1 // (C) Copyright David Abrahams 2002.
2 // (C) Copyright Jeremy Siek    2002.
3 // (C) Copyright Thomas Witt    2002.
4 // Distributed under the Boost Software License, Version 1.0. (See
5 // accompanying file LICENSE_1_0.txt or copy at
6 // http://www.boost.org/LICENSE_1_0.txt)
7 #ifndef BOOST_INTEROPERABLE_23022003THW_HPP
8 # define BOOST_INTEROPERABLE_23022003THW_HPP
9 
10 # include <boost/mpl/bool.hpp>
11 # include <boost/mpl/or.hpp>
12 
13 # include <boost/type_traits/is_convertible.hpp>
14 
15 # include <boost/iterator/detail/config_def.hpp> // must appear last
16 
17 namespace boost
18 {
19 
20   //
21   // Meta function that determines whether two
22   // iterator types are considered interoperable.
23   //
24   // Two iterator types A,B are considered interoperable if either
25   // A is convertible to B or vice versa.
26   // This interoperability definition is in sync with the
27   // standards requirements on constant/mutable container
28   // iterators (23.1 [lib.container.requirements]).
29   //
30   // For compilers that don't support is_convertible
31   // is_interoperable gives false positives. See comments
32   // on operator implementation for consequences.
33   //
34   template <typename A, typename B>
35   struct is_interoperable
36 # ifdef BOOST_NO_STRICT_ITERATOR_INTEROPERABILITY
37     : mpl::true_
38 # else
39     : mpl::or_<
40           is_convertible< A, B >
41         , is_convertible< B, A > >
42 # endif
43   {
44   };
45 
46 } // namespace boost
47 
48 # include <boost/iterator/detail/config_undef.hpp>
49 
50 #endif // BOOST_INTEROPERABLE_23022003THW_HPP
51