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 = char_traits<charT> >
13 // class basic_istream::sentry;
14 
15 // explicit sentry(basic_istream<charT,traits>& is, bool noskipws = false);
16 
17 #include <istream>
18 #include <cassert>
19 
20 int sync_called = 0;
21 
22 template <class CharT>
23 struct testbuf
24     : public std::basic_streambuf<CharT>
25 {
26     typedef std::basic_string<CharT> string_type;
27     typedef std::basic_streambuf<CharT> base;
28 private:
29     string_type str_;
30 public:
31 
32     testbuf() {}
33     testbuf(const string_type& str)
34         : str_(str)
35     {
36         base::setg(const_cast<CharT*>(str_.data()),
37                    const_cast<CharT*>(str_.data()),
38                    const_cast<CharT*>(str_.data()) + str_.size());
39     }
40 
41     CharT* eback() const {return base::eback();}
42     CharT* gptr() const {return base::gptr();}
43     CharT* egptr() const {return base::egptr();}
44 protected:
45 
46     int virtual sync()
47     {
48         ++sync_called;
49         return 1;
50     }
51 };
52 
53 int main()
54 {
55     {
56         std::istream is((testbuf<char>*)0);
57         std::istream::sentry sen(is, true);
58         assert(!(bool)sen);
59         assert(!is.good());
60         assert(is.gcount() == 0);
61         assert(sync_called == 0);
62     }
63     {
64         std::wistream is((testbuf<wchar_t>*)0);
65         std::wistream::sentry sen(is, true);
66         assert(!(bool)sen);
67         assert(!is.good());
68         assert(is.gcount() == 0);
69         assert(sync_called == 0);
70     }
71     {
72         testbuf<char> sb("   123");
73         std::istream is(&sb);
74         std::istream::sentry sen(is, true);
75         assert((bool)sen);
76         assert(is.good());
77         assert(is.gcount() == 0);
78         assert(sync_called == 0);
79         assert(sb.gptr() == sb.eback());
80     }
81     {
82         testbuf<wchar_t> sb(L"   123");
83         std::wistream is(&sb);
84         std::wistream::sentry sen(is, true);
85         assert((bool)sen);
86         assert(is.good());
87         assert(is.gcount() == 0);
88         assert(sync_called == 0);
89         assert(sb.gptr() == sb.eback());
90     }
91     {
92         testbuf<char> sb("   123");
93         std::istream is(&sb);
94         std::istream::sentry sen(is);
95         assert((bool)sen);
96         assert(is.good());
97         assert(sync_called == 0);
98         assert(sb.gptr() == sb.eback() + 3);
99     }
100     {
101         testbuf<wchar_t> sb(L"   123");
102         std::wistream is(&sb);
103         std::wistream::sentry sen(is);
104         assert((bool)sen);
105         assert(is.good());
106         assert(sync_called == 0);
107         assert(sb.gptr() == sb.eback() + 3);
108     }
109     {
110         testbuf<char> sb("      ");
111         std::istream is(&sb);
112         std::istream::sentry sen(is);
113         assert(!(bool)sen);
114         assert(is.fail());
115         assert(is.eof());
116         assert(sync_called == 0);
117         assert(sb.gptr() == sb.eback() + 6);
118     }
119     {
120         testbuf<char> sb("      ");
121         std::istream is(&sb);
122         std::istream::sentry sen(is, true);
123         assert((bool)sen);
124         assert(is.good());
125         assert(sync_called == 0);
126         assert(sb.gptr() == sb.eback());
127     }
128 }
129