boost_1_45_0/libs/iterator/doc/indirect_reference_ref.rst

.. Copyright David Abrahams 2004. Use, modification and distribution is
.. subject to the Boost Software License, Version 1.0. (See accompanying
.. file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

::

  template <class Dereferenceable>
  struct indirect_reference
  {
      typedef /* see below */ type;
  };

:Requires: For an object ``x`` of type ``Dereferenceable``, ``*x``
  is well-formed.  If ``++x`` is ill-formed it shall neither be
  ambiguous nor shall it violate access control, and
  ``pointee<Dereferenceable>::type&`` shall be well-formed.
  Otherwise ``iterator_traits<Dereferenceable>::reference`` shall
  be well formed.  [Note: These requirements need not apply to
  explicit or partial specializations of ``indirect_reference``]

``type`` is determined according to the following algorithm, where
``x`` is an object of type ``Dereferenceable``::

  if ( ++x is ill-formed )
      return ``pointee<Dereferenceable>::type&``
  else
      std::iterator_traits<Dereferenceable>::reference