third_party/llvm-project/libcxx/test/std/ranges/range.adaptors/range.lazy.split/range.lazy.split.inner/deref.pass.cpp

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// UNSUPPORTED: c++03, c++11, c++14, c++17

// constexpr decltype(auto) inner-iterator::operator*() const;

#include <ranges>

#include "../types.h"

constexpr bool test() {
  // Can call `inner-iterator::operator*`; `View` is a forward range.
  {
    SplitViewDiff v("abc def", " ");
    auto val = *v.begin();

    // Non-const iterator.
    {
      auto i = val.begin();
      static_assert(std::same_as<decltype(*i), char&>);
      assert(*i == 'a');
      assert(*(++i) == 'b');
      assert(*(++i) == 'c');
    }

    // Const iterator.
    {
      const auto ci = val.begin();
      static_assert(std::same_as<decltype(*ci), char&>);
      assert(*ci == 'a');
    }
  }

  // Can call `inner-iterator::operator*`; `View` is an input range.
  {
    SplitViewInput v("abc def", ' ');
    auto val = *v.begin();

    // Non-const iterator.
    {
      auto i = val.begin();
      static_assert(std::same_as<decltype(*i), char&>);
      assert(*i == 'a');
      assert(*(++i) == 'b');
      assert(*(++i) == 'c');
    }

    // Const iterator.
    {
      const auto ci = val.begin();
      static_assert(std::same_as<decltype(*ci), char&>);
      // Note: when the underlying range is an input range, `current` is stored in the `lazy_split_view` itself and
      // shared between `inner-iterator`s. Consequently, incrementing one iterator effectively increments all of them.
      assert(*ci == 'c');
    }
  }

  return true;
}

int main(int, char**) {
  test();
  static_assert(test());

  return 0;
}