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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 | namespace iterators { | |
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 iterators | |
47 | ||
48 | using iterators::is_interoperable; | |
49 | ||
50 | } // namespace boost | |
51 | ||
52 | # include <boost/iterator/detail/config_undef.hpp> | |
53 | ||
54 | #endif // BOOST_INTEROPERABLE_23022003THW_HPP |