1// Copyright David Abrahams, Daniel Wallin 2003.
2// Distributed under the Boost Software License, Version 1.0.
3// (See accompanying file LICENSE_1_0.txt or copy at
4// http://www.boost.org/LICENSE_1_0.txt)
5
6#ifndef BOOST_PARAMETER_AUX_PACK_PREDICATE_HPP
7#define BOOST_PARAMETER_AUX_PACK_PREDICATE_HPP
8
9namespace boost { namespace parameter { namespace aux {
10
11 // helper for get_predicate<...>, below
12 template <typename T>
13 struct get_predicate_or_default
14 {
15 typedef T type;
16 };
17
18 // helper for predicate<...>, below
19 template <typename T>
20 struct get_predicate
21 : ::boost::parameter::aux
22 ::get_predicate_or_default<typename T::predicate>
23 {
24 };
25}}} // namespace boost::parameter::aux
26
27#include <boost/parameter/aux_/use_default.hpp>
28#include <boost/parameter/aux_/always_true_predicate.hpp>
29
30namespace boost { namespace parameter { namespace aux {
31
32 template <>
33 struct get_predicate_or_default< ::boost::parameter::aux::use_default>
34 {
35 typedef ::boost::parameter::aux::always_true_predicate type;
36 };
37}}} // namespace boost::parameter::aux
38
39#include <boost/parameter/required.hpp>
40#include <boost/parameter/optional.hpp>
41#include <boost/parameter/config.hpp>
42
43#if defined(BOOST_PARAMETER_CAN_USE_MP11)
44#include <boost/mp11/integral.hpp>
45#include <boost/mp11/utility.hpp>
46#else
47#include <boost/mpl/bool.hpp>
48#include <boost/mpl/if.hpp>
49#include <boost/mpl/eval_if.hpp>
50#include <boost/mpl/identity.hpp>
51#endif
52
53namespace boost { namespace parameter { namespace aux {
54
55 template <typename T>
56#if defined(BOOST_PARAMETER_CAN_USE_MP11)
57 using predicate = ::boost::mp11::mp_if<
58 ::boost::mp11::mp_if<
59 ::boost::parameter::aux::is_optional<T>
60 , ::boost::mp11::mp_true
61 , ::boost::parameter::aux::is_required<T>
62 >
63 , ::boost::parameter::aux::get_predicate<T>
64 , ::boost::mp11::mp_identity<
65 ::boost::parameter::aux::always_true_predicate
66 >
67 >;
68#else
69 struct predicate
70 : ::boost::mpl::eval_if<
71 typename ::boost::mpl::if_<
72 ::boost::parameter::aux::is_optional<T>
73 , ::boost::mpl::true_
74 , ::boost::parameter::aux::is_required<T>
75 >::type
76 , ::boost::parameter::aux::get_predicate<T>
77 , ::boost::mpl::identity<
78 ::boost::parameter::aux::always_true_predicate
79 >
80 >
81 {
82 };
83#endif // BOOST_PARAMETER_CAN_USE_MP11
84}}} // namespace boost::parameter::aux
85
86#endif // include guard
87
88

source code of boost/libs/parameter/include/boost/parameter/aux_/pack/predicate.hpp