libcxx/test/std/iterators/predef.iterators/counted.iterator/minus.eq.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 // UNSUPPORTED: c++03, c++11, c++14, c++17
  10
  11 // constexpr counted_iterator& operator-=(iter_difference_t<I> n)
  12 //   requires random_access_iterator<I>;
  13
  14 #include <iterator>
  15
  16 #include "test_macros.h"
  17 #include "test_iterators.h"
  18
  19 template<class Iter>
  20 concept MinusEqEnabled = requires(Iter& iter) {
  21   iter -= 1;
  22 };
  23
  24 constexpr bool test() {
  25   int buffer[8] = {1, 2, 3, 4, 5, 6, 7, 8};
  26
  27   {
  28     using Counted = std::counted_iterator<random_access_iterator<int*>>;
  29     Counted iter(random_access_iterator<int*>{buffer + 2}, 6);
  30     assert((iter -= 2) == Counted(random_access_iterator<int*>{buffer}, 8));
  31     assert((iter -= 0) == Counted(random_access_iterator<int*>{buffer}, 8));
  32     assert(iter.count() == 8);
  33
  34     ASSERT_SAME_TYPE(decltype(iter -= 2), Counted&);
  35   }
  36   {
  37     using Counted = std::counted_iterator<contiguous_iterator<int*>>;
  38     Counted iter(contiguous_iterator<int*>{buffer + 2}, 6);
  39     assert((iter -= 2) == Counted(contiguous_iterator<int*>{buffer}, 8));
  40     assert((iter -= 0) == Counted(contiguous_iterator<int*>{buffer}, 8));
  41     assert(iter.count() == 8);
  42
  43     ASSERT_SAME_TYPE(decltype(iter -= 2), Counted&);
  44   }
  45   {
  46     static_assert( MinusEqEnabled<      std::counted_iterator<random_access_iterator<int*>>>);
  47     static_assert(!MinusEqEnabled<const std::counted_iterator<random_access_iterator<int*>>>);
  48   }
  49
  50
  51   return true;
  52 }
  53
  54 int main(int, char**) {
  55   test();
  56   static_assert(test());
  57
  58   return 0;
  59 }