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Add value list support to mp_second, mp_third. Refs #53.

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This commit is contained in:
Peter Dimov
2023-05-15 15:23:05 +03:00
parent d02f361b1b
commit 90669f2ff4
4 changed files with 84 additions and 0 deletions
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18
include/boost/mp11/list.hpp
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@@ -157,6 +157,15 @@ template<template<class...> class L, class T1, class T2, class... T> struct mp_s
using type = T2;
};
#if defined(BOOST_MP11_HAS_TEMPLATE_AUTO)
template<template<auto...> class L, auto A1, auto A2, auto... A> struct mp_second_impl<L<A1, A2, A...>>
{
using type = mp_value<A2>;
};
#endif
} // namespace detail
template<class L> using mp_second = typename detail::mp_second_impl<L>::type;
@@ -176,6 +185,15 @@ template<template<class...> class L, class T1, class T2, class T3, class... T> s
using type = T3;
};
#if defined(BOOST_MP11_HAS_TEMPLATE_AUTO)
template<template<auto...> class L, auto A1, auto A2, auto A3, auto... A> struct mp_third_impl<L<A1, A2, A3, A...>>
{
using type = mp_value<A3>;
};
#endif
} // namespace detail
template<class L> using mp_third = typename detail::mp_third_impl<L>::type;

2
test/Jamfile
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@@ -38,7 +38,9 @@ run mp_front_2.cpp ;
run mp_pop_front.cpp ;
run mp_pop_front_2.cpp ;
run mp_second.cpp ;
run mp_second_2.cpp ;
run mp_third.cpp ;
run mp_third_2.cpp ;
run mp_push_front.cpp ;
run mp_push_back.cpp ;
run mp_rename.cpp ;

32
test/mp_second_2.cpp Normal file
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@@ -0,0 +1,32 @@
// Copyright 2023 Peter Dimov
// Distributed under the Boost Software License, Version 1.0.
// https://www.boost.org/LICENSE_1_0.txt
#include <boost/mp11/list.hpp>
#if !defined(BOOST_MP11_HAS_TEMPLATE_AUTO)
#pragma message("Test skipped because BOOST_MP11_HAS_TEMPLATE_AUTO is not defined")
int main() {}
#else
#include <boost/mp11/integral.hpp>
#include <boost/core/lightweight_test_trait.hpp>
template<auto... A> struct L1 {};
template<int... I> struct L2 {};
int main()
{
using boost::mp11::mp_second;
using boost::mp11::mp_true;
using boost::mp11::mp_int;
BOOST_TEST_TRAIT_SAME(mp_second<L1<-1, true>>, mp_true);
BOOST_TEST_TRAIT_SAME(mp_second<L2<0, 1>>, mp_int<1>);
return boost::report_errors();
}
#endif

32
test/mp_third_2.cpp Normal file
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@@ -0,0 +1,32 @@
// Copyright 2023 Peter Dimov
// Distributed under the Boost Software License, Version 1.0.
// https://www.boost.org/LICENSE_1_0.txt
#include <boost/mp11/list.hpp>
#if !defined(BOOST_MP11_HAS_TEMPLATE_AUTO)
#pragma message("Test skipped because BOOST_MP11_HAS_TEMPLATE_AUTO is not defined")
int main() {}
#else
#include <boost/mp11/integral.hpp>
#include <boost/core/lightweight_test_trait.hpp>
template<auto... A> struct L1 {};
template<int... I> struct L2 {};
int main()
{
using boost::mp11::mp_third;
using boost::mp11::mp_false;
using boost::mp11::mp_int;
BOOST_TEST_TRAIT_SAME(mp_third<L1<-1, true, false>>, mp_false);
BOOST_TEST_TRAIT_SAME(mp_third<L2<0, 1, 2>>, mp_int<2>);
return boost::report_errors();
}
#endif