libcxx/include/__format/formatter_output.h

   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_FORMATTER_OUTPUT_H
  11 #define _LIBCPP___FORMAT_FORMATTER_OUTPUT_H
  12
  13 #include <__algorithm/ranges_copy.h>
  14 #include <__algorithm/ranges_fill_n.h>
  15 #include <__algorithm/ranges_transform.h>
  16 #include <__bit/countl.h>
  17 #include <__concepts/same_as.h>
  18 #include <__config>
  19 #include <__cstddef/ptrdiff_t.h>
  20 #include <__cstddef/size_t.h>
  21 #include <__format/buffer.h>
  22 #include <__format/concepts.h>
  23 #include <__format/formatter.h>
  24 #include <__format/parser_std_format_spec.h>
  25 #include <__format/unicode.h>
  26 #include <__iterator/back_insert_iterator.h>
  27 #include <__iterator/concepts.h>
  28 #include <__iterator/iterator_traits.h>
  29 #include <__memory/addressof.h>
  30 #include <__memory/pointer_traits.h>
  31 #include <__utility/move.h>
  32 #include <__utility/unreachable.h>
  33 #include <string_view>
  34
  35 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  36 #  pragma GCC system_header
  37 #endif
  38
  39 _LIBCPP_PUSH_MACROS
  40 #include <__undef_macros>
  41
  42 _LIBCPP_BEGIN_NAMESPACE_STD
  43
  44 #if _LIBCPP_STD_VER >= 20
  45
  46 namespace __formatter {
  47
  48 _LIBCPP_HIDE_FROM_ABI constexpr char __hex_to_upper(char __c) {
  49   switch (__c) {
  50   case 'a':
  51     return 'A';
  52   case 'b':
  53     return 'B';
  54   case 'c':
  55     return 'C';
  56   case 'd':
  57     return 'D';
  58   case 'e':
  59     return 'E';
  60   case 'f':
  61     return 'F';
  62   }
  63   return __c;
  64 }
  65
  66 struct _LIBCPP_EXPORTED_FROM_ABI __padding_size_result {
  67   size_t __before_;
  68   size_t __after_;
  69 };
  70
  71 _LIBCPP_HIDE_FROM_ABI constexpr __padding_size_result
  72 __padding_size(size_t __size, size_t __width, __format_spec::__alignment __align) {
  73   _LIBCPP_ASSERT_INTERNAL(__width > __size, "don't call this function when no padding is required");
  74   _LIBCPP_ASSERT_INTERNAL(
  75       __align != __format_spec::__alignment::__zero_padding, "the caller should have handled the zero-padding");
  76
  77   size_t __fill = __width - __size;
  78   switch (__align) {
  79   case __format_spec::__alignment::__zero_padding:
  80     __libcpp_unreachable();
  81
  82   case __format_spec::__alignment::__left:
  83     return {0, __fill};
  84
  85   case __format_spec::__alignment::__center: {
  86     // The extra padding is divided per [format.string.std]/3
  87     // __before = floor(__fill, 2);
  88     // __after = ceil(__fill, 2);
  89     size_t __before = __fill / 2;
  90     size_t __after  = __fill - __before;
  91     return {__before, __after};
  92   }
  93   case __format_spec::__alignment::__default:
  94   case __format_spec::__alignment::__right:
  95     return {__fill, 0};
  96   }
  97   __libcpp_unreachable();
  98 }
  99
 100 /// Copy wrapper.
 101 ///
 102 /// This uses a "mass output function" of __format::__output_buffer when possible.
 103 template <__fmt_char_type _CharT, __fmt_char_type _OutCharT = _CharT>
 104 _LIBCPP_HIDE_FROM_ABI auto
 105 __copy(basic_string_view<_CharT> __str, output_iterator<const _OutCharT&> auto __out_it) -> decltype(__out_it) {
 106   if constexpr (std::same_as<decltype(__out_it), std::back_insert_iterator<__format::__output_buffer<_OutCharT>>>) {
 107     __out_it.__get_container()->__copy(__str);
 108     return __out_it;
 109   } else if constexpr (std::same_as<decltype(__out_it), typename __format::__retarget_buffer<_OutCharT>::__iterator>) {
 110     __out_it.__buffer_->__copy(__str);
 111     return __out_it;
 112   } else {
 113     return std::ranges::copy(__str, std::move(__out_it)).out;
 114   }
 115 }
 116
 117 template <contiguous_iterator _Iterator,
 118           __fmt_char_type _CharT    = typename iterator_traits<_Iterator>::value_type,
 119           __fmt_char_type _OutCharT = _CharT>
 120 _LIBCPP_HIDE_FROM_ABI auto
 121 __copy(_Iterator __first, _Iterator __last, output_iterator<const _OutCharT&> auto __out_it) -> decltype(__out_it) {
 122   return __formatter::__copy(basic_string_view{__first, __last}, std::move(__out_it));
 123 }
 124
 125 template <contiguous_iterator _Iterator,
 126           __fmt_char_type _CharT    = typename iterator_traits<_Iterator>::value_type,
 127           __fmt_char_type _OutCharT = _CharT>
 128 _LIBCPP_HIDE_FROM_ABI auto
 129 __copy(_Iterator __first, size_t __n, output_iterator<const _OutCharT&> auto __out_it) -> decltype(__out_it) {
 130   return __formatter::__copy(basic_string_view{std::to_address(__first), __n}, std::move(__out_it));
 131 }
 132
 133 /// Transform wrapper.
 134 ///
 135 /// This uses a "mass output function" of __format::__output_buffer when possible.
 136 template <contiguous_iterator _Iterator,
 137           __fmt_char_type _CharT    = typename iterator_traits<_Iterator>::value_type,
 138           __fmt_char_type _OutCharT = _CharT,
 139           class _UnaryOperation>
 140 _LIBCPP_HIDE_FROM_ABI auto
 141 __transform(_Iterator __first,
 142             _Iterator __last,
 143             output_iterator<const _OutCharT&> auto __out_it,
 144             _UnaryOperation __operation) -> decltype(__out_it) {
 145   if constexpr (std::same_as<decltype(__out_it), std::back_insert_iterator<__format::__output_buffer<_OutCharT>>>) {
 146     __out_it.__get_container()->__transform(__first, __last, std::move(__operation));
 147     return __out_it;
 148   } else if constexpr (std::same_as<decltype(__out_it), typename __format::__retarget_buffer<_OutCharT>::__iterator>) {
 149     __out_it.__buffer_->__transform(__first, __last, std::move(__operation));
 150     return __out_it;
 151   } else {
 152     return std::ranges::transform(__first, __last, std::move(__out_it), __operation).out;
 153   }
 154 }
 155
 156 /// Fill wrapper.
 157 ///
 158 /// This uses a "mass output function" of __format::__output_buffer when possible.
 159 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
 160 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, _CharT __value) {
 161   if constexpr (std::same_as<decltype(__out_it), std::back_insert_iterator<__format::__output_buffer<_CharT>>>) {
 162     __out_it.__get_container()->__fill(__n, __value);
 163     return __out_it;
 164   } else if constexpr (std::same_as<decltype(__out_it), typename __format::__retarget_buffer<_CharT>::__iterator>) {
 165     __out_it.__buffer_->__fill(__n, __value);
 166     return __out_it;
 167   } else {
 168     return std::ranges::fill_n(std::move(__out_it), __n, __value);
 169   }
 170 }
 171
 172 #  if _LIBCPP_HAS_UNICODE
 173 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
 174   requires(same_as<_CharT, char>)
 175 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
 176   std::size_t __bytes = std::countl_one(static_cast<unsigned char>(__value.__data[0]));
 177   if (__bytes == 0)
 178     return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
 179
 180   for (size_t __i = 0; __i < __n; ++__i)
 181     __out_it = __formatter::__copy(
 182         std::addressof(__value.__data[0]), std::addressof(__value.__data[0]) + __bytes, std::move(__out_it));
 183   return __out_it;
 184 }
 185
 186 #    if _LIBCPP_HAS_WIDE_CHARACTERS
 187 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
 188   requires(same_as<_CharT, wchar_t> && sizeof(wchar_t) == 2)
 189 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
 190   if (!__unicode::__is_high_surrogate(__value.__data[0]))
 191     return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
 192
 193   for (size_t __i = 0; __i < __n; ++__i)
 194     __out_it = __formatter::__copy(
 195         std::addressof(__value.__data[0]), std::addressof(__value.__data[0]) + 2, std::move(__out_it));
 196   return __out_it;
 197 }
 198
 199 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
 200   requires(same_as<_CharT, wchar_t> && sizeof(wchar_t) == 4)
 201 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
 202   return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
 203 }
 204 #    endif // _LIBCPP_HAS_WIDE_CHARACTERS
 205 #  else    // _LIBCPP_HAS_UNICODE
 206 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
 207 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
 208   return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
 209 }
 210 #  endif   // _LIBCPP_HAS_UNICODE
 211
 212 /// Writes the input to the output with the required padding.
 213 ///
 214 /// Since the output column width is specified the function can be used for
 215 /// ASCII and Unicode output.
 216 ///
 217 /// \pre \a __size <= \a __width. Using this function when this pre-condition
 218 ///      doesn't hold incurs an unwanted overhead.
 219 ///
 220 /// \param __str       The string to write.
 221 /// \param __out_it    The output iterator to write to.
 222 /// \param __specs     The parsed formatting specifications.
 223 /// \param __size      The (estimated) output column width. When the elements
 224 ///                    to be written are ASCII the following condition holds
 225 ///                    \a __size == \a __last - \a __first.
 226 ///
 227 /// \returns           An iterator pointing beyond the last element written.
 228 ///
 229 /// \note The type of the elements in range [\a __first, \a __last) can differ
 230 /// from the type of \a __specs. Integer output uses \c std::to_chars for its
 231 /// conversion, which means the [\a __first, \a __last) always contains elements
 232 /// of the type \c char.
 233 template <class _CharT, class _ParserCharT>
 234 _LIBCPP_HIDE_FROM_ABI auto
 235 __write(basic_string_view<_CharT> __str,
 236         output_iterator<const _CharT&> auto __out_it,
 237         __format_spec::__parsed_specifications<_ParserCharT> __specs,
 238         ptrdiff_t __size) -> decltype(__out_it) {
 239   if (__size >= __specs.__width_)
 240     return __formatter::__copy(__str, std::move(__out_it));
 241
 242   __padding_size_result __padding = __formatter::__padding_size(__size, __specs.__width_, __specs.__std_.__alignment_);
 243   __out_it                        = __formatter::__fill(std::move(__out_it), __padding.__before_, __specs.__fill_);
 244   __out_it                        = __formatter::__copy(__str, std::move(__out_it));
 245   return __formatter::__fill(std::move(__out_it), __padding.__after_, __specs.__fill_);
 246 }
 247
 248 template <contiguous_iterator _Iterator, class _ParserCharT>
 249 _LIBCPP_HIDE_FROM_ABI auto
 250 __write(_Iterator __first,
 251         _Iterator __last,
 252         output_iterator<const iter_value_t<_Iterator>&> auto __out_it,
 253         __format_spec::__parsed_specifications<_ParserCharT> __specs,
 254         ptrdiff_t __size) -> decltype(__out_it) {
 255   _LIBCPP_ASSERT_VALID_INPUT_RANGE(__first <= __last, "Not a valid range");
 256   return __formatter::__write(basic_string_view{__first, __last}, std::move(__out_it), __specs, __size);
 257 }
 258
 259 /// \overload
 260 ///
 261 /// Calls the function above where \a __size = \a __last - \a __first.
 262 template <contiguous_iterator _Iterator, class _ParserCharT>
 263 _LIBCPP_HIDE_FROM_ABI auto
 264 __write(_Iterator __first,
 265         _Iterator __last,
 266         output_iterator<const iter_value_t<_Iterator>&> auto __out_it,
 267         __format_spec::__parsed_specifications<_ParserCharT> __specs) -> decltype(__out_it) {
 268   _LIBCPP_ASSERT_VALID_INPUT_RANGE(__first <= __last, "Not a valid range");
 269   return __formatter::__write(__first, __last, std::move(__out_it), __specs, __last - __first);
 270 }
 271
 272 template <contiguous_iterator _Iterator,
 273           class _CharT = typename iterator_traits<_Iterator>::value_type,
 274           class _ParserCharT,
 275           class _UnaryOperation>
 276 _LIBCPP_HIDE_FROM_ABI auto __write_transformed(
 277     _Iterator __first,
 278     _Iterator __last,
 279     output_iterator<const _CharT&> auto __out_it,
 280     __format_spec::__parsed_specifications<_ParserCharT> __specs,
 281     _UnaryOperation __op) -> decltype(__out_it) {
 282   _LIBCPP_ASSERT_VALID_INPUT_RANGE(__first <= __last, "Not a valid range");
 283
 284   ptrdiff_t __size = __last - __first;
 285   if (__size >= __specs.__width_)
 286     return __formatter::__transform(__first, __last, std::move(__out_it), __op);
 287
 288   __padding_size_result __padding = __formatter::__padding_size(__size, __specs.__width_, __specs.__alignment_);
 289   __out_it                        = __formatter::__fill(std::move(__out_it), __padding.__before_, __specs.__fill_);
 290   __out_it                        = __formatter::__transform(__first, __last, std::move(__out_it), __op);
 291   return __formatter::__fill(std::move(__out_it), __padding.__after_, __specs.__fill_);
 292 }
 293
 294 /// Writes a string using format's width estimation algorithm.
 295 ///
 296 /// \pre !__specs.__has_precision()
 297 ///
 298 /// \note When \c _LIBCPP_HAS_UNICODE is false the function assumes the input is ASCII.
 299 template <class _CharT>
 300 _LIBCPP_HIDE_FROM_ABI auto __write_string_no_precision(
 301     basic_string_view<_CharT> __str,
 302     output_iterator<const _CharT&> auto __out_it,
 303     __format_spec::__parsed_specifications<_CharT> __specs) -> decltype(__out_it) {
 304   _LIBCPP_ASSERT_INTERNAL(!__specs.__has_precision(), "use __write_string");
 305
 306   // No padding -> copy the string
 307   if (!__specs.__has_width())
 308     return __formatter::__copy(__str, std::move(__out_it));
 309
 310   // Note when the estimated width is larger than size there's no padding. So
 311   // there's no reason to get the real size when the estimate is larger than or
 312   // equal to the minimum field width.
 313   size_t __size =
 314       __format_spec::__estimate_column_width(__str, __specs.__width_, __format_spec::__column_width_rounding::__up)
 315           .__width_;
 316   return __formatter::__write(__str, std::move(__out_it), __specs, __size);
 317 }
 318
 319 template <class _CharT>
 320 _LIBCPP_HIDE_FROM_ABI int __truncate(basic_string_view<_CharT>& __str, int __precision) {
 321   __format_spec::__column_width_result __result =
 322       __format_spec::__estimate_column_width(__str, __precision, __format_spec::__column_width_rounding::__down);
 323   __str = basic_string_view<_CharT>{__str.begin(), __result.__last_};
 324   return __result.__width_;
 325 }
 326
 327 } // namespace __formatter
 328
 329 #endif // _LIBCPP_STD_VER >= 20
 330
 331 _LIBCPP_END_NAMESPACE_STD
 332
 333 _LIBCPP_POP_MACROS
 334
 335 #endif // _LIBCPP___FORMAT_FORMATTER_OUTPUT_H