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src/boost/iterator/iterator_facade.hpp  view on Meta::CPAN

    template <class ValueType, class Reference>
    struct use_operator_brackets_proxy
      : mpl::not_<
            mpl::and_<
                // Really we want an is_copy_constructible trait here,
                // but is_POD will have to suffice in the meantime.
                boost::is_POD<ValueType>
              , iterator_writability_disabled<ValueType,Reference>
            >
        >
    {};
        
    template <class Iterator, class Value, class Reference>
    struct operator_brackets_result
    {
        typedef typename mpl::if_<
            use_operator_brackets_proxy<Value,Reference>
          , operator_brackets_proxy<Iterator>
          , Value
        >::type type;
    };

    template <class Iterator>
    operator_brackets_proxy<Iterator> make_operator_brackets_result(Iterator const& iter, mpl::true_)
    {
        return operator_brackets_proxy<Iterator>(iter);
    }

    template <class Iterator>
    typename Iterator::value_type make_operator_brackets_result(Iterator const& iter, mpl::false_)
    {
      return *iter;
    }

    struct choose_difference_type
    {
        template <class I1, class I2>
        struct apply
          :
# ifdef BOOST_NO_ONE_WAY_ITERATOR_INTEROP
          iterator_difference<I1>
# elif BOOST_WORKAROUND(BOOST_MSVC, < 1300)
          mpl::if_<
              is_convertible<I2,I1>
            , typename I1::difference_type
            , typename I2::difference_type
          >
# else 
          mpl::eval_if<
              is_convertible<I2,I1>
            , iterator_difference<I1>
            , iterator_difference<I2>
          >
# endif 
        {};

    };
  } // namespace detail


  // Macros which describe the declarations of binary operators
# ifdef BOOST_NO_STRICT_ITERATOR_INTEROPERABILITY
#  define BOOST_ITERATOR_FACADE_INTEROP_HEAD(prefix, op, result_type)       \
    template <                                                              \
        class Derived1, class V1, class TC1, class Reference1, class Difference1 \
      , class Derived2, class V2, class TC2, class Reference2, class Difference2 \
    >                                                                       \
    prefix typename mpl::apply2<result_type,Derived1,Derived2>::type \
    operator op(                                                            \
        iterator_facade<Derived1, V1, TC1, Reference1, Difference1> const& lhs   \
      , iterator_facade<Derived2, V2, TC2, Reference2, Difference2> const& rhs)
# else 
#  define BOOST_ITERATOR_FACADE_INTEROP_HEAD(prefix, op, result_type)   \
    template <                                                          \
        class Derived1, class V1, class TC1, class Reference1, class Difference1 \
      , class Derived2, class V2, class TC2, class Reference2, class Difference2 \
    >                                                                   \
    prefix typename boost::detail::enable_if_interoperable<             \
        Derived1, Derived2                                              \
      , typename mpl::apply2<result_type,Derived1,Derived2>::type       \
    >::type                                                             \
    operator op(                                                        \
        iterator_facade<Derived1, V1, TC1, Reference1, Difference1> const& lhs   \
      , iterator_facade<Derived2, V2, TC2, Reference2, Difference2> const& rhs)
# endif 

#  define BOOST_ITERATOR_FACADE_PLUS_HEAD(prefix,args)              \
    template <class Derived, class V, class TC, class R, class D>   \
    prefix Derived operator+ args

  //
  // Helper class for granting access to the iterator core interface.
  //
  // The simple core interface is used by iterator_facade. The core
  // interface of a user/library defined iterator type should not be made public
  // so that it does not clutter the public interface. Instead iterator_core_access
  // should be made friend so that iterator_facade can access the core
  // interface through iterator_core_access.
  //
  class iterator_core_access
  {
# if defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)                  
      // Tasteless as this may seem, making all members public allows member templates
      // to work in the absence of member template friends.
   public:
# else
      
      template <class I, class V, class TC, class R, class D> friend class iterator_facade;

#  define BOOST_ITERATOR_FACADE_RELATION(op)                                \
      BOOST_ITERATOR_FACADE_INTEROP_HEAD(friend,op, boost::detail::always_bool2);

      BOOST_ITERATOR_FACADE_RELATION(==)
      BOOST_ITERATOR_FACADE_RELATION(!=)

      BOOST_ITERATOR_FACADE_RELATION(<)
      BOOST_ITERATOR_FACADE_RELATION(>)
      BOOST_ITERATOR_FACADE_RELATION(<=)
      BOOST_ITERATOR_FACADE_RELATION(>=)
#  undef BOOST_ITERATOR_FACADE_RELATION