122 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>& unget();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();}41};42 43int main(int, char**)44{45 {46 testbuf<char> sb(" 123456789");47 std::istream is(&sb);48 is.get();49 is.get();50 is.get();51 is.unget();52 assert(is.good());53 assert(is.gcount() == 0);54 is.unget();55 assert(is.good());56 assert(is.gcount() == 0);57 is.unget();58 assert(is.good());59 assert(is.gcount() == 0);60 is.unget();61 assert(is.bad());62 assert(is.gcount() == 0);63 }64#ifndef TEST_HAS_NO_WIDE_CHARACTERS65 {66 testbuf<wchar_t> sb(L" 123456789");67 std::wistream is(&sb);68 is.get();69 is.get();70 is.get();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.good());79 assert(is.gcount() == 0);80 is.unget();81 assert(is.bad());82 assert(is.gcount() == 0);83 }84#endif85#ifndef TEST_HAS_NO_EXCEPTIONS86 {87 testbuf<char> sb;88 std::basic_istream<char> is(&sb);89 is.exceptions(std::ios_base::badbit);90 bool threw = false;91 try {92 is.unget();93 } catch (std::ios_base::failure&) {94 threw = true;95 }96 assert(threw);97 assert( is.bad());98 assert(!is.eof());99 assert( is.fail());100 }101#ifndef TEST_HAS_NO_WIDE_CHARACTERS102 {103 testbuf<wchar_t> sb;104 std::basic_istream<wchar_t> is(&sb);105 is.exceptions(std::ios_base::badbit);106 bool threw = false;107 try {108 is.unget();109 } catch (std::ios_base::failure&) {110 threw = true;111 }112 assert(threw);113 assert( is.bad());114 assert(!is.eof());115 assert( is.fail());116 }117#endif118#endif // TEST_HAS_NO_EXCEPTIONS119 120 return 0;121}122