libstdc++-v3/testsuite/24_iterators/range_operations/prev.cc

   1 // Copyright (C) 2019-2021 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 <iterator>
  22 #include <testsuite_hooks.h>
  23 #include <testsuite_iterators.h>
  24
  25 using __gnu_test::test_range;
  26 using __gnu_test::random_access_iterator_wrapper;
  27 using __gnu_test::bidirectional_iterator_wrapper;
  28 using __gnu_test::forward_iterator_wrapper;
  29 using __gnu_test::input_iterator_wrapper;
  30 using __gnu_test::output_iterator_wrapper;
  31
  32 void
  33 test01()
  34 {
  35   int a[10] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
  36   test_range<int, random_access_iterator_wrapper> r(a);
  37   auto begin = r.begin();
  38   auto end = r.end();
  39   auto endi = std::ranges::next(begin, end);
  40   VERIFY( *std::ranges::prev(endi) == 9 );
  41   VERIFY(  std::ranges::prev(begin, 0) == begin );
  42   VERIFY( *std::ranges::prev(endi, 1) == 9 );
  43   VERIFY( *std::ranges::prev(endi, 3) == 7 );
  44   VERIFY( *std::ranges::prev(begin, -4) == 4 );
  45   VERIFY(  std::ranges::prev(begin, 0, begin) == begin );
  46   VERIFY(  std::ranges::prev(begin, 5, begin) == begin );
  47   VERIFY(  std::ranges::prev(begin, -5, begin) == begin );
  48   VERIFY(  std::ranges::prev(begin, 0, endi) == begin );
  49   VERIFY( *std::ranges::prev(endi, 5, begin) == 5 );
  50   VERIFY(  std::ranges::prev(endi, 55, begin) == begin );
  51   VERIFY(  std::ranges::prev(endi, 0, endi) == end );
  52   VERIFY(  std::ranges::prev(endi, -5, endi) == end );
  53   VERIFY(  std::ranges::prev(endi, -55, endi) == end );
  54   VERIFY(  std::ranges::prev(endi, 0, begin) == end );
  55   VERIFY( *std::ranges::prev(begin, -5, endi) == 5 );
  56   VERIFY(  std::ranges::prev(begin, -55, endi) == end );
  57 }
  58
  59 void
  60 test02()
  61 {
  62   int a[10] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
  63   test_range<int, bidirectional_iterator_wrapper> r(a);
  64   auto begin = r.begin();
  65   auto end = r.end();
  66   auto endi = std::ranges::next(begin, end);
  67   VERIFY( *std::ranges::prev(endi) == 9 );
  68   VERIFY(  std::ranges::prev(begin, 0) == begin );
  69   VERIFY( *std::ranges::prev(endi, 1) == 9 );
  70   VERIFY( *std::ranges::prev(endi, 3) == 7 );
  71   VERIFY( *std::ranges::prev(begin, -4) == 4 );
  72   VERIFY(  std::ranges::prev(begin, 0, begin) == begin );
  73   VERIFY(  std::ranges::prev(begin, 5, begin) == begin );
  74   VERIFY(  std::ranges::prev(begin, -5, begin) == begin );
  75   VERIFY(  std::ranges::prev(begin, 0, endi) == begin );
  76   VERIFY( *std::ranges::prev(endi, 5, begin) == 5 );
  77   VERIFY(  std::ranges::prev(endi, 55, begin) == begin );
  78   VERIFY(  std::ranges::prev(endi, 0, endi) == end );
  79   VERIFY(  std::ranges::prev(endi, -5, endi) == end );
  80   VERIFY(  std::ranges::prev(endi, -55, endi) == end );
  81   VERIFY(  std::ranges::prev(endi, 0, begin) == end );
  82   VERIFY( *std::ranges::prev(begin, -5, endi) == 5 );
  83   VERIFY(  std::ranges::prev(begin, -55, endi) == end );
  84 }
  85
  86 template<typename T>
  87   concept can_prev = requires(T& t) { std::ranges::prev(t); }
  88     || requires(T& t) { std::ranges::prev(t, 1); }
  89     || requires(T& t) { std::ranges::prev(t, 1, t); };
  90
  91 static_assert( !can_prev<forward_iterator_wrapper<int>> );
  92 static_assert( !can_prev<input_iterator_wrapper<int>> );
  93 static_assert( !can_prev<output_iterator_wrapper<int>> );
  94
  95 int
  96 main()
  97 {
  98   test01();
  99   test02();
 100 }