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Add mp_nth_element

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This commit is contained in:
Peter Dimov
2017-10-15 16:56:22 +03:00
parent a5e74b2951
commit c14d6030c2
4 changed files with 124 additions and 0 deletions
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12
doc/mp11/algorithm.adoc
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@@ -441,6 +441,18 @@ using L1 = mp_list<std::ratio<1,2>, std::ratio<1,4>>;
using R1 = mp_sort<L1, std::ratio_less>; // mp_list<ratio<1,4>, ratio<1,2>>
----
## mp_nth_element_c<L, I, P>
template<class L, std::size_t I, template<class...> class P> using mp_nth_element_c = /*...*/;
Returns the element at position `I` in `mp_sort<L, P>`.
## mp_nth_element<L, I, P>
template<class L, class I, template<class...> class P> using mp_nth_element = /*...*/;
Like `mp_nth_element_c`, but with a type argument `I`. `I::value` must be a nonnegative number.
## mp_min_element<L, P>
template<class L, template<class...> class P> using mp_min_element = /*...*/;

39
include/boost/mp11/algorithm.hpp
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@@ -508,6 +508,45 @@ template<template<class...> class L, class T1, class... T, template<class...> cl
template<class L, template<class...> class P> using mp_sort = typename detail::mp_sort_impl<L, P>::type;
// mp_nth_element(_c)<L, I, P>
namespace detail
{
template<class L, std::size_t I, template<class...> class P> struct mp_nth_element_impl;
template<template<class...> class L, class T1, std::size_t I, template<class...> class P> struct mp_nth_element_impl<L<T1>, I, P>
{
static_assert( I == 0, "mp_nth_element index out of range" );
using type = T1;
};
template<template<class...> class L, class T1, class... T, std::size_t I, template<class...> class P> struct mp_nth_element_impl<L<T1, T...>, I, P>
{
static_assert( I < 1 + sizeof...(T), "mp_nth_element index out of range" );
template<class U> using F = P<U, T1>;
using part = mp_partition<L<T...>, F>;
using L1 = mp_first<part>;
static std::size_t const N1 = mp_size<L1>::value;
using L2 = mp_second<part>;
using type = typename mp_cond<
mp_bool<(I < N1)>, mp_nth_element_impl<L1, I, P>,
mp_bool<(I == N1)>, mp_identity<T1>,
mp_true, mp_nth_element_impl<L2, I - N1 - 1, P>
>::type;
};
} // namespace detail
template<class L, std::size_t I, template<class...> class P> using mp_nth_element_c = typename detail::mp_nth_element_impl<L, I, P>::type;
template<class L, class I, template<class...> class P> using mp_nth_element = typename detail::mp_nth_element_impl<L, std::size_t{ I::value }, P>::type;
// mp_find<L, V>
namespace detail
{

1
test/Jamfile
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@@ -80,6 +80,7 @@ run mp_with_index_cx.cpp ;
run mp_from_sequence.cpp ;
run mp_min_element.cpp ;
run mp_max_element.cpp ;
run mp_nth_element.cpp ;
# integral
run integral.cpp ;

72
test/mp_nth_element.cpp Normal file
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@@ -0,0 +1,72 @@
// Copyright 2017 Peter Dimov.
//
// 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/mp11/algorithm.hpp>
#include <boost/mp11/list.hpp>
#include <boost/mp11/integral.hpp>
#include <boost/mp11/function.hpp>
#include <boost/core/lightweight_test_trait.hpp>
#include <type_traits>
#include <tuple>
int main()
{
using boost::mp11::mp_nth_element;
using boost::mp11::mp_nth_element_c;
using boost::mp11::mp_list_c;
using boost::mp11::mp_sort;
using boost::mp11::mp_less;
using boost::mp11::mp_at_c;
using boost::mp11::mp_size_t;
using boost::mp11::mp_rename;
{
using L1 = mp_list_c<int, 7, 1, 11, 3, 2, 2, 4>;
using L2 = mp_sort<L1, mp_less>;
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element_c<L1, 0, mp_less>, mp_at_c<L2, 0>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element_c<L1, 1, mp_less>, mp_at_c<L2, 1>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element_c<L1, 2, mp_less>, mp_at_c<L2, 2>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element_c<L1, 3, mp_less>, mp_at_c<L2, 3>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element_c<L1, 4, mp_less>, mp_at_c<L2, 4>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element_c<L1, 5, mp_less>, mp_at_c<L2, 5>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element_c<L1, 6, mp_less>, mp_at_c<L2, 6>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element<L1, mp_size_t<0>, mp_less>, mp_at_c<L2, 0>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element<L1, mp_size_t<1>, mp_less>, mp_at_c<L2, 1>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element<L1, mp_size_t<2>, mp_less>, mp_at_c<L2, 2>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element<L1, mp_size_t<3>, mp_less>, mp_at_c<L2, 3>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element<L1, mp_size_t<4>, mp_less>, mp_at_c<L2, 4>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element<L1, mp_size_t<5>, mp_less>, mp_at_c<L2, 5>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element<L1, mp_size_t<6>, mp_less>, mp_at_c<L2, 6>>));
}
{
using L1 = mp_rename<mp_list_c<int, 7, 1, 11, 3, 2, 2, 4>, std::tuple>;
using L2 = mp_sort<L1, mp_less>;
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element_c<L1, 0, mp_less>, mp_at_c<L2, 0>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element_c<L1, 1, mp_less>, mp_at_c<L2, 1>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element_c<L1, 2, mp_less>, mp_at_c<L2, 2>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element_c<L1, 3, mp_less>, mp_at_c<L2, 3>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element_c<L1, 4, mp_less>, mp_at_c<L2, 4>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element_c<L1, 5, mp_less>, mp_at_c<L2, 5>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element_c<L1, 6, mp_less>, mp_at_c<L2, 6>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element<L1, mp_size_t<0>, mp_less>, mp_at_c<L2, 0>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element<L1, mp_size_t<1>, mp_less>, mp_at_c<L2, 1>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element<L1, mp_size_t<2>, mp_less>, mp_at_c<L2, 2>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element<L1, mp_size_t<3>, mp_less>, mp_at_c<L2, 3>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element<L1, mp_size_t<4>, mp_less>, mp_at_c<L2, 4>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element<L1, mp_size_t<5>, mp_less>, mp_at_c<L2, 5>>));
BOOST_TEST_TRAIT_TRUE((std::is_same<mp_nth_element<L1, mp_size_t<6>, mp_less>, mp_at_c<L2, 6>>));
}
return boost::report_errors();
}