//===----------------------------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

// <string>

// const_reference at(size_type pos) const;
//       reference at(size_type pos);

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

template <class S>
void
test(S s, typename S::size_type pos)
{
    try
    {
        const S& cs = s;
        assert(s.at(pos) == s[pos]);
        assert(cs.at(pos) == cs[pos]);
        assert(pos < cs.size());
    }
    catch (std::out_of_range&)
    {
        assert(pos >= s.size());
    }
}

int main()
{
    typedef std::string S;
    test(S(), 0);
    test(S("123"), 0);
    test(S("123"), 1);
    test(S("123"), 2);
    test(S("123"), 3);
}