//===----------------------------------------------------------------------===//
//
// 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>

// basic_string<charT,traits,Allocator>&
//   assign(const basic_string<charT,traits>& str, size_type pos, size_type n=npos); // constexpr since C++20
// the =npos was added for C++14

#include <string>
#include <stdexcept>
#include <cassert>

#include "test_macros.h"
#include "min_allocator.h"

template <class S>
TEST_CONSTEXPR_CXX20 void
test(S s, S str, typename S::size_type pos, typename S::size_type n, S expected)
{
    if (pos <= str.size())
    {
        s.assign(str, pos, n);
        LIBCPP_ASSERT(s.__invariants());
        assert(s == expected);
    }
#ifndef TEST_HAS_NO_EXCEPTIONS
    else if (!TEST_IS_CONSTANT_EVALUATED)
    {
        try
        {
            s.assign(str, pos, n);
            assert(false);
        }
        catch (std::out_of_range&)
        {
            assert(pos > str.size());
        }
    }
#endif
}

template <class S>
TEST_CONSTEXPR_CXX20 void
test_npos(S s, S str, typename S::size_type pos, S expected)
{
    if (pos <= str.size())
    {
        s.assign(str, pos);
        LIBCPP_ASSERT(s.__invariants());
        assert(s == expected);
    }
#ifndef TEST_HAS_NO_EXCEPTIONS
    else if (!TEST_IS_CONSTANT_EVALUATED)
    {
        try
        {
            s.assign(str, pos);
            assert(false);
        }
        catch (std::out_of_range&)
        {
            assert(pos > str.size());
        }
    }
#endif
}

template <class S>
TEST_CONSTEXPR_CXX20 void test_string() {
  test(S(), S(), 0, 0, S());
  test(S(), S(), 1, 0, S());
  test(S(), S("12345"), 0, 3, S("123"));
  test(S(), S("12345"), 1, 4, S("2345"));
  test(S(), S("12345"), 3, 15, S("45"));
  test(S(), S("12345"), 5, 15, S(""));
  test(S(), S("12345"), 6, 15, S("not happening"));
  test(S(), S("12345678901234567890"), 0, 0, S());
  test(S(), S("12345678901234567890"), 1, 1, S("2"));
  test(S(), S("12345678901234567890"), 2, 3, S("345"));
  test(S(), S("12345678901234567890"), 12, 13, S("34567890"));
  test(S(), S("12345678901234567890"), 21, 13, S("not happening"));

  test(S("12345"), S(), 0, 0, S());
  test(S("12345"), S("12345"), 2, 2, S("34"));
  test(S("12345"), S("1234567890"), 0, 100, S("1234567890"));

  test(S("12345678901234567890"), S(), 0, 0, S());
  test(S("12345678901234567890"), S("12345"), 1, 3, S("234"));
  test(S("12345678901234567890"), S("12345678901234567890"), 5, 10,
        S("6789012345"));
}

TEST_CONSTEXPR_CXX20 bool test() {
  test_string<std::string>();
#if TEST_STD_VER >= 11
  test_string<std::basic_string<char, std::char_traits<char>, min_allocator<char>>>();
#endif

  {
    typedef std::string S;
    test_npos(S(), S(), 0, S());
    test_npos(S(), S(), 1, S());
    test_npos(S(), S("12345"), 0, S("12345"));
    test_npos(S(), S("12345"), 1, S("2345"));
    test_npos(S(), S("12345"), 3, S("45"));
    test_npos(S(), S("12345"), 5, S(""));
    test_npos(S(), S("12345"), 6, S("not happening"));
  }

  return true;
}

int main(int, char**)
{
  test();
#if TEST_STD_VER > 17
  static_assert(test());
#endif

  return 0;
}