diff options
Diffstat (limited to 'boost/fusion/support/detail/index_sequence.hpp')
| -rw-r--r-- | boost/fusion/support/detail/index_sequence.hpp | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/boost/fusion/support/detail/index_sequence.hpp b/boost/fusion/support/detail/index_sequence.hpp index 1b596e7239..e86def005e 100644 --- a/boost/fusion/support/detail/index_sequence.hpp +++ b/boost/fusion/support/detail/index_sequence.hpp @@ -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 |