| 1 | // Boost.TypeErasure library |
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| 2 | // |
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| 3 | // Copyright 2011 Steven Watanabe |
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| 4 | // |
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| 5 | // Distributed under the Boost Software License Version 1.0. (See |
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| 6 | // accompanying file LICENSE_1_0.txt or copy at |
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| 7 | // http://www.boost.org/LICENSE_1_0.txt) |
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| 8 | // |
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| 9 | // $Id$ |
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| 10 | |
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| 11 | #ifndef BOOST_TYPE_ERASURE_DETAIL_IS_PLACEHOLDER_HPP_INCLUDED |
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| 12 | #define BOOST_TYPE_ERASURE_DETAIL_IS_PLACEHOLDER_HPP_INCLUDED |
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| 13 | |
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| 14 | #include <boost/mpl/bool.hpp> |
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| 15 | |
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| 16 | namespace boost { |
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| 17 | |
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| 18 | namespace type_erasure { |
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| 19 | |
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| 20 | #ifdef BOOST_TYPE_ERASURE_DOXYGEN |
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| 21 | |
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| 22 | /** A metafunction that indicates whether a type is a @ref placeholder. */ |
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| 23 | template<class T> |
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| 24 | struct is_placeholder {}; |
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| 25 | |
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| 26 | #else |
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| 27 | |
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| 28 | template<class T, class Enable = void> |
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| 29 | struct is_placeholder : ::boost::mpl::false_ {}; |
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| 30 | |
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| 31 | template<class T> |
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| 32 | struct is_placeholder<T, typename T::_boost_type_erasure_is_placeholder> : |
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| 33 | ::boost::mpl::true_ {}; |
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| 34 | |
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| 35 | #endif |
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| 36 | |
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| 37 | } |
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| 38 | } |
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| 39 | |
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| 40 | #endif |
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| 41 | |
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