libcxx/test/std/ranges/range.factories/range.iota.view/size.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 // UNSUPPORTED: c++03, c++11, c++14, c++17
  10
  11 // constexpr auto size() const requires see below;
  12
  13 #include <cassert>
  14 #include <concepts>
  15 #include <limits>
  16 #include <ranges>
  17
  18 #include "test_macros.h"
  19 #include "types.h"
  20
  21 constexpr bool test() {
  22   // Both are integer like and both are less than zero.
  23   {
  24     const std::ranges::iota_view<int, int> io(-10, -5);
  25     assert(io.size() == 5);
  26   }
  27   {
  28     const std::ranges::iota_view<int, int> io(-10, -10);
  29     assert(io.size() == 0);
  30   }
  31
  32   // Both are integer like and "value_" is less than zero.
  33   {
  34     const std::ranges::iota_view<int, int> io(-10, 10);
  35     assert(io.size() == 20);
  36   }
  37   {
  38 // TODO: this is invalid with the current implementation. We need to file an LWG issue to
  39 // fix this. Essentially the issue is: An int's min and max are -2147483648 and 2147483647
  40 // which means the negated min cannot be represented as an integer; it needs to be cast to
  41 // an unsigned type first. That seems to be what the
  42 // to-unsigned-like(bound_) + to-unsigned-like(-value_))
  43 // part of https://eel.is/c++draft/range.iota#view-15 is doing, but I think it's doing it
  44 // wrong. It should be to-unsigned-like(bound_) - to-unsigned-like(value_)) (cast to
  45 // unsigned first).
  46 //     const std::ranges::iota_view<int, int> io(std::numeric_limits<int>::min(), std::numeric_limits<int>::max());
  47 //     assert(io.size() == (static_cast<unsigned>(std::numeric_limits<int>::max()) * 2) + 1);
  48   }
  49
  50   // It is UB for "bound_" to be less than "value_" i.e.: iota_view<int, int> io(10, -5).
  51
  52   // Both are integer like and neither less than zero.
  53   {
  54     const std::ranges::iota_view<int, int> io(10, 20);
  55     assert(io.size() == 10);
  56   }
  57   {
  58     const std::ranges::iota_view<int, int> io(10, 10);
  59     assert(io.size() == 0);
  60   }
  61   {
  62     const std::ranges::iota_view<int, int> io(0, 0);
  63     assert(io.size() == 0);
  64   }
  65   {
  66     const std::ranges::iota_view<int, int> io(0, std::numeric_limits<int>::max());
  67     constexpr auto imax = std::numeric_limits<int>::max();
  68     assert(io.size() == imax);
  69   }
  70
  71   // Neither are integer like.
  72   {
  73     const std::ranges::iota_view<SomeInt, SomeInt> io(SomeInt(-20), SomeInt(-10));
  74     assert(io.size() == 10);
  75   }
  76   {
  77     const std::ranges::iota_view<SomeInt, SomeInt> io(SomeInt(-10), SomeInt(-10));
  78     assert(io.size() == 0);
  79   }
  80   {
  81     const std::ranges::iota_view<SomeInt, SomeInt> io(SomeInt(0), SomeInt(0));
  82     assert(io.size() == 0);
  83   }
  84   {
  85     const std::ranges::iota_view<SomeInt, SomeInt> io(SomeInt(10), SomeInt(20));
  86     assert(io.size() == 10);
  87   }
  88   {
  89     const std::ranges::iota_view<SomeInt, SomeInt> io(SomeInt(10), SomeInt(10));
  90     assert(io.size() == 0);
  91   }
  92
  93   // Make sure iota_view<short, short> works properly. For details,
  94   // see https://github.com/llvm/llvm-project/issues/67551.
  95   {
  96     static_assert(std::ranges::sized_range<std::ranges::iota_view<short, short>>);
  97     std::ranges::iota_view<short, short> io(10, 20);
  98     std::same_as<unsigned int> auto sz = io.size();
  99     assert(sz == 10);
 100   }
 101
 102   return true;
 103 }
 104
 105 int main(int, char**) {
 106   test();
 107   static_assert(test());
 108
 109   return 0;
 110 }