| 1 | // (C) Copyright David Abrahams 2001. |
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| 2 | // Distributed under the Boost Software License, Version 1.0. (See |
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| 3 | // accompanying file LICENSE_1_0.txt or copy at |
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| 4 | // http://www.boost.org/LICENSE_1_0.txt) |
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| 5 | // |
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| 6 | // See http://www.boost.org for most recent version including documentation. |
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| 7 | |
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| 8 | // Revision History |
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| 9 | // 09 Feb 01 Applied John Maddock's Borland patch Moving <true> |
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| 10 | // specialization to unspecialized template (David Abrahams) |
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| 11 | // 06 Feb 01 Created (David Abrahams) |
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| 12 | |
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| 13 | #ifndef SELECT_TYPE_DWA20010206_HPP |
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| 14 | # define SELECT_TYPE_DWA20010206_HPP |
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| 15 | |
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| 16 | namespace boost { namespace detail { |
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| 17 | |
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| 18 | // Template class if_true -- select among 2 types based on a bool constant expression |
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| 19 | // Usage: |
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| 20 | // typename if_true<(bool_const_expression)>::template then<true_type, false_type>::type |
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| 21 | |
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| 22 | // HP aCC cannot deal with missing names for template value parameters |
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| 23 | template <bool b> struct if_true |
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| 24 | { |
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| 25 | template <class T, class F> |
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| 26 | struct then { typedef T type; }; |
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| 27 | }; |
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| 28 | |
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| 29 | template <> |
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| 30 | struct if_true<false> |
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| 31 | { |
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| 32 | template <class T, class F> |
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| 33 | struct then { typedef F type; }; |
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| 34 | }; |
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| 35 | }} |
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| 36 | #endif // SELECT_TYPE_DWA20010206_HPP |
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| 37 | |
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