1//-----------------------------------------------------------------------------
2// boost variant/detail/initializer.hpp header file
3// See http://www.boost.org for updates, documentation, and revision history.
4//-----------------------------------------------------------------------------
5//
6// Copyright (c) 2002-2003
7// Eric Friedman, Itay Maman
8//
9// Distributed under the Boost Software License, Version 1.0. (See
10// accompanying file LICENSE_1_0.txt or copy at
11// http://www.boost.org/LICENSE_1_0.txt)
12
13#ifndef BOOST_VARIANT_DETAIL_INITIALIZER_HPP
14#define BOOST_VARIANT_DETAIL_INITIALIZER_HPP
15
16#include <new> // for placement new
17
18#include <boost/config.hpp>
19
20#include <boost/call_traits.hpp>
21#include <boost/detail/reference_content.hpp>
22#include <boost/variant/recursive_wrapper_fwd.hpp>
23#include <boost/variant/detail/move.hpp>
24
25#if !defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE)
26# include <boost/mpl/aux_/value_wknd.hpp>
27# include <boost/mpl/int.hpp>
28# include <boost/mpl/iter_fold.hpp>
29# include <boost/mpl/next.hpp>
30# include <boost/mpl/deref.hpp>
31# include <boost/mpl/pair.hpp>
32# include <boost/mpl/protect.hpp>
33#else
34# include <boost/variant/variant_fwd.hpp>
35# include <boost/preprocessor/cat.hpp>
36# include <boost/preprocessor/enum.hpp>
37# include <boost/preprocessor/repeat.hpp>
38#endif
39
40namespace boost {
41namespace detail { namespace variant {
42
43///////////////////////////////////////////////////////////////////////////////
44// (detail) support to simulate standard overload resolution rules
45//
46// The below initializers allows variant to follow standard overload
47// resolution rules over the specified set of bounded types.
48//
49// On compilers where using declarations in class templates can correctly
50// avoid name hiding, use an optimal solution based on the variant's typelist.
51//
52// Otherwise, use a preprocessor workaround based on knowledge of the fixed
53// size of the variant's psuedo-variadic template parameter list.
54//
55
56#if !defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE)
57
58// (detail) quoted metafunction make_initializer_node
59//
60// Exposes a pair whose first type is a node in the initializer hierarchy.
61//
62struct make_initializer_node
63{
64 template <typename BaseIndexPair, typename Iterator>
65 struct apply
66 {
67 private: // helpers, for metafunction result (below)
68
69 typedef typename BaseIndexPair::first
70 base;
71 typedef typename BaseIndexPair::second
72 index;
73
74 class initializer_node
75 : public base
76 {
77 private: // helpers, for static functions (below)
78
79 typedef typename mpl::deref<Iterator>::type
80 recursive_enabled_T;
81 typedef typename unwrap_recursive<recursive_enabled_T>::type
82 public_T;
83
84#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
85 typedef boost::is_reference<public_T>
86 is_reference_content_t;
87
88 typedef typename boost::mpl::if_<is_reference_content_t, public_T, const public_T& >::type
89 param_T;
90
91 template <class T> struct disable_overload{};
92
93 typedef typename boost::mpl::if_<is_reference_content_t, disable_overload<public_T>, public_T&& >::type
94 param2_T;
95#else
96 typedef typename call_traits<public_T>::param_type
97 param_T;
98#endif
99
100 public: // static functions
101
102 using base::initialize;
103
104 static int initialize(void* dest, param_T operand)
105 {
106 typedef typename boost::detail::make_reference_content<
107 recursive_enabled_T
108 >::type internal_T;
109
110 new(dest) internal_T(operand);
111 return BOOST_MPL_AUX_VALUE_WKND(index)::value; // which
112 }
113
114#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
115 static int initialize(void* dest, param2_T operand)
116 {
117 // This assert must newer trigger, because all the reference contents are
118 // handled by the initilize(void* dest, param_T operand) function above
119 BOOST_ASSERT(!is_reference_content_t::value);
120
121 typedef typename boost::mpl::if_<is_reference_content_t, param2_T, recursive_enabled_T>::type value_T;
122 new(dest) value_T( boost::detail::variant::move(operand) );
123 return BOOST_MPL_AUX_VALUE_WKND(index)::value; // which
124 }
125#endif
126 };
127
128 friend class initializer_node;
129
130 public: // metafunction result
131
132 typedef mpl::pair<
133 initializer_node
134 , typename mpl::next< index >::type
135 > type;
136
137 };
138};
139
140// (detail) class initializer_root
141//
142// Every level of the initializer hierarchy must expose the name
143// "initialize," so initializer_root provides a dummy function:
144//
145class initializer_root
146{
147public: // static functions
148
149 static void initialize();
150
151};
152
153#else // defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE)
154
155 // Obsolete. Remove.
156 #define BOOST_VARIANT_AUX_PP_INITIALIZER_TEMPLATE_PARAMS \
157 BOOST_VARIANT_ENUM_PARAMS(typename recursive_enabled_T) \
158 /**/
159
160 // Obsolete. Remove.
161 #define BOOST_VARIANT_AUX_PP_INITIALIZER_DEFINE_PARAM_T(N) \
162 typedef typename unwrap_recursive< \
163 BOOST_PP_CAT(recursive_enabled_T,N) \
164 >::type BOOST_PP_CAT(public_T,N); \
165 typedef typename call_traits< \
166 BOOST_PP_CAT(public_T,N) \
167 >::param_type BOOST_PP_CAT(param_T,N); \
168 /**/
169
170template < BOOST_VARIANT_ENUM_PARAMS(typename recursive_enabled_T) >
171struct preprocessor_list_initializer
172{
173public: // static functions
174
175 #define BOOST_VARIANT_AUX_PP_INITIALIZE_FUNCTION(z,N,_) \
176 typedef typename unwrap_recursive< \
177 BOOST_PP_CAT(recursive_enabled_T,N) \
178 >::type BOOST_PP_CAT(public_T,N); \
179 typedef typename call_traits< \
180 BOOST_PP_CAT(public_T,N) \
181 >::param_type BOOST_PP_CAT(param_T,N); \
182 static int initialize( \
183 void* dest \
184 , BOOST_PP_CAT(param_T,N) operand \
185 ) \
186 { \
187 typedef typename boost::detail::make_reference_content< \
188 BOOST_PP_CAT(recursive_enabled_T,N) \
189 >::type internal_T; \
190 \
191 new(dest) internal_T(operand); \
192 return (N); /*which*/ \
193 } \
194 /**/
195
196 BOOST_PP_REPEAT(
197 BOOST_VARIANT_LIMIT_TYPES
198 , BOOST_VARIANT_AUX_PP_INITIALIZE_FUNCTION
199 , _
200 )
201
202 #undef BOOST_VARIANT_AUX_PP_INITIALIZE_FUNCTION
203
204};
205
206#endif // BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE workaround
207
208}} // namespace detail::variant
209} // namespace boost
210
211///////////////////////////////////////////////////////////////////////////////
212// macro BOOST_VARIANT_AUX_INITIALIZER_T
213//
214// Given both the variant's typelist and a basename for forming the list of
215// bounded types (i.e., T becomes T1, T2, etc.), exposes the initializer
216// most appropriate to the current compiler.
217//
218
219#if !defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE)
220
221#define BOOST_VARIANT_AUX_INITIALIZER_T( mpl_seq, typename_base ) \
222 ::boost::mpl::iter_fold< \
223 mpl_seq \
224 , ::boost::mpl::pair< \
225 ::boost::detail::variant::initializer_root \
226 , ::boost::mpl::int_<0> \
227 > \
228 , ::boost::mpl::protect< \
229 ::boost::detail::variant::make_initializer_node \
230 > \
231 >::type::first \
232 /**/
233
234#else // defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE)
235
236 // Obsolete. Remove.
237 #define BOOST_VARIANT_AUX_PP_INITIALIZER_TEMPLATE_ARGS(typename_base) \
238 BOOST_VARIANT_ENUM_PARAMS(typename_base) \
239 /**/
240
241#define BOOST_VARIANT_AUX_INITIALIZER_T( mpl_seq, typename_base ) \
242 ::boost::detail::variant::preprocessor_list_initializer< \
243 BOOST_VARIANT_ENUM_PARAMS(typename_base) \
244 > \
245 /**/
246
247#endif // BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE workaround
248
249#endif // BOOST_VARIANT_DETAIL_INITIALIZER_HPP
250