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 // basic_istream<charT,traits>& putback(char_type c); 13 14 #include <istream> 15 #include <cassert> 16 17 template <class CharT> 18 struct testbuf 19 : public std::basic_streambuf<CharT> 20 { 21 typedef std::basic_string<CharT> string_type; 22 typedef std::basic_streambuf<CharT> base; 23 private: 24 string_type str_; 25 public: 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 41 int 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
