readsome.pass.cpp revision a90c6dd46005b2b14de3bb889a8d03bb34bd3256 
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
17template <class CharT>
18struct testbuf
19    : public std::basic_streambuf<CharT>
20{
21    typedef std::basic_string<CharT> string_type;
22    typedef std::basic_streambuf<CharT> base;
23private:
24    string_type str_;
25public:
26
27    testbuf() {}
28    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
36    CharT* eback() const {return base::eback();}
37    CharT* gptr() const {return base::gptr();}
38    CharT* egptr() const {return base::egptr();}
39};
40
41int 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