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fusion/example/extension/detail/next_impl.hpp
IncludeGuardian ce8b031f54 Swap include guards to #ifndef (#271)
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>
2024-02-25 12:37:08 +08:00

47 lines
1.3 KiB
C++

/*=============================================================================
Copyright (c) 2001-2011 Joel de Guzman
Copyright (c) 2006 Dan Marsden
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
==============================================================================*/
#ifndef BOOST_FUSION_NEXT_IMPL_20060222_1859
#define BOOST_FUSION_NEXT_IMPL_20060222_1859
namespace example
{
struct example_struct_iterator_tag;
template<typename Struct, int Pos>
struct example_struct_iterator;
}
namespace boost { namespace fusion {
namespace extension
{
template<typename Tag>
struct next_impl;
template<>
struct next_impl<example::example_struct_iterator_tag>
{
template<typename Iterator>
struct apply
{
typedef typename Iterator::struct_type struct_type;
typedef typename Iterator::index index;
typedef example::example_struct_iterator<struct_type, index::value + 1> type;
static type
call(Iterator const& i)
{
return type(i.struct_);
}
};
};
}
}}
#endif