llvm/libcxx/test/std/input.output/file.streams/fstreams/filebuf.assign/nonmember_swap.pass.cpp

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

// <fstream>

// template <class charT, class traits = char_traits<charT> >
// class basic_filebuf

// template <class charT, class traits>
// void
// swap(basic_filebuf<charT, traits>& x, basic_filebuf<charT, traits>& y);

#include <fstream>
#include <cassert>
#include "test_macros.h"
#include "platform_support.h"

int main(int, char**)
{
    std::string temp = get_temp_file_name();
    {
        std::filebuf f;
        assert(f.open(temp.c_str(), std::ios_base::out | std::ios_base::in
                                               | std::ios_base::trunc) != 0);
        assert(f.is_open());
        assert(f.sputn("123", 3) == 3);
        f.pubseekoff(1, std::ios_base::beg);
        assert(f.sgetc() == '2');
        std::filebuf f2;
        swap(f2, f);
        assert(!f.is_open());
        assert(f2.is_open());
        assert(f2.sgetc() == '2');
    }
    std::remove(temp.c_str());

    // lhs uses a small buffer, rhs is empty
    {
        std::filebuf f;
        assert(f.open(temp.c_str(), std::ios_base::out | std::ios_base::in
                                               | std::ios_base::trunc) != 0);
        assert(f.is_open());
        assert(f.sputn("123", 3) == 3);
        f.pubseekoff(1, std::ios_base::beg);
        assert(f.sgetc() == '2');
        std::filebuf f2;
        swap(f, f2);
        assert(!f.is_open());
        assert(f2.is_open());
        assert(f2.sgetc() == '2');
    }
    std::remove(temp.c_str());

    // neither lhs nor rhs use the small buffer
    {
        std::string tmpA = get_temp_file_name();
        std::string tmpB = get_temp_file_name();

        {
            // currently the small buffer has size 8
            std::ofstream sa(tmpA), sb(tmpB);
            sa << "0123456789";
            sb << "abcdefghij";
        }

        std::filebuf f1, f2;
        assert(f1.open(tmpA, std::ios_base::in) != 0);
        assert(f2.open(tmpB, std::ios_base::in) != 0);
        assert(f1.sgetc() == '0');
        assert(f2.sgetc() == 'a');

        swap(f1, f2);

        assert(f1.sgetc() == 'a');
        assert(f2.sgetc() == '0');

        std::remove(tmpA.c_str());
        std::remove(tmpB.c_str());
    }

#ifndef TEST_HAS_NO_WIDE_CHARACTERS
    {
        std::wfilebuf f;
        assert(f.open(temp.c_str(), std::ios_base::out | std::ios_base::in
                                               | std::ios_base::trunc) != 0);
        assert(f.is_open());
        assert(f.sputn(L"123", 3) == 3);
        f.pubseekoff(1, std::ios_base::beg);
        assert(f.sgetc() == L'2');
        std::wfilebuf f2;
        swap(f2, f);
        assert(!f.is_open());
        assert(f2.is_open());
        assert(f2.sgetc() == L'2');
    }
    std::remove(temp.c_str());
#endif

  return 0;
}