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