libstdc++-v3/testsuite/25_algorithms/fold_left/1.cc

   1 // { dg-do run { target c++23 } }
   2 // { dg-add-options no_pch }
   3
   4 #include <algorithm>
   5
   6 #if __cpp_lib_ranges_fold != 202207L
   7 # error "Feature-test macro __cpp_lib_ranges_fold has wrong value in <algorithm>"
   8 #endif
   9
  10 #include <ranges>
  11 #include <testsuite_iterators.h>
  12
  13 namespace ranges = std::ranges;
  14 namespace views = std::views;
  15
  16 constexpr bool
  17 test01()
  18 {
  19   int x[] = {1, 2, 3, 4, 5};
  20   auto f = [](int&& acc, int& x) {
  21     return 2 * acc + x;
  22   };
  23   VERIFY( ranges::fold_left(x, 0, f) == 57 );
  24   VERIFY( ranges::fold_left(x, 1, f) == 89 );
  25   VERIFY( ranges::fold_left(x+0, x+0, 1, f) == 1 );
  26
  27   VERIFY( ranges::fold_left_first(x, f).value() == 57 );
  28   VERIFY( !ranges::fold_left_first(x+0, x+0, f).has_value() );
  29
  30   return true;
  31 }
  32
  33 void
  34 test02()
  35 {
  36   int x[] = {1, 2, 3, 4, 5};
  37   auto f = [](int&& acc, int& x) {
  38     return 2 * acc + x;
  39   };
  40
  41   __gnu_test::test_input_range<int> rx(x);
  42   ranges::in_value_result ivr = ranges::fold_left_with_iter(rx, 0, f);
  43   VERIFY( ivr.in == rx.end() );
  44   VERIFY( ivr.value == 57 );
  45
  46   rx.bounds.first = x;
  47   ranges::in_value_result ivr2 = ranges::fold_left_first_with_iter(rx, f);
  48   VERIFY( ivr2.in == rx.end() );
  49   VERIFY( ivr2.value.value() == 57 );
  50
  51   rx.bounds.first = x;
  52   auto v = rx | views::take(0);
  53   ranges::in_value_result ivr3 = ranges::fold_left_first_with_iter(v, f);
  54   VERIFY( ivr3.in == v.end() );
  55   VERIFY( !ivr3.value.has_value() );
  56 }
  57
  58 constexpr bool
  59 test03()
  60 {
  61   double x[] = {0.5, 0.25, 0.125, 0.125};
  62   VERIFY( ranges::fold_left(x, 0, std::plus{}) == 1.0 );
  63   VERIFY( ranges::fold_left_with_iter(x, 0, std::plus{}).value == 1.0 );
  64
  65   return true;
  66 }
  67
  68 int
  69 main()
  70 {
  71   static_assert(test01());
  72   test02();
  73   static_assert(test03());
  74 }