//===----------------------------------------------------------------------===//
//
// 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

// <span>

// [[nodiscard]] constexpr bool empty() const noexcept;
//

#include <span>
#include <cassert>
#include <string>

#include "test_macros.h"

struct A {};
constexpr int iArr1[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
int iArr2[]           = {10, 11, 12, 13, 14, 15, 16, 17, 18, 19};

int main(int, char**) {
  static_assert(noexcept(std::span<int>().empty()), "");
  static_assert(noexcept(std::span<int, 0>().empty()), "");

  static_assert(std::span<int>().empty(), "");
  static_assert(std::span<long>().empty(), "");
  static_assert(std::span<double>().empty(), "");
  static_assert(std::span<A>().empty(), "");
  static_assert(std::span<std::string>().empty(), "");

  static_assert(std::span<int, 0>().empty(), "");
  static_assert(std::span<long, 0>().empty(), "");
  static_assert(std::span<double, 0>().empty(), "");
  static_assert(std::span<A, 0>().empty(), "");
  static_assert(std::span<std::string, 0>().empty(), "");

  static_assert(!std::span<const int>(iArr1, 1).empty(), "");
  static_assert(!std::span<const int>(iArr1, 2).empty(), "");
  static_assert(!std::span<const int>(iArr1, 3).empty(), "");
  static_assert(!std::span<const int>(iArr1, 4).empty(), "");
  static_assert(!std::span<const int>(iArr1, 5).empty(), "");

  assert((std::span<int>().empty()));
  assert((std::span<long>().empty()));
  assert((std::span<double>().empty()));
  assert((std::span<A>().empty()));
  assert((std::span<std::string>().empty()));

  assert((std::span<int, 0>().empty()));
  assert((std::span<long, 0>().empty()));
  assert((std::span<double, 0>().empty()));
  assert((std::span<A, 0>().empty()));
  assert((std::span<std::string, 0>().empty()));

  assert(!(std::span<int, 1>(iArr2, 1).empty()));
  assert(!(std::span<int, 2>(iArr2, 2).empty()));
  assert(!(std::span<int, 3>(iArr2, 3).empty()));
  assert(!(std::span<int, 4>(iArr2, 4).empty()));
  assert(!(std::span<int, 5>(iArr2, 5).empty()));

  std::string s;
  assert(((std::span<std::string>(&s, (std::size_t)0)).empty()));
  assert(!((std::span<std::string>(&s, 1).empty())));

  return 0;
}