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