| 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_SAME_TYPE_HPP_INCLUDED |
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| 12 | #define BOOST_TYPE_ERASURE_SAME_TYPE_HPP_INCLUDED |
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| 13 | |
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| 14 | namespace boost { |
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| 15 | namespace type_erasure { |
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| 16 | |
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| 17 | /** |
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| 18 | * A built in concept that indicates that two |
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| 19 | * types are the same. Either T or U or both |
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| 20 | * can be placeholders. |
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| 21 | * |
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| 22 | * \warning Any number of instances of @ref deduced |
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| 23 | * can be connected with @ref same_type, but there |
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| 24 | * should be at most one regular placeholder in |
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| 25 | * the group. same_type<_a, _b> is not allowed. |
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| 26 | * The reason for this is that the library needs |
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| 27 | * to normalize all the placeholders, and in this |
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| 28 | * context there is no way to decide whether to |
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| 29 | * use @ref _a or @ref _b. |
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| 30 | */ |
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| 31 | template<class T, class U> |
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| 32 | struct same_type {}; |
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| 33 | |
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| 34 | } |
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| 35 | } |
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| 36 | |
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| 37 | #endif |
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| 38 | |
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