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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-exception7//8//===----------------------------------------------------------------------===//9 10#ifndef _LIBCPP___FORMAT_RANGE_FORMATTER_H11#define _LIBCPP___FORMAT_RANGE_FORMATTER_H12 13#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)14# pragma GCC system_header15#endif16 17#include <__algorithm/ranges_copy.h>18#include <__chrono/statically_widen.h>19#include <__concepts/same_as.h>20#include <__config>21#include <__format/buffer.h>22#include <__format/concepts.h>23#include <__format/fmt_pair_like.h>24#include <__format/format_context.h>25#include <__format/format_error.h>26#include <__format/formatter.h>27#include <__format/formatter_output.h>28#include <__format/parser_std_format_spec.h>29#include <__iterator/back_insert_iterator.h>30#include <__ranges/concepts.h>31#include <__ranges/data.h>32#include <__ranges/from_range.h>33#include <__ranges/size.h>34#include <__type_traits/remove_cvref.h>35#include <string_view>36 37_LIBCPP_BEGIN_NAMESPACE_STD38 39#if _LIBCPP_STD_VER >= 2340 41template <class _Tp, class _CharT = char>42 requires same_as<remove_cvref_t<_Tp>, _Tp> && formattable<_Tp, _CharT>43struct range_formatter {44 _LIBCPP_HIDE_FROM_ABI constexpr void set_separator(basic_string_view<_CharT> __separator) noexcept {45 __separator_ = __separator;46 }47 _LIBCPP_HIDE_FROM_ABI constexpr void48 set_brackets(basic_string_view<_CharT> __opening_bracket, basic_string_view<_CharT> __closing_bracket) noexcept {49 __opening_bracket_ = __opening_bracket;50 __closing_bracket_ = __closing_bracket;51 }52 53 _LIBCPP_HIDE_FROM_ABI constexpr formatter<_Tp, _CharT>& underlying() noexcept { return __underlying_; }54 _LIBCPP_HIDE_FROM_ABI constexpr const formatter<_Tp, _CharT>& underlying() const noexcept { return __underlying_; }55 56 template <class _ParseContext>57 _LIBCPP_HIDE_FROM_ABI constexpr typename _ParseContext::iterator parse(_ParseContext& __ctx) {58 auto __begin = __parser_.__parse(__ctx, __format_spec::__fields_range);59 auto __end = __ctx.end();60 // Note the cases where __begin == __end in this code only happens when the61 // replacement-field has no terminating }, or when the parse is manually62 // called with a format-spec. The former is an error and the latter means63 // using a formatter without the format functions or print.64 if (__begin == __end) [[unlikely]]65 return __parse_empty_range_underlying_spec(__ctx, __begin);66 67 // The n field overrides a possible m type, therefore delay applying the68 // effect of n until the type has been procesed.69 __parse_type(__begin, __end);70 if (__parser_.__clear_brackets_)71 set_brackets({}, {});72 if (__begin == __end) [[unlikely]]73 return __parse_empty_range_underlying_spec(__ctx, __begin);74 75 bool __has_range_underlying_spec = *__begin == _CharT(':');76 if (__has_range_underlying_spec) {77 // range-underlying-spec:78 // : format-spec79 ++__begin;80 } else if (__begin != __end && *__begin != _CharT('}'))81 // When there is no underlaying range the current parse should have82 // consumed the format-spec. If not, the not consumed input will be83 // processed by the underlying. For example {:-} for a range in invalid,84 // the sign field is not present. Without this check the underlying_ will85 // get -} as input which my be valid.86 std::__throw_format_error("The format specifier should consume the input or end with a '}'");87 88 __ctx.advance_to(__begin);89 __begin = __underlying_.parse(__ctx);90 91 // This test should not be required if __has_range_underlying_spec is false.92 // However this test makes sure the underlying formatter left the parser in93 // a valid state. (Note this is not a full protection against evil parsers.94 // For example95 // } this is test for the next argument {}96 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^97 // could consume more than it should.98 if (__begin != __end && *__begin != _CharT('}'))99 std::__throw_format_error("The format specifier should consume the input or end with a '}'");100 101 if (__parser_.__type_ != __format_spec::__type::__default) {102 // [format.range.formatter]/6103 // If the range-type is s or ?s, then there shall be no n option and no104 // range-underlying-spec.105 if (__parser_.__clear_brackets_) {106 if (__parser_.__type_ == __format_spec::__type::__string)107 std::__throw_format_error("The n option and type s can't be used together");108 std::__throw_format_error("The n option and type ?s can't be used together");109 }110 if (__has_range_underlying_spec) {111 if (__parser_.__type_ == __format_spec::__type::__string)112 std::__throw_format_error("Type s and an underlying format specification can't be used together");113 std::__throw_format_error("Type ?s and an underlying format specification can't be used together");114 }115 } else if (!__has_range_underlying_spec)116 std::__set_debug_format(__underlying_);117 118 return __begin;119 }120 121 template <ranges::input_range _Rp, class _FormatContext>122 requires formattable<ranges::range_reference_t<_Rp>, _CharT> &&123 same_as<remove_cvref_t<ranges::range_reference_t<_Rp>>, _Tp>124 _LIBCPP_HIDE_FROM_ABI typename _FormatContext::iterator format(_Rp&& __range, _FormatContext& __ctx) const {125 __format_spec::__parsed_specifications<_CharT> __specs = __parser_.__get_parsed_std_specifications(__ctx);126 127 if (!__specs.__has_width())128 return __format_range(__range, __ctx, __specs);129 130 // The size of the buffer needed is:131 // - open bracket characters132 // - close bracket character133 // - n elements where every element may have a different size134 // - (n -1) separators135 // The size of the element is hard to predict, knowing the type helps but136 // it depends on the format-spec. As an initial estimate we guess 6137 // characters.138 // Typically both brackets are 1 character and the separator is 2139 // characters. Which means there will be140 // (n - 1) * 2 + 1 + 1 = n * 2 character141 // So estimate 8 times the range size as buffer.142 std::size_t __capacity_hint = 0;143 if constexpr (std::ranges::sized_range<_Rp>)144 __capacity_hint = 8 * ranges::size(__range);145 __format::__retarget_buffer<_CharT> __buffer{__capacity_hint};146 basic_format_context<typename __format::__retarget_buffer<_CharT>::__iterator, _CharT> __c{147 __buffer.__make_output_iterator(), __ctx};148 149 __format_range(__range, __c, __specs);150 151 return __formatter::__write_string_no_precision(__buffer.__view(), __ctx.out(), __specs);152 }153 154 template <ranges::input_range _Rp, class _FormatContext>155 typename _FormatContext::iterator _LIBCPP_HIDE_FROM_ABI156 __format_range(_Rp&& __range, _FormatContext& __ctx, __format_spec::__parsed_specifications<_CharT> __specs) const {157 if constexpr (same_as<_Tp, _CharT>) {158 switch (__specs.__std_.__type_) {159 case __format_spec::__type::__string:160 case __format_spec::__type::__debug:161 return __format_as_string(__range, __ctx, __specs.__std_.__type_ == __format_spec::__type::__debug);162 default:163 return __format_as_sequence(__range, __ctx);164 }165 } else166 return __format_as_sequence(__range, __ctx);167 }168 169 template <ranges::input_range _Rp, class _FormatContext>170 _LIBCPP_HIDE_FROM_ABI typename _FormatContext::iterator171 __format_as_string(_Rp&& __range, _FormatContext& __ctx, bool __debug_format) const {172 // When the range is contiguous use a basic_string_view instead to avoid a173 // copy of the underlying data. The basic_string_view formatter174 // specialization is the "basic" string formatter in libc++.175 if constexpr (ranges::contiguous_range<_Rp> && std::ranges::sized_range<_Rp>) {176 std::formatter<basic_string_view<_CharT>, _CharT> __formatter;177 if (__debug_format)178 __formatter.set_debug_format();179 return __formatter.format(180 basic_string_view<_CharT>{181 ranges::data(__range),182 ranges::size(__range),183 },184 __ctx);185 } else {186 std::formatter<basic_string<_CharT>, _CharT> __formatter;187 if (__debug_format)188 __formatter.set_debug_format();189 return __formatter.format(basic_string<_CharT>{from_range, __range}, __ctx);190 }191 }192 193 template <ranges::input_range _Rp, class _FormatContext>194 _LIBCPP_HIDE_FROM_ABI typename _FormatContext::iterator195 __format_as_sequence(_Rp&& __range, _FormatContext& __ctx) const {196 __ctx.advance_to(ranges::copy(__opening_bracket_, __ctx.out()).out);197 bool __use_separator = false;198 for (auto&& __e : __range) {199 if (__use_separator)200 __ctx.advance_to(ranges::copy(__separator_, __ctx.out()).out);201 else202 __use_separator = true;203 204 __ctx.advance_to(__underlying_.format(__e, __ctx));205 }206 207 return ranges::copy(__closing_bracket_, __ctx.out()).out;208 }209 210 __format_spec::__parser<_CharT> __parser_{.__alignment_ = __format_spec::__alignment::__left};211 212private:213 template <contiguous_iterator _Iterator>214 _LIBCPP_HIDE_FROM_ABI constexpr void __parse_type(_Iterator& __begin, _Iterator __end) {215 switch (*__begin) {216 case _CharT('m'):217 if constexpr (__fmt_pair_like<_Tp>) {218 set_brackets(_LIBCPP_STATICALLY_WIDEN(_CharT, "{"), _LIBCPP_STATICALLY_WIDEN(_CharT, "}"));219 set_separator(_LIBCPP_STATICALLY_WIDEN(_CharT, ", "));220 ++__begin;221 } else222 std::__throw_format_error("Type m requires a pair or a tuple with two elements");223 break;224 225 case _CharT('s'):226 if constexpr (same_as<_Tp, _CharT>) {227 __parser_.__type_ = __format_spec::__type::__string;228 ++__begin;229 } else230 std::__throw_format_error("Type s requires character type as formatting argument");231 break;232 233 case _CharT('?'):234 ++__begin;235 if (__begin == __end || *__begin != _CharT('s'))236 std::__throw_format_error("The format specifier should consume the input or end with a '}'");237 if constexpr (same_as<_Tp, _CharT>) {238 __parser_.__type_ = __format_spec::__type::__debug;239 ++__begin;240 } else241 std::__throw_format_error("Type ?s requires character type as formatting argument");242 }243 }244 245 template <class _ParseContext>246 _LIBCPP_HIDE_FROM_ABI constexpr typename _ParseContext::iterator247 __parse_empty_range_underlying_spec(_ParseContext& __ctx, typename _ParseContext::iterator __begin) {248 __ctx.advance_to(__begin);249 [[maybe_unused]] typename _ParseContext::iterator __result = __underlying_.parse(__ctx);250 _LIBCPP_ASSERT_INTERNAL(__result == __begin,251 "the underlying's parse function should not advance the input beyond the end of the input");252 return __begin;253 }254 255 formatter<_Tp, _CharT> __underlying_;256 basic_string_view<_CharT> __separator_ = _LIBCPP_STATICALLY_WIDEN(_CharT, ", ");257 basic_string_view<_CharT> __opening_bracket_ = _LIBCPP_STATICALLY_WIDEN(_CharT, "[");258 basic_string_view<_CharT> __closing_bracket_ = _LIBCPP_STATICALLY_WIDEN(_CharT, "]");259};260 261#endif // _LIBCPP_STD_VER >= 23262 263_LIBCPP_END_NAMESPACE_STD264 265#endif // _LIBCPP___FORMAT_RANGE_FORMATTER_H266