libcxx/test/std/ranges/range.utility/range.subrange/ctor.default.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 subrange() requires default_initializable<I>;
  12
  13 #include <ranges>
  14
  15 #include <cassert>
  16 #include <cstddef>
  17
  18 #include "test_iterators.h"
  19
  20 // An input_or_output_iterator that is not default constructible so we can test
  21 // the `requires` on subrange's default constructor.
  22 struct NoDefaultIterator {
  23   using difference_type = std::ptrdiff_t;
  24   NoDefaultIterator() = delete;
  25   NoDefaultIterator& operator++();
  26   void operator++(int);
  27   int& operator*() const;
  28   friend bool operator==(NoDefaultIterator const&, NoDefaultIterator const&);
  29 };
  30 static_assert(std::input_or_output_iterator<NoDefaultIterator>);
  31
  32 // A sentinel type for the above iterator
  33 struct Sentinel {
  34   friend bool operator==(NoDefaultIterator const&, Sentinel const&);
  35   friend bool operator==(Sentinel const&, NoDefaultIterator const&);
  36   friend bool operator!=(NoDefaultIterator const&, Sentinel const&);
  37   friend bool operator!=(Sentinel const&, NoDefaultIterator const&);
  38 };
  39
  40 constexpr bool test() {
  41   {
  42     static_assert(!std::is_default_constructible_v<std::ranges::subrange<NoDefaultIterator, Sentinel, std::ranges::subrange_kind::sized>>);
  43     static_assert(!std::is_default_constructible_v<std::ranges::subrange<NoDefaultIterator, Sentinel, std::ranges::subrange_kind::unsized>>);
  44   }
  45
  46   {
  47     using Iter = forward_iterator<int*>;
  48     std::ranges::subrange<Iter, Iter, std::ranges::subrange_kind::sized> subrange;
  49     assert(subrange.begin() == Iter());
  50     assert(subrange.end() == Iter());
  51   }
  52   {
  53     using Iter = forward_iterator<int*>;
  54     std::ranges::subrange<Iter, Iter, std::ranges::subrange_kind::unsized> subrange;
  55     assert(subrange.begin() == Iter());
  56     assert(subrange.end() == Iter());
  57   }
  58
  59   return true;
  60 }
  61
  62 int main(int, char**) {
  63   test();
  64   static_assert(test());
  65
  66   return 0;
  67 }