libcxx/include/__cxx03/__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 <__cxx03/__algorithm/ranges_copy.h>
  14 #include <__cxx03/__algorithm/ranges_fill_n.h>
  15 #include <__cxx03/__algorithm/ranges_transform.h>
  16 #include <__cxx03/__bit/countl.h>
  17 #include <__cxx03/__concepts/same_as.h>
  18 #include <__cxx03/__config>
  19 #include <__cxx03/__format/buffer.h>
  20 #include <__cxx03/__format/concepts.h>
  21 #include <__cxx03/__format/formatter.h>
  22 #include <__cxx03/__format/parser_std_format_spec.h>
  23 #include <__cxx03/__format/unicode.h>
  24 #include <__cxx03/__iterator/back_insert_iterator.h>
  25 #include <__cxx03/__iterator/concepts.h>
  26 #include <__cxx03/__iterator/iterator_traits.h>
  27 #include <__cxx03/__memory/addressof.h>
  28 #include <__cxx03/__memory/pointer_traits.h>
  29 #include <__cxx03/__utility/move.h>
  30 #include <__cxx03/__utility/unreachable.h>
  31 #include <__cxx03/cstddef>
  32 #include <__cxx03/string_view>
  33
  34 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  35 #  pragma GCC system_header
  36 #endif
  37
  38 _LIBCPP_PUSH_MACROS
  39 #include <__cxx03/__undef_macros>
  40
  41 _LIBCPP_BEGIN_NAMESPACE_STD
  42
  43 #if _LIBCPP_STD_VER >= 20
  44
  45 namespace __formatter {
  46
  47 _LIBCPP_HIDE_FROM_ABI constexpr char __hex_to_upper(char __c) {
  48   switch (__c) {
  49   case 'a':
  50     return 'A';
  51   case 'b':
  52     return 'B';
  53   case 'c':
  54     return 'C';
  55   case 'd':
  56     return 'D';
  57   case 'e':
  58     return 'E';
  59   case 'f':
  60     return 'F';
  61   }
  62   return __c;
  63 }
  64
  65 struct _LIBCPP_EXPORTED_FROM_ABI __padding_size_result {
  66   size_t __before_;
  67   size_t __after_;
  68 };
  69
  70 _LIBCPP_HIDE_FROM_ABI constexpr __padding_size_result
  71 __padding_size(size_t __size, size_t __width, __format_spec::__alignment __align) {
  72   _LIBCPP_ASSERT_INTERNAL(__width > __size, "don't call this function when no padding is required");
  73   _LIBCPP_ASSERT_INTERNAL(
  74       __align != __format_spec::__alignment::__zero_padding, "the caller should have handled the zero-padding");
  75
  76   size_t __fill = __width - __size;
  77   switch (__align) {
  78   case __format_spec::__alignment::__zero_padding:
  79     __libcpp_unreachable();
  80
  81   case __format_spec::__alignment::__left:
  82     return {0, __fill};
  83
  84   case __format_spec::__alignment::__center: {
  85     // The extra padding is divided per [format.string.std]/3
  86     // __before = floor(__fill, 2);
  87     // __after = ceil(__fill, 2);
  88     size_t __before = __fill / 2;
  89     size_t __after  = __fill - __before;
  90     return {__before, __after};
  91   }
  92   case __format_spec::__alignment::__default:
  93   case __format_spec::__alignment::__right:
  94     return {__fill, 0};
  95   }
  96   __libcpp_unreachable();
  97 }
  98
  99 /// Copy wrapper.
 100 ///
 101 /// This uses a "mass output function" of __format::__output_buffer when possible.
 102 template <__fmt_char_type _CharT, __fmt_char_type _OutCharT = _CharT>
 103 _LIBCPP_HIDE_FROM_ABI auto
 104 __copy(basic_string_view<_CharT> __str, output_iterator<const _OutCharT&> auto __out_it) -> decltype(__out_it) {
 105   if constexpr (std::same_as<decltype(__out_it), std::back_insert_iterator<__format::__output_buffer<_OutCharT>>>) {
 106     __out_it.__get_container()->__copy(__str);
 107     return __out_it;
 108   } else if constexpr (std::same_as<decltype(__out_it), typename __format::__retarget_buffer<_OutCharT>::__iterator>) {
 109     __out_it.__buffer_->__copy(__str);
 110     return __out_it;
 111   } else {
 112     return std::ranges::copy(__str, std::move(__out_it)).out;
 113   }
 114 }
 115
 116 template <contiguous_iterator _Iterator,
 117           __fmt_char_type _CharT    = typename iterator_traits<_Iterator>::value_type,
 118           __fmt_char_type _OutCharT = _CharT>
 119 _LIBCPP_HIDE_FROM_ABI auto
 120 __copy(_Iterator __first, _Iterator __last, output_iterator<const _OutCharT&> auto __out_it) -> decltype(__out_it) {
 121   return __formatter::__copy(basic_string_view{__first, __last}, std::move(__out_it));
 122 }
 123
 124 template <contiguous_iterator _Iterator,
 125           __fmt_char_type _CharT    = typename iterator_traits<_Iterator>::value_type,
 126           __fmt_char_type _OutCharT = _CharT>
 127 _LIBCPP_HIDE_FROM_ABI auto
 128 __copy(_Iterator __first, size_t __n, output_iterator<const _OutCharT&> auto __out_it) -> decltype(__out_it) {
 129   return __formatter::__copy(basic_string_view{std::to_address(__first), __n}, std::move(__out_it));
 130 }
 131
 132 /// Transform wrapper.
 133 ///
 134 /// This uses a "mass output function" of __format::__output_buffer when possible.
 135 template <contiguous_iterator _Iterator,
 136           __fmt_char_type _CharT    = typename iterator_traits<_Iterator>::value_type,
 137           __fmt_char_type _OutCharT = _CharT,
 138           class _UnaryOperation>
 139 _LIBCPP_HIDE_FROM_ABI auto
 140 __transform(_Iterator __first,
 141             _Iterator __last,
 142             output_iterator<const _OutCharT&> auto __out_it,
 143             _UnaryOperation __operation) -> decltype(__out_it) {
 144   if constexpr (std::same_as<decltype(__out_it), std::back_insert_iterator<__format::__output_buffer<_OutCharT>>>) {
 145     __out_it.__get_container()->__transform(__first, __last, std::move(__operation));
 146     return __out_it;
 147   } else if constexpr (std::same_as<decltype(__out_it), typename __format::__retarget_buffer<_OutCharT>::__iterator>) {
 148     __out_it.__buffer_->__transform(__first, __last, std::move(__operation));
 149     return __out_it;
 150   } else {
 151     return std::ranges::transform(__first, __last, std::move(__out_it), __operation).out;
 152   }
 153 }
 154
 155 /// Fill wrapper.
 156 ///
 157 /// This uses a "mass output function" of __format::__output_buffer when possible.
 158 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
 159 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, _CharT __value) {
 160   if constexpr (std::same_as<decltype(__out_it), std::back_insert_iterator<__format::__output_buffer<_CharT>>>) {
 161     __out_it.__get_container()->__fill(__n, __value);
 162     return __out_it;
 163   } else if constexpr (std::same_as<decltype(__out_it), typename __format::__retarget_buffer<_CharT>::__iterator>) {
 164     __out_it.__buffer_->__fill(__n, __value);
 165     return __out_it;
 166   } else {
 167     return std::ranges::fill_n(std::move(__out_it), __n, __value);
 168   }
 169 }
 170
 171 #  ifndef _LIBCPP_HAS_NO_UNICODE
 172 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
 173   requires(same_as<_CharT, char>)
 174 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
 175   std::size_t __bytes = std::countl_one(static_cast<unsigned char>(__value.__data[0]));
 176   if (__bytes == 0)
 177     return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
 178
 179   for (size_t __i = 0; __i < __n; ++__i)
 180     __out_it = __formatter::__copy(
 181         std::addressof(__value.__data[0]), std::addressof(__value.__data[0]) + __bytes, std::move(__out_it));
 182   return __out_it;
 183 }
 184
 185 #    ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
 186 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
 187   requires(same_as<_CharT, wchar_t> && sizeof(wchar_t) == 2)
 188 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
 189   if (!__unicode::__is_high_surrogate(__value.__data[0]))
 190     return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
 191
 192   for (size_t __i = 0; __i < __n; ++__i)
 193     __out_it = __formatter::__copy(
 194         std::addressof(__value.__data[0]), std::addressof(__value.__data[0]) + 2, std::move(__out_it));
 195   return __out_it;
 196 }
 197
 198 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
 199   requires(same_as<_CharT, wchar_t> && sizeof(wchar_t) == 4)
 200 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
 201   return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
 202 }
 203 #    endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
 204 #  else    // _LIBCPP_HAS_NO_UNICODE
 205 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
 206 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
 207   return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
 208 }
 209 #  endif   // _LIBCPP_HAS_NO_UNICODE
 210
 211 /// Writes the input to the output with the required padding.
 212 ///
 213 /// Since the output column width is specified the function can be used for
 214 /// ASCII and Unicode output.
 215 ///
 216 /// \pre \a __size <= \a __width. Using this function when this pre-condition
 217 ///      doesn't hold incurs an unwanted overhead.
 218 ///
 219 /// \param __str       The string to write.
 220 /// \param __out_it    The output iterator to write to.
 221 /// \param __specs     The parsed formatting specifications.
 222 /// \param __size      The (estimated) output column width. When the elements
 223 ///                    to be written are ASCII the following condition holds
 224 ///                    \a __size == \a __last - \a __first.
 225 ///
 226 /// \returns           An iterator pointing beyond the last element written.
 227 ///
 228 /// \note The type of the elements in range [\a __first, \a __last) can differ
 229 /// from the type of \a __specs. Integer output uses \c std::to_chars for its
 230 /// conversion, which means the [\a __first, \a __last) always contains elements
 231 /// of the type \c char.
 232 template <class _CharT, class _ParserCharT>
 233 _LIBCPP_HIDE_FROM_ABI auto
 234 __write(basic_string_view<_CharT> __str,
 235         output_iterator<const _CharT&> auto __out_it,
 236         __format_spec::__parsed_specifications<_ParserCharT> __specs,
 237         ptrdiff_t __size) -> decltype(__out_it) {
 238   if (__size >= __specs.__width_)
 239     return __formatter::__copy(__str, std::move(__out_it));
 240
 241   __padding_size_result __padding = __formatter::__padding_size(__size, __specs.__width_, __specs.__std_.__alignment_);
 242   __out_it                        = __formatter::__fill(std::move(__out_it), __padding.__before_, __specs.__fill_);
 243   __out_it                        = __formatter::__copy(__str, std::move(__out_it));
 244   return __formatter::__fill(std::move(__out_it), __padding.__after_, __specs.__fill_);
 245 }
 246
 247 template <contiguous_iterator _Iterator, class _ParserCharT>
 248 _LIBCPP_HIDE_FROM_ABI auto
 249 __write(_Iterator __first,
 250         _Iterator __last,
 251         output_iterator<const iter_value_t<_Iterator>&> auto __out_it,
 252         __format_spec::__parsed_specifications<_ParserCharT> __specs,
 253         ptrdiff_t __size) -> decltype(__out_it) {
 254   _LIBCPP_ASSERT_VALID_INPUT_RANGE(__first <= __last, "Not a valid range");
 255   return __formatter::__write(basic_string_view{__first, __last}, std::move(__out_it), __specs, __size);
 256 }
 257
 258 /// \overload
 259 ///
 260 /// Calls the function above where \a __size = \a __last - \a __first.
 261 template <contiguous_iterator _Iterator, class _ParserCharT>
 262 _LIBCPP_HIDE_FROM_ABI auto
 263 __write(_Iterator __first,
 264         _Iterator __last,
 265         output_iterator<const iter_value_t<_Iterator>&> auto __out_it,
 266         __format_spec::__parsed_specifications<_ParserCharT> __specs) -> decltype(__out_it) {
 267   _LIBCPP_ASSERT_VALID_INPUT_RANGE(__first <= __last, "Not a valid range");
 268   return __formatter::__write(__first, __last, std::move(__out_it), __specs, __last - __first);
 269 }
 270
 271 template <contiguous_iterator _Iterator,
 272           class _CharT = typename iterator_traits<_Iterator>::value_type,
 273           class _ParserCharT,
 274           class _UnaryOperation>
 275 _LIBCPP_HIDE_FROM_ABI auto __write_transformed(
 276     _Iterator __first,
 277     _Iterator __last,
 278     output_iterator<const _CharT&> auto __out_it,
 279     __format_spec::__parsed_specifications<_ParserCharT> __specs,
 280     _UnaryOperation __op) -> decltype(__out_it) {
 281   _LIBCPP_ASSERT_VALID_INPUT_RANGE(__first <= __last, "Not a valid range");
 282
 283   ptrdiff_t __size = __last - __first;
 284   if (__size >= __specs.__width_)
 285     return __formatter::__transform(__first, __last, std::move(__out_it), __op);
 286
 287   __padding_size_result __padding = __formatter::__padding_size(__size, __specs.__width_, __specs.__alignment_);
 288   __out_it                        = __formatter::__fill(std::move(__out_it), __padding.__before_, __specs.__fill_);
 289   __out_it                        = __formatter::__transform(__first, __last, std::move(__out_it), __op);
 290   return __formatter::__fill(std::move(__out_it), __padding.__after_, __specs.__fill_);
 291 }
 292
 293 /// Writes a string using format's width estimation algorithm.
 294 ///
 295 /// \pre !__specs.__has_precision()
 296 ///
 297 /// \note When \c _LIBCPP_HAS_NO_UNICODE is defined the function assumes the
 298 /// 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