source: NonGTP/Boost/boost/detail/ob_call_traits.hpp @ 857

Revision 857, 3.9 KB checked in by igarcia, 19 years ago (diff)
RevLine 
[857]1//  (C) Copyright Steve Cleary, Beman Dawes, Howard Hinnant & John Maddock 2000.
2//  Use, modification and distribution are subject to the Boost Software License,
3//  Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
4//  http://www.boost.org/LICENSE_1_0.txt).
5//
6//  See http://www.boost.org/libs/utility for most recent version including documentation.
7//
8//  Crippled version for crippled compilers:
9//  see libs/utility/call_traits.htm
10//
11
12/* Release notes:
13   01st October 2000:
14      Fixed call_traits on VC6, using "poor man's partial specialisation",
15      using ideas taken from "Generative programming" by Krzysztof Czarnecki
16      & Ulrich Eisenecker.
17*/
18
19#ifndef BOOST_OB_CALL_TRAITS_HPP
20#define BOOST_OB_CALL_TRAITS_HPP
21
22#ifndef BOOST_CONFIG_HPP
23#include <boost/config.hpp>
24#endif
25
26#ifndef BOOST_ARITHMETIC_TYPE_TRAITS_HPP
27#include <boost/type_traits/arithmetic_traits.hpp>
28#endif
29#ifndef BOOST_COMPOSITE_TYPE_TRAITS_HPP
30#include <boost/type_traits/composite_traits.hpp>
31#endif
32
33namespace boost{
34
35#ifdef BOOST_MSVC6_MEMBER_TEMPLATES
36//
37// use member templates to emulate
38// partial specialisation:
39//
40namespace detail{
41
42template <class T>
43struct standard_call_traits
44{
45   typedef T value_type;
46   typedef T& reference;
47   typedef const T& const_reference;
48   typedef const T& param_type;
49};
50template <class T>
51struct simple_call_traits
52{
53   typedef T value_type;
54   typedef T& reference;
55   typedef const T& const_reference;
56   typedef const T param_type;
57};
58template <class T>
59struct reference_call_traits
60{
61   typedef T value_type;
62   typedef T reference;
63   typedef T const_reference;
64   typedef T param_type;
65};
66
67template <bool pointer, bool arithmetic, bool reference>
68struct call_traits_chooser
69{
70   template <class T>
71   struct rebind
72   {
73      typedef standard_call_traits<T> type;
74   };
75};
76
77template <>
78struct call_traits_chooser<true, false, false>
79{
80   template <class T>
81   struct rebind
82   {
83      typedef simple_call_traits<T> type;
84   };
85};
86
87template <>
88struct call_traits_chooser<false, false, true>
89{
90   template <class T>
91   struct rebind
92   {
93      typedef reference_call_traits<T> type;
94   };
95};
96
97template <bool size_is_small>
98struct call_traits_sizeof_chooser2
99{
100   template <class T>
101   struct small_rebind
102   {
103      typedef simple_call_traits<T> small_type;
104   };
105};
106
107template<>
108struct call_traits_sizeof_chooser2<false>
109{
110   template <class T>
111   struct small_rebind
112   {
113      typedef standard_call_traits<T> small_type;
114   };
115};
116
117template <>
118struct call_traits_chooser<false, true, false>
119{
120   template <class T>
121   struct rebind
122   {
123      enum { sizeof_choice = (sizeof(T) <= sizeof(void*)) };
124      typedef call_traits_sizeof_chooser2<(sizeof(T) <= sizeof(void*))> chooser;
125      typedef typename chooser::template small_rebind<T> bound_type;
126      typedef typename bound_type::small_type type;
127   };
128};
129
130} // namespace detail
131template <typename T>
132struct call_traits
133{
134private:
135    typedef detail::call_traits_chooser<
136         ::boost::is_pointer<T>::value,
137         ::boost::is_arithmetic<T>::value,
138         ::boost::is_reference<T>::value
139      > chooser;
140   typedef typename chooser::template rebind<T> bound_type;
141   typedef typename bound_type::type call_traits_type;
142public:
143   typedef typename call_traits_type::value_type       value_type;
144   typedef typename call_traits_type::reference        reference;
145   typedef typename call_traits_type::const_reference  const_reference;
146   typedef typename call_traits_type::param_type       param_type;
147};
148
149#else
150//
151// sorry call_traits is completely non-functional
152// blame your broken compiler:
153//
154
155template <typename T>
156struct call_traits
157{
158   typedef T value_type;
159   typedef T& reference;
160   typedef const T& const_reference;
161   typedef const T& param_type;
162};
163
164#endif // member templates
165
166}
167
168#endif // BOOST_OB_CALL_TRAITS_HPP
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