// (C) Copyright David Abrahams 2002.

// (C) Copyright Jeremy Siek    2002.

// (C) Copyright Thomas Witt    2002.

// Distributed under 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)

#ifndef BOOST_INTEROPERABLE_23022003THW_HPP

# define BOOST_INTEROPERABLE_23022003THW_HPP

# include <boost/mpl/bool.hpp>

# include <boost/mpl/or.hpp>

# include <boost/type_traits/is_convertible.hpp>

# include <boost/iterator/detail/config_def.hpp> // must appear last

namespace boost

{

  //

  // Meta function that determines whether two

  // iterator types are considered interoperable.

  //

  // Two iterator types A,B are considered interoperable if either

  // A is convertible to B or vice versa.

  // This interoperability definition is in sync with the

  // standards requirements on constant/mutable container

  // iterators (23.1 [lib.container.requirements]).

  //

  // For compilers that don't support is_convertible 

  // is_interoperable gives false positives. See comments

  // on operator implementation for consequences.

  //

  template <typename A, typename B>

  struct is_interoperable

# ifdef BOOST_NO_STRICT_ITERATOR_INTEROPERABILITY

    : mpl::true_

# else

    : mpl::or_<

          is_convertible< A, B >

        , is_convertible< B, A > >

# endif

  { 

  };

} // namespace boost

# include <boost/iterator/detail/config_undef.hpp>

#endif // BOOST_INTEROPERABLE_23022003THW_HPP