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 40 template <class _Tp, class _CharT = char> 41 requires same_as<remove_cvref_t<_Tp>, _Tp> && formattable<_Tp, _CharT> 42 struct _LIBCPP_TEMPLATE_VIS 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}; 210 211 private: 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 265