libc/src/__support/CPP/utility/integer_sequence.h

   1 //===-- integer_sequence utility --------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 #ifndef LLVM_LIBC_SRC___SUPPORT_CPP_UTILITY_INTEGER_SEQUENCE_H
   9 #define LLVM_LIBC_SRC___SUPPORT_CPP_UTILITY_INTEGER_SEQUENCE_H
  10
  11 #include "src/__support/CPP/type_traits/is_integral.h"
  12
  13 namespace LIBC_NAMESPACE::cpp {
  14
  15 // integer_sequence
  16 template <typename T, T... Ints> struct integer_sequence {
  17   static_assert(cpp::is_integral_v<T>);
  18   template <T Next> using append = integer_sequence<T, Ints..., Next>;
  19 };
  20
  21 namespace detail {
  22 template <typename T, int N> struct make_integer_sequence {
  23   using type =
  24       typename make_integer_sequence<T, N - 1>::type::template append<N>;
  25 };
  26 template <typename T> struct make_integer_sequence<T, -1> {
  27   using type = integer_sequence<T>;
  28 };
  29 } // namespace detail
  30
  31 template <typename T, int N>
  32 using make_integer_sequence =
  33     typename detail::make_integer_sequence<T, N - 1>::type;
  34
  35 } // namespace LIBC_NAMESPACE::cpp
  36
  37 #endif // LLVM_LIBC_SRC___SUPPORT_CPP_UTILITY_INTEGER_SEQUENCE_H