putback.pass.cpp revision f5256e16dfc425c1d466f6308d4026d529ce9e0b 
1//===----------------------------------------------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10// <istream>
11
12// basic_istream<charT,traits>& putback(char_type c);
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(" 123456789");
45        std::istream is(&sb);
46        is.get();
47        is.get();
48        is.get();
49        is.putback('a');
50        assert(is.bad());
51        assert(is.gcount() == 0);
52        is.clear();
53        is.putback('2');
54        assert(is.good());
55        assert(is.gcount() == 0);
56        is.putback('1');
57        assert(is.good());
58        assert(is.gcount() == 0);
59        is.putback(' ');
60        assert(is.good());
61        assert(is.gcount() == 0);
62        is.putback(' ');
63        assert(is.bad());
64        assert(is.gcount() == 0);
65    }
66    {
67        testbuf<wchar_t> sb(L" 123456789");
68        std::wistream is(&sb);
69        is.get();
70        is.get();
71        is.get();
72        is.putback(L'a');
73        assert(is.bad());
74        assert(is.gcount() == 0);
75        is.clear();
76        is.putback(L'2');
77        assert(is.good());
78        assert(is.gcount() == 0);
79        is.putback(L'1');
80        assert(is.good());
81        assert(is.gcount() == 0);
82        is.putback(L' ');
83        assert(is.good());
84        assert(is.gcount() == 0);
85        is.putback(L' ');
86        assert(is.bad());
87        assert(is.gcount() == 0);
88    }
89}
90