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Detect std::integer_sequence availability.

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It will allow to reuse compiler cache easier.
This commit is contained in:
Kohei Takahashi
2016-02-13 11:57:41 +09:00
parent 1774972237
commit b88daeb697
1 changed files with 20 additions and 0 deletions
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20
include/boost/fusion/support/detail/index_sequence.hpp
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@ -12,8 +12,27 @@
#include <boost/fusion/support/config.hpp>
#include <cstddef>
// GCC5 has O(logN) implementation, see https://gcc.gnu.org/PR66059 .
#if (defined(__cpp_lib_integer_sequence) && __cpp_lib_integer_sequence >= 201304) \
|| (defined(BOOST_LIBSTDCXX_VERSION) \
&& BOOST_LIBSTDCXX_VERSION >= 500000 && __cplusplus >= 201402)
#include <utility>
#define BOOST_FUSION_STDLIB_HAS_INTEGER_SEQUENCE
#endif
namespace boost { namespace fusion { namespace detail
{
#ifdef BOOST_FUSION_STDLIB_HAS_INTEGER_SEQUENCE
// Use aliasing templates without checking availability, the compiler should work.
template <std::size_t ...Ints>
using index_sequence = std::index_sequence<Ints...>;
template <std::size_t N>
struct make_index_sequence
{
using type = std::make_index_sequence<N>;
};
#else
template <std::size_t ...Ints>
struct index_sequence
{
@ -53,6 +72,7 @@ namespace boost { namespace fusion { namespace detail
struct make_index_sequence<0>
: index_sequence<>
{};
#endif
}}}
#endif