__cxx03/__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___CXX03___FORMAT_FORMATTER_OUTPUT_H
0011 #define _LIBCPP___CXX03___FORMAT_FORMATTER_OUTPUT_H
0012
0013 #include <__cxx03/__algorithm/ranges_copy.h>
0014 #include <__cxx03/__algorithm/ranges_fill_n.h>
0015 #include <__cxx03/__algorithm/ranges_transform.h>
0016 #include <__cxx03/__bit/countl.h>
0017 #include <__cxx03/__concepts/same_as.h>
0018 #include <__cxx03/__config>
0019 #include <__cxx03/__format/buffer.h>
0020 #include <__cxx03/__format/concepts.h>
0021 #include <__cxx03/__format/formatter.h>
0022 #include <__cxx03/__format/parser_std_format_spec.h>
0023 #include <__cxx03/__format/unicode.h>
0024 #include <__cxx03/__iterator/back_insert_iterator.h>
0025 #include <__cxx03/__iterator/concepts.h>
0026 #include <__cxx03/__iterator/iterator_traits.h>
0027 #include <__cxx03/__memory/addressof.h>
0028 #include <__cxx03/__memory/pointer_traits.h>
0029 #include <__cxx03/__utility/move.h>
0030 #include <__cxx03/__utility/unreachable.h>
0031 #include <__cxx03/cstddef>
0032 #include <__cxx03/string_view>
0033
0034 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0035 #  pragma GCC system_header
0036 #endif
0037
0038 _LIBCPP_PUSH_MACROS
0039 #include <__cxx03/__undef_macros>
0040
0041 _LIBCPP_BEGIN_NAMESPACE_STD
0042
0043 #if _LIBCPP_STD_VER >= 20
0044
0045 namespace __formatter {
0046
0047 _LIBCPP_HIDE_FROM_ABI constexpr char __hex_to_upper(char __c) {
0048   switch (__c) {
0049   case 'a':
0050     return 'A';
0051   case 'b':
0052     return 'B';
0053   case 'c':
0054     return 'C';
0055   case 'd':
0056     return 'D';
0057   case 'e':
0058     return 'E';
0059   case 'f':
0060     return 'F';
0061   }
0062   return __c;
0063 }
0064
0065 struct _LIBCPP_EXPORTED_FROM_ABI __padding_size_result {
0066   size_t __before_;
0067   size_t __after_;
0068 };
0069
0070 _LIBCPP_HIDE_FROM_ABI constexpr __padding_size_result
0071 __padding_size(size_t __size, size_t __width, __format_spec::__alignment __align) {
0072   _LIBCPP_ASSERT_INTERNAL(__width > __size, "don't call this function when no padding is required");
0073   _LIBCPP_ASSERT_INTERNAL(
0074       __align != __format_spec::__alignment::__zero_padding, "the caller should have handled the zero-padding");
0075
0076   size_t __fill = __width - __size;
0077   switch (__align) {
0078   case __format_spec::__alignment::__zero_padding:
0079     __libcpp_unreachable();
0080
0081   case __format_spec::__alignment::__left:
0082     return {0, __fill};
0083
0084   case __format_spec::__alignment::__center: {
0085     // The extra padding is divided per [format.string.std]/3
0086     // __before = floor(__fill, 2);
0087     // __after = ceil(__fill, 2);
0088     size_t __before = __fill / 2;
0089     size_t __after  = __fill - __before;
0090     return {__before, __after};
0091   }
0092   case __format_spec::__alignment::__default:
0093   case __format_spec::__alignment::__right:
0094     return {__fill, 0};
0095   }
0096   __libcpp_unreachable();
0097 }
0098
0099 /// Copy wrapper.
0100 ///
0101 /// This uses a "mass output function" of __format::__output_buffer when possible.
0102 template <__fmt_char_type _CharT, __fmt_char_type _OutCharT = _CharT>
0103 _LIBCPP_HIDE_FROM_ABI auto
0104 __copy(basic_string_view<_CharT> __str, output_iterator<const _OutCharT&> auto __out_it) -> decltype(__out_it) {
0105   if constexpr (std::same_as<decltype(__out_it), std::back_insert_iterator<__format::__output_buffer<_OutCharT>>>) {
0106     __out_it.__get_container()->__copy(__str);
0107     return __out_it;
0108   } else if constexpr (std::same_as<decltype(__out_it), typename __format::__retarget_buffer<_OutCharT>::__iterator>) {
0109     __out_it.__buffer_->__copy(__str);
0110     return __out_it;
0111   } else {
0112     return std::ranges::copy(__str, std::move(__out_it)).out;
0113   }
0114 }
0115
0116 template <contiguous_iterator _Iterator,
0117           __fmt_char_type _CharT    = typename iterator_traits<_Iterator>::value_type,
0118           __fmt_char_type _OutCharT = _CharT>
0119 _LIBCPP_HIDE_FROM_ABI auto
0120 __copy(_Iterator __first, _Iterator __last, output_iterator<const _OutCharT&> auto __out_it) -> decltype(__out_it) {
0121   return __formatter::__copy(basic_string_view{__first, __last}, std::move(__out_it));
0122 }
0123
0124 template <contiguous_iterator _Iterator,
0125           __fmt_char_type _CharT    = typename iterator_traits<_Iterator>::value_type,
0126           __fmt_char_type _OutCharT = _CharT>
0127 _LIBCPP_HIDE_FROM_ABI auto
0128 __copy(_Iterator __first, size_t __n, output_iterator<const _OutCharT&> auto __out_it) -> decltype(__out_it) {
0129   return __formatter::__copy(basic_string_view{std::to_address(__first), __n}, std::move(__out_it));
0130 }
0131
0132 /// Transform wrapper.
0133 ///
0134 /// This uses a "mass output function" of __format::__output_buffer when possible.
0135 template <contiguous_iterator _Iterator,
0136           __fmt_char_type _CharT    = typename iterator_traits<_Iterator>::value_type,
0137           __fmt_char_type _OutCharT = _CharT,
0138           class _UnaryOperation>
0139 _LIBCPP_HIDE_FROM_ABI auto
0140 __transform(_Iterator __first,
0141             _Iterator __last,
0142             output_iterator<const _OutCharT&> auto __out_it,
0143             _UnaryOperation __operation) -> decltype(__out_it) {
0144   if constexpr (std::same_as<decltype(__out_it), std::back_insert_iterator<__format::__output_buffer<_OutCharT>>>) {
0145     __out_it.__get_container()->__transform(__first, __last, std::move(__operation));
0146     return __out_it;
0147   } else if constexpr (std::same_as<decltype(__out_it), typename __format::__retarget_buffer<_OutCharT>::__iterator>) {
0148     __out_it.__buffer_->__transform(__first, __last, std::move(__operation));
0149     return __out_it;
0150   } else {
0151     return std::ranges::transform(__first, __last, std::move(__out_it), __operation).out;
0152   }
0153 }
0154
0155 /// Fill wrapper.
0156 ///
0157 /// This uses a "mass output function" of __format::__output_buffer when possible.
0158 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
0159 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, _CharT __value) {
0160   if constexpr (std::same_as<decltype(__out_it), std::back_insert_iterator<__format::__output_buffer<_CharT>>>) {
0161     __out_it.__get_container()->__fill(__n, __value);
0162     return __out_it;
0163   } else if constexpr (std::same_as<decltype(__out_it), typename __format::__retarget_buffer<_CharT>::__iterator>) {
0164     __out_it.__buffer_->__fill(__n, __value);
0165     return __out_it;
0166   } else {
0167     return std::ranges::fill_n(std::move(__out_it), __n, __value);
0168   }
0169 }
0170
0171 #  ifndef _LIBCPP_HAS_NO_UNICODE
0172 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
0173   requires(same_as<_CharT, char>)
0174 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
0175   std::size_t __bytes = std::countl_one(static_cast<unsigned char>(__value.__data[0]));
0176   if (__bytes == 0)
0177     return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
0178
0179   for (size_t __i = 0; __i < __n; ++__i)
0180     __out_it = __formatter::__copy(
0181         std::addressof(__value.__data[0]), std::addressof(__value.__data[0]) + __bytes, std::move(__out_it));
0182   return __out_it;
0183 }
0184
0185 #    ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
0186 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
0187   requires(same_as<_CharT, wchar_t> && sizeof(wchar_t) == 2)
0188 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
0189   if (!__unicode::__is_high_surrogate(__value.__data[0]))
0190     return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
0191
0192   for (size_t __i = 0; __i < __n; ++__i)
0193     __out_it = __formatter::__copy(
0194         std::addressof(__value.__data[0]), std::addressof(__value.__data[0]) + 2, std::move(__out_it));
0195   return __out_it;
0196 }
0197
0198 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
0199   requires(same_as<_CharT, wchar_t> && sizeof(wchar_t) == 4)
0200 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
0201   return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
0202 }
0203 #    endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
0204 #  else    // _LIBCPP_HAS_NO_UNICODE
0205 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
0206 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
0207   return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
0208 }
0209 #  endif   // _LIBCPP_HAS_NO_UNICODE
0210
0211 /// Writes the input to the output with the required padding.
0212 ///
0213 /// Since the output column width is specified the function can be used for
0214 /// ASCII and Unicode output.
0215 ///
0216 /// \pre \a __size <= \a __width. Using this function when this pre-condition
0217 ///      doesn't hold incurs an unwanted overhead.
0218 ///
0219 /// \param __str       The string to write.
0220 /// \param __out_it    The output iterator to write to.
0221 /// \param __specs     The parsed formatting specifications.
0222 /// \param __size      The (estimated) output column width. When the elements
0223 ///                    to be written are ASCII the following condition holds
0224 ///                    \a __size == \a __last - \a __first.
0225 ///
0226 /// \returns           An iterator pointing beyond the last element written.
0227 ///
0228 /// \note The type of the elements in range [\a __first, \a __last) can differ
0229 /// from the type of \a __specs. Integer output uses \c std::to_chars for its
0230 /// conversion, which means the [\a __first, \a __last) always contains elements
0231 /// of the type \c char.
0232 template <class _CharT, class _ParserCharT>
0233 _LIBCPP_HIDE_FROM_ABI auto
0234 __write(basic_string_view<_CharT> __str,
0235         output_iterator<const _CharT&> auto __out_it,
0236         __format_spec::__parsed_specifications<_ParserCharT> __specs,
0237         ptrdiff_t __size) -> decltype(__out_it) {
0238   if (__size >= __specs.__width_)
0239     return __formatter::__copy(__str, std::move(__out_it));
0240
0241   __padding_size_result __padding = __formatter::__padding_size(__size, __specs.__width_, __specs.__std_.__alignment_);
0242   __out_it                        = __formatter::__fill(std::move(__out_it), __padding.__before_, __specs.__fill_);
0243   __out_it                        = __formatter::__copy(__str, std::move(__out_it));
0244   return __formatter::__fill(std::move(__out_it), __padding.__after_, __specs.__fill_);
0245 }
0246
0247 template <contiguous_iterator _Iterator, class _ParserCharT>
0248 _LIBCPP_HIDE_FROM_ABI auto
0249 __write(_Iterator __first,
0250         _Iterator __last,
0251         output_iterator<const iter_value_t<_Iterator>&> auto __out_it,
0252         __format_spec::__parsed_specifications<_ParserCharT> __specs,
0253         ptrdiff_t __size) -> decltype(__out_it) {
0254   _LIBCPP_ASSERT_VALID_INPUT_RANGE(__first <= __last, "Not a valid range");
0255   return __formatter::__write(basic_string_view{__first, __last}, std::move(__out_it), __specs, __size);
0256 }
0257
0258 /// \overload
0259 ///
0260 /// Calls the function above where \a __size = \a __last - \a __first.
0261 template <contiguous_iterator _Iterator, class _ParserCharT>
0262 _LIBCPP_HIDE_FROM_ABI auto
0263 __write(_Iterator __first,
0264         _Iterator __last,
0265         output_iterator<const iter_value_t<_Iterator>&> auto __out_it,
0266         __format_spec::__parsed_specifications<_ParserCharT> __specs) -> decltype(__out_it) {
0267   _LIBCPP_ASSERT_VALID_INPUT_RANGE(__first <= __last, "Not a valid range");
0268   return __formatter::__write(__first, __last, std::move(__out_it), __specs, __last - __first);
0269 }
0270
0271 template <contiguous_iterator _Iterator,
0272           class _CharT = typename iterator_traits<_Iterator>::value_type,
0273           class _ParserCharT,
0274           class _UnaryOperation>
0275 _LIBCPP_HIDE_FROM_ABI auto __write_transformed(
0276     _Iterator __first,
0277     _Iterator __last,
0278     output_iterator<const _CharT&> auto __out_it,
0279     __format_spec::__parsed_specifications<_ParserCharT> __specs,
0280     _UnaryOperation __op) -> decltype(__out_it) {
0281   _LIBCPP_ASSERT_VALID_INPUT_RANGE(__first <= __last, "Not a valid range");
0282
0283   ptrdiff_t __size = __last - __first;
0284   if (__size >= __specs.__width_)
0285     return __formatter::__transform(__first, __last, std::move(__out_it), __op);
0286
0287   __padding_size_result __padding = __formatter::__padding_size(__size, __specs.__width_, __specs.__alignment_);
0288   __out_it                        = __formatter::__fill(std::move(__out_it), __padding.__before_, __specs.__fill_);
0289   __out_it                        = __formatter::__transform(__first, __last, std::move(__out_it), __op);
0290   return __formatter::__fill(std::move(__out_it), __padding.__after_, __specs.__fill_);
0291 }
0292
0293 /// Writes a string using format's width estimation algorithm.
0294 ///
0295 /// \pre !__specs.__has_precision()
0296 ///
0297 /// \note When \c _LIBCPP_HAS_NO_UNICODE is defined the function assumes the
0298 /// 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___CXX03___FORMAT_FORMATTER_OUTPUT_H