libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.nav/decrement-assign.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 // <iterator>
  10
  11 // reverse_iterator
  12
  13 // requires RandomAccessIterator<Iter>
  14 // reverse_iterator& operator-=(difference_type n); // constexpr in C++17
  15
  16 #include <iterator>
  17 #include <cassert>
  18
  19 #include "test_macros.h"
  20 #include "test_iterators.h"
  21
  22 template <class It>
  23 TEST_CONSTEXPR_CXX17 void test(It i, typename std::iterator_traits<It>::difference_type n, It x) {
  24     std::reverse_iterator<It> r(i);
  25     std::reverse_iterator<It>& rr = r -= n;
  26     assert(r.base() == x);
  27     assert(&rr == &r);
  28 }
  29
  30 TEST_CONSTEXPR_CXX17 bool tests() {
  31     const char* s = "1234567890";
  32     test(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s+10));
  33 #if TEST_STD_VER >= 20
  34     test(cpp20_random_access_iterator<const char*>(s + 5), 5, cpp20_random_access_iterator<const char*>(s + 10));
  35 #endif
  36     test(s+5, 5, s+10);
  37     return true;
  38 }
  39
  40 int main(int, char**) {
  41     tests();
  42 #if TEST_STD_VER > 14
  43     static_assert(tests(), "");
  44 #endif
  45     return 0;
  46 }