libcxx/test/std/iterators/predef.iterators/counted.iterator/decrement.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--()
  12 //  requires bidirectional_iterator<I>;
  13 // constexpr counted_iterator operator--(int)
  14 //  requires bidirectional_iterator<I>;
  15
  16 #include <iterator>
  17
  18 #include "test_macros.h"
  19 #include "test_iterators.h"
  20
  21 template<class Iter>
  22 concept MinusEnabled = requires(Iter& iter) {
  23   iter--;
  24   --iter;
  25 };
  26
  27 constexpr bool test() {
  28   int buffer[8] = {1, 2, 3, 4, 5, 6, 7, 8};
  29
  30   {
  31     using Counted = std::counted_iterator<bidirectional_iterator<int*>>;
  32     std::counted_iterator iter(bidirectional_iterator<int*>{buffer + 2}, 6);
  33     assert(iter-- == Counted(bidirectional_iterator<int*>{buffer + 2}, 6));
  34     assert(--iter == Counted(bidirectional_iterator<int*>{buffer}, 8));
  35     assert(iter.count() == 8);
  36
  37     ASSERT_SAME_TYPE(decltype(iter--), Counted);
  38     ASSERT_SAME_TYPE(decltype(--iter), Counted&);
  39   }
  40   {
  41     using Counted = std::counted_iterator<random_access_iterator<int*>>;
  42     Counted iter(random_access_iterator<int*>{buffer + 2}, 6);
  43     assert(iter-- == Counted(random_access_iterator<int*>{buffer + 2}, 6));
  44     assert(--iter == Counted(random_access_iterator<int*>{buffer}, 8));
  45     assert(iter.count() == 8);
  46
  47     ASSERT_SAME_TYPE(decltype(iter--), Counted);
  48     ASSERT_SAME_TYPE(decltype(--iter), Counted&);
  49   }
  50   {
  51     using Counted = std::counted_iterator<contiguous_iterator<int*>>;
  52     std::counted_iterator iter(contiguous_iterator<int*>{buffer + 2}, 6);
  53     assert(iter-- == Counted(contiguous_iterator<int*>{buffer + 2}, 6));
  54     assert(--iter == Counted(contiguous_iterator<int*>{buffer}, 8));
  55     assert(iter.count() == 8);
  56
  57     ASSERT_SAME_TYPE(decltype(iter--), Counted);
  58     ASSERT_SAME_TYPE(decltype(--iter), Counted&);
  59   }
  60
  61   {
  62     static_assert( MinusEnabled<std::counted_iterator<contiguous_iterator<int*>>>);
  63     static_assert(!MinusEnabled<const std::counted_iterator<contiguous_iterator<int*>>>);
  64     static_assert(!MinusEnabled<std::counted_iterator<forward_iterator<int*>>>);
  65   }
  66
  67   return true;
  68 }
  69
  70 int main(int, char**) {
  71   test();
  72   static_assert(test());
  73
  74   return 0;
  75 }