1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 // <sstream>
10 
11 // template <class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
12 // class basic_stringbuf
13 
14 // int_type pbackfail(int_type c = traits::eof());
15 
16 #include <sstream>
17 #include <cassert>
18 
19 template <class CharT>
20 struct testbuf
21     : public std::basic_stringbuf<CharT>
22 {
23     typedef std::basic_stringbuf<CharT> base;
24     explicit testbuf(const std::basic_string<CharT>& str,
25                      std::ios_base::openmode which = std::ios_base::in | std::ios_base::out)
26         : base(str, which) {}
27 
28     typename base::int_type
29         pbackfail(typename base::int_type c = base::traits_type::eof())
30         {return base::pbackfail(c);}
31 
32     void pbump(int n) {base::pbump(n);}
33 };
34 
35 int main(int, char**)
36 {
37     {  // sanity check
38     testbuf<char> tb("");
39     tb.pbackfail();
40     }
41     {
42         testbuf<char> sb("123", std::ios_base::in);
43         assert(sb.sgetc() == '1');
44         assert(sb.snextc() == '2');
45         assert(sb.snextc() == '3');
46         assert(sb.sgetc() == '3');
47         assert(sb.snextc() == std::char_traits<char>::eof());
48         assert(sb.pbackfail('3') == '3');
49         assert(sb.pbackfail('3') == std::char_traits<char>::eof());
50         assert(sb.pbackfail('2') == '2');
51         assert(sb.pbackfail(std::char_traits<char>::eof()) != std::char_traits<char>::eof());
52         assert(sb.pbackfail(std::char_traits<char>::eof()) == std::char_traits<char>::eof());
53         assert(sb.str() == "123");
54     }
55     {
56         testbuf<char> sb("123");
57         assert(sb.sgetc() == '1');
58         assert(sb.snextc() == '2');
59         assert(sb.snextc() == '3');
60         assert(sb.sgetc() == '3');
61         assert(sb.snextc() == std::char_traits<char>::eof());
62         assert(sb.pbackfail('3') == '3');
63         assert(sb.pbackfail('3') == '3');
64         assert(sb.pbackfail(std::char_traits<char>::eof()) != std::char_traits<char>::eof());
65         assert(sb.pbackfail(std::char_traits<char>::eof()) == std::char_traits<char>::eof());
66         assert(sb.str() == "133");
67     }
68     {
69         testbuf<wchar_t> sb(L"123", std::ios_base::in);
70         assert(sb.sgetc() == L'1');
71         assert(sb.snextc() == L'2');
72         assert(sb.snextc() == L'3');
73         assert(sb.sgetc() == L'3');
74         assert(sb.snextc() == std::char_traits<wchar_t>::eof());
75         assert(sb.pbackfail(L'3') == L'3');
76         assert(sb.pbackfail(L'3') == std::char_traits<wchar_t>::eof());
77         assert(sb.pbackfail(L'2') == L'2');
78         assert(sb.pbackfail(std::char_traits<wchar_t>::eof()) != std::char_traits<wchar_t>::eof());
79         assert(sb.pbackfail(std::char_traits<wchar_t>::eof()) == std::char_traits<wchar_t>::eof());
80         assert(sb.str() == L"123");
81     }
82     {
83         testbuf<wchar_t> sb(L"123");
84         assert(sb.sgetc() == L'1');
85         assert(sb.snextc() == L'2');
86         assert(sb.snextc() == L'3');
87         assert(sb.sgetc() == L'3');
88         assert(sb.snextc() == std::char_traits<wchar_t>::eof());
89         assert(sb.pbackfail(L'3') == L'3');
90         assert(sb.pbackfail(L'3') == L'3');
91         assert(sb.pbackfail(std::char_traits<wchar_t>::eof()) != std::char_traits<wchar_t>::eof());
92         assert(sb.pbackfail(std::char_traits<wchar_t>::eof()) == std::char_traits<wchar_t>::eof());
93         assert(sb.str() == L"133");
94     }
95 
96   return 0;
97 }
98