libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.elem/dereference.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 // reference operator*() const; // constexpr in C++17
  14
  15 // Be sure to respect LWG 198:
  16 //    http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#198
  17 // LWG 198 was superseded by LWG 2360
  18 //    http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#2360
  19
  20 #include <iterator>
  21 #include <cassert>
  22
  23 #include "test_macros.h"
  24
  25 class A
  26 {
  27     int data_;
  28 public:
  29     A() : data_(1) {}
  30     A(const A&) = default;
  31     A& operator=(const A&) = default;
  32     ~A() {data_ = -1;}
  33
  34     friend bool operator==(const A& x, const A& y)
  35         {return x.data_ == y.data_;}
  36 };
  37
  38 template <class It>
  39 void
  40 test(It i, typename std::iterator_traits<It>::value_type x)
  41 {
  42     std::reverse_iterator<It> r(i);
  43     assert(*r == x);
  44 }
  45
  46 int main(int, char**)
  47 {
  48     A a;
  49     test(&a+1, A());
  50
  51 #if TEST_STD_VER > 14
  52     {
  53         constexpr const char *p = "123456789";
  54         typedef std::reverse_iterator<const char *> RI;
  55         constexpr RI it1 = std::make_reverse_iterator(p+1);
  56         constexpr RI it2 = std::make_reverse_iterator(p+2);
  57         static_assert(*it1 == p[0], "");
  58         static_assert(*it2 == p[1], "");
  59     }
  60 #endif
  61
  62   return 0;
  63 }