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 <__availability> 19 #include <__chrono/statically_widen.h> 20 #include <__concepts/same_as.h> 21 #include <__config> 22 #include <__format/buffer.h> 23 #include <__format/concepts.h> 24 #include <__format/format_args.h> 25 #include <__format/format_context.h> 26 #include <__format/format_error.h> 27 #include <__format/formatter.h> 28 #include <__format/formatter_output.h> 29 #include <__format/parser_std_format_spec.h> 30 #include <__iterator/back_insert_iterator.h> 31 #include <__ranges/concepts.h> 32 #include <__ranges/data.h> 33 #include <__ranges/size.h> 34 #include <__type_traits/remove_cvref.h> 35 #include <string_view> 36 37 _LIBCPP_BEGIN_NAMESPACE_STD 38 39 #if _LIBCPP_STD_VER > 20 40 41 template <class _Tp, class _CharT = char> 42 requires same_as<remove_cvref_t<_Tp>, _Tp> && formattable<_Tp, _CharT> 43 struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT range_formatter { set_separatorrange_formatter44 _LIBCPP_HIDE_FROM_ABI constexpr void set_separator(basic_string_view<_CharT> __separator) { 45 __separator_ = __separator; 46 } 47 _LIBCPP_HIDE_FROM_ABI constexpr void set_bracketsrange_formatter48 set_brackets(basic_string_view<_CharT> __opening_bracket, basic_string_view<_CharT> __closing_bracket) { 49 __opening_bracket_ = __opening_bracket; 50 __closing_bracket_ = __closing_bracket; 51 } 52 underlyingrange_formatter53 _LIBCPP_HIDE_FROM_ABI constexpr formatter<_Tp, _CharT>& underlying() { return __underlying_; } underlyingrange_formatter54 _LIBCPP_HIDE_FROM_ABI constexpr const formatter<_Tp, _CharT>& underlying() const { return __underlying_; } 55 56 template <class _ParseContext> parserange_formatter57 _LIBCPP_HIDE_FROM_ABI constexpr typename _ParseContext::iterator parse(_ParseContext& __parse_ctx) { 58 const _CharT* __begin = __parser_.__parse(__parse_ctx, __format_spec::__fields_range); 59 const _CharT* __end = __parse_ctx.end(); 60 if (__begin == __end) 61 return __begin; 62 63 // The n field overrides a possible m type, therefore delay applying the 64 // effect of n until the type has been procesed. 65 bool __clear_brackets = (*__begin == _CharT('n')); 66 if (__clear_brackets) { 67 ++__begin; 68 if (__begin == __end) { 69 // Since there is no more data, clear the brackets before returning. 70 set_brackets({}, {}); 71 return __begin; 72 } 73 } 74 75 __parse_type(__begin, __end); 76 if (__clear_brackets) 77 set_brackets({}, {}); 78 if (__begin == __end) 79 return __begin; 80 81 bool __has_range_underlying_spec = *__begin == _CharT(':'); 82 if (__parser_.__type_ != __format_spec::__type::__default) { 83 // [format.range.formatter]/6 84 // If the range-type is s or ?s, then there shall be no n option and no 85 // range-underlying-spec. 86 if (__clear_brackets) { 87 if (__parser_.__type_ == __format_spec::__type::__string) 88 std::__throw_format_error("The n option and type s can't be used together"); 89 std::__throw_format_error("The n option and type ?s can't be used together"); 90 } 91 if (__has_range_underlying_spec) { 92 if (__parser_.__type_ == __format_spec::__type::__string) 93 std::__throw_format_error("Type s and an underlying format specification can't be used together"); 94 std::__throw_format_error("Type ?s and an underlying format specification can't be used together"); 95 } 96 } else if (!__has_range_underlying_spec) 97 std::__set_debug_format(__underlying_); 98 99 if (__has_range_underlying_spec) { 100 // range-underlying-spec: 101 // : format-spec 102 ++__begin; 103 if (__begin == __end) 104 return __begin; 105 106 __parse_ctx.advance_to(__begin); 107 __begin = __underlying_.parse(__parse_ctx); 108 } 109 110 if (__begin != __end && *__begin != _CharT('}')) 111 std::__throw_format_error("The format-spec should consume the input or end with a '}'"); 112 113 return __begin; 114 } 115 116 template <ranges::input_range _Rp, class _FormatContext> 117 requires formattable<ranges::range_reference_t<_Rp>, _CharT> && 118 same_as<remove_cvref_t<ranges::range_reference_t<_Rp>>, _Tp> formatrange_formatter119 _LIBCPP_HIDE_FROM_ABI typename _FormatContext::iterator format(_Rp&& __range, _FormatContext& __ctx) const { 120 __format_spec::__parsed_specifications<_CharT> __specs = __parser_.__get_parsed_std_specifications(__ctx); 121 122 if (!__specs.__has_width()) 123 return __format_range(__range, __ctx, __specs); 124 125 // The size of the buffer needed is: 126 // - open bracket characters 127 // - close bracket character 128 // - n elements where every element may have a different size 129 // - (n -1) separators 130 // The size of the element is hard to predict, knowing the type helps but 131 // it depends on the format-spec. As an initial estimate we guess 6 132 // characters. 133 // Typically both brackets are 1 character and the separator is 2 134 // characters. Which means there will be 135 // (n - 1) * 2 + 1 + 1 = n * 2 character 136 // So estimate 8 times the range size as buffer. 137 std::size_t __capacity_hint = 0; 138 if constexpr (std::ranges::sized_range<_Rp>) 139 __capacity_hint = 8 * ranges::size(__range); 140 __format::__retarget_buffer<_CharT> __buffer{__capacity_hint}; 141 basic_format_context<typename __format::__retarget_buffer<_CharT>::__iterator, _CharT> __c{ 142 __buffer.__make_output_iterator(), __ctx}; 143 144 __format_range(__range, __c, __specs); 145 146 return __formatter::__write_string_no_precision(__buffer.__view(), __ctx.out(), __specs); 147 } 148 149 template <ranges::input_range _Rp, class _FormatContext> 150 typename _FormatContext::iterator _LIBCPP_HIDE_FROM_ABI __format_rangerange_formatter151 __format_range(_Rp&& __range, _FormatContext& __ctx, __format_spec::__parsed_specifications<_CharT> __specs) const { 152 if constexpr (same_as<_Tp, _CharT>) { 153 switch (__specs.__std_.__type_) { 154 case __format_spec::__type::__string: 155 case __format_spec::__type::__debug: 156 return __format_as_string(__range, __ctx, __specs.__std_.__type_ == __format_spec::__type::__debug); 157 default: 158 return __format_as_sequence(__range, __ctx); 159 } 160 } else 161 return __format_as_sequence(__range, __ctx); 162 } 163 164 template <ranges::input_range _Rp, class _FormatContext> 165 _LIBCPP_HIDE_FROM_ABI typename _FormatContext::iterator __format_as_stringrange_formatter166 __format_as_string(_Rp&& __range, _FormatContext& __ctx, bool __debug_format) const { 167 // When the range is contiguous use a basic_string_view instead to avoid a 168 // copy of the underlying data. The basic_string_view formatter 169 // specialization is the "basic" string formatter in libc++. 170 if constexpr (ranges::contiguous_range<_Rp> && std::ranges::sized_range<_Rp>) { 171 std::formatter<basic_string_view<_CharT>, _CharT> __formatter; 172 if (__debug_format) 173 __formatter.set_debug_format(); 174 return __formatter.format( 175 basic_string_view<_CharT>{ 176 ranges::data(__range), 177 ranges::size(__range), 178 }, 179 __ctx); 180 } else { 181 std::formatter<basic_string<_CharT>, _CharT> __formatter; 182 if (__debug_format) 183 __formatter.set_debug_format(); 184 // P2106's from_range has not been implemented yet. Instead use a simple 185 // copy operation. 186 // TODO FMT use basic_string's "from_range" constructor. 187 // return std::formatter<basic_string<_CharT>, _CharT>{}.format(basic_string<_CharT>{from_range, __range}, __ctx); 188 basic_string<_CharT> __str; 189 ranges::copy(__range, back_insert_iterator{__str}); 190 return __formatter.format(__str, __ctx); 191 } 192 } 193 194 template <ranges::input_range _Rp, class _FormatContext> 195 _LIBCPP_HIDE_FROM_ABI typename _FormatContext::iterator __format_as_sequencerange_formatter196 __format_as_sequence(_Rp&& __range, _FormatContext& __ctx) const { 197 __ctx.advance_to(ranges::copy(__opening_bracket_, __ctx.out()).out); 198 bool __use_separator = false; 199 for (auto&& __e : __range) { 200 if (__use_separator) 201 __ctx.advance_to(ranges::copy(__separator_, __ctx.out()).out); 202 else 203 __use_separator = true; 204 205 __ctx.advance_to(__underlying_.format(__e, __ctx)); 206 } 207 208 return ranges::copy(__closing_bracket_, __ctx.out()).out; 209 } 210 211 __format_spec::__parser<_CharT> __parser_{.__alignment_ = __format_spec::__alignment::__left}; 212 213 private: __parse_typerange_formatter214 _LIBCPP_HIDE_FROM_ABI constexpr void __parse_type(const _CharT*& __begin, const _CharT* __end) { 215 switch (*__begin) { 216 case _CharT('m'): 217 if constexpr (__fmt_pair_like<_Tp>) { 218 set_brackets(_LIBCPP_STATICALLY_WIDEN(_CharT, "{"), _LIBCPP_STATICALLY_WIDEN(_CharT, "}")); 219 set_separator(_LIBCPP_STATICALLY_WIDEN(_CharT, ", ")); 220 ++__begin; 221 } else 222 std::__throw_format_error("The range-format-spec type m requires two elements for a pair or tuple"); 223 break; 224 225 case _CharT('s'): 226 if constexpr (same_as<_Tp, _CharT>) { 227 __parser_.__type_ = __format_spec::__type::__string; 228 ++__begin; 229 } else 230 std::__throw_format_error("The range-format-spec type s requires formatting a character type"); 231 break; 232 233 case _CharT('?'): 234 ++__begin; 235 if (__begin == __end || *__begin != _CharT('s')) 236 std::__throw_format_error("The format-spec should consume the input or end with a '}'"); 237 if constexpr (same_as<_Tp, _CharT>) { 238 __parser_.__type_ = __format_spec::__type::__debug; 239 ++__begin; 240 } else 241 std::__throw_format_error("The range-format-spec type ?s requires formatting a character type"); 242 } 243 } 244 245 formatter<_Tp, _CharT> __underlying_; 246 basic_string_view<_CharT> __separator_ = _LIBCPP_STATICALLY_WIDEN(_CharT, ", "); 247 basic_string_view<_CharT> __opening_bracket_ = _LIBCPP_STATICALLY_WIDEN(_CharT, "["); 248 basic_string_view<_CharT> __closing_bracket_ = _LIBCPP_STATICALLY_WIDEN(_CharT, "]"); 249 }; 250 251 #endif //_LIBCPP_STD_VER > 20 252 253 _LIBCPP_END_NAMESPACE_STD 254 255 #endif // _LIBCPP___FORMAT_RANGE_FORMATTER_H 256