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>& unget(); 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.unget(); 50 assert(is.good()); 51 assert(is.gcount() == 0); 52 is.unget(); 53 assert(is.good()); 54 assert(is.gcount() == 0); 55 is.unget(); 56 assert(is.good()); 57 assert(is.gcount() == 0); 58 is.unget(); 59 assert(is.bad()); 60 assert(is.gcount() == 0); 61 } 62 { 63 testbuf<wchar_t> sb(L" 123456789"); 64 std::wistream is(&sb); 65 is.get(); 66 is.get(); 67 is.get(); 68 is.unget(); 69 assert(is.good()); 70 assert(is.gcount() == 0); 71 is.unget(); 72 assert(is.good()); 73 assert(is.gcount() == 0); 74 is.unget(); 75 assert(is.good()); 76 assert(is.gcount() == 0); 77 is.unget(); 78 assert(is.bad()); 79 assert(is.gcount() == 0); 80 } 81 } 82
