xref: /llvm-project-15.0.7/libcxx/include/format (revision 15c809e8) 
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_FORMAT
11#define _LIBCPP_FORMAT
12
13/*
14
15namespace std {
16  // [format.context], class template basic_format_context
17  template<class Out, class charT> class basic_format_context;
18  using format_context = basic_format_context<unspecified, char>;
19  using wformat_context = basic_format_context<unspecified, wchar_t>;
20
21  // [format.args], class template basic_format_args
22  template<class Context> class basic_format_args;
23  using format_args = basic_format_args<format_context>;
24  using wformat_args = basic_format_args<wformat_context>;
25
26  // [format.functions], formatting functions
27  template<class... Args>
28    string format(string_view fmt, const Args&... args);
29  template<class... Args>
30    wstring format(wstring_view fmt, const Args&... args);
31  template<class... Args>
32    string format(const locale& loc, string_view fmt, const Args&... args);
33  template<class... Args>
34    wstring format(const locale& loc, wstring_view fmt, const Args&... args);
35
36  string vformat(string_view fmt, format_args args);
37  wstring vformat(wstring_view fmt, wformat_args args);
38  string vformat(const locale& loc, string_view fmt, format_args args);
39  wstring vformat(const locale& loc, wstring_view fmt, wformat_args args);
40
41  template<class Out, class... Args>
42    Out format_to(Out out, string_view fmt, const Args&... args);
43  template<class Out, class... Args>
44    Out format_to(Out out, wstring_view fmt, const Args&... args);
45  template<class Out, class... Args>
46    Out format_to(Out out, const locale& loc, string_view fmt, const Args&... args);
47  template<class Out, class... Args>
48    Out format_to(Out out, const locale& loc, wstring_view fmt, const Args&... args);
49
50  template<class Out>
51    Out vformat_to(Out out, string_view fmt, format_args args);
52  template<class Out>
53    Out vformat_to(Out out, wstring_view fmt, wformat_args args);
54  template<class Out>
55    Out vformat_to(Out out, const locale& loc, string_view fmt,
56                   format_args char> args);
57  template<class Out>
58    Out vformat_to(Out out, const locale& loc, wstring_view fmt,
59                   wformat_args args);
60
61  template<class Out> struct format_to_n_result {
62    Out out;
63    iter_difference_t<Out> size;
64  };
65  template<class Out, class... Args>
66    format_to_n_result<Out> format_to_n(Out out, iter_difference_t<Out> n,
67                                        string_view fmt, const Args&... args);
68  template<class Out, class... Args>
69    format_to_n_result<Out> format_to_n(Out out, iter_difference_t<Out> n,
70                                        wstring_view fmt, const Args&... args);
71  template<class Out, class... Args>
72    format_to_n_result<Out> format_to_n(Out out, iter_difference_t<Out> n,
73                                        const locale& loc, string_view fmt,
74                                        const Args&... args);
75  template<class Out, class... Args>
76    format_to_n_result<Out> format_to_n(Out out, iter_difference_t<Out> n,
77                                        const locale& loc, wstring_view fmt,
78                                        const Args&... args);
79
80  template<class... Args>
81    size_t formatted_size(string_view fmt, const Args&... args);
82  template<class... Args>
83    size_t formatted_size(wstring_view fmt, const Args&... args);
84  template<class... Args>
85    size_t formatted_size(const locale& loc, string_view fmt, const Args&... args);
86  template<class... Args>
87    size_t formatted_size(const locale& loc, wstring_view fmt, const Args&... args);
88
89  // [format.formatter], formatter
90  template<class T, class charT = char> struct formatter;
91
92  // [format.parse.ctx], class template basic_format_parse_context
93  template<class charT> class basic_format_parse_context;
94  using format_parse_context = basic_format_parse_context<char>;
95  using wformat_parse_context = basic_format_parse_context<wchar_t>;
96
97  // [format.arguments], arguments
98  // [format.arg], class template basic_format_arg
99  template<class Context> class basic_format_arg;
100
101  template<class Visitor, class Context>
102    see below visit_format_arg(Visitor&& vis, basic_format_arg<Context> arg);
103
104  // [format.arg.store], class template format-arg-store
105  template<class Context, class... Args> struct format-arg-store;      // exposition only
106
107  template<class Context = format_context, class... Args>
108    format-arg-store<Context, Args...>
109      make_format_args(const Args&... args);
110  template<class... Args>
111    format-arg-store<wformat_context, Args...>
112      make_wformat_args(const Args&... args);
113
114  // [format.error], class format_error
115  class format_error;
116}
117
118*/
119
120#include <__assert> // all public C++ headers provide the assertion handler
121// Make sure all feature-test macros are available.
122#include <version>
123// Enable the contents of the header only when libc++ was built with LIBCXX_ENABLE_INCOMPLETE_FEATURES.
124#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT)
125
126#include <__algorithm/clamp.h>
127#include <__config>
128#include <__debug>
129#include <__format/buffer.h>
130#include <__format/concepts.h>
131#include <__format/enable_insertable.h>
132#include <__format/format_arg.h>
133#include <__format/format_args.h>
134#include <__format/format_context.h>
135#include <__format/format_error.h>
136#include <__format/format_fwd.h>
137#include <__format/format_parse_context.h>
138#include <__format/format_string.h>
139#include <__format/format_to_n_result.h>
140#include <__format/formatter.h>
141#include <__format/formatter_bool.h>
142#include <__format/formatter_char.h>
143#include <__format/formatter_floating_point.h>
144#include <__format/formatter_integer.h>
145#include <__format/formatter_pointer.h>
146#include <__format/formatter_string.h>
147#include <__format/parser_std_format_spec.h>
148#include <__variant/monostate.h>
149#include <array>
150#include <concepts>
151#include <string>
152#include <string_view>
153#include <type_traits>
154
155#ifndef _LIBCPP_HAS_NO_LOCALIZATION
156#include <locale>
157#endif
158
159#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
160#  pragma GCC system_header
161#endif
162
163_LIBCPP_BEGIN_NAMESPACE_STD
164
165#if _LIBCPP_STD_VER > 17
166
167// TODO FMT Move the implementation in this file to its own granular headers.
168
169// TODO FMT Evaluate which templates should be external templates. This
170// improves the efficiency of the header. However since the header is still
171// under heavy development and not all classes are stable it makes no sense
172// to do this optimization now.
173
174using format_args = basic_format_args<format_context>;
175#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
176using wformat_args = basic_format_args<wformat_context>;
177#endif
178
179template <class _Context, class... _Args>
180struct _LIBCPP_TEMPLATE_VIS __format_arg_store {
181  // TODO FMT Use a built-in array.
182  array<basic_format_arg<_Context>, sizeof...(_Args)> __args;
183};
184
185template <class _Context = format_context, class... _Args>
186_LIBCPP_HIDE_FROM_ABI __format_arg_store<_Context, _Args...>
187make_format_args(const _Args&... __args) {
188  return {basic_format_arg<_Context>(__args)...};
189}
190
191#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
192template <class... _Args>
193_LIBCPP_HIDE_FROM_ABI __format_arg_store<wformat_context, _Args...>
194make_wformat_args(const _Args&... __args) {
195  return _VSTD::make_format_args<wformat_context>(__args...);
196}
197#endif
198
199namespace __format {
200
201template <class _CharT, class _ParseCtx, class _Ctx>
202_LIBCPP_HIDE_FROM_ABI const _CharT*
203__handle_replacement_field(const _CharT* __begin, const _CharT* __end,
204                           _ParseCtx& __parse_ctx, _Ctx& __ctx) {
205  __format::__parse_number_result __r =
206      __format::__parse_arg_id(__begin, __end, __parse_ctx);
207
208  switch (*__r.__ptr) {
209  case _CharT(':'):
210    // The arg-id has a format-specifier, advance the input to the format-spec.
211    __parse_ctx.advance_to(__r.__ptr + 1);
212    break;
213  case _CharT('}'):
214    // The arg-id has no format-specifier.
215    __parse_ctx.advance_to(__r.__ptr);
216    break;
217  default:
218    __throw_format_error(
219        "The replacement field arg-id should terminate at a ':' or '}'");
220  }
221
222  _VSTD::visit_format_arg(
223      [&](auto __arg) {
224        if constexpr (same_as<decltype(__arg), monostate>)
225          __throw_format_error("Argument index out of bounds");
226        else if constexpr (same_as<decltype(__arg), typename basic_format_arg<_Ctx>::handle>)
227          __arg.format(__parse_ctx, __ctx);
228        else {
229          formatter<decltype(__arg), _CharT> __formatter;
230          __parse_ctx.advance_to(__formatter.parse(__parse_ctx));
231          __ctx.advance_to(__formatter.format(__arg, __ctx));
232        }
233      },
234      __ctx.arg(__r.__value));
235
236  __begin = __parse_ctx.begin();
237  if (__begin == __end || *__begin != _CharT('}'))
238    __throw_format_error("The replacement field misses a terminating '}'");
239
240  return ++__begin;
241}
242
243template <class _ParseCtx, class _Ctx>
244_LIBCPP_HIDE_FROM_ABI typename _Ctx::iterator
245__vformat_to(_ParseCtx&& __parse_ctx, _Ctx&& __ctx) {
246  using _CharT = typename _ParseCtx::char_type;
247  static_assert(same_as<typename _Ctx::char_type, _CharT>);
248
249  const _CharT* __begin = __parse_ctx.begin();
250  const _CharT* __end = __parse_ctx.end();
251  typename _Ctx::iterator __out_it = __ctx.out();
252  while (__begin != __end) {
253    switch (*__begin) {
254    case _CharT('{'):
255      ++__begin;
256      if (__begin == __end)
257        __throw_format_error("The format string terminates at a '{'");
258
259      if (*__begin != _CharT('{')) [[likely]] {
260        __ctx.advance_to(_VSTD::move(__out_it));
261        __begin =
262            __handle_replacement_field(__begin, __end, __parse_ctx, __ctx);
263        __out_it = __ctx.out();
264
265        // The output is written and __begin points to the next character. So
266        // start the next iteration.
267        continue;
268      }
269      // The string is an escape character.
270      break;
271
272    case _CharT('}'):
273      ++__begin;
274      if (__begin == __end || *__begin != _CharT('}'))
275        __throw_format_error(
276            "The format string contains an invalid escape sequence");
277
278      break;
279    }
280
281    // Copy the character to the output verbatim.
282    *__out_it++ = *__begin++;
283  }
284  return __out_it;
285}
286
287} // namespace __format
288
289template <class _OutIt, class _CharT, class _FormatOutIt>
290requires(output_iterator<_OutIt, const _CharT&>) _LIBCPP_HIDE_FROM_ABI _OutIt
291    __vformat_to(
292        _OutIt __out_it, basic_string_view<_CharT> __fmt,
293        basic_format_args<basic_format_context<_FormatOutIt, _CharT>> __args) {
294  if constexpr (same_as<_OutIt, _FormatOutIt>)
295    return _VSTD::__format::__vformat_to(
296        basic_format_parse_context{__fmt, __args.__size()},
297        _VSTD::__format_context_create(_VSTD::move(__out_it), __args));
298  else {
299    __format::__format_buffer<_OutIt, _CharT> __buffer{_VSTD::move(__out_it)};
300    _VSTD::__format::__vformat_to(
301        basic_format_parse_context{__fmt, __args.__size()},
302        _VSTD::__format_context_create(__buffer.make_output_iterator(),
303                                       __args));
304    return _VSTD::move(__buffer).out();
305  }
306}
307
308template <output_iterator<const char&> _OutIt>
309_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT _OutIt
310vformat_to(_OutIt __out_it, string_view __fmt, format_args __args) {
311  return _VSTD::__vformat_to(_VSTD::move(__out_it), __fmt, __args);
312}
313
314#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
315template <output_iterator<const wchar_t&> _OutIt>
316_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT _OutIt
317vformat_to(_OutIt __out_it, wstring_view __fmt, wformat_args __args) {
318  return _VSTD::__vformat_to(_VSTD::move(__out_it), __fmt, __args);
319}
320#endif
321
322template <output_iterator<const char&> _OutIt, class... _Args>
323_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT _OutIt
324format_to(_OutIt __out_it, string_view __fmt, const _Args&... __args) {
325  return _VSTD::vformat_to(_VSTD::move(__out_it), __fmt,
326                           _VSTD::make_format_args(__args...));
327}
328
329#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
330template <output_iterator<const wchar_t&> _OutIt, class... _Args>
331_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT _OutIt
332format_to(_OutIt __out_it, wstring_view __fmt, const _Args&... __args) {
333  return _VSTD::vformat_to(_VSTD::move(__out_it), __fmt,
334                           _VSTD::make_wformat_args(__args...));
335}
336#endif
337
338_LIBCPP_ALWAYS_INLINE inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT string
339vformat(string_view __fmt, format_args __args) {
340  string __res;
341  _VSTD::vformat_to(_VSTD::back_inserter(__res), __fmt, __args);
342  return __res;
343}
344
345#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
346_LIBCPP_ALWAYS_INLINE inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT wstring
347vformat(wstring_view __fmt, wformat_args __args) {
348  wstring __res;
349  _VSTD::vformat_to(_VSTD::back_inserter(__res), __fmt, __args);
350  return __res;
351}
352#endif
353
354template <class... _Args>
355_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT string
356format(string_view __fmt, const _Args&... __args) {
357  return _VSTD::vformat(__fmt, _VSTD::make_format_args(__args...));
358}
359
360#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
361template <class... _Args>
362_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT wstring
363format(wstring_view __fmt, const _Args&... __args) {
364  return _VSTD::vformat(__fmt, _VSTD::make_wformat_args(__args...));
365}
366#endif
367
368template <output_iterator<const char&> _OutIt, class... _Args>
369_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT format_to_n_result<_OutIt>
370format_to_n(_OutIt __out_it, iter_difference_t<_OutIt> __n, string_view __fmt,
371            const _Args&... __args) {
372  // TODO FMT Improve PoC: using std::string is inefficient.
373  string __str = _VSTD::vformat(__fmt, _VSTD::make_format_args(__args...));
374  iter_difference_t<_OutIt> __s = __str.size();
375  iter_difference_t<_OutIt> __m =
376      _VSTD::clamp(__n, iter_difference_t<_OutIt>(0), __s);
377  __out_it = _VSTD::copy_n(__str.begin(), __m, _VSTD::move(__out_it));
378  return {_VSTD::move(__out_it), __s};
379}
380
381#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
382template <output_iterator<const wchar_t&> _OutIt, class... _Args>
383_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT format_to_n_result<_OutIt>
384format_to_n(_OutIt __out_it, iter_difference_t<_OutIt> __n, wstring_view __fmt,
385            const _Args&... __args) {
386  // TODO FMT Improve PoC: using std::string is inefficient.
387  wstring __str = _VSTD::vformat(__fmt, _VSTD::make_wformat_args(__args...));
388  iter_difference_t<_OutIt> __s = __str.size();
389  iter_difference_t<_OutIt> __m =
390      _VSTD::clamp(__n, iter_difference_t<_OutIt>(0), __s);
391  __out_it = _VSTD::copy_n(__str.begin(), __m, _VSTD::move(__out_it));
392  return {_VSTD::move(__out_it), __s};
393}
394#endif
395
396template <class _CharT>
397_LIBCPP_HIDE_FROM_ABI size_t __vformatted_size(basic_string_view<_CharT> __fmt, auto __args) {
398  __format::__formatted_size_buffer<_CharT> __buffer;
399  _VSTD::__format::__vformat_to(basic_format_parse_context{__fmt, __args.__size()},
400                                _VSTD::__format_context_create(__buffer.make_output_iterator(), __args));
401  return _VSTD::move(__buffer).result();
402}
403
404template <class... _Args>
405_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT size_t formatted_size(string_view __fmt,
406                                                                                              const _Args&... __args) {
407  return _VSTD::__vformatted_size(__fmt, basic_format_args{_VSTD::make_format_args(__args...)});
408}
409
410#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
411template <class... _Args>
412_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT size_t formatted_size(wstring_view __fmt,
413                                                                                              const _Args&... __args) {
414  return _VSTD::__vformatted_size(__fmt, basic_format_args{_VSTD::make_wformat_args(__args...)});
415}
416#endif
417
418#ifndef _LIBCPP_HAS_NO_LOCALIZATION
419
420template <class _OutIt, class _CharT, class _FormatOutIt>
421requires(output_iterator<_OutIt, const _CharT&>) _LIBCPP_HIDE_FROM_ABI _OutIt
422    __vformat_to(
423        _OutIt __out_it, locale __loc, basic_string_view<_CharT> __fmt,
424        basic_format_args<basic_format_context<_FormatOutIt, _CharT>> __args) {
425  if constexpr (same_as<_OutIt, _FormatOutIt>)
426    return _VSTD::__format::__vformat_to(
427        basic_format_parse_context{__fmt, __args.__size()},
428        _VSTD::__format_context_create(_VSTD::move(__out_it), __args,
429                                       _VSTD::move(__loc)));
430  else {
431    __format::__format_buffer<_OutIt, _CharT> __buffer{_VSTD::move(__out_it)};
432    _VSTD::__format::__vformat_to(
433        basic_format_parse_context{__fmt, __args.__size()},
434        _VSTD::__format_context_create(__buffer.make_output_iterator(),
435                                       __args, _VSTD::move(__loc)));
436    return _VSTD::move(__buffer).out();
437  }
438}
439
440template <output_iterator<const char&> _OutIt>
441_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT _OutIt vformat_to(
442    _OutIt __out_it, locale __loc, string_view __fmt, format_args __args) {
443  return _VSTD::__vformat_to(_VSTD::move(__out_it), _VSTD::move(__loc), __fmt,
444                             __args);
445}
446
447#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
448template <output_iterator<const wchar_t&> _OutIt>
449_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT _OutIt vformat_to(
450    _OutIt __out_it, locale __loc, wstring_view __fmt, wformat_args __args) {
451  return _VSTD::__vformat_to(_VSTD::move(__out_it), _VSTD::move(__loc), __fmt,
452                             __args);
453}
454#endif
455
456template <output_iterator<const char&> _OutIt, class... _Args>
457_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT _OutIt format_to(
458    _OutIt __out_it, locale __loc, string_view __fmt, const _Args&... __args) {
459  return _VSTD::vformat_to(_VSTD::move(__out_it), _VSTD::move(__loc), __fmt,
460                           _VSTD::make_format_args(__args...));
461}
462
463#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
464template <output_iterator<const wchar_t&> _OutIt, class... _Args>
465_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT _OutIt format_to(
466    _OutIt __out_it, locale __loc, wstring_view __fmt, const _Args&... __args) {
467  return _VSTD::vformat_to(_VSTD::move(__out_it), _VSTD::move(__loc), __fmt,
468                           _VSTD::make_wformat_args(__args...));
469}
470#endif
471
472_LIBCPP_ALWAYS_INLINE inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT string
473vformat(locale __loc, string_view __fmt, format_args __args) {
474  string __res;
475  _VSTD::vformat_to(_VSTD::back_inserter(__res), _VSTD::move(__loc), __fmt,
476                    __args);
477  return __res;
478}
479
480#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
481_LIBCPP_ALWAYS_INLINE inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT wstring
482vformat(locale __loc, wstring_view __fmt, wformat_args __args) {
483  wstring __res;
484  _VSTD::vformat_to(_VSTD::back_inserter(__res), _VSTD::move(__loc), __fmt,
485                    __args);
486  return __res;
487}
488#endif
489
490template <class... _Args>
491_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT string
492format(locale __loc, string_view __fmt, const _Args&... __args) {
493  return _VSTD::vformat(_VSTD::move(__loc), __fmt,
494                        _VSTD::make_format_args(__args...));
495}
496
497#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
498template <class... _Args>
499_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT wstring
500format(locale __loc, wstring_view __fmt, const _Args&... __args) {
501  return _VSTD::vformat(_VSTD::move(__loc), __fmt,
502                        _VSTD::make_wformat_args(__args...));
503}
504#endif
505
506template <output_iterator<const char&> _OutIt, class... _Args>
507_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT format_to_n_result<_OutIt>
508format_to_n(_OutIt __out_it, iter_difference_t<_OutIt> __n, locale __loc,
509            string_view __fmt, const _Args&... __args) {
510  // TODO FMT Improve PoC: using std::string is inefficient.
511  string __str = _VSTD::vformat(_VSTD::move(__loc), __fmt,
512                                _VSTD::make_format_args(__args...));
513  iter_difference_t<_OutIt> __s = __str.size();
514  iter_difference_t<_OutIt> __m =
515      _VSTD::clamp(__n, iter_difference_t<_OutIt>(0), __s);
516  __out_it = _VSTD::copy_n(__str.begin(), __m, _VSTD::move(__out_it));
517  return {_VSTD::move(__out_it), __s};
518}
519
520#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
521template <output_iterator<const wchar_t&> _OutIt, class... _Args>
522_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT format_to_n_result<_OutIt>
523format_to_n(_OutIt __out_it, iter_difference_t<_OutIt> __n, locale __loc,
524            wstring_view __fmt, const _Args&... __args) {
525  // TODO FMT Improve PoC: using std::string is inefficient.
526  wstring __str = _VSTD::vformat(_VSTD::move(__loc), __fmt,
527                                 _VSTD::make_wformat_args(__args...));
528  iter_difference_t<_OutIt> __s = __str.size();
529  iter_difference_t<_OutIt> __m =
530      _VSTD::clamp(__n, iter_difference_t<_OutIt>(0), __s);
531  __out_it = _VSTD::copy_n(__str.begin(), __m, _VSTD::move(__out_it));
532  return {_VSTD::move(__out_it), __s};
533}
534#endif
535
536template <class _CharT>
537_LIBCPP_HIDE_FROM_ABI size_t __vformatted_size(locale __loc, basic_string_view<_CharT> __fmt, auto __args) {
538  __format::__formatted_size_buffer<_CharT> __buffer;
539  _VSTD::__format::__vformat_to(
540      basic_format_parse_context{__fmt, __args.__size()},
541      _VSTD::__format_context_create(__buffer.make_output_iterator(), __args, _VSTD::move(__loc)));
542  return _VSTD::move(__buffer).result();
543}
544
545template <class... _Args>
546_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT size_t formatted_size(locale __loc,
547                                                                                              string_view __fmt,
548                                                                                              const _Args&... __args) {
549  return _VSTD::__vformatted_size(_VSTD::move(__loc), __fmt, basic_format_args{_VSTD::make_format_args(__args...)});
550}
551
552#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
553template <class... _Args>
554_LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT size_t formatted_size(locale __loc,
555                                                                                              wstring_view __fmt,
556                                                                                              const _Args&... __args) {
557  return _VSTD::__vformatted_size(_VSTD::move(__loc), __fmt, basic_format_args{_VSTD::make_wformat_args(__args...)});
558}
559#endif
560
561#endif // _LIBCPP_HAS_NO_LOCALIZATION
562
563#endif //_LIBCPP_STD_VER > 17
564
565_LIBCPP_END_NAMESPACE_STD
566
567#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT)
568
569#endif // _LIBCPP_FORMAT
570