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The C and C++ Include Header Files
cat -n /usr/include/c++/15/ostream
1 // Output streams -*- C++ -*- 2 3 // Copyright (C) 1997-2025 Free Software Foundation, Inc. 4 // 5 // This file is part of the GNU ISO C++ Library. This library is free 6 // software; you can redistribute it and/or modify it under the 7 // terms of the GNU General Public License as published by the 8 // Free Software Foundation; either version 3, or (at your option) 9 // any later version. 10 11 // This library is distributed in the hope that it will be useful, 12 // but WITHOUT ANY WARRANTY; without even the implied warranty of 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 // GNU General Public License for more details. 15 16 // Under Section 7 of GPL version 3, you are granted additional 17 // permissions described in the GCC Runtime Library Exception, version 18 // 3.1, as published by the Free Software Foundation. 19 20 // You should have received a copy of the GNU General Public License and 21 // a copy of the GCC Runtime Library Exception along with this program; 22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 // <http://www.gnu.org/licenses/>. 24 25 /** @file include/ostream 26 * This is a Standard C++ Library header. 27 */ 28 29 // 30 // ISO C++ 14882: 27.6.2 Output streams 31 // 32 33 #ifndef _GLIBCXX_OSTREAM 34 #define _GLIBCXX_OSTREAM 1 35 36 #ifdef _GLIBCXX_SYSHDR 37 #pragma GCC system_header 38 #endif 39 40 #include <bits/requires_hosted.h> // iostreams 41 42 #include <bits/ostream.h> 43 #if __cplusplus > 202002L 44 # include <format> 45 #endif 46 47 # define __glibcxx_want_print 48 #include <bits/version.h> // __glibcxx_syncbuf 49 50 namespace std _GLIBCXX_VISIBILITY(default) 51 { 52 _GLIBCXX_BEGIN_NAMESPACE_VERSION 53 54 // Standard basic_ostream manipulators 55 56 /** 57 * @brief Write a newline and flush the stream. 58 * 59 * This manipulator is often mistakenly used when a simple newline is 60 * desired, leading to poor buffering performance. See 61 * https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html#io.streambuf.buffering 62 * for more on this subject. 63 */ 64 template<typename _CharT, typename _Traits> 65 inline basic_ostream<_CharT, _Traits>& 66 endl(basic_ostream<_CharT, _Traits>& __os) 67 { return flush(__os.put(__os.widen('\n'))); } 68 69 /** 70 * @brief Write a null character into the output sequence. 71 * 72 * <em>Null character</em> is @c CharT() by definition. For CharT 73 * of @c char, this correctly writes the ASCII @c NUL character 74 * string terminator. 75 */ 76 template<typename _CharT, typename _Traits> 77 inline basic_ostream<_CharT, _Traits>& 78 ends(basic_ostream<_CharT, _Traits>& __os) 79 { return __os.put(_CharT()); } 80 81 /** 82 * @brief Flushes the output stream. 83 * 84 * This manipulator simply calls the stream's @c flush() member function. 85 */ 86 template<typename _CharT, typename _Traits> 87 inline basic_ostream<_CharT, _Traits>& 88 flush(basic_ostream<_CharT, _Traits>& __os) 89 { return __os.flush(); } 90 91 #ifdef __glibcxx_syncbuf // C++ >= 20 && HOSTED && CXX11ABI 92 template<typename _CharT, typename _Traits> 93 class __syncbuf_base : public basic_streambuf<_CharT, _Traits> 94 { 95 public: 96 static bool* 97 _S_get(basic_streambuf<_CharT, _Traits>* __buf [[maybe_unused]]) noexcept 98 { 99 #if __cpp_rtti 100 if (auto __p = dynamic_cast<__syncbuf_base*>(__buf)) 101 return &__p->_M_emit_on_sync; 102 #endif 103 return nullptr; 104 } 105 106 protected: 107 __syncbuf_base(basic_streambuf<_CharT, _Traits>* __w = nullptr) 108 : _M_wrapped(__w) 109 { } 110 111 basic_streambuf<_CharT, _Traits>* _M_wrapped = nullptr; 112 bool _M_emit_on_sync = false; 113 bool _M_needs_sync = false; 114 }; 115 116 template<typename _CharT, typename _Traits> 117 inline basic_ostream<_CharT, _Traits>& 118 emit_on_flush(basic_ostream<_CharT, _Traits>& __os) 119 { 120 if (bool* __flag = __syncbuf_base<_CharT, _Traits>::_S_get(__os.rdbuf())) 121 *__flag = true; 122 return __os; 123 } 124 125 template<typename _CharT, typename _Traits> 126 inline basic_ostream<_CharT, _Traits>& 127 noemit_on_flush(basic_ostream<_CharT, _Traits>& __os) 128 { 129 if (bool* __flag = __syncbuf_base<_CharT, _Traits>::_S_get(__os.rdbuf())) 130 *__flag = false; 131 return __os; 132 } 133 134 template<typename _CharT, typename _Traits> 135 inline basic_ostream<_CharT, _Traits>& 136 flush_emit(basic_ostream<_CharT, _Traits>& __os) 137 { 138 struct _Restore 139 { 140 ~_Restore() { *_M_flag = _M_prev; } 141 142 bool _M_prev = false; 143 bool* _M_flag = &_M_prev; 144 } __restore; 145 146 if (bool* __flag = __syncbuf_base<_CharT, _Traits>::_S_get(__os.rdbuf())) 147 { 148 __restore._M_prev = *__flag; 149 __restore._M_flag = __flag; 150 *__flag = true; 151 } 152 153 __os.flush(); 154 return __os; 155 } 156 #endif // __glibcxx_syncbuf 157 158 #if __cpp_lib_print // C++ >= 23 159 inline void 160 vprint_nonunicode(ostream& __os, string_view __fmt, format_args __args) 161 { 162 ostream::sentry __cerb(__os); 163 if (__cerb) 164 { 165 __format::_Str_sink<char> __buf; 166 std::vformat_to(__buf.out(), __os.getloc(), __fmt, __args); 167 auto __out = __buf.view(); 168 169 __try 170 { 171 std::__ostream_write(__os, __out.data(), __out.size()); 172 } 173 __catch(const __cxxabiv1::__forced_unwind&) 174 { 175 __os._M_setstate(ios_base::badbit); 176 __throw_exception_again; 177 } 178 __catch(...) 179 { __os._M_setstate(ios_base::badbit); } 180 } 181 } 182 183 inline void 184 vprint_unicode(ostream& __os, string_view __fmt, format_args __args) 185 { 186 #if !defined(_WIN32) || defined(__CYGWIN__) 187 // For most targets we don't need to do anything special to write 188 // Unicode to a terminal. 189 std::vprint_nonunicode(__os, __fmt, __args); 190 #else 191 ostream::sentry __cerb(__os); 192 if (__cerb) 193 { 194 __format::_Str_sink<char> __buf; 195 std::vformat_to(__buf.out(), __os.getloc(), __fmt, __args); 196 auto __out = __buf.view(); 197 198 void* __open_terminal(streambuf*); 199 error_code __write_to_terminal(void*, span<char>); 200 // If stream refers to a terminal, write a Unicode string to it. 201 if (auto __term = __open_terminal(__os.rdbuf())) 202 { 203 #if !defined(_WIN32) || defined(__CYGWIN__) 204 // For POSIX, __open_terminal(streambuf*) uses fdopen to open a 205 // new file, so we would need to close it here. This code is not 206 // actually compiled because it's inside an #ifdef _WIN32 group, 207 // but just in case that changes in future ... 208 struct _Guard 209 { 210 _Guard(void* __p) : _M_f((FILE*)__p) { } 211 ~_Guard() { std::fclose(_M_f); } 212 _Guard(_Guard&&) = delete; 213 _Guard& operator=(_Guard&&) = delete; 214 FILE* _M_f; 215 }; 216 _Guard __g(__term); 217 #endif 218 219 ios_base::iostate __err = ios_base::goodbit; 220 __try 221 { 222 if (__os.rdbuf()->pubsync() == -1) 223 __err = ios::badbit; 224 else if (auto __e = __write_to_terminal(__term, __out)) 225 if (__e != std::make_error_code(errc::illegal_byte_sequence)) 226 __err = ios::badbit; 227 } 228 __catch(const __cxxabiv1::__forced_unwind&) 229 { 230 __os._M_setstate(ios_base::badbit); 231 __throw_exception_again; 232 } 233 __catch(...) 234 { __os._M_setstate(ios_base::badbit); } 235 236 if (__err) 237 __os.setstate(__err); 238 return; 239 } 240 241 // Otherwise just insert the string as vprint_nonunicode does. 242 __try 243 { 244 std::__ostream_write(__os, __out.data(), __out.size()); 245 } 246 __catch(const __cxxabiv1::__forced_unwind&) 247 { 248 __os._M_setstate(ios_base::badbit); 249 __throw_exception_again; 250 } 251 __catch(...) 252 { __os._M_setstate(ios_base::badbit); } 253 } 254 #endif // _WIN32 255 } 256 257 template<typename... _Args> 258 inline void 259 print(ostream& __os, format_string<_Args...> __fmt, _Args&&... __args) 260 { 261 auto __fmtargs = std::make_format_args(__args...); 262 if constexpr (__unicode::__literal_encoding_is_utf8()) 263 std::vprint_unicode(__os, __fmt.get(), __fmtargs); 264 else 265 std::vprint_nonunicode(__os, __fmt.get(), __fmtargs); 266 } 267 268 template<typename... _Args> 269 inline void 270 println(ostream& __os, format_string<_Args...> __fmt, _Args&&... __args) 271 { 272 // _GLIBCXX_RESOLVE_LIB_DEFECTS 273 // 4088. println ignores the locale imbued in std::ostream 274 std::print(__os, "{}\n", std::format(__os.getloc(), __fmt, 275 std::forward<_Args>(__args)...)); 276 } 277 278 // Defined for C++26, supported as an extension to C++23. 279 inline void println(ostream& __os) 280 { 281 #if defined(_WIN32) && !defined(__CYGWIN__) 282 if constexpr (__unicode::__literal_encoding_is_utf8()) 283 std::vprint_unicode(__os, "\n", std::make_format_args()); 284 else 285 #endif 286 __os.put('\n'); 287 } 288 289 #endif // __cpp_lib_print 290 291 _GLIBCXX_END_NAMESPACE_VERSION 292 } // namespace std 293 294 #include <bits/ostream.tcc> 295 296 #endif /* _GLIBCXX_OSTREAM */
