68 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// <fstream>10 11// int_type pbackfail(int_type c = traits::eof());12 13// FILE_DEPENDENCIES: underflow.dat14 15#include <fstream>16#include <cassert>17 18#include "test_macros.h"19 20template <class CharT>21struct test_buf22 : public std::basic_filebuf<CharT>23{24 typedef std::basic_filebuf<CharT> base;25 typedef typename base::char_type char_type;26 typedef typename base::int_type int_type;27 typedef typename base::traits_type traits_type;28 29 char_type* eback() const {return base::eback();}30 char_type* gptr() const {return base::gptr();}31 char_type* egptr() const {return base::egptr();}32 void gbump(int n) {base::gbump(n);}33 34 virtual int_type pbackfail(int_type c = traits_type::eof()) {return base::pbackfail(c);}35};36 37int main(int, char**)38{39 {40 test_buf<char> f;41 assert(f.open("underflow.dat", std::ios_base::in) != 0);42 assert(f.is_open());43 assert(f.sbumpc() == '1');44 assert(f.sgetc() == '2');45 typename test_buf<char>::int_type pbackResult = f.pbackfail('a');46 LIBCPP_ASSERT(pbackResult == -1);47 if (pbackResult != -1) {48 assert(f.sbumpc() == 'a');49 assert(f.sgetc() == '2');50 }51 }52 {53 test_buf<char> f;54 assert(f.open("underflow.dat", std::ios_base::in | std::ios_base::out) != 0);55 assert(f.is_open());56 assert(f.sbumpc() == '1');57 assert(f.sgetc() == '2');58 typename test_buf<char>::int_type pbackResult = f.pbackfail('a');59 LIBCPP_ASSERT(pbackResult == 'a');60 if (pbackResult != -1) {61 assert(f.sbumpc() == 'a');62 assert(f.sgetc() == '2');63 }64 }65 66 return 0;67}68