82 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// basic_istream<charT,traits>& seekg(pos_type pos);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 seekpos(typename base::pos_type sp,43 std::ios_base::openmode which)44 {45 assert(which == std::ios_base::in);46 return sp;47 }48};49 50int main(int, char**)51{52 {53 testbuf<char> sb(" 123456789");54 std::istream is(&sb);55 is.seekg(5);56 assert(is.good());57 is.seekg(-1);58 assert(is.fail());59 }60#ifndef TEST_HAS_NO_WIDE_CHARACTERS61 {62 testbuf<wchar_t> sb(L" 123456789");63 std::wistream is(&sb);64 is.seekg(5);65 assert(is.good());66 is.seekg(-1);67 assert(is.fail());68 }69#endif70 {71 testbuf<char> sb(" 123456789");72 std::istream is(&sb);73 is.setstate(std::ios_base::eofbit);74 assert(is.eof());75 is.seekg(5);76 assert(is.good());77 assert(!is.eof());78 }79 80 return 0;81}82