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

   1 // Copyright (C) 2019-2023 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-options "-std=gnu++2a" }
  19 // { dg-do run { target c++2a } }
  20
  21 #include <ranges>
  22 #include <testsuite_hooks.h>
  23 #include <testsuite_iterators.h>
  24
  25 static_assert(__gnu_test::is_customization_point_object(std::ranges::rend));
  26
  27 struct R1
  28 {
  29   int i = 0;
  30   int j = 0;
  31
  32   constexpr const int* rbegin() const { return &i; }
  33   constexpr const int* rend() const { return &i + 1; }
  34   friend constexpr const int* rbegin(const R1&&); // not defined
  35   friend constexpr const int* rend(const R1&&); // not defined
  36 };
  37
  38 // N.B. this is a lie, rend on an R1 rvalue will return a dangling pointer.
  39 template<> constexpr bool std::ranges::enable_borrowed_range<R1> = true;
  40
  41 void
  42 test01()
  43 {
  44   constexpr R1 r;
  45
  46   // decay-copy(t.rend()) if it is a valid expression
  47   // and its type S models sentinel_for<decltype(ranges::rbegin(E))>
  48
  49   static_assert( std::ranges::rend(r) == &r.i + 1 );
  50   static_assert( std::ranges::rend(std::move(r)) == &r.i + 1 );
  51 }
  52
  53 struct R2
  54 {
  55   int i = 0;
  56
  57   int* rbegin() noexcept { return &i + 1; }
  58   long* rend() noexcept { return nullptr; } // not a sentinel for rbegin()
  59
  60   friend long* rbegin(R2&) noexcept { return nullptr; }
  61   friend int* rend(R2& r) { return &r.i; }
  62 };
  63
  64 void
  65 test02()
  66 {
  67   R2 r;
  68
  69   // Otherwise, decay-copy(rend(t)) if it is a valid expression
  70   // and its type S models sentinel_for<decltype(ranges::rbegin(E))>
  71
  72   auto i1 = std::ranges::rbegin(r);
  73   auto i2 = rend(r);
  74   static_assert( std::sentinel_for<decltype(i2), decltype(i1)> );
  75   VERIFY( std::ranges::rend(r) == &r.i );
  76   static_assert( !noexcept(std::ranges::rend(r)) );
  77 }
  78
  79 struct R3
  80 {
  81   int a[2] = { };
  82   long l[2] = { };
  83
  84   constexpr const int* begin() const { return a; }
  85   constexpr const int* end() const { return a + 2; }
  86
  87   friend constexpr const long* begin(const R3&& r) { return r.l; }
  88   friend constexpr const long* end(const R3&& r) { return r.l + 2; }
  89 };
  90
  91 // N.B. this is a lie, begin/end on an R3 rvalue will return a dangling pointer.
  92 template<> constexpr bool std::ranges::enable_borrowed_range<R3> = true;
  93
  94 void
  95 test03()
  96 {
  97   constexpr R3 r;
  98
  99   // Otherwise, make_reverse_iterator(ranges::begin(t)) if both
 100   // ranges::begin(t) and ranges::end(t) are valid expressions
 101   // of the same type I which models bidirectional_iterator.
 102
 103   static_assert( std::ranges::rend(r)
 104       == std::make_reverse_iterator(std::ranges::begin(r)) );
 105   static_assert( std::ranges::rend(std::move(r))
 106       == std::make_reverse_iterator(std::ranges::begin(std::move(r))) );
 107 }
 108
 109 void
 110 test04()
 111 {
 112   struct R4
 113   : __gnu_test::test_range<int, __gnu_test::bidirectional_iterator_wrapper>
 114   {
 115     R4(int (&a)[2]) : test_range(a) { }
 116
 117     using test_range::begin;
 118
 119     // Replace test_range::end() to return same type as begin()
 120     // so ranges::rend will wrap it in a reverse_iterator.
 121     auto end() &
 122     {
 123       using __gnu_test::bidirectional_iterator_wrapper;
 124       return bidirectional_iterator_wrapper<int>(bounds.last, &bounds);
 125     }
 126   };
 127
 128   int a[2] = { };
 129   R4 r(a);
 130   VERIFY( std::ranges::rend(r) == std::make_reverse_iterator(std::ranges::begin(r)) );
 131 }
 132
 133 int
 134 main()
 135 {
 136   test01();
 137   test02();
 138   test03();
 139   test04();
 140 }