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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_RANGE_FORMATTER_H
11#define _LIBCPP___FORMAT_RANGE_FORMATTER_H
12
13#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
14# pragma GCC system_header
15#endif
16
17#include <__algorithm/ranges_copy.h>
18#include <__chrono/statically_widen.h>
19#include <__concepts/same_as.h>
20#include <__config>
21#include <__format/buffer.h>
22#include <__format/concepts.h>
23#include <__format/format_context.h>
24#include <__format/format_error.h>
25#include <__format/formatter.h>
26#include <__format/formatter_output.h>
27#include <__format/parser_std_format_spec.h>
28#include <__iterator/back_insert_iterator.h>
29#include <__ranges/concepts.h>
30#include <__ranges/data.h>
31#include <__ranges/from_range.h>
32#include <__ranges/size.h>
33#include <__type_traits/remove_cvref.h>
34#include <string_view>
35
36_LIBCPP_BEGIN_NAMESPACE_STD
37
38#if _LIBCPP_STD_VER >= 23
39
40template <class _Tp, class _CharT = char>
41 requires same_as<remove_cvref_t<_Tp>, _Tp> && formattable<_Tp, _CharT>
42struct range_formatter {
43 _LIBCPP_HIDE_FROM_ABI constexpr void set_separator(basic_string_view<_CharT> __separator) noexcept {
44 __separator_ = __separator;
45 }
46 _LIBCPP_HIDE_FROM_ABI constexpr void
47 set_brackets(basic_string_view<_CharT> __opening_bracket, basic_string_view<_CharT> __closing_bracket) noexcept {
48 __opening_bracket_ = __opening_bracket;
49 __closing_bracket_ = __closing_bracket;
50 }
51
52 _LIBCPP_HIDE_FROM_ABI constexpr formatter<_Tp, _CharT>& underlying() noexcept { return __underlying_; }
53 _LIBCPP_HIDE_FROM_ABI constexpr const formatter<_Tp, _CharT>& underlying() const noexcept { return __underlying_; }
54
55 template <class _ParseContext>
56 _LIBCPP_HIDE_FROM_ABI constexpr typename _ParseContext::iterator parse(_ParseContext& __ctx) {
57 auto __begin = __parser_.__parse(__ctx, __format_spec::__fields_range);
58 auto __end = __ctx.end();
59 // Note the cases where __begin == __end in this code only happens when the
60 // replacement-field has no terminating }, or when the parse is manually
61 // called with a format-spec. The former is an error and the latter means
62 // using a formatter without the format functions or print.
63 if (__begin == __end) [[unlikely]]
64 return __parse_empty_range_underlying_spec(__ctx, __begin);
65
66 // The n field overrides a possible m type, therefore delay applying the
67 // effect of n until the type has been procesed.
68 __parse_type(__begin, __end);
69 if (__parser_.__clear_brackets_)
70 set_brackets({}, {});
71 if (__begin == __end) [[unlikely]]
72 return __parse_empty_range_underlying_spec(__ctx, __begin);
73
74 bool __has_range_underlying_spec = *__begin == _CharT(':');
75 if (__has_range_underlying_spec) {
76 // range-underlying-spec:
77 // : format-spec
78 ++__begin;
79 } else if (__begin != __end && *__begin != _CharT('}'))
80 // When there is no underlaying range the current parse should have
81 // consumed the format-spec. If not, the not consumed input will be
82 // processed by the underlying. For example {:-} for a range in invalid,
83 // the sign field is not present. Without this check the underlying_ will
84 // get -} as input which my be valid.
85 std::__throw_format_error("The format specifier should consume the input or end with a '}'");
86
87 __ctx.advance_to(__begin);
88 __begin = __underlying_.parse(__ctx);
89
90 // This test should not be required if __has_range_underlying_spec is false.
91 // However this test makes sure the underlying formatter left the parser in
92 // a valid state. (Note this is not a full protection against evil parsers.
93 // For example
94 // } this is test for the next argument {}
95 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
96 // could consume more than it should.
97 if (__begin != __end && *__begin != _CharT('}'))
98 std::__throw_format_error("The format specifier should consume the input or end with a '}'");
99
100 if (__parser_.__type_ != __format_spec::__type::__default) {
101 // [format.range.formatter]/6
102 // If the range-type is s or ?s, then there shall be no n option and no
103 // range-underlying-spec.
104 if (__parser_.__clear_brackets_) {
105 if (__parser_.__type_ == __format_spec::__type::__string)
106 std::__throw_format_error("The n option and type s can't be used together");
107 std::__throw_format_error("The n option and type ?s can't be used together");
108 }
109 if (__has_range_underlying_spec) {
110 if (__parser_.__type_ == __format_spec::__type::__string)
111 std::__throw_format_error("Type s and an underlying format specification can't be used together");
112 std::__throw_format_error("Type ?s and an underlying format specification can't be used together");
113 }
114 } else if (!__has_range_underlying_spec)
115 std::__set_debug_format(__underlying_);
116
117 return __begin;
118 }
119
120 template <ranges::input_range _Rp, class _FormatContext>
121 requires formattable<ranges::range_reference_t<_Rp>, _CharT> &&
122 same_as<remove_cvref_t<ranges::range_reference_t<_Rp>>, _Tp>
123 _LIBCPP_HIDE_FROM_ABI typename _FormatContext::iterator format(_Rp&& __range, _FormatContext& __ctx) const {
124 __format_spec::__parsed_specifications<_CharT> __specs = __parser_.__get_parsed_std_specifications(__ctx);
125
126 if (!__specs.__has_width())
127 return __format_range(__range, __ctx, __specs);
128
129 // The size of the buffer needed is:
130 // - open bracket characters
131 // - close bracket character
132 // - n elements where every element may have a different size
133 // - (n -1) separators
134 // The size of the element is hard to predict, knowing the type helps but
135 // it depends on the format-spec. As an initial estimate we guess 6
136 // characters.
137 // Typically both brackets are 1 character and the separator is 2
138 // characters. Which means there will be
139 // (n - 1) * 2 + 1 + 1 = n * 2 character
140 // So estimate 8 times the range size as buffer.
141 std::size_t __capacity_hint = 0;
142 if constexpr (std::ranges::sized_range<_Rp>)
143 __capacity_hint = 8 * ranges::size(__range);
144 __format::__retarget_buffer<_CharT> __buffer{__capacity_hint};
145 basic_format_context<typename __format::__retarget_buffer<_CharT>::__iterator, _CharT> __c{
146 __buffer.__make_output_iterator(), __ctx};
147
148 __format_range(__range, __c, __specs);
149
150 return __formatter::__write_string_no_precision(__buffer.__view(), __ctx.out(), __specs);
151 }
152
153 template <ranges::input_range _Rp, class _FormatContext>
154 typename _FormatContext::iterator _LIBCPP_HIDE_FROM_ABI
155 __format_range(_Rp&& __range, _FormatContext& __ctx, __format_spec::__parsed_specifications<_CharT> __specs) const {
156 if constexpr (same_as<_Tp, _CharT>) {
157 switch (__specs.__std_.__type_) {
158 case __format_spec::__type::__string:
159 case __format_spec::__type::__debug:
160 return __format_as_string(__range, __ctx, __specs.__std_.__type_ == __format_spec::__type::__debug);
161 default:
162 return __format_as_sequence(__range, __ctx);
163 }
164 } else
165 return __format_as_sequence(__range, __ctx);
166 }
167
168 template <ranges::input_range _Rp, class _FormatContext>
169 _LIBCPP_HIDE_FROM_ABI typename _FormatContext::iterator
170 __format_as_string(_Rp&& __range, _FormatContext& __ctx, bool __debug_format) const {
171 // When the range is contiguous use a basic_string_view instead to avoid a
172 // copy of the underlying data. The basic_string_view formatter
173 // specialization is the "basic" string formatter in libc++.
174 if constexpr (ranges::contiguous_range<_Rp> && std::ranges::sized_range<_Rp>) {
175 std::formatter<basic_string_view<_CharT>, _CharT> __formatter;
176 if (__debug_format)
177 __formatter.set_debug_format();
178 return __formatter.format(
179 basic_string_view<_CharT>{
180 ranges::data(__range),
181 ranges::size(__range),
182 },
183 __ctx);
184 } else {
185 std::formatter<basic_string<_CharT>, _CharT> __formatter;
186 if (__debug_format)
187 __formatter.set_debug_format();
188 return __formatter.format(basic_string<_CharT>{from_range, __range}, __ctx);
189 }
190 }
191
192 template <ranges::input_range _Rp, class _FormatContext>
193 _LIBCPP_HIDE_FROM_ABI typename _FormatContext::iterator
194 __format_as_sequence(_Rp&& __range, _FormatContext& __ctx) const {
195 __ctx.advance_to(ranges::copy(__opening_bracket_, __ctx.out()).out);
196 bool __use_separator = false;
197 for (auto&& __e : __range) {
198 if (__use_separator)
199 __ctx.advance_to(ranges::copy(__separator_, __ctx.out()).out);
200 else
201 __use_separator = true;
202
203 __ctx.advance_to(__underlying_.format(__e, __ctx));
204 }
205
206 return ranges::copy(__closing_bracket_, __ctx.out()).out;
207 }
208
209 __format_spec::__parser<_CharT> __parser_{.__alignment_ = __format_spec::__alignment::__left};
210
211private:
212 template <contiguous_iterator _Iterator>
213 _LIBCPP_HIDE_FROM_ABI constexpr void __parse_type(_Iterator& __begin, _Iterator __end) {
214 switch (*__begin) {
215 case _CharT('m'):
216 if constexpr (__fmt_pair_like<_Tp>) {
217 set_brackets(_LIBCPP_STATICALLY_WIDEN(_CharT, "{"), _LIBCPP_STATICALLY_WIDEN(_CharT, "}"));
218 set_separator(_LIBCPP_STATICALLY_WIDEN(_CharT, ", "));
219 ++__begin;
220 } else
221 std::__throw_format_error("Type m requires a pair or a tuple with two elements");
222 break;
223
224 case _CharT('s'):
225 if constexpr (same_as<_Tp, _CharT>) {
226 __parser_.__type_ = __format_spec::__type::__string;
227 ++__begin;
228 } else
229 std::__throw_format_error("Type s requires character type as formatting argument");
230 break;
231
232 case _CharT('?'):
233 ++__begin;
234 if (__begin == __end || *__begin != _CharT('s'))
235 std::__throw_format_error("The format specifier should consume the input or end with a '}'");
236 if constexpr (same_as<_Tp, _CharT>) {
237 __parser_.__type_ = __format_spec::__type::__debug;
238 ++__begin;
239 } else
240 std::__throw_format_error("Type ?s requires character type as formatting argument");
241 }
242 }
243
244 template <class _ParseContext>
245 _LIBCPP_HIDE_FROM_ABI constexpr typename _ParseContext::iterator
246 __parse_empty_range_underlying_spec(_ParseContext& __ctx, typename _ParseContext::iterator __begin) {
247 __ctx.advance_to(__begin);
248 [[maybe_unused]] typename _ParseContext::iterator __result = __underlying_.parse(__ctx);
249 _LIBCPP_ASSERT_INTERNAL(__result == __begin,
250 "the underlying's parse function should not advance the input beyond the end of the input");
251 return __begin;
252 }
253
254 formatter<_Tp, _CharT> __underlying_;
255 basic_string_view<_CharT> __separator_ = _LIBCPP_STATICALLY_WIDEN(_CharT, ", ");
256 basic_string_view<_CharT> __opening_bracket_ = _LIBCPP_STATICALLY_WIDEN(_CharT, "[");
257 basic_string_view<_CharT> __closing_bracket_ = _LIBCPP_STATICALLY_WIDEN(_CharT, "]");
258};
259
260#endif // _LIBCPP_STD_VER >= 23
261
262_LIBCPP_END_NAMESPACE_STD
263
264#endif // _LIBCPP___FORMAT_RANGE_FORMATTER_H