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>& seekg(pos_type pos); 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 protected: 40 typename base::pos_type seekpos(typename base::pos_type sp, 41 std::ios_base::openmode which) 42 { 43 assert(which == std::ios_base::in); 44 return sp; 45 } 46 }; 47 48 int main() 49 { 50 { 51 testbuf<char> sb(" 123456789"); 52 std::istream is(&sb); 53 is.seekg(5); 54 assert(is.good()); 55 is.seekg(-1); 56 assert(is.fail()); 57 } 58 { 59 testbuf<wchar_t> sb(L" 123456789"); 60 std::wistream is(&sb); 61 is.seekg(5); 62 assert(is.good()); 63 is.seekg(-1); 64 assert(is.fail()); 65 } 66 } 67
