//===----------------------------------------------------------------------===//
//
// 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: !stdlib=libc++ && (c++03 || c++11 || c++14)

// <string_view>

// constexpr const_iterator begin() const;

#include <string_view>
#include <cassert>

#include "test_macros.h"

template <class S>
void test(S s) {
  const S& cs                    = s;
  typename S::iterator b         = s.begin();
  typename S::const_iterator cb1 = cs.begin();
  typename S::const_iterator cb2 = s.cbegin();
  if (!s.empty()) {
    assert(*b == s[0]);
    assert(&*b == &s[0]);
    assert(*cb1 == s[0]);
    assert(&*cb1 == &s[0]);
    assert(*cb2 == s[0]);
    assert(&*cb2 == &s[0]);
  }
  assert(b == cb1);
  assert(b == cb2);
  assert(cb1 == cb2);
}

int main(int, char**) {
  typedef std::string_view string_view;
#ifndef TEST_HAS_NO_CHAR8_T
  typedef std::u8string_view u8string_view;
#endif
  typedef std::u16string_view u16string_view;
  typedef std::u32string_view u32string_view;

  test(string_view());
  test(u16string_view());
  test(u32string_view());
  test(string_view("123"));
#ifndef TEST_HAS_NO_CHAR8_T
  test(u8string_view{u8"123"});
#endif
#if TEST_STD_VER >= 11
  test(u16string_view{u"123"});
  test(u32string_view{U"123"});
#endif

#ifndef TEST_HAS_NO_WIDE_CHARACTERS
  typedef std::wstring_view wstring_view;
  test(wstring_view());
  test(wstring_view(L"123"));
#endif

#if TEST_STD_VER > 11
  {
    constexpr string_view sv{"123", 3};
#  ifndef TEST_HAS_NO_CHAR8_T
    constexpr u8string_view u8sv{u8"123", 3};
#  endif
    constexpr u16string_view u16sv{u"123", 3};
    constexpr u32string_view u32sv{U"123", 3};

    static_assert(*sv.begin() == sv[0], "");
#  ifndef TEST_HAS_NO_CHAR8_T
    static_assert(*u8sv.begin() == u8sv[0], "");
#  endif
    static_assert(*u16sv.begin() == u16sv[0], "");
    static_assert(*u32sv.begin() == u32sv[0], "");

    static_assert(*sv.cbegin() == sv[0], "");
#  ifndef TEST_HAS_NO_CHAR8_T
    static_assert(*u8sv.cbegin() == u8sv[0], "");
#  endif
    static_assert(*u16sv.cbegin() == u16sv[0], "");
    static_assert(*u32sv.cbegin() == u32sv[0], "");

#  ifndef TEST_HAS_NO_WIDE_CHARACTERS
    {
      constexpr wstring_view wsv{L"123", 3};
      static_assert(*wsv.begin() == wsv[0], "");
      static_assert(*wsv.cbegin() == wsv[0], "");
    }
#  endif
  }
#endif // TEST_STD_VER > 11

  return 0;
}