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 16 #include "test_macros.h" 17 18 template <class CharT> 19 struct testbuf 20 : public std::basic_streambuf<CharT> 21 { 22 typedef std::basic_string<CharT> string_type; 23 typedef std::basic_streambuf<CharT> base; 24 private: 25 string_type str_; 26 public: 27 testbuftestbuf28 testbuf() {} testbuftestbuf29 testbuf(const string_type& str) 30 : str_(str) 31 { 32 base::setg(const_cast<CharT*>(str_.data()), 33 const_cast<CharT*>(str_.data()), 34 const_cast<CharT*>(str_.data()) + str_.size()); 35 } 36 ebacktestbuf37 CharT* eback() const {return base::eback();} gptrtestbuf38 CharT* gptr() const {return base::gptr();} egptrtestbuf39 CharT* egptr() const {return base::egptr();} 40 }; 41 main(int,char **)42int main(int, char**) 43 { 44 { 45 testbuf<char> sb(" 123456789"); 46 std::istream is(&sb); 47 is.get(); 48 is.get(); 49 is.get(); 50 is.putback('a'); 51 assert(is.bad()); 52 assert(is.gcount() == 0); 53 is.clear(); 54 is.putback('2'); 55 assert(is.good()); 56 assert(is.gcount() == 0); 57 is.putback('1'); 58 assert(is.good()); 59 assert(is.gcount() == 0); 60 is.putback(' '); 61 assert(is.good()); 62 assert(is.gcount() == 0); 63 is.putback(' '); 64 assert(is.bad()); 65 assert(is.gcount() == 0); 66 } 67 { 68 testbuf<wchar_t> sb(L" 123456789"); 69 std::wistream is(&sb); 70 is.get(); 71 is.get(); 72 is.get(); 73 is.putback(L'a'); 74 assert(is.bad()); 75 assert(is.gcount() == 0); 76 is.clear(); 77 is.putback(L'2'); 78 assert(is.good()); 79 assert(is.gcount() == 0); 80 is.putback(L'1'); 81 assert(is.good()); 82 assert(is.gcount() == 0); 83 is.putback(L' '); 84 assert(is.good()); 85 assert(is.gcount() == 0); 86 is.putback(L' '); 87 assert(is.bad()); 88 assert(is.gcount() == 0); 89 } 90 #ifndef TEST_HAS_NO_EXCEPTIONS 91 { 92 testbuf<char> sb; 93 std::basic_istream<char> is(&sb); 94 is.exceptions(std::ios_base::badbit); 95 bool threw = false; 96 try { 97 is.putback('x'); 98 } catch (std::ios_base::failure&) { 99 threw = true; 100 } 101 assert(threw); 102 assert( is.bad()); 103 assert(!is.eof()); 104 assert( is.fail()); 105 } 106 { 107 testbuf<wchar_t> sb; 108 std::basic_istream<wchar_t> is(&sb); 109 is.exceptions(std::ios_base::badbit); 110 bool threw = false; 111 try { 112 is.putback(L'x'); 113 } catch (std::ios_base::failure&) { 114 threw = true; 115 } 116 assert(threw); 117 assert( is.bad()); 118 assert(!is.eof()); 119 assert( is.fail()); 120 } 121 #endif 122 123 return 0; 124 } 125