source: NonGTP/Boost/boost/iterator/iterator_archetypes.hpp @ 857

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1// (C) Copyright Jeremy Siek 2002.
2// Distributed under the Boost Software License, Version 1.0. (See
3// accompanying file LICENSE_1_0.txt or copy at
4// http://www.boost.org/LICENSE_1_0.txt)
5
6#ifndef BOOST_ITERATOR_ARCHETYPES_HPP
7#define BOOST_ITERATOR_ARCHETYPES_HPP
8
9#include <boost/iterator/iterator_categories.hpp>
10#include <boost/operators.hpp>
11#include <boost/static_assert.hpp>
12#include <boost/iterator.hpp>
13
14#include <boost/iterator/detail/facade_iterator_category.hpp>
15
16#include <boost/type_traits/is_const.hpp>
17#include <boost/type_traits/add_const.hpp>
18#include <boost/type_traits/remove_const.hpp>
19#include <boost/type_traits/remove_cv.hpp>
20
21#include <boost/concept_archetype.hpp>
22
23#include <boost/mpl/aux_/msvc_eti_base.hpp>
24#include <boost/mpl/bitand.hpp>
25#include <boost/mpl/int.hpp>
26#include <boost/mpl/equal_to.hpp>
27#include <boost/mpl/if.hpp>
28#include <boost/mpl/eval_if.hpp>
29#include <boost/mpl/and.hpp>
30#include <boost/mpl/identity.hpp>
31
32#include <cstddef>
33
34namespace boost {
35
36template <class Value, class AccessCategory>
37struct access_archetype;
38
39template <class Derived, class Value, class AccessCategory, class TraversalCategory>
40struct traversal_archetype;
41
42namespace iterator_archetypes
43{
44  enum {
45      readable_iterator_bit = 1
46    , writable_iterator_bit = 2
47    , swappable_iterator_bit = 4
48    , lvalue_iterator_bit = 8
49  };
50
51  // Not quite tags, since dispatching wouldn't work.
52  typedef mpl::int_<readable_iterator_bit>::type readable_iterator_t;
53  typedef mpl::int_<writable_iterator_bit>::type writable_iterator_t;
54 
55  typedef mpl::int_<
56      (readable_iterator_bit|writable_iterator_bit)
57          >::type readable_writable_iterator_t;
58 
59  typedef mpl::int_<
60      (readable_iterator_bit|lvalue_iterator_bit)
61          >::type readable_lvalue_iterator_t;
62 
63  typedef mpl::int_<
64      (lvalue_iterator_bit|writable_iterator_bit)
65          >::type writable_lvalue_iterator_t;
66 
67  typedef mpl::int_<swappable_iterator_bit>::type swappable_iterator_t;
68  typedef mpl::int_<lvalue_iterator_bit>::type lvalue_iterator_t;
69
70  template <class Derived, class Base>
71  struct has_access
72    : mpl::equal_to<
73          mpl::bitand_<Derived,Base>
74        , Base
75      >
76  {};
77}
78
79namespace detail
80{
81  template <class T>
82  struct assign_proxy
83  {
84      assign_proxy& operator=(T) { return *this; }
85  };
86
87  template <class T>
88  struct read_proxy
89  {
90      operator T() { return static_object<T>::get(); }
91  };
92
93  template <class T>
94  struct read_write_proxy
95    : read_proxy<T> // Use to inherit from assign_proxy, but that doesn't work. -JGS
96  {
97      read_write_proxy& operator=(T) { return *this; }
98  };
99
100  template <class T>
101  struct arrow_proxy
102  {
103      T const* operator->() const { return 0; }
104  };
105
106  struct no_operator_brackets {};
107
108  template <class ValueType>
109  struct readable_operator_brackets
110  {
111      read_proxy<ValueType> operator[](std::ptrdiff_t n) const { return read_proxy<ValueType>(); }
112  };
113
114  template <class ValueType>
115  struct writable_operator_brackets
116  {
117      read_write_proxy<ValueType> operator[](std::ptrdiff_t n) const { return read_write_proxy<ValueType>(); }
118  };
119
120  template <class Value, class AccessCategory, class TraversalCategory>
121  struct operator_brackets
122    : mpl::aux::msvc_eti_base<
123          typename mpl::eval_if<
124              is_convertible<TraversalCategory, random_access_traversal_tag>
125            , mpl::eval_if<
126                  iterator_archetypes::has_access<
127                      AccessCategory
128                    , iterator_archetypes::writable_iterator_t
129                  >
130                , mpl::identity<writable_operator_brackets<Value> >
131                , mpl::if_<
132                      iterator_archetypes::has_access<
133                          AccessCategory
134                        , iterator_archetypes::readable_iterator_t
135                      >
136                    , readable_operator_brackets<Value>
137                    , no_operator_brackets
138                  >
139              >
140            , mpl::identity<no_operator_brackets>
141          >::type
142      >::type
143  {};
144 
145  template <class TraversalCategory>
146  struct traversal_archetype_impl
147  {
148      template <class Derived,class Value> struct archetype;
149  };
150
151  // Constructor argument for those iterators that
152  // are not default constructible
153  struct ctor_arg {};
154
155  template <class Derived, class Value, class TraversalCategory>
156  struct traversal_archetype_
157    : mpl::aux::msvc_eti_base<
158          typename traversal_archetype_impl<TraversalCategory>::template archetype<Derived,Value>
159      >::type
160  {
161      typedef typename
162        traversal_archetype_impl<TraversalCategory>::template archetype<Derived,Value>
163      base;
164     
165      traversal_archetype_() {}
166
167      traversal_archetype_(ctor_arg arg)
168        : base(arg)
169      {}
170  };
171
172  template <>
173  struct traversal_archetype_impl<incrementable_traversal_tag>
174  {
175      template<class Derived, class Value>
176      struct archetype
177      {
178          explicit archetype(ctor_arg) {}
179
180          struct bogus { }; // This use to be void, but that causes trouble for iterator_facade. Need more research. -JGS
181          typedef bogus difference_type;
182
183          Derived& operator++() { return (Derived&)static_object<Derived>::get(); }
184          Derived  operator++(int) const { return (Derived&)static_object<Derived>::get(); }
185      };
186  };
187
188  template <>
189  struct traversal_archetype_impl<single_pass_traversal_tag>
190  {
191      template<class Derived, class Value>
192      struct archetype
193        : public equality_comparable< traversal_archetype_<Derived, Value, single_pass_traversal_tag> >,
194          public traversal_archetype_<Derived, Value, incrementable_traversal_tag>
195      {
196          explicit archetype(ctor_arg arg)
197            : traversal_archetype_<Derived, Value, incrementable_traversal_tag>(arg)
198          {}
199      };
200  };
201
202  template <class Derived, class Value>
203  bool operator==(traversal_archetype_<Derived, Value, single_pass_traversal_tag> const&,
204                  traversal_archetype_<Derived, Value, single_pass_traversal_tag> const&) { return true; }
205 
206#if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
207  // doesn't seem to pick up != from equality_comparable
208  template <class Derived, class Value>
209  bool operator!=(traversal_archetype_<Derived, Value, single_pass_traversal_tag> const&,
210                  traversal_archetype_<Derived, Value, single_pass_traversal_tag> const&) { return true; }
211#endif
212  template <>
213  struct traversal_archetype_impl<forward_traversal_tag>
214  {
215      template<class Derived, class Value>
216      struct archetype
217        : public traversal_archetype_<Derived, Value, single_pass_traversal_tag>
218      {
219          archetype()
220            : traversal_archetype_<Derived, Value, single_pass_traversal_tag>(ctor_arg())
221          {}
222          typedef std::ptrdiff_t difference_type;
223      };
224  };
225
226  template <>
227  struct traversal_archetype_impl<bidirectional_traversal_tag>
228  {
229      template<class Derived, class Value>
230      struct archetype
231        : public traversal_archetype_<Derived, Value, forward_traversal_tag>
232      {
233          Derived& operator--() { return static_object<Derived>::get(); }
234          Derived  operator--(int) const { return static_object<Derived>::get(); }
235      };
236  };
237
238  template <>
239  struct traversal_archetype_impl<random_access_traversal_tag>
240  {
241      template<class Derived, class Value>
242      struct archetype
243        : public traversal_archetype_<Derived, Value, bidirectional_traversal_tag>
244      {
245          Derived& operator+=(std::ptrdiff_t) { return static_object<Derived>::get(); }
246          Derived& operator-=(std::ptrdiff_t) { return static_object<Derived>::get(); }
247      };
248  };
249
250  template <class Derived, class Value>
251  Derived& operator+(traversal_archetype_<Derived, Value, random_access_traversal_tag> const&,
252                     std::ptrdiff_t) { return static_object<Derived>::get(); }
253
254  template <class Derived, class Value>
255  Derived& operator+(std::ptrdiff_t,
256                     traversal_archetype_<Derived, Value, random_access_traversal_tag> const&)
257      { return static_object<Derived>::get(); }
258
259  template <class Derived, class Value>
260  Derived& operator-(traversal_archetype_<Derived, Value, random_access_traversal_tag> const&,
261                     std::ptrdiff_t)
262      { return static_object<Derived>::get(); }
263
264  template <class Derived, class Value>
265  std::ptrdiff_t operator-(traversal_archetype_<Derived, Value, random_access_traversal_tag> const&,
266                           traversal_archetype_<Derived, Value, random_access_traversal_tag> const&)
267      { return 0; }
268
269  template <class Derived, class Value>
270  bool operator<(traversal_archetype_<Derived, Value, random_access_traversal_tag> const&,
271                 traversal_archetype_<Derived, Value, random_access_traversal_tag> const&)
272      { return true; }
273
274  template <class Derived, class Value>
275  bool operator>(traversal_archetype_<Derived, Value, random_access_traversal_tag> const&,
276                 traversal_archetype_<Derived, Value, random_access_traversal_tag> const&)
277      { return true; }
278
279  template <class Derived, class Value>
280  bool operator<=(traversal_archetype_<Derived, Value, random_access_traversal_tag> const&,
281                 traversal_archetype_<Derived, Value, random_access_traversal_tag> const&)
282      { return true; }
283
284  template <class Derived, class Value>
285  bool operator>=(traversal_archetype_<Derived, Value, random_access_traversal_tag> const&,
286                 traversal_archetype_<Derived, Value, random_access_traversal_tag> const&)
287      { return true; }
288
289  struct bogus_type;
290
291  template <class Value>
292  struct convertible_type
293    : mpl::if_< is_const<Value>,
294                typename remove_const<Value>::type,
295                bogus_type >
296  {};
297
298} // namespace detail
299
300
301template <class> struct undefined;
302 
303template <class AccessCategory>
304struct iterator_access_archetype_impl
305{
306    template <class Value> struct archetype;
307};
308
309template <class Value, class AccessCategory>
310struct iterator_access_archetype
311  : mpl::aux::msvc_eti_base<
312        typename iterator_access_archetype_impl<
313            AccessCategory
314        >::template archetype<Value>
315    >::type
316{
317};
318
319template <>
320struct iterator_access_archetype_impl<
321    iterator_archetypes::readable_iterator_t
322>
323{
324    template <class Value>
325    struct archetype
326    {
327        typedef typename remove_cv<Value>::type value_type;
328        typedef Value                           reference;
329        typedef Value*                          pointer;
330
331        value_type operator*() const { return static_object<value_type>::get(); }
332
333        detail::arrow_proxy<Value> operator->() const { return detail::arrow_proxy<Value>(); }
334    };
335};
336
337template <>
338struct iterator_access_archetype_impl<
339    iterator_archetypes::writable_iterator_t
340>
341{
342    template <class Value>
343    struct archetype
344    {
345# if !BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
346        BOOST_STATIC_ASSERT(!is_const<Value>::value);
347# endif
348        typedef void value_type;
349        typedef void reference;
350        typedef void pointer;
351
352        detail::assign_proxy<Value> operator*() const { return detail::assign_proxy<Value>(); }
353    };
354};
355
356template <>
357struct iterator_access_archetype_impl<
358    iterator_archetypes::readable_writable_iterator_t
359>
360{
361    template <class Value>
362    struct archetype
363      : public virtual iterator_access_archetype<
364            Value, iterator_archetypes::readable_iterator_t
365        >
366    {
367        typedef detail::read_write_proxy<Value>    reference;
368
369        detail::read_write_proxy<Value> operator*() const { return detail::read_write_proxy<Value>(); }
370    };
371};
372
373template <>
374struct iterator_access_archetype_impl<iterator_archetypes::readable_lvalue_iterator_t>
375{
376    template <class Value>
377    struct archetype
378      : public virtual iterator_access_archetype<
379            Value, iterator_archetypes::readable_iterator_t
380        >
381    {
382        typedef Value&    reference;
383
384        Value& operator*() const { return static_object<Value>::get(); }
385        Value* operator->() const { return 0; }
386    };
387};
388 
389template <>
390struct iterator_access_archetype_impl<iterator_archetypes::writable_lvalue_iterator_t>
391{
392    template <class Value>
393    struct archetype
394      : public virtual iterator_access_archetype<
395            Value, iterator_archetypes::readable_lvalue_iterator_t
396        >
397    {
398# if !BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
399        BOOST_STATIC_ASSERT((!is_const<Value>::value));
400# endif
401    };
402};
403 
404
405template <class Value, class AccessCategory, class TraversalCategory>
406struct iterator_archetype;
407 
408template <class Value, class AccessCategory, class TraversalCategory>
409struct traversal_archetype_base
410  : detail::operator_brackets<
411        typename remove_cv<Value>::type
412      , AccessCategory
413      , TraversalCategory
414    >
415  , detail::traversal_archetype_<
416        iterator_archetype<Value, AccessCategory, TraversalCategory>
417      , Value
418      , TraversalCategory
419    >
420{
421};
422
423namespace detail
424{
425  template <class Value, class AccessCategory, class TraversalCategory>
426  struct iterator_archetype_base
427    : iterator_access_archetype<Value, AccessCategory>
428    , traversal_archetype_base<Value, AccessCategory, TraversalCategory>
429  {
430      typedef iterator_access_archetype<Value, AccessCategory> access;
431     
432      typedef typename detail::facade_iterator_category<
433          TraversalCategory
434        , typename mpl::eval_if<
435              iterator_archetypes::has_access<
436                  AccessCategory, iterator_archetypes::writable_iterator_t
437              >
438            , remove_const<Value>
439            , add_const<Value>
440          >::type
441        , typename access::reference
442      >::type iterator_category;
443
444      // Needed for some broken libraries (see below)
445      typedef boost::iterator<
446          iterator_category
447        , Value
448        , typename traversal_archetype_base<
449              Value, AccessCategory, TraversalCategory
450          >::difference_type
451        , typename access::pointer
452        , typename access::reference
453      > workaround_iterator_base;
454  };
455}
456
457template <class Value, class AccessCategory, class TraversalCategory>
458struct iterator_archetype
459  : public detail::iterator_archetype_base<Value, AccessCategory, TraversalCategory>
460
461    // These broken libraries require derivation from std::iterator
462    // (or related magic) in order to handle iter_swap and other
463    // iterator operations
464# if BOOST_WORKAROUND(BOOST_DINKUMWARE_STDLIB, < 310)           \
465    || BOOST_WORKAROUND(_RWSTD_VER, BOOST_TESTED_AT(0x20101))
466  , public detail::iterator_archetype_base<
467        Value, AccessCategory, TraversalCategory
468    >::workaround_iterator_base
469# endif
470{
471    // Derivation from std::iterator above caused references to nested
472    // types to be ambiguous, so now we have to redeclare them all
473    // here.
474# if BOOST_WORKAROUND(BOOST_DINKUMWARE_STDLIB, < 310)           \
475    || BOOST_WORKAROUND(_RWSTD_VER, BOOST_TESTED_AT(0x20101))
476   
477    typedef detail::iterator_archetype_base<
478        Value,AccessCategory,TraversalCategory
479    > base;
480   
481    typedef typename base::value_type value_type;
482    typedef typename base::reference reference;
483    typedef typename base::pointer pointer;
484    typedef typename base::difference_type difference_type;
485    typedef typename base::iterator_category iterator_category;
486# endif
487
488    iterator_archetype() { }
489    iterator_archetype(iterator_archetype const& x)
490      : detail::iterator_archetype_base<
491            Value
492          , AccessCategory
493          , TraversalCategory
494        >(x)
495    {}
496
497    iterator_archetype& operator=(iterator_archetype const&)
498        { return *this; }
499
500# if 0
501    // Optional conversion from mutable
502    iterator_archetype(
503        iterator_archetype<
504        typename detail::convertible_type<Value>::type
505      , AccessCategory
506      , TraversalCategory> const&
507    );
508# endif
509};
510
511} // namespace boost
512
513
514#endif // BOOST_ITERATOR_ARCHETYPES_HPP
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