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 // streamsize readsome(char_type* s, streamsize n);
13 
14 #include <istream>
15 #include <cassert>
16 
17 template <class CharT>
18 struct testbuf
19     : public std::basic_streambuf<CharT>
20 {
21     typedef std::basic_string<CharT> string_type;
22     typedef std::basic_streambuf<CharT> base;
23 private:
24     string_type str_;
25 public:
26 
testbuftestbuf27     testbuf() {}
testbuftestbuf28     testbuf(const string_type& str)
29         : str_(str)
30     {
31         base::setg(const_cast<CharT*>(str_.data()),
32                    const_cast<CharT*>(str_.data()),
33                    const_cast<CharT*>(str_.data()) + str_.size());
34     }
35 
ebacktestbuf36     CharT* eback() const {return base::eback();}
gptrtestbuf37     CharT* gptr() const {return base::gptr();}
egptrtestbuf38     CharT* egptr() const {return base::egptr();}
39 };
40 
main()41 int main()
42 {
43     {
44         testbuf<char> sb(" 1234567890");
45         std::istream is(&sb);
46         char s[5];
47         assert(is.readsome(s, 5) == 5);
48         assert(!is.eof());
49         assert(!is.fail());
50         assert(std::string(s, 5) == " 1234");
51         assert(is.gcount() == 5);
52         is.readsome(s, 5);
53         assert(!is.eof());
54         assert(!is.fail());
55         assert(std::string(s, 5) == "56789");
56         assert(is.gcount() == 5);
57         is.readsome(s, 5);
58         assert(!is.eof());
59         assert(!is.fail());
60         assert(is.gcount() == 1);
61         assert(std::string(s, 1) == "0");
62         assert(is.readsome(s, 5) == 0);
63     }
64     {
65         testbuf<wchar_t> sb(L" 1234567890");
66         std::wistream is(&sb);
67         wchar_t s[5];
68         assert(is.readsome(s, 5) == 5);
69         assert(!is.eof());
70         assert(!is.fail());
71         assert(std::wstring(s, 5) == L" 1234");
72         assert(is.gcount() == 5);
73         is.readsome(s, 5);
74         assert(!is.eof());
75         assert(!is.fail());
76         assert(std::wstring(s, 5) == L"56789");
77         assert(is.gcount() == 5);
78         is.readsome(s, 5);
79         assert(!is.eof());
80         assert(!is.fail());
81         assert(is.gcount() == 1);
82         assert(std::wstring(s, 1) == L"0");
83         assert(is.readsome(s, 5) == 0);
84     }
85 }
86