xref: /llvm-project-15.0.7/libcxx/test/std/strings/basic.string/string.iterators/begin.pass.cpp (revision 1cf41139)

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

//       iterator begin(); // constexpr since C++20
// const_iterator begin() const; // constexpr since C++20

#include <string>
#include <cassert>

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

template <class S>
TEST_CONSTEXPR_CXX20 void
test(S s)
{
    const S& cs = s;
    typename S::iterator b = s.begin();
    typename S::const_iterator cb = cs.begin();
    if (!s.empty())
    {
        assert(*b == s[0]);
    }
    assert(b == cb);
}

TEST_CONSTEXPR_CXX20 bool test() {
  {
    typedef std::string S;
    test(S());
    test(S("123"));
  }
#if TEST_STD_VER >= 11
  {
    typedef std::basic_string<char, std::char_traits<char>, min_allocator<char>> S;
    test(S());
    test(S("123"));
  }
#endif

  return true;
}

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

  return 0;
}