1// -*- C++ -*- 2//===----------------------------------------------------------------------===// 3// 4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5// See https://llvm.org/LICENSE.txt for license information. 6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7// 8//===----------------------------------------------------------------------===// 9 10#ifndef _LIBCPP_PRINT 11#define _LIBCPP_PRINT 12 13/* 14namespace std { 15 // [print.fun], print functions 16 template<class... Args> 17 void print(format_string<Args...> fmt, Args&&... args); 18 void println(); // Since C++26 19 template<class... Args> 20 void print(FILE* stream, format_string<Args...> fmt, Args&&... args); 21 void println(FILE* stream); // Since C++26 22 23 template<class... Args> 24 void println(format_string<Args...> fmt, Args&&... args); 25 template<class... Args> 26 void println(FILE* stream, format_string<Args...> fmt, Args&&... args); 27 28 void vprint_unicode(string_view fmt, format_args args); 29 void vprint_unicode(FILE* stream, string_view fmt, format_args args); 30 31 void vprint_nonunicode(string_view fmt, format_args args); 32 void vprint_nonunicode(FILE* stream, string_view fmt, format_args args); 33} 34*/ 35 36#if __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS) 37# include <__cxx03/print> 38#else 39# include <__assert> 40# include <__concepts/same_as.h> 41# include <__config> 42# include <__system_error/throw_system_error.h> 43# include <__utility/forward.h> 44# include <cerrno> 45# include <cstdio> 46# include <format> 47# include <string> 48# include <string_view> 49# include <version> 50 51# if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 52# pragma GCC system_header 53# endif 54 55_LIBCPP_BEGIN_NAMESPACE_STD 56 57# ifdef _LIBCPP_WIN32API 58_LIBCPP_EXPORTED_FROM_ABI bool __is_windows_terminal(FILE* __stream); 59 60# if _LIBCPP_HAS_WIDE_CHARACTERS 61// A wrapper for WriteConsoleW which is used to write to the Windows 62// console. This function is in the dylib to avoid pulling in windows.h 63// in the library headers. The function itself uses some private parts 64// of the dylib too. 65// 66// The function does not depend on the language standard used. Guarding 67// it with C++23 would fail since the dylib is currently built using C++20. 68// 69// Note the function is only implemented on the Windows platform. 70_LIBCPP_EXPORTED_FROM_ABI void __write_to_windows_console(FILE* __stream, wstring_view __view); 71# endif // _LIBCPP_HAS_WIDE_CHARACTERS 72# elif __has_include(<unistd.h>) 73_LIBCPP_EXPORTED_FROM_ABI bool __is_posix_terminal(FILE* __stream); 74# endif // _LIBCPP_WIN32API 75 76# if _LIBCPP_STD_VER >= 23 77 78# if _LIBCPP_HAS_UNICODE 79// This is the code to transcode UTF-8 to UTF-16. This is used on 80// Windows for the native Unicode API. The code is modeled to make it 81// easier to extend to 82// 83// P2728R0 Unicode in the Library, Part 1: UTF Transcoding 84// 85// This paper is still under heavy development so it makes no sense yet 86// to strictly follow the paper. 87namespace __unicode { 88 89// The names of these concepts are modelled after P2728R0, but the 90// implementation is not. char16_t may contain 32-bits so depending on the 91// number of bits is an issue. 92# ifdef _LIBCPP_SHORT_WCHAR 93template <class _Tp> 94concept __utf16_code_unit = 95 same_as<_Tp, char16_t> 96# if _LIBCPP_HAS_WIDE_CHARACTERS 97 || same_as<_Tp, wchar_t> 98# endif 99 ; 100template <class _Tp> 101concept __utf32_code_unit = same_as<_Tp, char32_t>; 102# else // _LIBCPP_SHORT_WCHAR 103template <class _Tp> 104concept __utf16_code_unit = same_as<_Tp, char16_t>; 105template <class _Tp> 106concept __utf32_code_unit = 107 same_as<_Tp, char32_t> 108# if _LIBCPP_HAS_WIDE_CHARACTERS 109 || same_as<_Tp, wchar_t> 110# endif 111 ; 112# endif // _LIBCPP_SHORT_WCHAR 113 114// Pass by reference since an output_iterator may not be copyable. 115template <class _OutIt> 116_LIBCPP_HIDE_FROM_ABI constexpr void __encode(_OutIt&, char32_t) = delete; 117 118template <class _OutIt> 119 requires __utf16_code_unit<iter_value_t<_OutIt>> 120_LIBCPP_HIDE_FROM_ABI constexpr void __encode(_OutIt& __out_it, char32_t __value) { 121 // [print.fun]/7 : "if `out` contains invalid code units, the behavior is undefined and implementations are encouraged 122 // to diagnose it". 123 _LIBCPP_ASSERT_UNCATEGORIZED(__is_scalar_value(__value), "an invalid unicode scalar value results in invalid UTF-16"); 124 125 if (__value < 0x10000) { 126 *__out_it++ = __value; 127 return; 128 } 129 130 __value -= 0x10000; 131 *__out_it++ = 0xd800 + (__value >> 10); 132 *__out_it++ = 0xdc00 + (__value & 0x3FF); 133} 134 135template <class _OutIt> 136 requires __utf32_code_unit<iter_value_t<_OutIt>> 137_LIBCPP_HIDE_FROM_ABI constexpr void __encode(_OutIt& __out_it, char32_t __value) { 138 // [print.fun]/7 : "if `out` contains invalid code units, the behavior is undefined and implementations are encouraged 139 // to diagnose it". 140 _LIBCPP_ASSERT_UNCATEGORIZED(__is_scalar_value(__value), "an invalid unicode scalar value results in invalid UTF-32"); 141 *__out_it++ = __value; 142} 143 144template <class _OutIt, input_iterator _InIt> 145 requires output_iterator<_OutIt, const iter_value_t<_OutIt>&> && (!same_as<iter_value_t<_OutIt>, iter_value_t<_InIt>>) 146_LIBCPP_HIDE_FROM_ABI constexpr _OutIt __transcode(_InIt __first, _InIt __last, _OutIt __out_it) { 147 // The __code_point_view has a basic_string_view interface. 148 // When transcoding becomes part of the standard we probably want to 149 // look at smarter algorithms. 150 // For example, when processing a code point that is encoded in 151 // 1 to 3 code units in UTF-8, the result will always be encoded 152 // in 1 code unit in UTF-16 (code points that require 4 code 153 // units in UTF-8 will require 2 code units in UTF-16). 154 // 155 // Note if P2728 is accepted types like int may become valid. In that case 156 // the __code_point_view should use a span. Libc++ will remove support for 157 // char_traits<int>. 158 159 // TODO PRINT Validate with clang-tidy 160 // NOLINTNEXTLINE(bugprone-dangling-handle) 161 basic_string_view<iter_value_t<_InIt>> __data{__first, __last}; 162 __code_point_view<iter_value_t<_InIt>> __view{__data.begin(), __data.end()}; 163 while (!__view.__at_end()) 164 __unicode::__encode(__out_it, __view.__consume().__code_point); 165 return __out_it; 166} 167 168} // namespace __unicode 169 170# endif // _LIBCPP_HAS_UNICODE 171 172namespace __print { 173 174// [print.fun]/2 175// Effects: If the ordinary literal encoding ([lex.charset]) is UTF-8, equivalent to: 176// vprint_unicode(stream, fmt.str, make_format_args(args...)); 177// Otherwise, equivalent to: 178// vprint_nonunicode(stream, fmt.str, make_format_args(args...)); 179// 180// Based on the compiler and its compilation flags this value is or is 181// not true. As mentioned in P2093R14 this only affects Windows. The 182// test below could also be done for 183// - GCC using __GNUC_EXECUTION_CHARSET_NAME 184// https://gcc.gnu.org/onlinedocs/cpp/Common-Predefined-Macros.html 185// - Clang using __clang_literal_encoding__ 186// https://clang.llvm.org/docs/LanguageExtensions.html#builtin-macros 187// (note at the time of writing Clang is hard-coded to UTF-8.) 188// 189 190# if !_LIBCPP_HAS_UNICODE 191inline constexpr bool __use_unicode_execution_charset = false; 192# elif defined(_MSVC_EXECUTION_CHARACTER_SET) 193// This is the same test MSVC STL uses in their implementation of <print> 194// See: https://learn.microsoft.com/en-us/windows/win32/intl/code-page-identifiers 195inline constexpr bool __use_unicode_execution_charset = _MSVC_EXECUTION_CHARACTER_SET == 65001; 196# else 197inline constexpr bool __use_unicode_execution_charset = true; 198# endif 199 200_LIBCPP_HIDE_FROM_ABI inline bool __is_terminal([[maybe_unused]] FILE* __stream) { 201 // The macro _LIBCPP_TESTING_PRINT_IS_TERMINAL is used to change 202 // the behavior in the test. This is not part of the public API. 203# ifdef _LIBCPP_TESTING_PRINT_IS_TERMINAL 204 return _LIBCPP_TESTING_PRINT_IS_TERMINAL(__stream); 205# elif _LIBCPP_AVAILABILITY_HAS_PRINT == 0 || !_LIBCPP_HAS_TERMINAL 206 return false; 207# elif defined(_LIBCPP_WIN32API) 208 return std::__is_windows_terminal(__stream); 209# elif __has_include(<unistd.h>) 210 return std::__is_posix_terminal(__stream); 211# else 212# error "Provide a way to determine whether a FILE* is a terminal" 213# endif 214} 215 216template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563). 217_LIBCPP_HIDE_FROM_ABI inline void 218__vprint_nonunicode(FILE* __stream, string_view __fmt, format_args __args, bool __write_nl) { 219 _LIBCPP_ASSERT_NON_NULL(__stream, "__stream must be a valid pointer to an output C stream"); 220 string __str = std::vformat(__fmt, __args); 221 if (__write_nl) 222 __str.push_back('\n'); 223 224 size_t __size = fwrite(__str.data(), 1, __str.size(), __stream); 225 if (__size < __str.size()) { 226 if (std::feof(__stream)) 227 std::__throw_system_error(EIO, "EOF while writing the formatted output"); 228 std::__throw_system_error(std::ferror(__stream), "failed to write formatted output"); 229 } 230} 231 232# if _LIBCPP_HAS_UNICODE 233 234// Note these helper functions are mainly used to aid testing. 235// On POSIX systems and Windows the output is no longer considered a 236// terminal when the output is redirected. Typically during testing the 237// output is redirected to be able to capture it. This makes it hard to 238// test this code path. 239template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563). 240_LIBCPP_HIDE_FROM_ABI inline void 241__vprint_unicode_posix(FILE* __stream, string_view __fmt, format_args __args, bool __write_nl, bool __is_terminal) { 242 // TODO PRINT Should flush errors throw too? 243 if (__is_terminal) 244 std::fflush(__stream); 245 246 __print::__vprint_nonunicode(__stream, __fmt, __args, __write_nl); 247} 248 249# if _LIBCPP_HAS_WIDE_CHARACTERS 250template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563). 251_LIBCPP_HIDE_FROM_ABI inline void 252__vprint_unicode_windows(FILE* __stream, string_view __fmt, format_args __args, bool __write_nl, bool __is_terminal) { 253 if (!__is_terminal) 254 return __print::__vprint_nonunicode(__stream, __fmt, __args, __write_nl); 255 256 // TODO PRINT Should flush errors throw too? 257 std::fflush(__stream); 258 259 string __str = std::vformat(__fmt, __args); 260 // UTF-16 uses the same number or less code units than UTF-8. 261 // However the size of the code unit is 16 bits instead of 8 bits. 262 // 263 // The buffer uses the worst-case estimate and should never resize. 264 // However when the string is large this could lead to OOM. Using a 265 // smaller size might work, but since the buffer uses a grow factor 266 // the final size might be larger when the estimate is wrong. 267 // 268 // TODO PRINT profile and improve the speed of this code. 269 __format::__retarget_buffer<wchar_t> __buffer{__str.size()}; 270 __unicode::__transcode(__str.begin(), __str.end(), __buffer.__make_output_iterator()); 271 if (__write_nl) 272 __buffer.push_back(L'\n'); 273 274 [[maybe_unused]] wstring_view __view = __buffer.__view(); 275 276 // The macro _LIBCPP_TESTING_PRINT_WRITE_TO_WINDOWS_CONSOLE_FUNCTION is used to change 277 // the behavior in the test. This is not part of the public API. 278# ifdef _LIBCPP_TESTING_PRINT_WRITE_TO_WINDOWS_CONSOLE_FUNCTION 279 _LIBCPP_TESTING_PRINT_WRITE_TO_WINDOWS_CONSOLE_FUNCTION(__stream, __view); 280# elif defined(_LIBCPP_WIN32API) 281 std::__write_to_windows_console(__stream, __view); 282# else 283 std::__throw_runtime_error("No defintion of _LIBCPP_TESTING_PRINT_WRITE_TO_WINDOWS_CONSOLE_FUNCTION and " 284 "__write_to_windows_console is not available."); 285# endif 286} 287# endif // _LIBCPP_HAS_WIDE_CHARACTERS 288 289template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563). 290_LIBCPP_HIDE_FROM_ABI inline void 291__vprint_unicode([[maybe_unused]] FILE* __stream, 292 [[maybe_unused]] string_view __fmt, 293 [[maybe_unused]] format_args __args, 294 [[maybe_unused]] bool __write_nl) { 295 _LIBCPP_ASSERT_NON_NULL(__stream, "__stream must be a valid pointer to an output C stream"); 296 297 // [print.fun] 298 // 7 - Effects: If stream refers to a terminal capable of displaying 299 // Unicode, writes out to the terminal using the native Unicode 300 // API; if out contains invalid code units, the behavior is 301 // undefined and implementations are encouraged to diagnose it. 302 // Otherwise writes out to stream unchanged. If the native 303 // Unicode API is used, the function flushes stream before 304 // writing out. 305 // 8 - Throws: Any exception thrown by the call to vformat 306 // ([format.err.report]). system_error if writing to the terminal 307 // or stream fails. May throw bad_alloc. 308 // 9 - Recommended practice: If invoking the native Unicode API 309 // requires transcoding, implementations should substitute 310 // invalid code units with U+FFFD replacement character per the 311 // Unicode Standard, Chapter 3.9 U+FFFD Substitution in 312 // Conversion. 313 314 // On non-Windows platforms the Unicode API is the normal file I/O API 315 // so there the call can be forwarded to the non_unicode API. On 316 // Windows there is a different API. This API requires transcoding. 317 318# ifndef _LIBCPP_WIN32API 319 __print::__vprint_unicode_posix(__stream, __fmt, __args, __write_nl, __print::__is_terminal(__stream)); 320# elif _LIBCPP_HAS_WIDE_CHARACTERS 321 __print::__vprint_unicode_windows(__stream, __fmt, __args, __write_nl, __print::__is_terminal(__stream)); 322# else 323# error "Windows builds with wchar_t disabled are not supported." 324# endif 325} 326 327# endif // _LIBCPP_HAS_UNICODE 328 329} // namespace __print 330 331template <class... _Args> 332_LIBCPP_HIDE_FROM_ABI void print(FILE* __stream, format_string<_Args...> __fmt, _Args&&... __args) { 333# if _LIBCPP_HAS_UNICODE 334 if constexpr (__print::__use_unicode_execution_charset) 335 __print::__vprint_unicode(__stream, __fmt.get(), std::make_format_args(__args...), false); 336 else 337 __print::__vprint_nonunicode(__stream, __fmt.get(), std::make_format_args(__args...), false); 338# else // _LIBCPP_HAS_UNICODE 339 __print::__vprint_nonunicode(__stream, __fmt.get(), std::make_format_args(__args...), false); 340# endif // _LIBCPP_HAS_UNICODE 341} 342 343template <class... _Args> 344_LIBCPP_HIDE_FROM_ABI void print(format_string<_Args...> __fmt, _Args&&... __args) { 345 std::print(stdout, __fmt, std::forward<_Args>(__args)...); 346} 347 348template <class... _Args> 349_LIBCPP_HIDE_FROM_ABI void println(FILE* __stream, format_string<_Args...> __fmt, _Args&&... __args) { 350# if _LIBCPP_HAS_UNICODE 351 // Note the wording in the Standard is inefficient. The output of 352 // std::format is a std::string which is then copied. This solution 353 // just appends a newline at the end of the output. 354 if constexpr (__print::__use_unicode_execution_charset) 355 __print::__vprint_unicode(__stream, __fmt.get(), std::make_format_args(__args...), true); 356 else 357 __print::__vprint_nonunicode(__stream, __fmt.get(), std::make_format_args(__args...), true); 358# else // _LIBCPP_HAS_UNICODE 359 __print::__vprint_nonunicode(__stream, __fmt.get(), std::make_format_args(__args...), true); 360# endif // _LIBCPP_HAS_UNICODE 361} 362 363template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563). 364_LIBCPP_HIDE_FROM_ABI inline void println(FILE* __stream) { 365 std::print(__stream, "\n"); 366} 367 368template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563). 369_LIBCPP_HIDE_FROM_ABI inline void println() { 370 println(stdout); 371} 372 373template <class... _Args> 374_LIBCPP_HIDE_FROM_ABI void println(format_string<_Args...> __fmt, _Args&&... __args) { 375 std::println(stdout, __fmt, std::forward<_Args>(__args)...); 376} 377 378# if _LIBCPP_HAS_UNICODE 379template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563). 380_LIBCPP_HIDE_FROM_ABI inline void vprint_unicode(FILE* __stream, string_view __fmt, format_args __args) { 381 __print::__vprint_unicode(__stream, __fmt, __args, false); 382} 383 384template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563). 385_LIBCPP_HIDE_FROM_ABI inline void vprint_unicode(string_view __fmt, format_args __args) { 386 std::vprint_unicode(stdout, __fmt, __args); 387} 388 389# endif // _LIBCPP_HAS_UNICODE 390 391template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563). 392_LIBCPP_HIDE_FROM_ABI inline void vprint_nonunicode(FILE* __stream, string_view __fmt, format_args __args) { 393 __print::__vprint_nonunicode(__stream, __fmt, __args, false); 394} 395 396template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563). 397_LIBCPP_HIDE_FROM_ABI inline void vprint_nonunicode(string_view __fmt, format_args __args) { 398 std::vprint_nonunicode(stdout, __fmt, __args); 399} 400 401# endif // _LIBCPP_STD_VER >= 23 402 403_LIBCPP_END_NAMESPACE_STD 404 405#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS) 406 407#endif // _LIBCPP_PRINT 408