libcxx/test/std/utilities/template.bitset/bitset.members/to_ullong.pass.cpp

   1 //===----------------------------------------------------------------------===//
   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
   9 // unsigned long long to_ullong() const; // constexpr since C++23
  10
  11 #include <bitset>
  12 #include <algorithm>
  13 #include <type_traits>
  14 #include <climits>
  15 #include <cassert>
  16
  17 #include "test_macros.h"
  18
  19 template <std::size_t N>
  20 TEST_CONSTEXPR_CXX23 void test_to_ullong() {
  21     const std::size_t M = sizeof(unsigned long long) * CHAR_BIT < N ? sizeof(unsigned long long) * CHAR_BIT : N;
  22     const bool is_M_zero = std::integral_constant<bool, M == 0>::value; // avoid compiler warnings
  23     const std::size_t X = is_M_zero ? sizeof(unsigned long long) * CHAR_BIT - 1 : sizeof(unsigned long long) * CHAR_BIT - M;
  24     const unsigned long long max = is_M_zero ? 0 : (unsigned long long)(-1) >> X;
  25     unsigned long long tests[] = {
  26         0,
  27         std::min<unsigned long long>(1, max),
  28         std::min<unsigned long long>(2, max),
  29         std::min<unsigned long long>(3, max),
  30         std::min(max, max-3),
  31         std::min(max, max-2),
  32         std::min(max, max-1),
  33         max
  34     };
  35     for (unsigned long long j : tests) {
  36          std::bitset<N> v(j);
  37         assert(j == v.to_ullong());
  38     }
  39     { // test values bigger than can fit into the bitset
  40         const unsigned long long val = 0x55AAAAFFFFAAAA55ULL;
  41         const bool canFit = N < sizeof(unsigned long long) * CHAR_BIT;
  42         const unsigned long long mask = canFit ? (1ULL << (canFit ? N : 0)) - 1 : (unsigned long long)(-1); // avoid compiler warnings
  43         std::bitset<N> v(val);
  44         assert(v.to_ullong() == (val & mask)); // we shouldn't return bit patterns from outside the limits of the bitset.
  45     }
  46 }
  47
  48 TEST_CONSTEXPR_CXX23 bool test() {
  49   test_to_ullong<0>();
  50   test_to_ullong<1>();
  51   test_to_ullong<31>();
  52   test_to_ullong<32>();
  53   test_to_ullong<33>();
  54   test_to_ullong<63>();
  55   test_to_ullong<64>();
  56   test_to_ullong<65>();
  57   test_to_ullong<1000>();
  58
  59   return true;
  60 }
  61
  62 int main(int, char**) {
  63   test();
  64 #if TEST_STD_VER > 20
  65   static_assert(test());
  66 #endif
  67
  68   return 0;
  69 }