seekp.pass.cpp revision b64f8b07c104c6cc986570ac8ee0ed16a9f23976 
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(pos_type pos);
16
17#include <ostream>
18#include <cassert>
19
20int seekpos_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    seekpos(typename base::pos_type sp, std::ios_base::openmode which)
33    {
34        ++seekpos_called;
35        assert(which == std::ios_base::out);
36        return sp;
37    }
38};
39
40int main()
41{
42    {
43        std::ostream os((std::streambuf*)0);
44        assert(&os.seekp(5) == &os);
45        assert(seekpos_called == 0);
46    }
47    {
48        testbuf<char> sb;
49        std::ostream os(&sb);
50        assert(&os.seekp(10) == &os);
51        assert(seekpos_called == 1);
52        assert(os.good());
53        assert(&os.seekp(-1) == &os);
54        assert(seekpos_called == 2);
55        assert(os.fail());
56    }
57}
58