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Add value list support to mp_at. Refs #53.

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Peter Dimov
2023-05-16 19:13:56 +03:00
parent 799c2e6079
commit 73626ba3bc
3 changed files with 75 additions and 1 deletions
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11
include/boost/mp11/algorithm.hpp
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@@ -352,11 +352,20 @@ template<template<class...> class L, class... T, std::size_t I> struct mp_at_c_i
using type = __type_pack_element<I, T...>;
};
#if defined(BOOST_MP11_HAS_TEMPLATE_AUTO)
template<template<auto...> class L, auto... A, std::size_t I> struct mp_at_c_impl<L<A...>, I>
{
using type = __type_pack_element<I, mp_value<A>...>;
};
#endif
#else
template<class L, std::size_t I> struct mp_at_c_impl
{
using _map = mp_transform<mp_list, mp_iota<mp_size<L> >, L>;
using _map = mp_transform<mp_list, mp_iota<mp_size<L> >, mp_rename<L, mp_list>>;
using type = mp_second<mp_map_find<_map, mp_size_t<I> > >;
};

1
test/Jamfile
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@@ -94,6 +94,7 @@ run mp_drop.cpp ;
run mp_iota.cpp ;
run mp_iota_2.cpp ;
run mp_at.cpp ;
run mp_at_2.cpp ;
run mp_at_sf.cpp : : : <toolset>gcc-4.7:<warnings>all ;
run mp_take.cpp ;
run mp_replace.cpp ;

64
test/mp_at_2.cpp Normal file
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@@ -0,0 +1,64 @@
// Copyright 2023 Peter Dimov
// Distributed under the Boost Software License, Version 1.0.
// https://www.boost.org/LICENSE_1_0.txt
#include <boost/mp11/algorithm.hpp>
#include <boost/mp11/integral.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/core/lightweight_test_trait.hpp>
template<auto... A> struct V1 {};
template<int... I> struct V2 {};
int main()
{
using boost::mp11::mp_at;
using boost::mp11::mp_at_c;
using boost::mp11::mp_false;
using boost::mp11::mp_true;
using boost::mp11::mp_int;
using boost::mp11::mp_size_t;
{
using L1 = V1<false, 0, true, 1, std::size_t(2)>;
BOOST_TEST_TRAIT_SAME(mp_at_c<L1, 0>, mp_false);
BOOST_TEST_TRAIT_SAME(mp_at_c<L1, 1>, mp_int<0>);
BOOST_TEST_TRAIT_SAME(mp_at_c<L1, 2>, mp_true);
BOOST_TEST_TRAIT_SAME(mp_at_c<L1, 3>, mp_int<1>);
BOOST_TEST_TRAIT_SAME(mp_at_c<L1, 4>, mp_size_t<2>);
BOOST_TEST_TRAIT_SAME(mp_at<L1, mp_size_t<0>>, mp_false);
BOOST_TEST_TRAIT_SAME(mp_at<L1, mp_size_t<1>>, mp_int<0>);
BOOST_TEST_TRAIT_SAME(mp_at<L1, mp_size_t<2>>, mp_true);
BOOST_TEST_TRAIT_SAME(mp_at<L1, mp_size_t<3>>, mp_int<1>);
BOOST_TEST_TRAIT_SAME(mp_at<L1, mp_size_t<4>>, mp_size_t<2>);
}
{
using L1 = V2<1, 2, 3, 4, 5>;
BOOST_TEST_TRAIT_SAME(mp_at_c<L1, 0>, mp_int<1>);
BOOST_TEST_TRAIT_SAME(mp_at_c<L1, 1>, mp_int<2>);
BOOST_TEST_TRAIT_SAME(mp_at_c<L1, 2>, mp_int<3>);
BOOST_TEST_TRAIT_SAME(mp_at_c<L1, 3>, mp_int<4>);
BOOST_TEST_TRAIT_SAME(mp_at_c<L1, 4>, mp_int<5>);
BOOST_TEST_TRAIT_SAME(mp_at<L1, mp_size_t<0>>, mp_int<1>);
BOOST_TEST_TRAIT_SAME(mp_at<L1, mp_size_t<1>>, mp_int<2>);
BOOST_TEST_TRAIT_SAME(mp_at<L1, mp_size_t<2>>, mp_int<3>);
BOOST_TEST_TRAIT_SAME(mp_at<L1, mp_size_t<3>>, mp_int<4>);
BOOST_TEST_TRAIT_SAME(mp_at<L1, mp_size_t<4>>, mp_int<5>);
}
return boost::report_errors();
}
#endif