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