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/__config>
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# if _LIBCPP_STD_VER >= 23
56
57_LIBCPP_BEGIN_NAMESPACE_STD
58
59# ifdef _LIBCPP_WIN32API
60_LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
61_LIBCPP_EXPORTED_FROM_ABI bool __is_windows_terminal(FILE* __stream);
62
63# if _LIBCPP_HAS_WIDE_CHARACTERS
64// A wrapper for WriteConsoleW which is used to write to the Windows
65// console. This function is in the dylib to avoid pulling in windows.h
66// in the library headers. The function itself uses some private parts
67// of the dylib too.
68//
69// The function does not depend on the language standard used. Guarding
70// it with C++23 would fail since the dylib is currently built using C++20.
71//
72// Note the function is only implemented on the Windows platform.
73_LIBCPP_EXPORTED_FROM_ABI void __write_to_windows_console(FILE* __stream, wstring_view __view);
74# endif // _LIBCPP_HAS_WIDE_CHARACTERS
75_LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
76# endif // _LIBCPP_WIN32API
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++ = static_cast<iter_value_t<_OutIt>>(__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# ifdef _LIBCPP_WIN32API
201_LIBCPP_HIDE_FROM_ABI inline bool __is_terminal([[maybe_unused]] FILE* __stream) {
202 // The macro _LIBCPP_TESTING_PRINT_IS_TERMINAL is used to change
203 // the behavior in the test. This is not part of the public API.
204# ifdef _LIBCPP_TESTING_PRINT_IS_TERMINAL
205 return _LIBCPP_TESTING_PRINT_IS_TERMINAL(__stream);
206# else
207 return std::__is_windows_terminal(__stream);
208# endif
209}
210# endif // _LIBCPP_WIN32API
211
212[[noreturn]] _LIBCPP_HIDE_FROM_ABI inline void __handle_output_error(FILE* __stream) {
213 if (std::feof(__stream))
214 std::__throw_system_error(EIO, what_arg: "EOF while writing the formatted output");
215 std::__throw_system_error(ev: std::ferror(__stream), what_arg: "failed to write formatted output");
216}
217
218template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563).
219_LIBCPP_HIDE_FROM_ABI inline void __output_nonunicode(FILE* __stream, string_view __text) {
220 _LIBCPP_ASSERT_NON_NULL(__stream, "__stream must be a valid pointer to an output C stream");
221 size_t __size = std::fwrite(ptr: __text.data(), size: 1, n: __text.size(), s: __stream);
222 if (__size < __text.size())
223 __print::__handle_output_error(__stream);
224}
225
226# if _LIBCPP_HAS_UNICODE
227
228// Note these helper functions are mainly used to aid testing.
229// On POSIX systems and Windows the output is no longer considered a
230// terminal when the output is redirected. Typically during testing the
231// output is redirected to be able to capture it. This makes it hard to
232// test this code path.
233
234# if _LIBCPP_HAS_WIDE_CHARACTERS
235template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563).
236_LIBCPP_HIDE_FROM_ABI inline void __output_unicode_windows([[maybe_unused]] FILE* __stream, string_view __text) {
237 // UTF-16 uses the same number or less code units than UTF-8.
238 // However the size of the code unit is 16 bits instead of 8 bits.
239 //
240 // The buffer uses the worst-case estimate and should never resize.
241 // However when the string is large this could lead to OOM. Using a
242 // smaller size might work, but since the buffer uses a grow factor
243 // the final size might be larger when the estimate is wrong.
244 //
245 // TODO PRINT profile and improve the speed of this code.
246 __format::__retarget_buffer<wchar_t> __buffer{__text.size()};
247 __unicode::__transcode(first: __text.begin(), last: __text.end(), out_it: __buffer.__make_output_iterator());
248 [[maybe_unused]] wstring_view __view = __buffer.__view();
249
250 // The macro _LIBCPP_TESTING_PRINT_WRITE_TO_WINDOWS_CONSOLE_FUNCTION is used to change
251 // the behavior in the test. This is not part of the public API.
252# ifdef _LIBCPP_TESTING_PRINT_WRITE_TO_WINDOWS_CONSOLE_FUNCTION
253 _LIBCPP_TESTING_PRINT_WRITE_TO_WINDOWS_CONSOLE_FUNCTION(__stream, __view);
254# elif defined(_LIBCPP_WIN32API)
255 std::__write_to_windows_console(__stream, __view);
256# else
257 std::__throw_runtime_error("No defintion of _LIBCPP_TESTING_PRINT_WRITE_TO_WINDOWS_CONSOLE_FUNCTION and "
258 "__write_to_windows_console is not available.");
259# endif
260}
261# endif // _LIBCPP_HAS_WIDE_CHARACTERS
262
263template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563).
264_LIBCPP_HIDE_FROM_ABI inline void __output_unicode([[maybe_unused]] FILE* __stream, string_view __text) {
265 _LIBCPP_ASSERT_NON_NULL(__stream, "__stream must be a valid pointer to an output C stream");
266
267 // [print.fun]
268 // 7 - Effects: If stream refers to a terminal capable of displaying
269 // Unicode, writes out to the terminal using the native Unicode
270 // API; if out contains invalid code units, the behavior is
271 // undefined and implementations are encouraged to diagnose it.
272 // Otherwise writes out to stream unchanged. If the native
273 // Unicode API is used, the function flushes stream before
274 // writing out.
275 // 9 - Recommended practice: If invoking the native Unicode API
276 // requires transcoding, implementations should substitute
277 // invalid code units with U+FFFD replacement character per the
278 // Unicode Standard, Chapter 3.9 U+FFFD Substitution in
279 // Conversion.
280
281 // On non-Windows platforms the Unicode API is the normal file I/O API
282 // so there the call can be forwarded to the non_unicode API. On
283 // Windows there is a different API. This API requires transcoding.
284
285# ifndef _LIBCPP_WIN32API
286 __print::__output_nonunicode(__stream, __text);
287# elif _LIBCPP_HAS_WIDE_CHARACTERS
288 if (__print::__is_terminal(__stream)) {
289 // TODO PRINT Should flush errors throw too?
290 std::fflush(__stream);
291 __print::__output_unicode_windows(__stream, __text);
292 } else {
293 __print::__output_nonunicode(__stream, __text);
294 }
295# else
296# error "Windows builds with wchar_t disabled are not supported."
297# endif
298}
299
300# endif // _LIBCPP_HAS_UNICODE
301
302} // namespace __print
303
304template <class... _Args>
305_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE void
306print(FILE* _LIBCPP_DIAGNOSE_NULLPTR __stream, format_string<_Args...> __fmt, _Args&&... __args) {
307 auto __result = std::vformat(__fmt.get(), std::make_format_args(__args...));
308# if _LIBCPP_HAS_UNICODE
309 if constexpr (__print::__use_unicode_execution_charset)
310 __print::__output_unicode(__stream, __result);
311 else
312 __print::__output_nonunicode(__stream, __result);
313# else // _LIBCPP_HAS_UNICODE
314 __print::__output_nonunicode(__stream, __result);
315# endif // _LIBCPP_HAS_UNICODE
316}
317
318template <class... _Args>
319_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE void print(format_string<_Args...> __fmt, _Args&&... __args) {
320 std::print(stdout, __fmt, std::forward<_Args>(__args)...);
321}
322
323template <class... _Args>
324_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE void
325println(FILE* _LIBCPP_DIAGNOSE_NULLPTR __stream, format_string<_Args...> __fmt, _Args&&... __args) {
326 auto __result = std::vformat(__fmt.get(), std::make_format_args(__args...));
327 __result.push_back('\n');
328# if _LIBCPP_HAS_UNICODE
329 // Note the wording in the Standard is inefficient. The output of
330 // std::format is a std::string which is then copied. This solution
331 // just appends a newline at the end of the output.
332 if constexpr (__print::__use_unicode_execution_charset)
333 __print::__output_unicode(__stream, __result);
334 else
335 __print::__output_nonunicode(__stream, __result);
336# else // _LIBCPP_HAS_UNICODE
337 __print::__output_nonunicode(__stream, __result);
338# endif // _LIBCPP_HAS_UNICODE
339}
340
341template <class _Void = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563).
342_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE inline void println(FILE* _LIBCPP_DIAGNOSE_NULLPTR __stream) {
343 std::print(__stream, (_Void(), "\n"));
344}
345
346template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563).
347_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE inline void println() {
348 println(stdout);
349}
350
351template <class... _Args>
352_LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE void println(format_string<_Args...> __fmt, _Args&&... __args) {
353 std::println(stdout, __fmt, std::forward<_Args>(__args)...);
354}
355
356# if _LIBCPP_HAS_UNICODE
357template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563).
358_LIBCPP_HIDE_FROM_ABI inline void
359vprint_unicode(FILE* _LIBCPP_DIAGNOSE_NULLPTR __stream, string_view __fmt, format_args __args) {
360 __print::__output_unicode(__stream, text: std::vformat(__fmt, __args));
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 vprint_unicode(string_view __fmt, format_args __args) {
365 std::vprint_unicode(stdout, __fmt, __args);
366}
367
368# endif // _LIBCPP_HAS_UNICODE
369
370template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563).
371_LIBCPP_HIDE_FROM_ABI inline void
372vprint_nonunicode(FILE* _LIBCPP_DIAGNOSE_NULLPTR __stream, string_view __fmt, format_args __args) {
373 __print::__output_nonunicode(__stream, text: std::vformat(__fmt, __args));
374}
375
376template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563).
377_LIBCPP_HIDE_FROM_ABI inline void vprint_nonunicode(string_view __fmt, format_args __args) {
378 std::vprint_nonunicode(stdout, __fmt, __args);
379}
380
381_LIBCPP_END_NAMESPACE_STD
382
383# endif // _LIBCPP_STD_VER >= 23
384
385#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
386
387#endif // _LIBCPP_PRINT
388