1//===----------------------------------------------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is dual licensed under the MIT and the University of Illinois Open
6// Source Licenses. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10// <ostream>
11
12// template <class charT, class traits = char_traits<charT> >
13//   class basic_ostream;
14
15// basic_ostream<charT,traits>& seekp(off_type off, ios_base::seekdir dir);
16
17#include <ostream>
18#include <cassert>
19
20int seekoff_called = 0;
21
22template <class CharT>
23struct testbuf
24    : public std::basic_streambuf<CharT>
25{
26    typedef std::basic_streambuf<CharT> base;
27    testbuf() {}
28
29protected:
30
31    typename base::pos_type
32    seekoff(typename base::off_type off, std::ios_base::seekdir way,
33                                         std::ios_base::openmode which)
34    {
35        ++seekoff_called;
36        assert(way == std::ios_base::beg);
37        assert(which == std::ios_base::out);
38        return off;
39    }
40};
41
42int main()
43{
44    {
45        std::ostream os((std::streambuf*)0);
46        assert(&os.seekp(5, std::ios_base::beg) == &os);
47        assert(seekoff_called == 0);
48    }
49    {
50        testbuf<char> sb;
51        std::ostream os(&sb);
52        assert(&os.seekp(10, std::ios_base::beg) == &os);
53        assert(seekoff_called == 1);
54        assert(os.good());
55        assert(&os.seekp(-1, std::ios_base::beg) == &os);
56        assert(seekoff_called == 2);
57        assert(os.fail());
58    }
59}
60