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29 lines
877 B
29 lines
877 B
5 years ago
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#ifndef BOOST_CONTRACT_DETAIL_NONE_HPP_
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#define BOOST_CONTRACT_DETAIL_NONE_HPP_
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// Copyright (C) 2008-2018 Lorenzo Caminiti
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// Distributed under the Boost Software License, Version 1.0 (see accompanying
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// file LICENSE_1_0.txt or a copy at http://www.boost.org/LICENSE_1_0.txt).
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// See: http://www.boost.org/doc/libs/release/libs/contract/doc/html/index.html
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namespace boost { namespace contract { namespace detail {
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// Tag for "no type".
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struct none {
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// Some lib code use this to avoid unused local var warnings on #if, etc.
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static none& value() {
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static none none_value;
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return none_value;
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}
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};
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// Transform `void` to `none` type (for convenience, instead of using MPL).
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template<typename T> struct none_if_void { typedef T type; };
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template<> struct none_if_void<void> { typedef none type; };
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} } } // namespace
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#endif // #include guard
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