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// <istream>
10
11// basic_istream<charT,traits>& putback(char_type c);
12
13#include <istream>
14#include <cassert>
15#include <streambuf>
16
17#include "test_macros.h"
18
19template <class CharT>
20struct testbuf
21 : public std::basic_streambuf<CharT>
22{
23 typedef std::basic_string<CharT> string_type;
24 typedef std::basic_streambuf<CharT> base;
25private:
26 string_type str_;
27public:
28
29 testbuf() {}
30 testbuf(const string_type& str)
31 : str_(str)
32 {
33 base::setg(const_cast<CharT*>(str_.data()),
34 const_cast<CharT*>(str_.data()),
35 const_cast<CharT*>(str_.data()) + str_.size());
36 }
37
38 CharT* eback() const {return base::eback();}
39 CharT* gptr() const {return base::gptr();}
40 CharT* egptr() const {return base::egptr();}
41};
42
43int main(int, char**)
44{
45 {
46 testbuf<char> sb(" 123456789");
47 std::istream is(&sb);
48 is.get();
49 is.get();
50 is.get();
51 is.putback(c: 'a');
52 assert(is.bad());
53 assert(is.gcount() == 0);
54 is.clear();
55 is.putback(c: '2');
56 assert(is.good());
57 assert(is.gcount() == 0);
58 is.putback(c: '1');
59 assert(is.good());
60 assert(is.gcount() == 0);
61 is.putback(c: ' ');
62 assert(is.good());
63 assert(is.gcount() == 0);
64 is.putback(c: ' ');
65 assert(is.bad());
66 assert(is.gcount() == 0);
67 }
68#ifndef TEST_HAS_NO_WIDE_CHARACTERS
69 {
70 testbuf<wchar_t> sb(L" 123456789");
71 std::wistream is(&sb);
72 is.get();
73 is.get();
74 is.get();
75 is.putback(c: L'a');
76 assert(is.bad());
77 assert(is.gcount() == 0);
78 is.clear();
79 is.putback(c: L'2');
80 assert(is.good());
81 assert(is.gcount() == 0);
82 is.putback(c: L'1');
83 assert(is.good());
84 assert(is.gcount() == 0);
85 is.putback(c: L' ');
86 assert(is.good());
87 assert(is.gcount() == 0);
88 is.putback(c: L' ');
89 assert(is.bad());
90 assert(is.gcount() == 0);
91 }
92#endif
93#ifndef TEST_HAS_NO_EXCEPTIONS
94 {
95 testbuf<char> sb;
96 std::basic_istream<char> is(&sb);
97 is.exceptions(std::ios_base::badbit);
98 bool threw = false;
99 try {
100 is.putback('x');
101 } catch (std::ios_base::failure&) {
102 threw = true;
103 }
104 assert(threw);
105 assert( is.bad());
106 assert(!is.eof());
107 assert( is.fail());
108 }
109#ifndef TEST_HAS_NO_WIDE_CHARACTERS
110 {
111 testbuf<wchar_t> sb;
112 std::basic_istream<wchar_t> is(&sb);
113 is.exceptions(std::ios_base::badbit);
114 bool threw = false;
115 try {
116 is.putback(L'x');
117 } catch (std::ios_base::failure&) {
118 threw = true;
119 }
120 assert(threw);
121 assert( is.bad());
122 assert(!is.eof());
123 assert( is.fail());
124 }
125#endif
126#endif // TEST_HAS_NO_EXCEPTIONS
127
128 return 0;
129}
130

source code of libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/putback.pass.cpp