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

// <string>

// template<> struct char_traits<char16_t>

// static int compare(const char_type* s1, const char_type* s2, size_t n);
// constexpr in C++17

#include <string>
#include <cassert>

#include "test_macros.h"

#if TEST_STD_VER > 14
constexpr bool test_constexpr()
{
    return std::char_traits<char16_t>::compare(u"123", u"223", 3) < 0
        && std::char_traits<char16_t>::compare(u"223", u"123", 3) > 0
        && std::char_traits<char16_t>::compare(u"123", u"123", 3) == 0;
}
#endif


int main(int, char**)
{
#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
#if TEST_STD_VER >= 11
    assert(std::char_traits<char16_t>::compare(u"", u"", 0) == 0);
    assert(std::char_traits<char16_t>::compare(NULL, NULL, 0) == 0);

    assert(std::char_traits<char16_t>::compare(u"1", u"1", 1) == 0);
    assert(std::char_traits<char16_t>::compare(u"1", u"2", 1) < 0);
    assert(std::char_traits<char16_t>::compare(u"2", u"1", 1) > 0);

    assert(std::char_traits<char16_t>::compare(u"12", u"12", 2) == 0);
    assert(std::char_traits<char16_t>::compare(u"12", u"13", 2) < 0);
    assert(std::char_traits<char16_t>::compare(u"12", u"22", 2) < 0);
    assert(std::char_traits<char16_t>::compare(u"13", u"12", 2) > 0);
    assert(std::char_traits<char16_t>::compare(u"22", u"12", 2) > 0);

    assert(std::char_traits<char16_t>::compare(u"123", u"123", 3) == 0);
    assert(std::char_traits<char16_t>::compare(u"123", u"223", 3) < 0);
    assert(std::char_traits<char16_t>::compare(u"123", u"133", 3) < 0);
    assert(std::char_traits<char16_t>::compare(u"123", u"124", 3) < 0);
    assert(std::char_traits<char16_t>::compare(u"223", u"123", 3) > 0);
    assert(std::char_traits<char16_t>::compare(u"133", u"123", 3) > 0);
    assert(std::char_traits<char16_t>::compare(u"124", u"123", 3) > 0);
#endif

#if TEST_STD_VER > 14
    static_assert(test_constexpr(), "" );
#endif
#endif  // _LIBCPP_HAS_NO_UNICODE_CHARS

  return 0;
}