ceph/src/boost/boost/mp11/integer_sequence.hpp

   1 #ifndef BOOST_MP11_INTEGER_SEQUENCE_HPP_INCLUDED
   2 #define BOOST_MP11_INTEGER_SEQUENCE_HPP_INCLUDED
   3
   4 //  Copyright 2015, 2017 Peter Dimov.
   5 //
   6 //  Distributed under the Boost Software License, Version 1.0.
   7 //
   8 //  See accompanying file LICENSE_1_0.txt or copy at
   9 //  http://www.boost.org/LICENSE_1_0.txt
  10
  11 #include <cstddef>
  12
  13 namespace boost
  14 {
  15 namespace mp11
  16 {
  17
  18 // integer_sequence
  19 template<class T, T... I> struct integer_sequence
  20 {
  21 };
  22
  23 // detail::make_integer_sequence_impl
  24 namespace detail
  25 {
  26
  27 // iseq_if_c
  28 template<bool C, class T, class E> struct iseq_if_c_impl;
  29
  30 template<class T, class E> struct iseq_if_c_impl<true, T, E>
  31 {
  32     using type = T;
  33 };
  34
  35 template<class T, class E> struct iseq_if_c_impl<false, T, E>
  36 {
  37     using type = E;
  38 };
  39
  40 template<bool C, class T, class E> using iseq_if_c = typename iseq_if_c_impl<C, T, E>::type;
  41
  42 // iseq_identity
  43 template<class T> struct iseq_identity
  44 {
  45     using type = T;
  46 };
  47
  48 template<class S1, class S2> struct append_integer_sequence;
  49
  50 template<class T, T... I, T... J> struct append_integer_sequence<integer_sequence<T, I...>, integer_sequence<T, J...>>
  51 {
  52     using type = integer_sequence< T, I..., ( J + sizeof...(I) )... >;
  53 };
  54
  55 template<class T, T N> struct make_integer_sequence_impl;
  56
  57 template<class T, T N> struct make_integer_sequence_impl_
  58 {
  59 private:
  60
  61     static_assert( N >= 0, "make_integer_sequence<T, N>: N must not be negative" );
  62
  63     static T const M = N / 2;
  64     static T const R = N % 2;
  65
  66     using S1 = typename make_integer_sequence_impl<T, M>::type;
  67     using S2 = typename append_integer_sequence<S1, S1>::type;
  68     using S3 = typename make_integer_sequence_impl<T, R>::type;
  69     using S4 = typename append_integer_sequence<S2, S3>::type;
  70
  71 public:
  72
  73     using type = S4;
  74 };
  75
  76 template<class T, T N> struct make_integer_sequence_impl: iseq_if_c<N == 0, iseq_identity<integer_sequence<T>>, iseq_if_c<N == 1, iseq_identity<integer_sequence<T, 0>>, make_integer_sequence_impl_<T, N>>>
  77 {
  78 };
  79
  80 } // namespace detail
  81
  82 // make_integer_sequence
  83 template<class T, T N> using make_integer_sequence = typename detail::make_integer_sequence_impl<T, N>::type;
  84
  85 // index_sequence
  86 template<std::size_t... I> using index_sequence = integer_sequence<std::size_t, I...>;
  87
  88 // make_index_sequence
  89 template<std::size_t N> using make_index_sequence = make_integer_sequence<std::size_t, N>;
  90
  91 // index_sequence_for
  92 template<class... T> using index_sequence_for = make_integer_sequence<std::size_t, sizeof...(T)>;
  93
  94 } // namespace mp11
  95 } // namespace boost
  96
  97 #endif // #ifndef BOOST_MP11_INTEGER_SEQUENCE_HPP_INCLUDED