1 // Copyright (C) 2007 Peder Holt
2 
3 // Use, modification and distribution is subject to the Boost Software
4 // License, Version 1.0. (http://www.boost.org/LICENSE_1_0.txt)
5 
6 #ifndef BOOST_TYPEOF_MSVC_TYPEOF_IMPL_HPP_INCLUDED
7 # define BOOST_TYPEOF_MSVC_TYPEOF_IMPL_HPP_INCLUDED
8 
9 # include <boost/config.hpp>
10 # include <boost/config/workaround.hpp>
11 # include <boost/typeof/constant.hpp>
12 
13 namespace boost
14 {
15     namespace type_of
16     {
17 
18         template<int N> struct encode_counter : encode_counter<N - 1> {};
19         template<> struct encode_counter<0> {};
20 
21         char (*encode_index(...))[1];
22 
23 # define BOOST_TYPEOF_INDEX(T) (sizeof(*boost::type_of::encode_index((boost::type_of::encode_counter<1000>*)0)))
24 # define BOOST_TYPEOF_NEXT_INDEX(next) friend char (*encode_index(encode_counter<next>*))[next];
25 
26 
27         //Typeof code
28 
29         template<typename ID>
30         struct msvc_extract_type
31         {
32             struct id2type;
33         };
34 
35         template<typename T, typename ID>
36         struct msvc_register_type : msvc_extract_type<ID>
37         {
38             typedef msvc_extract_type<ID> base_type;
39             struct base_type::id2type // This uses nice VC6.5 and VC7.1 bugfeature, also works for Digital Mars
40             {
41                 typedef T type;
42             };
43         };
44 
45 
46         template<int ID>
47         struct msvc_typeid_wrapper {
48             typedef typename msvc_extract_type<constant<int,ID> >::id2type id2type;
49             typedef typename id2type::type type;
50         };
51 
52         //Tie it all together
53         template<typename T>
54         struct encode_type
55         {
56             //Get the next available compile time constants index
57             BOOST_STATIC_CONSTANT(unsigned,value=BOOST_TYPEOF_INDEX(T));
58             //Instantiate the template
59             typedef typename msvc_register_type<T,constant<int,value> >::id2type type;
60             //Set the next compile time constants index
61             BOOST_STATIC_CONSTANT(unsigned,next=value+1);
62             //Increment the compile time constant (only needed when extensions are not active
63             BOOST_TYPEOF_NEXT_INDEX(next);
64         };
65 
66         template<class T>
67         struct sizer
68         {
69             typedef char(*type)[encode_type<T>::value];
70         };
71 
72         template<typename T>
73             typename sizer<T>::type encode_start(T const&);
74 
75         template<typename Organizer, typename T>
76         msvc_register_type<T,Organizer> typeof_register_type(const T&,Organizer* =0);
77 
78 # define BOOST_TYPEOF(expr) \
79     boost::type_of::msvc_typeid_wrapper<sizeof(*boost::type_of::encode_start(expr))>::type
80 
81 # define BOOST_TYPEOF_TPL(expr) typename BOOST_TYPEOF(expr)
82 
83 # define BOOST_TYPEOF_NESTED_TYPEDEF_TPL(name,expr) \
84     struct name {\
85         BOOST_STATIC_CONSTANT(int,_typeof_register_value=sizeof(boost::type_of::typeof_register_type<name>(expr)));\
86         typedef typename boost::type_of::msvc_extract_type<name>::id2type id2type;\
87         typedef typename id2type::type type;\
88     };
89 
90 # define BOOST_TYPEOF_NESTED_TYPEDEF(name,expr) \
91     struct name {\
92         BOOST_STATIC_CONSTANT(int,_typeof_register_value=sizeof(boost::type_of::typeof_register_type<name>(expr)));\
93         typedef boost::type_of::msvc_extract_type<name>::id2type id2type;\
94         typedef id2type::type type;\
95     };
96 
97     }
98 }
99 
100 #endif//BOOST_TYPEOF_MSVC_TYPEOF_IMPL_HPP_INCLUDED
101