iterator.hpp

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BOOST_TT_AUX_BOOL_TRAIT_DEF1(
    is_stlport_40_debug_iterator,T,::boost::detail::is_stlport_40_debug_iterator_impl<T>::value)

template <class T>
struct stlport_40_debug_iterator_traits
{
    typedef typename T::value_type value_type;
    typedef typename T::reference reference;
    typedef typename T::pointer pointer;
    typedef typename T::difference_type difference_type;
    typedef typename T::_Iterator_category iterator_category;
};
#   endif // BOOST_BAD_CONTAINER_ITERATOR_CATEGORY_TYPEDEF 

template <class T> struct pointer_iterator_traits;

#   ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
template <class T>
struct pointer_iterator_traits<T*>
{
    typedef typename remove_const<T>::type value_type;
    typedef T* pointer;
    typedef T& reference;
    typedef std::random_access_iterator_tag iterator_category;
    typedef std::ptrdiff_t difference_type;
};
#   else

// In case of no template partial specialization, and if T is a
// pointer, iterator_traits<T>::value_type can still be computed.  For
// some basic types, remove_pointer is manually defined in
// type_traits/broken_compiler_spec.hpp. For others, do it yourself.

template<class P> class please_invoke_BOOST_TT_BROKEN_COMPILER_SPEC_on_cv_unqualified_pointee;

template<class P>
struct pointer_value_type
  : mpl::if_<
        is_same<P, typename remove_pointer<P>::type>
      , please_invoke_BOOST_TT_BROKEN_COMPILER_SPEC_on_cv_unqualified_pointee<P>
      , typename remove_const<
            typename remove_pointer<P>::type
        >::type
    >
{
};


template<class P>
struct pointer_reference
  : mpl::if_<
        is_same<P, typename remove_pointer<P>::type>
      , please_invoke_BOOST_TT_BROKEN_COMPILER_SPEC_on_cv_unqualified_pointee<P>
      , typename remove_pointer<P>::type&
    >
{
};

template <class T>
struct pointer_iterator_traits
{
    typedef T pointer;
    typedef std::random_access_iterator_tag iterator_category;
    typedef std::ptrdiff_t difference_type;

    typedef typename pointer_value_type<T>::type value_type;
    typedef typename pointer_reference<T>::type reference;
};

#   endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION

// We'll sort iterator types into one of these classifications, from which we
// can determine the difference_type, pointer, reference, and value_type
template <class Iterator>
struct standard_iterator_traits
{
    typedef typename Iterator::difference_type difference_type;
    typedef typename Iterator::value_type value_type;
    typedef typename Iterator::pointer pointer;
    typedef typename Iterator::reference reference;
    typedef typename Iterator::iterator_category iterator_category;
};

template <class Iterator>
struct msvc_stdlib_mutable_traits
    : std::iterator_traits<Iterator>
{
    typedef typename std::iterator_traits<Iterator>::distance_type difference_type;
    typedef typename std::iterator_traits<Iterator>::value_type* pointer;
    typedef typename std::iterator_traits<Iterator>::value_type& reference;
};

template <class Iterator>
struct msvc_stdlib_const_traits
    : std::iterator_traits<Iterator>
{
    typedef typename std::iterator_traits<Iterator>::distance_type difference_type;
    typedef const typename std::iterator_traits<Iterator>::value_type* pointer;
    typedef const typename std::iterator_traits<Iterator>::value_type& reference;
};

#   ifdef BOOST_BAD_OUTPUT_ITERATOR_SPECIALIZATION
template <class Iterator>
struct is_bad_output_iterator
    : is_base_and_derived<
        std::iterator<std::output_iterator_tag,void,void,void,void>
        , Iterator>
{
};

struct bad_output_iterator_traits
{
    typedef void value_type;
    typedef void difference_type;
    typedef std::output_iterator_tag iterator_category;
    typedef void pointer;
    typedef void reference;
};
#   endif

// If we're looking at an MSVC6 (old Dinkumware) ``standard''
// iterator, this will generate an appropriate traits class. 
template <class Iterator>
struct msvc_stdlib_iterator_traits
    : mpl::if_<
       is_mutable_iterator<Iterator>
       , msvc_stdlib_mutable_traits<Iterator>
       , msvc_stdlib_const_traits<Iterator>
      >::type
{};

template <class Iterator>
struct non_pointer_iterator_traits
    : mpl::if_<
        // if the iterator contains all the right nested types...
        is_full_iterator_traits<Iterator>
        // Use a standard iterator_traits implementation
        , standard_iterator_traits<Iterator>
#   ifdef BOOST_BAD_CONTAINER_ITERATOR_CATEGORY_TYPEDEF
        // Check for STLPort 4.0 broken _Iterator_category type
        , mpl::if_<
             is_stlport_40_debug_iterator<Iterator>
             , stlport_40_debug_iterator_traits<Iterator>
#   endif
        // Otherwise, assume it's a Dinkum iterator
        , msvc_stdlib_iterator_traits<Iterator>
#   ifdef BOOST_BAD_CONTAINER_ITERATOR_CATEGORY_TYPEDEF
        >::type
#   endif 
    >::type
{
};

template <class Iterator>
struct iterator_traits_aux
    : mpl::if_<
        is_pointer<Iterator>
        , pointer_iterator_traits<Iterator>
        , non_pointer_iterator_traits<Iterator>
    >::type
{
};

template <class Iterator>
struct iterator_traits
{
    // Explicit forwarding from base class needed to keep MSVC6 happy
    // under some circumstances.
 private:
#   ifdef BOOST_BAD_OUTPUT_ITERATOR_SPECIALIZATION
    typedef 
    typename mpl::if_<
        is_bad_output_iterator<Iterator>
        , bad_output_iterator_traits
        , iterator_traits_aux<Iterator>
    >::type base;
#   else
    typedef iterator_traits_aux<Iterator> base;
#   endif
 public:
    typedef typename base::value_type value_type;
    typedef typename base::pointer pointer;
    typedef typename base::reference reference;
    typedef typename base::difference_type difference_type;
    typedef typename base::iterator_category iterator_category;
};

// This specialization cuts off ETI (Early Template Instantiation) for MSVC.
template <> struct iterator_traits<int>
{
    typedef int value_type;
    typedef int pointer;
    typedef int reference;
    typedef int difference_type;
    typedef int iterator_category;
};

}} // namespace boost::detail

#  endif // workarounds

namespace boost { namespace detail {

namespace iterator_traits_
{
  template <class Iterator, class Difference>
  struct distance_select
  {
      static Difference execute(Iterator i1, const Iterator i2, ...)
      {
          Difference result = 0;
          while (i1 != i2)
          {
              ++i1;
              ++result;
          }
          return result;
      }

      static Difference execute(Iterator i1, const Iterator i2, std::random_access_iterator_tag*)
      {
          return i2 - i1;
      }
  };
} // namespace boost::detail::iterator_traits_

template <class Iterator>
inline typename iterator_traits<Iterator>::difference_type
distance(Iterator first, Iterator last)
{
    typedef typename iterator_traits<Iterator>::difference_type diff_t;
    typedef typename ::boost::detail::iterator_traits<Iterator>::iterator_category iterator_category;
    
    return iterator_traits_::distance_select<Iterator,diff_t>::execute(
        first, last, (iterator_category*)0);
}

}}

# endif


# undef BOOST_BAD_CONTAINER_ITERATOR_CATEGORY_TYPEDEF
# undef BOOST_BAD_OUTPUT_ITERATOR_SPECIALIZATION

#endif // ITERATOR_DWA122600_HPP_