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Make boost::tuple tuple-like to support structured bindings

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This commit is contained in:
Peter Dimov
2018-01-03 19:26:11 +02:00
parent c51d8a9495
commit 16731d2689
6 changed files with 247 additions and 10 deletions
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21
include/boost/tuple/detail/tuple_basic.hpp
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@ -37,6 +37,7 @@
#include <boost/type_traits/cv_traits.hpp>
#include <boost/type_traits/function_traits.hpp>
#include <boost/type_traits/integral_constant.hpp>
#include <boost/utility/swap.hpp>
#include <boost/detail/workaround.hpp> // needed for BOOST_WORKAROUND
@ -420,28 +421,28 @@ struct cons<HT, null_type> {
// templates for finding out the length of the tuple -------------------
template<class T>
struct length {
BOOST_STATIC_CONSTANT(int, value = 1 + length<typename T::tail_type>::value);
struct length: boost::integral_constant<int, 1 + length<typename T::tail_type>::value>
{
};
template<>
struct length<tuple<> > {
BOOST_STATIC_CONSTANT(int, value = 0);
struct length<tuple<> >: boost::integral_constant<int, 0>
{
};
template<>
struct length<tuple<> const> {
BOOST_STATIC_CONSTANT(int, value = 0);
struct length<tuple<> const>: boost::integral_constant<int, 0>
{
};
template<>
struct length<null_type> {
BOOST_STATIC_CONSTANT(int, value = 0);
struct length<null_type>: boost::integral_constant<int, 0>
{
};
template<>
struct length<null_type const> {
BOOST_STATIC_CONSTANT(int, value = 0);
struct length<null_type const>: boost::integral_constant<int, 0>
{
};
namespace detail {

39
include/boost/tuple/tuple.hpp
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@ -63,5 +63,44 @@ get(const tuples::cons<HT, TT>& c) {
} // end namespace boost
#if !defined(BOOST_NO_CXX11_HDR_TUPLE)
#include <tuple>
#include <cstddef>
namespace std
{
// std::tuple_size
template<class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8, class T9, class T10>
struct tuple_size< boost::tuples::tuple<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10> >:
boost::tuples::length< boost::tuples::tuple<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10> >
{
};
template<class H, class T> struct tuple_size< boost::tuples::cons<H, T> >: boost::tuples::length< boost::tuples::cons<H, T> >
{
};
template<> struct tuple_size< boost::tuples::null_type >: boost::tuples::length< boost::tuples::null_type >
{
};
// std::tuple_element
template<std::size_t I, class T1, class T2, class T3, class T4, class T5, class T6, class T7, class T8, class T9, class T10>
struct tuple_element< I, boost::tuples::tuple<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10> >:
boost::tuples::element< I, boost::tuples::tuple<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10> >
{
};
template<std::size_t I, class H, class T> struct tuple_element< I, boost::tuples::cons<H, T> >: boost::tuples::element< I, boost::tuples::cons<H, T> >
{
};
} // namespace std
#endif // !defined(BOOST_NO_CXX11_HDR_TUPLE)
#endif // BOOST_TUPLE_HPP

3
test/Jamfile
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@ -5,4 +5,7 @@ test-suite tuple :
[ run tuple_test_bench.cpp ]
[ run io_test.cpp ]
[ run another_tuple_test_bench.cpp ]
[ run std_tuple_size.cpp ]
[ run std_tuple_element.cpp ]
[ run structured_bindings.cpp ]
;

56
test/std_tuple_element.cpp Normal file
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@ -0,0 +1,56 @@
// Copyright 2017 Peter Dimov.
// Distributed under the Boost Software License, Version 1.0.
#include <boost/tuple/tuple.hpp>
#include <boost/core/lightweight_test_trait.hpp>
#include <boost/type_traits/is_same.hpp>
#include <boost/config.hpp>
#include <boost/config/pragma_message.hpp>
#if defined(BOOST_NO_CXX11_HDR_TUPLE)
BOOST_PRAGMA_MESSAGE("Skipping std::tuple_element tests for lack of <tuple>")
int main() {}
#else
#include <tuple>
template<class Tp, std::size_t I, class E> void test()
{
BOOST_TEST_TRAIT_TRUE((boost::is_same<typename std::tuple_element<I, Tp>::type, E>));
typedef typename Tp::inherited Tp2;
BOOST_TEST_TRAIT_TRUE((boost::is_same<typename std::tuple_element<I, Tp2>::type, E>));
}
template<int> struct X
{
};
int main()
{
test<boost::tuple<X<0> const>, 0, X<0> const>();
test<boost::tuple<X<0> const, X<1> const>, 0, X<0> const>();
test<boost::tuple<X<0> const, X<1> const>, 1, X<1> const>();
test<boost::tuple<X<0> const, X<1> const, X<2> const>, 0, X<0> const>();
test<boost::tuple<X<0> const, X<1> const, X<2> const>, 1, X<1> const>();
test<boost::tuple<X<0> const, X<1> const, X<2> const>, 2, X<2> const>();
test<boost::tuple<X<0> const, X<1> const, X<2> const, X<3> const>, 0, X<0> const>();
test<boost::tuple<X<0> const, X<1> const, X<2> const, X<3> const>, 1, X<1> const>();
test<boost::tuple<X<0> const, X<1> const, X<2> const, X<3> const>, 2, X<2> const>();
test<boost::tuple<X<0> const, X<1> const, X<2> const, X<3> const>, 3, X<3> const>();
test<boost::tuple<X<0> const, X<1> const, X<2> const, X<3> const, X<4> const>, 0, X<0> const>();
test<boost::tuple<X<0> const, X<1> const, X<2> const, X<3> const, X<4> const>, 1, X<1> const>();
test<boost::tuple<X<0> const, X<1> const, X<2> const, X<3> const, X<4> const>, 2, X<2> const>();
test<boost::tuple<X<0> const, X<1> const, X<2> const, X<3> const, X<4> const>, 3, X<3> const>();
test<boost::tuple<X<0> const, X<1> const, X<2> const, X<3> const, X<4> const>, 4, X<4> const>();
return boost::report_errors();
}
#endif

61
test/std_tuple_size.cpp Normal file
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@ -0,0 +1,61 @@
// Copyright 2017 Peter Dimov.
// Distributed under the Boost Software License, Version 1.0.
#include <boost/tuple/tuple.hpp>
#include <boost/core/lightweight_test.hpp>
#include <boost/config.hpp>
#include <boost/config/pragma_message.hpp>
#if defined(BOOST_NO_CXX11_HDR_TUPLE)
BOOST_PRAGMA_MESSAGE("Skipping std::tuple_size tests for lack of <tuple>")
int main() {}
#else
#include <tuple>
template<class Tp> void test( std::size_t x )
{
BOOST_TEST_EQ( std::tuple_size< Tp >::value, x );
BOOST_TEST_EQ( std::tuple_size< typename Tp::inherited >::value, x );
}
struct V
{
};
int main()
{
test< boost::tuple<> >( 0 );
test< boost::tuple<V> >( 1 );
test< boost::tuple<V, V> >( 2 );
test< boost::tuple<V, V, V> >( 3 );
test< boost::tuple<V, V, V, V> >( 4 );
test< boost::tuple<V, V, V, V, V> >( 5 );
test< boost::tuple<V, V, V, V, V, V> >( 6 );
test< boost::tuple<V, V, V, V, V, V, V> >( 7 );
test< boost::tuple<V, V, V, V, V, V, V, V> >( 8 );
test< boost::tuple<V, V, V, V, V, V, V, V, V> >( 9 );
test< boost::tuple<V, V, V, V, V, V, V, V, V, V> >( 10 );
#if !defined(BOOST_NO_CXX11_DECLTYPE)
BOOST_TEST_EQ( std::tuple_size<decltype(boost::make_tuple())>::value, 0 );
BOOST_TEST_EQ( std::tuple_size<decltype(boost::make_tuple(1))>::value, 1 );
BOOST_TEST_EQ( std::tuple_size<decltype(boost::make_tuple(1, 2))>::value, 2 );
BOOST_TEST_EQ( std::tuple_size<decltype(boost::make_tuple(1, 2, 3))>::value, 3 );
BOOST_TEST_EQ( std::tuple_size<decltype(boost::make_tuple(1, 2, 3, 4))>::value, 4 );
BOOST_TEST_EQ( std::tuple_size<decltype(boost::make_tuple(1, 2, 3, 4, 5))>::value, 5 );
BOOST_TEST_EQ( std::tuple_size<decltype(boost::make_tuple(1, 2, 3, 4, 5, 6))>::value, 6 );
BOOST_TEST_EQ( std::tuple_size<decltype(boost::make_tuple(1, 2, 3, 4, 5, 6, 7))>::value, 7 );
BOOST_TEST_EQ( std::tuple_size<decltype(boost::make_tuple(1, 2, 3, 4, 5, 6, 7, 8))>::value, 8 );
BOOST_TEST_EQ( std::tuple_size<decltype(boost::make_tuple(1, 2, 3, 4, 5, 6, 7, 8, 9))>::value, 9 );
BOOST_TEST_EQ( std::tuple_size<decltype(boost::make_tuple(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))>::value, 10 );
#endif
return boost::report_errors();
}
#endif

77
test/structured_bindings.cpp Normal file
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@ -0,0 +1,77 @@
// Copyright 2017 Peter Dimov.
// Distributed under the Boost Software License, Version 1.0.
#include <boost/tuple/tuple.hpp>
#include <boost/core/lightweight_test.hpp>
#include <boost/config.hpp>
#include <boost/config/pragma_message.hpp>
#if defined(BOOST_NO_CXX17_STRUCTURED_BINDINGS)
BOOST_PRAGMA_MESSAGE("Skipping structured bindings test, not supported")
int main() {}
#else
int main()
{
// make_tuple
{
auto [x1] = boost::make_tuple( 1 );
BOOST_TEST_EQ( x1, 1 );
}
{
auto [x1, x2] = boost::make_tuple( 1, 2 );
BOOST_TEST_EQ( x1, 1 );
BOOST_TEST_EQ( x2, 2 );
}
{
auto [x1, x2, x3] = boost::make_tuple( 1, 2, 3 );
BOOST_TEST_EQ( x1, 1 );
BOOST_TEST_EQ( x2, 2 );
BOOST_TEST_EQ( x3, 3 );
}
{
auto [x1, x2, x3, x4] = boost::make_tuple( 1, 2, 3, 4 );
BOOST_TEST_EQ( x1, 1 );
BOOST_TEST_EQ( x2, 2 );
BOOST_TEST_EQ( x3, 3 );
BOOST_TEST_EQ( x4, 4 );
}
// tuple
{
auto [x1] = boost::tuple<int>( 1 );
BOOST_TEST_EQ( x1, 1 );
}
{
auto [x1, x2] = boost::tuple<int, int>( 1, 2 );
BOOST_TEST_EQ( x1, 1 );
BOOST_TEST_EQ( x2, 2 );
}
{
auto [x1, x2, x3] = boost::tuple<int, int, int>( 1, 2, 3 );
BOOST_TEST_EQ( x1, 1 );
BOOST_TEST_EQ( x2, 2 );
BOOST_TEST_EQ( x3, 3 );
}
{
auto [x1, x2, x3, x4] = boost::tuple<int, int, int, int>( 1, 2, 3, 4 );
BOOST_TEST_EQ( x1, 1 );
BOOST_TEST_EQ( x2, 2 );
BOOST_TEST_EQ( x3, 3 );
BOOST_TEST_EQ( x4, 4 );
}
return boost::report_errors();
}
#endif