1#ifndef BOOST_MP11_DETAIL_MP_COPY_IF_HPP_INCLUDED
2#define BOOST_MP11_DETAIL_MP_COPY_IF_HPP_INCLUDED
3
4// Copyright 2015-2019 Peter Dimov.
5//
6// Distributed under the Boost Software License, Version 1.0.
7//
8// See accompanying file LICENSE_1_0.txt or copy at
9// http://www.boost.org/LICENSE_1_0.txt
10
11#include <boost/mp11/utility.hpp>
12#include <boost/mp11/detail/mp_list.hpp>
13#include <boost/mp11/detail/mp_append.hpp>
14#include <boost/mp11/detail/config.hpp>
15
16namespace boost
17{
18namespace mp11
19{
20
21// mp_copy_if<L, P>
22namespace detail
23{
24
25template<class L, template<class...> class P> struct mp_copy_if_impl
26{
27};
28
29template<template<class...> class L, class... T, template<class...> class P> struct mp_copy_if_impl<L<T...>, P>
30{
31#if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, < 1920 )
32 template<class U> struct _f { using type = mp_if<P<U>, mp_list<U>, mp_list<>>; };
33 using type = mp_append<L<>, typename _f<T>::type...>;
34#else
35 template<class U> using _f = mp_if<P<U>, mp_list<U>, mp_list<>>;
36 using type = mp_append<L<>, _f<T>...>;
37#endif
38};
39
40} // namespace detail
41
42template<class L, template<class...> class P> using mp_copy_if = typename detail::mp_copy_if_impl<L, P>::type;
43template<class L, class Q> using mp_copy_if_q = mp_copy_if<L, Q::template fn>;
44
45} // namespace mp11
46} // namespace boost
47
48#endif // #ifndef BOOST_MP11_DETAIL_MP_COPY_IF_HPP_INCLUDED
49

source code of include/boost/mp11/detail/mp_copy_if.hpp