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Compilers implement a multiple-include optimization where they avoid preprocessing an included file if it is "properly guarded". Compilers differ as to what constitutes a "properly guarded" file. In particular, Microsoft Visual Studio does not recognize `#if !defined(GUARD)` for the optimization. This does not affect the correctness of using Fusion on Microsoft Visual Studio, but it will increase the time taken to build any project on this compiler. This commit changes all include guards to use `#ifndef`, but leaves all other `#if !defined` preprocessor directives that are not related to guarding a file. Co-authored-by: IncludeGuardian <hello@includeguardian.io>
51 lines
1.2 KiB
C++
51 lines
1.2 KiB
C++
/*=============================================================================
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Copyright (c) 2001-2011 Joel de Guzman
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Copyright (c) 2005-2006 Dan Marsden
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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 copy at http://www.boost.org/LICENSE_1_0.txt)
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==============================================================================*/
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#ifndef BOOST_FUSION_VALUE_AT_KEY_IMPL_20060223_2025
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#define BOOST_FUSION_VALUE_AT_KEY_IMPL_20060223_2025
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namespace fields
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{
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struct name;
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struct age;
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}
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namespace example
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{
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struct example_sequence_tag;
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}
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namespace boost { namespace fusion {
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namespace extension
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{
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template<typename Tag>
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struct value_at_key_impl;
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template<>
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struct value_at_key_impl<example::example_sequence_tag>
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{
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template<typename Sequence, typename N>
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struct apply;
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template<typename Sequence>
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struct apply<Sequence, fields::name>
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{
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typedef std::string type;
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};
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template<typename Sequence>
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struct apply<Sequence, fields::age>
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{
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typedef int type;
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};
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};
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}
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}}
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#endif
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