updated tag mechanism for iterators using Dave's idea

[SVN r612]

example/reverse_iterator.cpp

@@ -7,8 +7,9 @@
 int main()
 {
   int x[] = { 1, 2, 3, 4 };
-  boost::reverse_iterator<int*, int, int&, int*, std::random_access_iterator_tag, std::ptrdiff_t>
-    first(x + 4), last(x);
+  boost::reverse_iterator<int*, int, int&, int*, 
+    boost::iterator_tag<boost::mutable_lvalue_iterator_tag, boost::random_access_traversal_tag>
+    , std::ptrdiff_t> first(x + 4), last(x);
   std::copy(first, last, std::ostream_iterator<int>(std::cout, " "));
   std::cout << std::endl;
   return 0;

include/boost/iterator/iterator_adaptors.hpp

@@ -7,14 +7,11 @@
 
 namespace boost {
 
-template <class Final, class V, class R, class P, class RC, class TC, class D>
-struct repository
-    : iterator<typename cvt_iterator_category<RC, TC>::type, V, D, P, R>
+template <class Final, class V, class R, class P, class C, class D>
+struct repository : iterator<C, V, D, P, R>
 
 {
     typedef Final final;
-    typedef RC return_category;
-    typedef TC traversal_category;
 };
 
 template <class Base>
@@ -105,17 +102,17 @@ typename Base1::difference_type operator-(
 
 
 template <class Final
-          , class V, class R, class P, class RC, class TC, class D
+          , class V, class R, class P, class C, class D
           , class B = iterator_arith<
              iterator_comparisons<
-        downcastable<repository<Final, V, R, P, RC, TC, D> > > >
+        downcastable<repository<Final, V, R, P, C, D> > > >
          >
 struct iterator_adaptor : B, new_iterator_base
 {
     typedef V value_type;
     typedef R reference;
     typedef P pointer;
-    typedef typename B::iterator_category iterator_category;
+    typedef C iterator_category;
     typedef D difference_type;
 
     reference operator*() const
@@ -139,7 +136,7 @@ struct iterator_adaptor : B, new_iterator_base
     { Final result(downcast()); return result -= x; }
 
     template <class Final2, class V2, class R2, class P2, class B2>
-    bool equal(iterator_adaptor<Final2,V2,R2,P2,RC,TC,D,B2> const& x) const
+    bool equal(iterator_adaptor<Final2,V2,R2,P2,C,D,B2> const& x) const
     {
         return this->downcast().base() == x.downcast().base();
     }
@@ -153,7 +150,7 @@ struct iterator_adaptor : B, new_iterator_base
 
     template <class Final2, class B2, class V2, class R2, class P2>
     difference_type
-    distance_from(const iterator_adaptor<Final2,V2,R2,P2,RC,TC,D,B2>& y) const
+    distance_from(const iterator_adaptor<Final2,V2,R2,P2,C,D,B2>& y) const
     {
         return y.downcast().base() - this->downcast().base();//?
     }
@@ -164,13 +161,13 @@ struct iterator_adaptor : B, new_iterator_base
 
 
 template <class Base, 
-          class V, class R, class P, class RC, class TC, class D>
+          class V, class R, class P, class C, class D>
 struct reverse_iterator
     : iterator_adaptor<
-         reverse_iterator<Base, V, R, P, RC, TC, D>, V, R, P, RC, TC, D
+         reverse_iterator<Base, V, R, P, C, D>, V, R, P, C, D
       >
 {
-    typedef iterator_adaptor<reverse_iterator<Base, V, R, P, RC, TC, D>, V, R, P, RC, TC, D> super;
+    typedef iterator_adaptor<reverse_iterator<Base, V, R, P, C, D>, V, R, P, C, D> super;
     
 //  friend class super;
     // hmm, I don't like the next two lines
@@ -185,7 +182,7 @@ struct reverse_iterator
     Base const& base() const { return m_base; }
     
     template <class B2, class V2, class R2, class P2>
-    reverse_iterator(const reverse_iterator<B2,V2,R2,P2,RC,TC,D>& y)
+    reverse_iterator(const reverse_iterator<B2,V2,R2,P2,C,D>& y)
         : m_base(y.m_base) { }
 
 
@@ -200,7 +197,7 @@ struct reverse_iterator
 
     template <class B2, class V2, class R2, class P2>
     typename super::difference_type
-    distance_from(const reverse_iterator<B2,V2,R2,P2,RC,TC,D>& y) const
+    distance_from(const reverse_iterator<B2,V2,R2,P2,C,D>& y) const
     {
         return m_base - y.m_base;
     }

include/boost/iterator/iterator_categories.hpp

@@ -220,6 +220,14 @@ namespace boost {
     >::type type;
   };
 
+  template <class ReturnTag, class TraversalTag>
+  struct iterator_tag : cvt_iterator_category<ReturnTag, TraversalTag>::type
+  {
+    typedef ReturnTag returns;
+    typedef TraversalTag traversal;
+  };
+
+
 } // namespace boost
 
 #endif // BOOST_ITERATOR_CATEGORIES_HPP

include/boost/iterator/iterator_concepts.hpp

@@ -26,7 +26,8 @@ namespace boost_concepts {
   public:
     typedef typename std::iterator_traits<Iterator>::value_type value_type;
     typedef typename std::iterator_traits<Iterator>::reference reference;
-    typedef typename boost::return_category<Iterator>::type return_category;
+    typedef typename std::iterator_traits<Iterator>::iterator_category iterator_category;
+    typedef typename iterator_category::returns return_category;
 
     void constraints() {
       boost::function_requires< boost::SGIAssignableConcept<Iterator> >();
@@ -47,7 +48,8 @@ namespace boost_concepts {
   template <typename Iterator, typename ValueType>
   class WritableIteratorConcept {
   public:
-    typedef typename boost::return_category<Iterator>::type return_category;
+    typedef typename std::iterator_traits<Iterator>::iterator_category iterator_category;
+    typedef typename iterator_category::returns return_category;
 
     void constraints() {
       boost::function_requires< boost::SGIAssignableConcept<Iterator> >();
@@ -69,7 +71,8 @@ namespace boost_concepts {
   public:
     typedef typename std::iterator_traits<Iterator>::value_type value_type;
     typedef typename std::iterator_traits<Iterator>::reference reference;
-    typedef typename boost::return_category<Iterator>::type return_category;
+    typedef typename std::iterator_traits<Iterator>::iterator_category iterator_category;
+    typedef typename iterator_category::returns return_category;
 
     void constraints() {
       boost::function_requires< ReadableIteratorConcept<Iterator> >();
@@ -91,7 +94,8 @@ namespace boost_concepts {
   public:
     typedef typename std::iterator_traits<Iterator>::value_type value_type;
     typedef typename std::iterator_traits<Iterator>::reference reference;
-    typedef typename boost::return_category<Iterator>::type return_category;
+    typedef typename std::iterator_traits<Iterator>::iterator_category iterator_category;
+    typedef typename iterator_category::returns return_category;
 
     void constraints() {
       boost::function_requires< ReadableIteratorConcept<Iterator> >();
@@ -115,8 +119,8 @@ namespace boost_concepts {
   template <typename Iterator>
   class ForwardTraversalConcept {
   public:
-    typedef typename boost::traversal_category<Iterator>::type
-      traversal_category;
+    typedef typename std::iterator_traits<Iterator>::iterator_category iterator_category;
+    typedef typename iterator_category::traversal traversal_category;
 
     void constraints() {
       boost::function_requires< boost::SGIAssignableConcept<Iterator> >();
@@ -135,8 +139,8 @@ namespace boost_concepts {
   template <typename Iterator>
   class BidirectionalTraversalConcept {
   public:
-    typedef typename boost::traversal_category<Iterator>::type 
-      traversal_category;
+    typedef typename std::iterator_traits<Iterator>::iterator_category iterator_category;
+    typedef typename iterator_category::traversal traversal_category;
 
     void constraints() {
       boost::function_requires< ForwardTraversalConcept<Iterator> >();
@@ -153,8 +157,8 @@ namespace boost_concepts {
   template <typename Iterator>
   class RandomAccessTraversalConcept {
   public:
-    typedef typename boost::traversal_category<Iterator>::type
-      traversal_category;
+    typedef typename std::iterator_traits<Iterator>::iterator_category iterator_category;
+    typedef typename iterator_category::traversal traversal_category;
     typedef typename std::iterator_traits<Iterator>::difference_type
       difference_type;
 

test/iterator_adaptor_cc.cpp

@@ -8,14 +8,16 @@ int main()
 {
   {
     typedef boost::reverse_iterator<int*, int, int&, int*, 
-      boost::mutable_lvalue_iterator_tag, boost::random_access_traversal_tag, std::ptrdiff_t> rev_iter;
+      boost::iterator_tag<boost::mutable_lvalue_iterator_tag, boost::random_access_traversal_tag>, 
+      std::ptrdiff_t> rev_iter;
     boost::function_requires< boost_concepts::MutableLvalueIteratorConcept<rev_iter> >();
     boost::function_requires< boost_concepts::RandomAccessTraversalConcept<rev_iter> >();
     boost::function_requires< boost::RandomAccessIteratorConcept<rev_iter> >();
   }
   {
     typedef boost::reverse_iterator<std::list<int>::const_iterator, int, const int&, const int*, 
-      boost::constant_lvalue_iterator_tag, boost::bidirectional_traversal_tag, std::ptrdiff_t> rev_iter;
+      boost::iterator_tag<boost::constant_lvalue_iterator_tag, boost::bidirectional_traversal_tag>
+      , std::ptrdiff_t> rev_iter;
     boost::function_requires< boost_concepts::ConstantLvalueIteratorConcept<rev_iter> >();
     boost::function_requires< boost_concepts::BidirectionalTraversalConcept<rev_iter> >();
     boost::function_requires< boost::BidirectionalIteratorConcept<rev_iter> >();