70 lines · cpp
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-exception6//7//===----------------------------------------------------------------------===//8 9// <istream>10 11// pos_type tellg();12 13#include <istream>14#include <cassert>15#include <streambuf>16 17#include "test_macros.h"18 19template <class CharT>20struct testbuf21 : 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();}41protected:42 typename base::pos_type seekoff(typename base::off_type off,43 std::ios_base::seekdir way,44 std::ios_base::openmode which)45 {46 assert(off == 0);47 assert(way == std::ios_base::cur);48 assert(which == std::ios_base::in);49 return 5;50 }51};52 53int main(int, char**)54{55 {56 testbuf<char> sb(" 123456789");57 std::istream is(&sb);58 assert(is.tellg() == 5);59 }60#ifndef TEST_HAS_NO_WIDE_CHARACTERS61 {62 testbuf<wchar_t> sb(L" 123456789");63 std::wistream is(&sb);64 assert(is.tellg() == 5);65 }66#endif67 68 return 0;69}70