| // (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 { |
| namespace iterators { |
| |
| // |
| // 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 iterators |
| |
| using iterators::is_interoperable; |
| |
| } // namespace boost |
| |
| # include <boost/iterator/detail/config_undef.hpp> |
| |
| #endif // BOOST_INTEROPERABLE_23022003THW_HPP |