1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 // <ostream>
10 
11 // template <class charT, class traits = char_traits<charT> >
12 //   class basic_ostream;
13 
14 // basic_ostream<charT,traits>& operator<<
15 //           (basic_ostream<charT,traits>& (*pf)(basic_ostream<charT,traits>&))
16 
17 #include <ostream>
18 #include <cassert>
19 
20 #include "test_macros.h"
21 
22 template <class CharT>
23 class testbuf
24     : public std::basic_streambuf<CharT>
25 {
26     typedef std::basic_streambuf<CharT> base;
27     std::basic_string<CharT> str_;
28 public:
testbuf()29     testbuf()
30     {
31     }
32 
str() const33     std::basic_string<CharT> str() const
34         {return std::basic_string<CharT>(base::pbase(), base::pptr());}
35 
36 protected:
37 
38     virtual typename base::int_type
overflow(typename base::int_type ch=base::traits_type::eof ())39         overflow(typename base::int_type ch = base::traits_type::eof())
40         {
41             if (ch != base::traits_type::eof())
42             {
43                 int n = static_cast<int>(str_.size());
44                 str_.push_back(static_cast<CharT>(ch));
45                 str_.resize(str_.capacity());
46                 base::setp(const_cast<CharT*>(str_.data()),
47                            const_cast<CharT*>(str_.data() + str_.size()));
48                 base::pbump(n+1);
49             }
50             return ch;
51         }
52 };
53 
54 template <class CharT>
55 std::basic_ostream<CharT>&
f(std::basic_ostream<CharT> & os)56 f(std::basic_ostream<CharT>& os)
57 {
58     os << "testing...";
59     return os;
60 }
61 
main(int,char **)62 int main(int, char**)
63 {
64     {
65         testbuf<char> sb;
66         std::ostream os(&sb);
67         os << f;
68         assert(sb.str() == "testing...");
69     }
70 
71   return 0;
72 }
73