1// Boost.TypeErasure library
2//
3// Copyright 2011 Steven Watanabe
4//
5// Distributed under the Boost Software License Version 1.0. (See
6// accompanying file LICENSE_1_0.txt or copy at
7// http://www.boost.org/LICENSE_1_0.txt)
8//
9// $Id$
10
11#ifndef BOOST_TYPE_ERASURE_ITERATOR_HPP_INCLUDED
12#define BOOST_TYPE_ERASURE_ITERATOR_HPP_INCLUDED
13
14#include <iterator>
15#include <boost/mpl/vector.hpp>
16#include <boost/mpl/if.hpp>
17#include <boost/iterator/iterator_adaptor.hpp>
18#include <boost/iterator/iterator_categories.hpp>
19#include <boost/type_traits/remove_const.hpp>
20#include <boost/type_traits/remove_reference.hpp>
21#include <boost/type_erasure/operators.hpp>
22#include <boost/type_erasure/builtin.hpp>
23#include <boost/type_erasure/deduced.hpp>
24#include <boost/type_erasure/is_placeholder.hpp>
25
26namespace boost {
27
28namespace type_erasure {
29
30/** INTERNAL ONLY */
31template<>
32struct is_placeholder< ::boost::use_default> : ::boost::mpl::false_ {};
33
34namespace detail {
35
36template<class T>
37struct iterator_value_type_impl
38{
39 typedef typename ::std::iterator_traits<T>::value_type type;
40};
41
42}
43
44/** INTERNAL ONLY */
45template<class T>
46struct iterator_value_type
47{
48 typedef typename ::boost::mpl::eval_if<
49 ::boost::type_erasure::is_placeholder<T>,
50 ::boost::mpl::identity<void>,
51 ::boost::type_erasure::detail::iterator_value_type_impl<T>
52 >::type type;
53};
54
55template<
56 class Traversal,
57 class T = _self,
58 class Reference = ::boost::use_default,
59 class DifferenceType = ::std::ptrdiff_t,
60 class ValueType = typename deduced<iterator_value_type<T> >::type
61>
62struct iterator;
63
64#ifdef BOOST_TYPE_ERASURE_DOXYGEN
65
66/**
67 * The @ref iterator concept can be used for any iterator category.
68 *
69 * \tparam Traversal must be one of @c boost::incrementable_traversal_tag,
70 * @c boost::single_pass_traversal_tag, @c boost::forward_traversal_tag,
71 * @c boost::bidirectional_traversal_tag, and @c boost::random_access_traversal_tag.
72 * \tparam T The placeholder representing the iterator.
73 * \tparam Reference The reference type. If it is boost::use_default, then
74 * reference will be value_type&.
75 * \tparam DifferenceType The iterator's difference type.
76 *
77 * The value_type of the iterator is deduced. To force it to be
78 * a specific type, use the @ref same_type concept.
79 *
80 * Example:
81 *
82 * \code
83 * mpl::vector<
84 * iterator<boost::forward_traversal_tag>,
85 * same_type<iterator<boost::forward_traversal_tag>::value_type, int> > int_it;
86 * \endcode
87 */
88template<
89 class Traversal,
90 class T = _self,
91 class Reference = boost::use_default,
92 class DifferenceType = std::ptrdiff_t
93>
94struct iterator
95{
96 typedef detail::unspecified value_type;
97 typedef Reference reference;
98 typedef DifferenceType difference_type;
99};
100
101template<
102 class T = _self,
103 class Reference = boost::use_default,
104 class DifferenceType = std::ptrdiff_t
105>
106struct forward_iterator :
107 iterator<boost::forward_traversal_tag, T, Reference, DifferenceType>
108{};
109
110template<
111 class T = _self,
112 class Reference = boost::use_default,
113 class DifferenceType = std::ptrdiff_t
114>
115struct bidirectional_iterator :
116 iterator<boost::bidirectional_traversal_tag, T, Reference, DifferenceType>
117{};
118
119template<
120 class T = _self,
121 class Reference = boost::use_default,
122 class DifferenceType = std::ptrdiff_t
123>
124struct random_access_iterator :
125 iterator<boost::random_access_traversal_tag, T, Reference, DifferenceType>
126{
127};
128
129#else
130
131/** INTERNAL ONLY */
132template<class Reference, class ValueType>
133struct iterator_reference
134{
135 typedef Reference type;
136};
137
138/** INTERNAL ONLY */
139template<class ValueType>
140struct iterator_reference< ::boost::use_default, ValueType>
141{
142 typedef ValueType& type;
143};
144
145template<class T, class Reference, class DifferenceType, class ValueType>
146struct iterator< ::boost::no_traversal_tag, T, Reference, DifferenceType, ValueType> :
147 boost::mpl::vector<
148 copy_constructible<T>,
149 constructible<T()>,
150 equality_comparable<T>,
151 dereferenceable<typename iterator_reference<Reference, ValueType>::type, T>,
152 assignable<T>
153 >
154{
155 typedef ValueType value_type;
156 typedef typename iterator_reference<Reference, ValueType>::type reference;
157 typedef DifferenceType difference_type;
158};
159
160template<class T, class Reference, class DifferenceType, class ValueType>
161struct iterator< ::boost::incrementable_traversal_tag, T, Reference, DifferenceType, ValueType> :
162 boost::mpl::vector<
163 iterator< ::boost::no_traversal_tag, T, Reference, DifferenceType>,
164 incrementable<T>
165 >
166{
167 typedef ValueType value_type;
168 typedef typename iterator_reference<Reference, ValueType>::type reference;
169 typedef DifferenceType difference_type;
170};
171
172template<class T, class Reference, class DifferenceType, class ValueType>
173struct iterator< ::boost::single_pass_traversal_tag, T, Reference, DifferenceType, ValueType> :
174 iterator< ::boost::incrementable_traversal_tag, T, Reference, DifferenceType, ValueType>
175{};
176
177template<class T, class Reference, class DifferenceType, class ValueType>
178struct iterator< ::boost::forward_traversal_tag, T, Reference, DifferenceType, ValueType> :
179 iterator< ::boost::incrementable_traversal_tag, T, Reference, DifferenceType, ValueType>
180{};
181
182template<class T, class Reference, class DifferenceType, class ValueType>
183struct iterator< ::boost::bidirectional_traversal_tag, T, Reference, DifferenceType, ValueType> :
184 boost::mpl::vector<
185 iterator< ::boost::incrementable_traversal_tag, T, Reference, DifferenceType, ValueType>,
186 decrementable<T>
187 >
188{
189 typedef ValueType value_type;
190 typedef typename iterator_reference<Reference, ValueType>::type reference;
191 typedef DifferenceType difference_type;
192};
193
194template<class T, class Reference, class DifferenceType, class ValueType>
195struct iterator< ::boost::random_access_traversal_tag, T, Reference, DifferenceType, ValueType> :
196 boost::mpl::vector<
197 iterator< ::boost::bidirectional_traversal_tag, T, Reference, DifferenceType, ValueType>,
198 addable<T, DifferenceType, T>,
199 addable<DifferenceType, T, T>,
200 subtractable<T, DifferenceType, T>,
201 subtractable<T, T, DifferenceType>,
202 subscriptable<typename iterator_reference<Reference, ValueType>::type, T, DifferenceType>
203 >
204{
205 typedef ValueType value_type;
206 typedef typename iterator_reference<Reference, ValueType>::type reference;
207 typedef DifferenceType difference_type;
208};
209
210template<
211 class T = _self,
212 class Reference = ::boost::use_default,
213 class DifferenceType = ::std::ptrdiff_t,
214 class ValueType = typename deduced<iterator_value_type<T> >::type
215>
216struct forward_iterator :
217 iterator< ::boost::forward_traversal_tag, T, Reference, DifferenceType, ValueType>
218{};
219
220template<
221 class T = _self,
222 class Reference = ::boost::use_default,
223 class DifferenceType = ::std::ptrdiff_t,
224 class ValueType = typename deduced<iterator_value_type<T> >::type
225>
226struct bidirectional_iterator :
227 iterator< ::boost::bidirectional_traversal_tag, T, Reference, DifferenceType, ValueType>
228{};
229
230template<
231 class T = _self,
232 class Reference = ::boost::use_default,
233 class DifferenceType = ::std::ptrdiff_t,
234 class ValueType = typename deduced<iterator_value_type<T> >::type
235>
236struct random_access_iterator :
237 iterator< ::boost::random_access_traversal_tag, T, Reference, DifferenceType, ValueType>
238{
239};
240
241#endif
242
243/// \cond show_operators
244
245template<class T, class Reference, class DifferenceType, class ValueType, class Base>
246struct concept_interface<iterator< ::boost::no_traversal_tag, T, Reference, DifferenceType, ValueType>, Base, T>
247 : Base
248{
249 typedef typename rebind_any<Base, ValueType>::type value_type;
250 typedef typename rebind_any<
251 Base,
252 typename iterator_reference<Reference, ValueType>::type
253 >::type reference;
254 typedef DifferenceType difference_type;
255 typedef typename ::boost::mpl::if_< ::boost::is_reference<reference>,
256 typename ::boost::remove_reference<reference>::type*,
257 value_type*
258 >::type pointer;
259};
260
261template<class T, class Reference, class DifferenceType, class ValueType, class Base>
262struct concept_interface<iterator< ::boost::forward_traversal_tag, T, Reference, DifferenceType, ValueType>, Base, T>
263 : Base
264{
265 typedef std::forward_iterator_tag iterator_category;
266};
267
268template<class T, class Reference, class DifferenceType, class ValueType, class Base>
269struct concept_interface<forward_iterator<T, Reference, DifferenceType, ValueType>, Base, T>
270 : Base
271{
272 typedef std::forward_iterator_tag iterator_category;
273};
274
275template<class T, class Reference, class DifferenceType, class ValueType, class Base>
276struct concept_interface<iterator< ::boost::bidirectional_traversal_tag, T, Reference, DifferenceType, ValueType>, Base, T>
277 : Base
278{
279 typedef std::bidirectional_iterator_tag iterator_category;
280};
281
282template<class T, class Reference, class DifferenceType, class ValueType, class Base>
283struct concept_interface<bidirectional_iterator<T, Reference, DifferenceType, ValueType>, Base, T>
284 : Base
285{
286 typedef std::bidirectional_iterator_tag iterator_category;
287};
288
289template<class T, class Reference, class DifferenceType, class ValueType, class Base>
290struct concept_interface<iterator< ::boost::random_access_traversal_tag, T, Reference, DifferenceType, ValueType>, Base, T>
291 : Base
292{
293 typedef std::random_access_iterator_tag iterator_category;
294};
295
296template<class T, class Reference, class DifferenceType, class ValueType, class Base>
297struct concept_interface<random_access_iterator<T, Reference, DifferenceType, ValueType>, Base, T>
298 : Base
299{
300 typedef std::random_access_iterator_tag iterator_category;
301};
302
303/// \endcond
304
305}
306}
307
308#endif
309

source code of boost/libs/type_erasure/include/boost/type_erasure/iterator.hpp