factoring the specialized iterator adaptors

[SVN r19467]

doc/reverse_iterator_ref.rst

@@ -0,0 +1,69 @@
+::
+
+  template <class Iterator>
+  class reverse_iterator :
+    public iterator_adaptor< reverse_iterator<Iterator>, Iterator >
+  {
+    friend class iterator_core_access;
+  public:
+    reverse_iterator() {}
+    explicit reverse_iterator(Iterator x) ;
+
+    template<class OtherIterator>
+    reverse_iterator(
+        reverse_iterator<OtherIterator> const& r
+      , typename enable_if_convertible<OtherIterator, Iterator>::type* = 0 // exposition
+    );
+
+  private: // as-if specification
+    typename reverse_iterator::reference dereference() const { return *prior(this->base()); }
+
+    void increment() { --this->base_reference(); }
+    void decrement() { ++this->base_reference(); }
+
+    void advance(typename reverse_iterator::difference_type n)
+    {
+        this->base_reference() += -n;
+    }
+
+    template <class OtherIterator>
+    typename reverse_iterator::difference_type
+    distance_to(reverse_iterator<OtherIterator> const& y) const
+    {
+        return this->base_reference() - y.base();
+    }
+
+  };
+
+
+``reverse_iterator`` requirements
+.................................
+
+The base ``Iterator`` must be a model of Bidirectional Traversal
+Iterator. The resulting ``reverse_iterator`` will be a model of the
+most refined standard traversal and access concepts that are modeled
+by ``Iterator``.
+
+
+``reverse_iterator();``
+
+:Requires: ``Iterator`` must be Default Constructible.
+:Returns: An instance of ``reverse_iterator`` with a
+  default constructed base object.
+
+``explicit reverse_iterator(Iterator x);``
+
+:Returns: An instance of ``reverse_iterator`` with a
+  base object copy constructed from ``x``.
+
+
+::
+
+    template<class OtherIterator>
+    reverse_iterator(
+        reverse_iterator<OtherIterator> const& r
+      , typename enable_if_convertible<OtherIterator, Iterator>::type* = 0 // exposition
+    );
+
+:Requires: ``OtherIterator`` is implicitly convertible to ``Iterator``.
+:Returns: An instance of ``reverse_iterator`` that is a copy of ``r``.