1
2// (C) Copyright John Maddock 2017.
3// Use, modification and distribution are subject to the Boost Software License,
4// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
5// http://www.boost.org/LICENSE_1_0.txt).
6//
7// See http://www.boost.org/libs/type_traits for most recent version including documentation.
8
9#ifndef BOOST_TT_IS_COMPLETE_HPP_INCLUDED
10#define BOOST_TT_IS_COMPLETE_HPP_INCLUDED
11
12#include <boost/type_traits/integral_constant.hpp>
13#include <boost/type_traits/remove_reference.hpp>
14#include <boost/type_traits/is_function.hpp>
15#include <boost/config/workaround.hpp>
16
17/*
18 * CAUTION:
19 * ~~~~~~~~
20 *
21 * THIS TRAIT EXISTS SOLELY TO GENERATE HARD ERRORS WHEN A ANOTHER TRAIT
22 * WHICH REQUIRES COMPLETE TYPES AS ARGUMENTS IS PASSED AN INCOMPLETE TYPE
23 *
24 * DO NOT MAKE GENERAL USE OF THIS TRAIT, AS THE COMPLETENESS OF A TYPE
25 * VARIES ACROSS TRANSLATION UNITS AS WELL AS WITHIN A SINGLE UNIT.
26 *
27*/
28
29namespace boost {
30
31
32//
33// We will undef this if the trait isn't fully functional:
34//
35#define BOOST_TT_HAS_WORKING_IS_COMPLETE
36
37#if !defined(BOOST_NO_SFINAE_EXPR) && !BOOST_WORKAROUND(BOOST_MSVC, <= 1900) && !BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40600)
38
39 namespace detail{
40
41 template <unsigned N>
42 struct ok_tag { double d; char c[N]; };
43
44 template <class T>
45 ok_tag<sizeof(T)> check_is_complete(int);
46 template <class T>
47 char check_is_complete(...);
48 }
49
50 template <class T> struct is_complete
51 : public integral_constant<bool, ::boost::is_function<typename boost::remove_reference<T>::type>::value || (sizeof(detail::check_is_complete<T>(0)) != sizeof(char))> {};
52
53#elif !defined(BOOST_NO_SFINAE) && !defined(BOOST_NO_CXX11_FUNCTION_TEMPLATE_DEFAULT_ARGS) && !BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40500)
54
55 namespace detail
56 {
57
58 template <class T>
59 struct is_complete_imp
60 {
61 template <class U, class = decltype(sizeof(std::declval< U >())) >
62 static type_traits::yes_type check(U*);
63
64 template <class U>
65 static type_traits::no_type check(...);
66
67 static const bool value = sizeof(check<T>(0)) == sizeof(type_traits::yes_type);
68 };
69
70} // namespace detail
71
72
73 template <class T>
74 struct is_complete : boost::integral_constant<bool, ::boost::is_function<typename boost::remove_reference<T>::type>::value || ::boost::detail::is_complete_imp<T>::value>
75 {};
76 template <class T>
77 struct is_complete<T&> : boost::is_complete<T> {};
78
79#else
80
81 template <class T> struct is_complete
82 : public boost::integral_constant<bool, true> {};
83
84#undef BOOST_TT_HAS_WORKING_IS_COMPLETE
85
86#endif
87
88} // namespace boost
89
90#endif // BOOST_TT_IS_COMPLETE_HPP_INCLUDED
91