iterator_archetypes.hpp

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  template <class Derived, class Value>
  Derived& operator-(traversal_archetype_<Derived, Value, random_access_traversal_tag> const&,
                     std::ptrdiff_t)
      { return static_object<Derived>::get(); }

  template <class Derived, class Value>
  std::ptrdiff_t operator-(traversal_archetype_<Derived, Value, random_access_traversal_tag> const&,
                           traversal_archetype_<Derived, Value, random_access_traversal_tag> const&)
      { return 0; }

  template <class Derived, class Value>
  bool operator<(traversal_archetype_<Derived, Value, random_access_traversal_tag> const&,
                 traversal_archetype_<Derived, Value, random_access_traversal_tag> const&)
      { return true; }

  template <class Derived, class Value>
  bool operator>(traversal_archetype_<Derived, Value, random_access_traversal_tag> const&,
                 traversal_archetype_<Derived, Value, random_access_traversal_tag> const&)
      { return true; }

  template <class Derived, class Value>
  bool operator<=(traversal_archetype_<Derived, Value, random_access_traversal_tag> const&,
                 traversal_archetype_<Derived, Value, random_access_traversal_tag> const&)
      { return true; }

  template <class Derived, class Value>
  bool operator>=(traversal_archetype_<Derived, Value, random_access_traversal_tag> const&,
                 traversal_archetype_<Derived, Value, random_access_traversal_tag> const&)
      { return true; }

  struct bogus_type;

  template <class Value>
  struct convertible_type
    : mpl::if_< is_const<Value>,
                typename remove_const<Value>::type,
                bogus_type >
  {};

} // namespace detail


template <class> struct undefined;
  
template <class AccessCategory>
struct iterator_access_archetype_impl
{
    template <class Value> struct archetype;
};

template <class Value, class AccessCategory>
struct iterator_access_archetype
  : mpl::aux::msvc_eti_base<
        typename iterator_access_archetype_impl<
            AccessCategory
        >::template archetype<Value>
    >::type
{
};

template <>
struct iterator_access_archetype_impl<
    iterator_archetypes::readable_iterator_t
>
{
    template <class Value>
    struct archetype
    {
        typedef typename remove_cv<Value>::type value_type;
        typedef Value                           reference;
        typedef Value*                          pointer;

        value_type operator*() const { return static_object<value_type>::get(); }

        detail::arrow_proxy<Value> operator->() const { return detail::arrow_proxy<Value>(); }
    };
};

template <>
struct iterator_access_archetype_impl<
    iterator_archetypes::writable_iterator_t
>
{
    template <class Value>
    struct archetype
    {
# if !BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
        BOOST_STATIC_ASSERT(!is_const<Value>::value);
# endif 
        typedef void value_type;
        typedef void reference;
        typedef void pointer;

        detail::assign_proxy<Value> operator*() const { return detail::assign_proxy<Value>(); }
    };
};

template <>
struct iterator_access_archetype_impl<
    iterator_archetypes::readable_writable_iterator_t
>
{
    template <class Value>
    struct archetype
      : public virtual iterator_access_archetype<
            Value, iterator_archetypes::readable_iterator_t
        >
    {
        typedef detail::read_write_proxy<Value>    reference;

        detail::read_write_proxy<Value> operator*() const { return detail::read_write_proxy<Value>(); }
    };
};

template <>
struct iterator_access_archetype_impl<iterator_archetypes::readable_lvalue_iterator_t>
{
    template <class Value>
    struct archetype
      : public virtual iterator_access_archetype<
            Value, iterator_archetypes::readable_iterator_t
        >
    {
        typedef Value&    reference;

        Value& operator*() const { return static_object<Value>::get(); }
        Value* operator->() const { return 0; }
    };
};
  
template <>
struct iterator_access_archetype_impl<iterator_archetypes::writable_lvalue_iterator_t>
{
    template <class Value>
    struct archetype
      : public virtual iterator_access_archetype<
            Value, iterator_archetypes::readable_lvalue_iterator_t
        >
    {
# if !BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
        BOOST_STATIC_ASSERT((!is_const<Value>::value));
# endif 
    };
};
  

template <class Value, class AccessCategory, class TraversalCategory>
struct iterator_archetype;
  
template <class Value, class AccessCategory, class TraversalCategory>
struct traversal_archetype_base 
  : detail::operator_brackets<
        typename remove_cv<Value>::type
      , AccessCategory
      , TraversalCategory
    >
  , detail::traversal_archetype_<
        iterator_archetype<Value, AccessCategory, TraversalCategory>
      , Value
      , TraversalCategory
    >
{
};

namespace detail
{
  template <class Value, class AccessCategory, class TraversalCategory>
  struct iterator_archetype_base
    : iterator_access_archetype<Value, AccessCategory>
    , traversal_archetype_base<Value, AccessCategory, TraversalCategory>
  {
      typedef iterator_access_archetype<Value, AccessCategory> access;
      
      typedef typename detail::facade_iterator_category<
          TraversalCategory
        , typename mpl::eval_if<
              iterator_archetypes::has_access<
                  AccessCategory, iterator_archetypes::writable_iterator_t
              >
            , remove_const<Value>
            , add_const<Value>
          >::type
        , typename access::reference
      >::type iterator_category;

      // Needed for some broken libraries (see below)
      typedef boost::iterator<
          iterator_category
        , Value
        , typename traversal_archetype_base<
              Value, AccessCategory, TraversalCategory
          >::difference_type
        , typename access::pointer
        , typename access::reference
      > workaround_iterator_base;
  };
}

template <class Value, class AccessCategory, class TraversalCategory>
struct iterator_archetype
  : public detail::iterator_archetype_base<Value, AccessCategory, TraversalCategory>

    // These broken libraries require derivation from std::iterator
    // (or related magic) in order to handle iter_swap and other
    // iterator operations
# if BOOST_WORKAROUND(BOOST_DINKUMWARE_STDLIB, < 310)           \
    || BOOST_WORKAROUND(_RWSTD_VER, BOOST_TESTED_AT(0x20101))
  , public detail::iterator_archetype_base<
        Value, AccessCategory, TraversalCategory
    >::workaround_iterator_base
# endif 
{
    // Derivation from std::iterator above caused references to nested
    // types to be ambiguous, so now we have to redeclare them all
    // here.
# if BOOST_WORKAROUND(BOOST_DINKUMWARE_STDLIB, < 310)           \
    || BOOST_WORKAROUND(_RWSTD_VER, BOOST_TESTED_AT(0x20101))
    
    typedef detail::iterator_archetype_base<
        Value,AccessCategory,TraversalCategory
    > base;
    
    typedef typename base::value_type value_type;
    typedef typename base::reference reference;
    typedef typename base::pointer pointer;
    typedef typename base::difference_type difference_type;
    typedef typename base::iterator_category iterator_category;
# endif

    iterator_archetype() { }
    iterator_archetype(iterator_archetype const& x)
      : detail::iterator_archetype_base<
            Value
          , AccessCategory
          , TraversalCategory
        >(x)
    {}

    iterator_archetype& operator=(iterator_archetype const&)
        { return *this; }

# if 0
    // Optional conversion from mutable
    iterator_archetype(
        iterator_archetype<
        typename detail::convertible_type<Value>::type
      , AccessCategory
      , TraversalCategory> const&
    );
# endif
};

} // namespace boost


#endif // BOOST_ITERATOR_ARCHETYPES_HPP