> const>();
52
53 return boost::report_errors();
54}
55
56#endif
57

source code of boost/libs/tuple/test/std_tuple_element.cpp