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 // <istream>
11 
12 // template <class charT, class traits>
13 //   basic_istream<charT,traits>&
14 //   ws(basic_istream<charT,traits>& is);
15 
16 #include <istream>
17 #include <cassert>
18 
19 template <class CharT>
20 struct testbuf
21     : public std::basic_streambuf<CharT>
22 {
23     typedef std::basic_string<CharT> string_type;
24     typedef std::basic_streambuf<CharT> base;
25 private:
26     string_type str_;
27 public:
28 
29     testbuf() {}
30     testbuf(const string_type& str)
31         : str_(str)
32     {
33         base::setg(const_cast<CharT*>(str_.data()),
34                    const_cast<CharT*>(str_.data()),
35                    const_cast<CharT*>(str_.data()) + str_.size());
36     }
37 
38     CharT* eback() const {return base::eback();}
39     CharT* gptr() const {return base::gptr();}
40     CharT* egptr() const {return base::egptr();}
41 };
42 
43 int main()
44 {
45     {
46         testbuf<char> sb("   123");
47         std::istream is(&sb);
48         ws(is);
49         assert(is.good());
50         assert(is.peek() == '1');
51     }
52     {
53         testbuf<wchar_t> sb(L"   123");
54         std::wistream is(&sb);
55         ws(is);
56         assert(is.good());
57         assert(is.peek() == L'1');
58     }
59 }
60