libstdc++-v3/testsuite/std/ranges/access/rbegin.cc

   1 // Copyright (C) 2019-2024 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // { dg-do run { target c++20 } }
  19
  20 #include <ranges>
  21 #include <testsuite_hooks.h>
  22 #include <testsuite_iterators.h>
  23
  24 static_assert(__gnu_test::is_customization_point_object(std::ranges::rbegin));
  25
  26 struct R1
  27 {
  28   int i = 0;
  29   int j = 0;
  30
  31   constexpr const int* rbegin() const { return &i; }
  32   friend constexpr const int* rbegin(const R1&& r) { return &r.j; }
  33 };
  34
  35 // N.B. this is a lie, rbegin on an R1 rvalue will return a dangling pointer.
  36 template<> constexpr bool std::ranges::enable_borrowed_range<R1> = true;
  37
  38 void
  39 test01()
  40 {
  41   constexpr R1 r;
  42   // decay-copy(t.rbegin()) if it is a valid expression
  43   // and its type I models input_or_output_iterator.
  44   static_assert( std::ranges::rbegin(r) == &r.i );
  45   static_assert( std::ranges::rbegin(std::move(r)) == &r.i );
  46 }
  47
  48 struct R2
  49 {
  50   int a[2] = { };
  51
  52   constexpr const int* begin() const { return a; }
  53   constexpr const int* end() const { return a + 2; }
  54
  55   friend constexpr const long* begin(const R2&&); // not defined
  56   friend constexpr const long* end(const R2&&); // not defined
  57 };
  58
  59 // N.B. this is a lie, begin/end on an R2 rvalue will return a dangling pointer.
  60 template<> constexpr bool std::ranges::enable_borrowed_range<R2> = true;
  61
  62 void
  63 test02()
  64 {
  65   constexpr R2 r;
  66   // Otherwise, decay-copy(rbegin(t)) if it is a valid expression
  67   // and its type I models input_or_output_iterator [...]
  68   static_assert( std::ranges::rbegin(r)
  69       == std::make_reverse_iterator(std::ranges::end(r)) );
  70   static_assert( std::ranges::rbegin(std::move(r))
  71       == std::make_reverse_iterator(std::ranges::end(std::move(r))) );
  72 }
  73
  74 void
  75 test03()
  76 {
  77   struct R3
  78   : __gnu_test::test_range<int, __gnu_test::bidirectional_iterator_wrapper>
  79   {
  80     R3(int (&a)[2]) : test_range(a) { }
  81
  82     using test_range::begin;
  83
  84     // Replace test_range::end() to return same type as begin()
  85     // so ranges::rbegin will wrap it in a reverse_iterator .
  86     auto end() &
  87     {
  88       using __gnu_test::bidirectional_iterator_wrapper;
  89       return bidirectional_iterator_wrapper<int>(bounds.last, &bounds);
  90     }
  91   };
  92
  93   int a[2] = { };
  94   R3 r(a);
  95
  96   // Otherwise, make_reverse_iterator(ranges::end(t)) if both ranges::begin(t)
  97   // and ranges::end(t) are valid expressions of the same type I which models
  98   // bidirectional_iterator.
  99
 100   VERIFY( std::ranges::rbegin(r) == std::make_reverse_iterator(std::ranges::end(r)) );
 101 }
 102
 103 int
 104 main()
 105 {
 106   test01();
 107   test02();
 108   test03();
 109 }