forked from boostorg/mp11
59 lines
1.7 KiB
C++
59 lines
1.7 KiB
C++
// Copyright 2023 Jody Hagins
|
|
// Distributed under the Boost Software License, Version 1.0.
|
|
// https://www.boost.org/LICENSE_1_0.txt
|
|
|
|
#include <boost/mp11.hpp>
|
|
using namespace boost::mp11;
|
|
|
|
// A simple metafunction that takes the first three items from a list
|
|
template <typename T>
|
|
using take3 = mp_take<T, mp_int<3>>;
|
|
|
|
// Directly call take3
|
|
static_assert(mp_same<
|
|
take3<mp_iota_c<9>>,
|
|
mp_list<mp_size_t<0>, mp_size_t<1>, mp_size_t<2>>>::value, "");
|
|
|
|
// Invoke a quoted take3 (mp_quote<take3>)
|
|
static_assert(mp_same<
|
|
mp_invoke_q<mp_quote<take3>, mp_iota_c<9>>,
|
|
mp_list<mp_size_t<0>, mp_size_t<1>, mp_size_t<2>>>::value, "");
|
|
|
|
#if !BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, < 1900 )
|
|
|
|
// Invoke a composed take3 (mp_compose<take3>)
|
|
static_assert(mp_same<
|
|
mp_invoke_q<mp_compose<take3>, mp_iota_c<9>>,
|
|
mp_list<mp_size_t<0>, mp_size_t<1>, mp_size_t<2>>>::value, "");
|
|
|
|
#endif
|
|
|
|
// If we apply the following iteration, we expect to get all triplets of the list.
|
|
using expected = mp_list<
|
|
mp_list<mp_size_t<0>, mp_size_t<1>, mp_size_t<2>>,
|
|
mp_list<mp_size_t<3>, mp_size_t<4>, mp_size_t<5>>,
|
|
mp_list<mp_size_t<6>, mp_size_t<7>, mp_size_t<8>>>;
|
|
|
|
// First using mp_quote - this works as expected
|
|
static_assert(
|
|
mp_same<
|
|
mp_iterate_q<
|
|
mp_iota_c<9>,
|
|
mp_quote<take3>,
|
|
mp_bind_back<mp_drop, mp_int<3>>>,
|
|
expected>::value, "");
|
|
|
|
#if !BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, < 1900 )
|
|
|
|
// Next, simply replace mp_quote with mp_compose. We expect to get the same answer,
|
|
// but we get a hard compiler error instead.
|
|
static_assert(
|
|
mp_same<
|
|
mp_iterate_q<
|
|
mp_iota_c<9>,
|
|
mp_compose<take3>,
|
|
mp_bind_back<mp_drop, mp_int<3>>>,
|
|
expected>::value, "");
|
|
|
|
#endif
|