ceph/src/boost/libs/context/include/boost/context/detail/index_sequence.hpp

   1
   2 //          Copyright Oliver Kowalke 2014.
   3 // Distributed under the Boost Software License, Version 1.0.
   4 //    (See accompanying file LICENSE_1_0.txt or copy at
   5 //          http://www.boost.org/LICENSE_1_0.txt)
   6
   7 #ifndef BOOST_CONTEXT_DETAIL_INDEX_SEQUENCE_H
   8 #define BOOST_CONTEXT_DETAIL_INDEX_SEQUENCE_H
   9
  10 #include <cstddef>
  11
  12 #include <boost/config.hpp>
  13
  14 #include <boost/context/detail/config.hpp>
  15
  16 #ifdef BOOST_HAS_ABI_HEADERS
  17 # include BOOST_ABI_PREFIX
  18 #endif
  19
  20 namespace boost {
  21 namespace context {
  22 namespace detail {
  23
  24 #if ! defined(BOOST_CONTEXT_NO_CXX14_INTEGER_SEQUENCE)
  25 template< std::size_t ... I >
  26 using index_sequence = std::index_sequence< I ... >;
  27 template< std::size_t I >
  28 using make_index_sequence = std::make_index_sequence< I >;
  29 template< typename ... T >
  30 using index_sequence_for = std::index_sequence_for< T ... >;
  31 #else
  32 //http://stackoverflow.com/questions/17424477/implementation-c14-make-integer-sequence
  33
  34 template< std::size_t ... I >
  35 struct index_sequence {
  36     using type = index_sequence;
  37     using value_type = std::size_t;
  38     static constexpr std::size_t size() {
  39         return sizeof ... (I);
  40     }
  41 };
  42
  43 template< typename Seq1, typename Seq2 >
  44 struct concat_sequence;
  45
  46 template< std::size_t ... I1, std::size_t ... I2 >
  47 struct concat_sequence< index_sequence< I1 ... >, index_sequence< I2 ... > > : public index_sequence< I1 ..., (sizeof ... (I1)+I2) ... > {
  48 };
  49
  50 template< std::size_t I >
  51 struct make_index_sequence : public concat_sequence< typename make_index_sequence< I/2 >::type,
  52                                                      typename make_index_sequence< I-I/2 >::type > {
  53 };
  54
  55 template<>
  56 struct make_index_sequence< 0 > : public index_sequence<> {
  57 };
  58 template<>
  59 struct make_index_sequence< 1 > : public index_sequence< 0 > {
  60 };
  61
  62 template< typename ... T >
  63 using index_sequence_for = make_index_sequence< sizeof ... (T) >;
  64 #endif
  65
  66 }}}
  67
  68 #ifdef BOOST_HAS_ABI_HEADERS
  69 #include BOOST_ABI_SUFFIX
  70 #endif
  71
  72 #endif // BOOST_CONTEXT_DETAIL_INDEX_SEQUENCE_H