v1/__format/formatter_output.h

0001 // -*- C++ -*-
0002 //===----------------------------------------------------------------------===//
0003 //
0004 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0005 // See https://llvm.org/LICENSE.txt for license information.
0006 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0007 //
0008 //===----------------------------------------------------------------------===//
0009
0010 #ifndef _LIBCPP___FORMAT_FORMATTER_OUTPUT_H
0011 #define _LIBCPP___FORMAT_FORMATTER_OUTPUT_H
0012
0013 #include <__algorithm/ranges_copy.h>
0014 #include <__algorithm/ranges_fill_n.h>
0015 #include <__algorithm/ranges_transform.h>
0016 #include <__bit/countl.h>
0017 #include <__concepts/same_as.h>
0018 #include <__config>
0019 #include <__cstddef/ptrdiff_t.h>
0020 #include <__cstddef/size_t.h>
0021 #include <__format/buffer.h>
0022 #include <__format/concepts.h>
0023 #include <__format/formatter.h>
0024 #include <__format/parser_std_format_spec.h>
0025 #include <__format/unicode.h>
0026 #include <__iterator/back_insert_iterator.h>
0027 #include <__iterator/concepts.h>
0028 #include <__iterator/iterator_traits.h>
0029 #include <__memory/addressof.h>
0030 #include <__memory/pointer_traits.h>
0031 #include <__utility/move.h>
0032 #include <__utility/unreachable.h>
0033 #include <string_view>
0034
0035 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0036 #  pragma GCC system_header
0037 #endif
0038
0039 _LIBCPP_PUSH_MACROS
0040 #include <__undef_macros>
0041
0042 _LIBCPP_BEGIN_NAMESPACE_STD
0043
0044 #if _LIBCPP_STD_VER >= 20
0045
0046 namespace __formatter {
0047
0048 _LIBCPP_HIDE_FROM_ABI constexpr char __hex_to_upper(char __c) {
0049   switch (__c) {
0050   case 'a':
0051     return 'A';
0052   case 'b':
0053     return 'B';
0054   case 'c':
0055     return 'C';
0056   case 'd':
0057     return 'D';
0058   case 'e':
0059     return 'E';
0060   case 'f':
0061     return 'F';
0062   }
0063   return __c;
0064 }
0065
0066 struct _LIBCPP_EXPORTED_FROM_ABI __padding_size_result {
0067   size_t __before_;
0068   size_t __after_;
0069 };
0070
0071 _LIBCPP_HIDE_FROM_ABI constexpr __padding_size_result
0072 __padding_size(size_t __size, size_t __width, __format_spec::__alignment __align) {
0073   _LIBCPP_ASSERT_INTERNAL(__width > __size, "don't call this function when no padding is required");
0074   _LIBCPP_ASSERT_INTERNAL(
0075       __align != __format_spec::__alignment::__zero_padding, "the caller should have handled the zero-padding");
0076
0077   size_t __fill = __width - __size;
0078   switch (__align) {
0079   case __format_spec::__alignment::__zero_padding:
0080     __libcpp_unreachable();
0081
0082   case __format_spec::__alignment::__left:
0083     return {0, __fill};
0084
0085   case __format_spec::__alignment::__center: {
0086     // The extra padding is divided per [format.string.std]/3
0087     // __before = floor(__fill, 2);
0088     // __after = ceil(__fill, 2);
0089     size_t __before = __fill / 2;
0090     size_t __after  = __fill - __before;
0091     return {__before, __after};
0092   }
0093   case __format_spec::__alignment::__default:
0094   case __format_spec::__alignment::__right:
0095     return {__fill, 0};
0096   }
0097   __libcpp_unreachable();
0098 }
0099
0100 /// Copy wrapper.
0101 ///
0102 /// This uses a "mass output function" of __format::__output_buffer when possible.
0103 template <__fmt_char_type _CharT, __fmt_char_type _OutCharT = _CharT>
0104 _LIBCPP_HIDE_FROM_ABI auto
0105 __copy(basic_string_view<_CharT> __str, output_iterator<const _OutCharT&> auto __out_it) -> decltype(__out_it) {
0106   if constexpr (std::same_as<decltype(__out_it), std::back_insert_iterator<__format::__output_buffer<_OutCharT>>>) {
0107     __out_it.__get_container()->__copy(__str);
0108     return __out_it;
0109   } else if constexpr (std::same_as<decltype(__out_it), typename __format::__retarget_buffer<_OutCharT>::__iterator>) {
0110     __out_it.__buffer_->__copy(__str);
0111     return __out_it;
0112   } else {
0113     return std::ranges::copy(__str, std::move(__out_it)).out;
0114   }
0115 }
0116
0117 template <contiguous_iterator _Iterator,
0118           __fmt_char_type _CharT    = typename iterator_traits<_Iterator>::value_type,
0119           __fmt_char_type _OutCharT = _CharT>
0120 _LIBCPP_HIDE_FROM_ABI auto
0121 __copy(_Iterator __first, _Iterator __last, output_iterator<const _OutCharT&> auto __out_it) -> decltype(__out_it) {
0122   return __formatter::__copy(basic_string_view{__first, __last}, std::move(__out_it));
0123 }
0124
0125 template <contiguous_iterator _Iterator,
0126           __fmt_char_type _CharT    = typename iterator_traits<_Iterator>::value_type,
0127           __fmt_char_type _OutCharT = _CharT>
0128 _LIBCPP_HIDE_FROM_ABI auto
0129 __copy(_Iterator __first, size_t __n, output_iterator<const _OutCharT&> auto __out_it) -> decltype(__out_it) {
0130   return __formatter::__copy(basic_string_view{std::to_address(__first), __n}, std::move(__out_it));
0131 }
0132
0133 /// Transform wrapper.
0134 ///
0135 /// This uses a "mass output function" of __format::__output_buffer when possible.
0136 template <contiguous_iterator _Iterator,
0137           __fmt_char_type _CharT    = typename iterator_traits<_Iterator>::value_type,
0138           __fmt_char_type _OutCharT = _CharT,
0139           class _UnaryOperation>
0140 _LIBCPP_HIDE_FROM_ABI auto
0141 __transform(_Iterator __first,
0142             _Iterator __last,
0143             output_iterator<const _OutCharT&> auto __out_it,
0144             _UnaryOperation __operation) -> decltype(__out_it) {
0145   if constexpr (std::same_as<decltype(__out_it), std::back_insert_iterator<__format::__output_buffer<_OutCharT>>>) {
0146     __out_it.__get_container()->__transform(__first, __last, std::move(__operation));
0147     return __out_it;
0148   } else if constexpr (std::same_as<decltype(__out_it), typename __format::__retarget_buffer<_OutCharT>::__iterator>) {
0149     __out_it.__buffer_->__transform(__first, __last, std::move(__operation));
0150     return __out_it;
0151   } else {
0152     return std::ranges::transform(__first, __last, std::move(__out_it), __operation).out;
0153   }
0154 }
0155
0156 /// Fill wrapper.
0157 ///
0158 /// This uses a "mass output function" of __format::__output_buffer when possible.
0159 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
0160 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, _CharT __value) {
0161   if constexpr (std::same_as<decltype(__out_it), std::back_insert_iterator<__format::__output_buffer<_CharT>>>) {
0162     __out_it.__get_container()->__fill(__n, __value);
0163     return __out_it;
0164   } else if constexpr (std::same_as<decltype(__out_it), typename __format::__retarget_buffer<_CharT>::__iterator>) {
0165     __out_it.__buffer_->__fill(__n, __value);
0166     return __out_it;
0167   } else {
0168     return std::ranges::fill_n(std::move(__out_it), __n, __value);
0169   }
0170 }
0171
0172 #  if _LIBCPP_HAS_UNICODE
0173 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
0174   requires(same_as<_CharT, char>)
0175 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
0176   std::size_t __bytes = std::countl_one(static_cast<unsigned char>(__value.__data[0]));
0177   if (__bytes == 0)
0178     return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
0179
0180   for (size_t __i = 0; __i < __n; ++__i)
0181     __out_it = __formatter::__copy(
0182         std::addressof(__value.__data[0]), std::addressof(__value.__data[0]) + __bytes, std::move(__out_it));
0183   return __out_it;
0184 }
0185
0186 #    if _LIBCPP_HAS_WIDE_CHARACTERS
0187 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
0188   requires(same_as<_CharT, wchar_t> && sizeof(wchar_t) == 2)
0189 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
0190   if (!__unicode::__is_high_surrogate(__value.__data[0]))
0191     return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
0192
0193   for (size_t __i = 0; __i < __n; ++__i)
0194     __out_it = __formatter::__copy(
0195         std::addressof(__value.__data[0]), std::addressof(__value.__data[0]) + 2, std::move(__out_it));
0196   return __out_it;
0197 }
0198
0199 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
0200   requires(same_as<_CharT, wchar_t> && sizeof(wchar_t) == 4)
0201 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
0202   return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
0203 }
0204 #    endif // _LIBCPP_HAS_WIDE_CHARACTERS
0205 #  else    // _LIBCPP_HAS_UNICODE
0206 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
0207 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
0208   return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
0209 }
0210 #  endif   // _LIBCPP_HAS_UNICODE
0211
0212 /// Writes the input to the output with the required padding.
0213 ///
0214 /// Since the output column width is specified the function can be used for
0215 /// ASCII and Unicode output.
0216 ///
0217 /// \pre \a __size <= \a __width. Using this function when this pre-condition
0218 ///      doesn't hold incurs an unwanted overhead.
0219 ///
0220 /// \param __str       The string to write.
0221 /// \param __out_it    The output iterator to write to.
0222 /// \param __specs     The parsed formatting specifications.
0223 /// \param __size      The (estimated) output column width. When the elements
0224 ///                    to be written are ASCII the following condition holds
0225 ///                    \a __size == \a __last - \a __first.
0226 ///
0227 /// \returns           An iterator pointing beyond the last element written.
0228 ///
0229 /// \note The type of the elements in range [\a __first, \a __last) can differ
0230 /// from the type of \a __specs. Integer output uses \c std::to_chars for its
0231 /// conversion, which means the [\a __first, \a __last) always contains elements
0232 /// of the type \c char.
0233 template <class _CharT, class _ParserCharT>
0234 _LIBCPP_HIDE_FROM_ABI auto
0235 __write(basic_string_view<_CharT> __str,
0236         output_iterator<const _CharT&> auto __out_it,
0237         __format_spec::__parsed_specifications<_ParserCharT> __specs,
0238         ptrdiff_t __size) -> decltype(__out_it) {
0239   if (__size >= __specs.__width_)
0240     return __formatter::__copy(__str, std::move(__out_it));
0241
0242   __padding_size_result __padding = __formatter::__padding_size(__size, __specs.__width_, __specs.__std_.__alignment_);
0243   __out_it                        = __formatter::__fill(std::move(__out_it), __padding.__before_, __specs.__fill_);
0244   __out_it                        = __formatter::__copy(__str, std::move(__out_it));
0245   return __formatter::__fill(std::move(__out_it), __padding.__after_, __specs.__fill_);
0246 }
0247
0248 template <contiguous_iterator _Iterator, class _ParserCharT>
0249 _LIBCPP_HIDE_FROM_ABI auto
0250 __write(_Iterator __first,
0251         _Iterator __last,
0252         output_iterator<const iter_value_t<_Iterator>&> auto __out_it,
0253         __format_spec::__parsed_specifications<_ParserCharT> __specs,
0254         ptrdiff_t __size) -> decltype(__out_it) {
0255   _LIBCPP_ASSERT_VALID_INPUT_RANGE(__first <= __last, "Not a valid range");
0256   return __formatter::__write(basic_string_view{__first, __last}, std::move(__out_it), __specs, __size);
0257 }
0258
0259 /// \overload
0260 ///
0261 /// Calls the function above where \a __size = \a __last - \a __first.
0262 template <contiguous_iterator _Iterator, class _ParserCharT>
0263 _LIBCPP_HIDE_FROM_ABI auto
0264 __write(_Iterator __first,
0265         _Iterator __last,
0266         output_iterator<const iter_value_t<_Iterator>&> auto __out_it,
0267         __format_spec::__parsed_specifications<_ParserCharT> __specs) -> decltype(__out_it) {
0268   _LIBCPP_ASSERT_VALID_INPUT_RANGE(__first <= __last, "Not a valid range");
0269   return __formatter::__write(__first, __last, std::move(__out_it), __specs, __last - __first);
0270 }
0271
0272 template <contiguous_iterator _Iterator,
0273           class _CharT = typename iterator_traits<_Iterator>::value_type,
0274           class _ParserCharT,
0275           class _UnaryOperation>
0276 _LIBCPP_HIDE_FROM_ABI auto __write_transformed(
0277     _Iterator __first,
0278     _Iterator __last,
0279     output_iterator<const _CharT&> auto __out_it,
0280     __format_spec::__parsed_specifications<_ParserCharT> __specs,
0281     _UnaryOperation __op) -> decltype(__out_it) {
0282   _LIBCPP_ASSERT_VALID_INPUT_RANGE(__first <= __last, "Not a valid range");
0283
0284   ptrdiff_t __size = __last - __first;
0285   if (__size >= __specs.__width_)
0286     return __formatter::__transform(__first, __last, std::move(__out_it), __op);
0287
0288   __padding_size_result __padding = __formatter::__padding_size(__size, __specs.__width_, __specs.__alignment_);
0289   __out_it                        = __formatter::__fill(std::move(__out_it), __padding.__before_, __specs.__fill_);
0290   __out_it                        = __formatter::__transform(__first, __last, std::move(__out_it), __op);
0291   return __formatter::__fill(std::move(__out_it), __padding.__after_, __specs.__fill_);
0292 }
0293
0294 /// Writes a string using format's width estimation algorithm.
0295 ///
0296 /// \pre !__specs.__has_precision()
0297 ///
0298 /// \note When \c _LIBCPP_HAS_UNICODE is false the function assumes the input is ASCII.
0299 template <class _CharT>
0300 _LIBCPP_HIDE_FROM_ABI auto __write_string_no_precision(
0301     basic_string_view<_CharT> __str,
0302     output_iterator<const _CharT&> auto __out_it,
0303     __format_spec::__parsed_specifications<_CharT> __specs) -> decltype(__out_it) {
0304   _LIBCPP_ASSERT_INTERNAL(!__specs.__has_precision(), "use __write_string");
0305
0306   // No padding -> copy the string
0307   if (!__specs.__has_width())
0308     return __formatter::__copy(__str, std::move(__out_it));
0309
0310   // Note when the estimated width is larger than size there's no padding. So
0311   // there's no reason to get the real size when the estimate is larger than or
0312   // equal to the minimum field width.
0313   size_t __size =
0314       __format_spec::__estimate_column_width(__str, __specs.__width_, __format_spec::__column_width_rounding::__up)
0315           .__width_;
0316   return __formatter::__write(__str, std::move(__out_it), __specs, __size);
0317 }
0318
0319 template <class _CharT>
0320 _LIBCPP_HIDE_FROM_ABI int __truncate(basic_string_view<_CharT>& __str, int __precision) {
0321   __format_spec::__column_width_result __result =
0322       __format_spec::__estimate_column_width(__str, __precision, __format_spec::__column_width_rounding::__down);
0323   __str = basic_string_view<_CharT>{__str.begin(), __result.__last_};
0324   return __result.__width_;
0325 }
0326
0327 } // namespace __formatter
0328
0329 #endif // _LIBCPP_STD_VER >= 20
0330
0331 _LIBCPP_END_NAMESPACE_STD
0332
0333 _LIBCPP_POP_MACROS
0334
0335 #endif // _LIBCPP___FORMAT_FORMATTER_OUTPUT_H