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_TUPLE_H 11 #define _LIBCPP___FORMAT_FORMATTER_TUPLE_H 12 13 #include <__algorithm/ranges_copy.h> 14 #include <__chrono/statically_widen.h> 15 #include <__config> 16 #include <__format/buffer.h> 17 #include <__format/concepts.h> 18 #include <__format/format_context.h> 19 #include <__format/format_error.h> 20 #include <__format/format_parse_context.h> 21 #include <__format/formatter.h> 22 #include <__format/formatter_output.h> 23 #include <__format/parser_std_format_spec.h> 24 #include <__type_traits/remove_cvref.h> 25 #include <__utility/integer_sequence.h> 26 #include <__utility/pair.h> 27 #include <string_view> 28 #include <tuple> 29 30 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 31 # pragma GCC system_header 32 #endif 33 34 _LIBCPP_BEGIN_NAMESPACE_STD 35 36 #if _LIBCPP_STD_VER >= 23 37 38 template <__fmt_char_type _CharT, class _Tuple, formattable<_CharT>... _Args> 39 struct _LIBCPP_TEMPLATE_VIS __formatter_tuple { set_separator__formatter_tuple40 _LIBCPP_HIDE_FROM_ABI constexpr void set_separator(basic_string_view<_CharT> __separator) noexcept { 41 __separator_ = __separator; 42 } 43 _LIBCPP_HIDE_FROM_ABI constexpr void set_brackets__formatter_tuple44 set_brackets(basic_string_view<_CharT> __opening_bracket, basic_string_view<_CharT> __closing_bracket) noexcept { 45 __opening_bracket_ = __opening_bracket; 46 __closing_bracket_ = __closing_bracket; 47 } 48 49 template <class _ParseContext> parse__formatter_tuple50 _LIBCPP_HIDE_FROM_ABI constexpr typename _ParseContext::iterator parse(_ParseContext& __ctx) { 51 auto __begin = __parser_.__parse(__ctx, __format_spec::__fields_tuple); 52 53 auto __end = __ctx.end(); 54 // Note 'n' is part of the type here 55 if (__parser_.__clear_brackets_) 56 set_brackets({}, {}); 57 else if (__begin != __end && *__begin == _CharT('m')) { 58 if constexpr (sizeof...(_Args) == 2) { 59 set_separator(_LIBCPP_STATICALLY_WIDEN(_CharT, ": ")); 60 set_brackets({}, {}); 61 ++__begin; 62 } else 63 std::__throw_format_error("Type m requires a pair or a tuple with two elements"); 64 } 65 66 if (__begin != __end && *__begin != _CharT('}')) 67 std::__throw_format_error("The format specifier should consume the input or end with a '}'"); 68 69 __ctx.advance_to(__begin); 70 71 // [format.tuple]/7 72 // ... For each element e in underlying_, if e.set_debug_format() 73 // is a valid expression, calls e.set_debug_format(). 74 std::__for_each_index_sequence(make_index_sequence<sizeof...(_Args)>(), [&]<size_t _Index> { 75 auto& __formatter = std::get<_Index>(__underlying_); 76 __formatter.parse(__ctx); 77 // Unlike the range_formatter we don't guard against evil parsers. Since 78 // this format-spec never has a format-spec for the underlying type 79 // adding the test would give additional overhead. 80 std::__set_debug_format(__formatter); 81 }); 82 83 return __begin; 84 } 85 86 template <class _FormatContext> 87 typename _FormatContext::iterator _LIBCPP_HIDE_FROM_ABI format__formatter_tuple88 format(conditional_t<(formattable<const _Args, _CharT> && ...), const _Tuple&, _Tuple&> __tuple, 89 _FormatContext& __ctx) const { 90 __format_spec::__parsed_specifications<_CharT> __specs = __parser_.__get_parsed_std_specifications(__ctx); 91 92 if (!__specs.__has_width()) 93 return __format_tuple(__tuple, __ctx); 94 95 // The size of the buffer needed is: 96 // - open bracket characters 97 // - close bracket character 98 // - n elements where every element may have a different size 99 // - (n -1) separators 100 // The size of the element is hard to predict, knowing the type helps but 101 // it depends on the format-spec. As an initial estimate we guess 6 102 // characters. 103 // Typically both brackets are 1 character and the separator is 2 104 // characters. Which means there will be 105 // (n - 1) * 2 + 1 + 1 = n * 2 character 106 // So estimate 8 times the range size as buffer. 107 __format::__retarget_buffer<_CharT> __buffer{8 * tuple_size_v<_Tuple>}; 108 basic_format_context<typename __format::__retarget_buffer<_CharT>::__iterator, _CharT> __c{ 109 __buffer.__make_output_iterator(), __ctx}; 110 111 __format_tuple(__tuple, __c); 112 113 return __formatter::__write_string_no_precision(basic_string_view{__buffer.__view()}, __ctx.out(), __specs); 114 } 115 116 template <class _FormatContext> __format_tuple__formatter_tuple117 _LIBCPP_HIDE_FROM_ABI typename _FormatContext::iterator __format_tuple(auto&& __tuple, _FormatContext& __ctx) const { 118 __ctx.advance_to(std::ranges::copy(__opening_bracket_, __ctx.out()).out); 119 120 std::__for_each_index_sequence(make_index_sequence<sizeof...(_Args)>(), [&]<size_t _Index> { 121 if constexpr (_Index) 122 __ctx.advance_to(std::ranges::copy(__separator_, __ctx.out()).out); 123 __ctx.advance_to(std::get<_Index>(__underlying_).format(std::get<_Index>(__tuple), __ctx)); 124 }); 125 126 return std::ranges::copy(__closing_bracket_, __ctx.out()).out; 127 } 128 129 __format_spec::__parser<_CharT> __parser_{.__alignment_ = __format_spec::__alignment::__left}; 130 131 private: 132 tuple<formatter<remove_cvref_t<_Args>, _CharT>...> __underlying_; 133 basic_string_view<_CharT> __separator_ = _LIBCPP_STATICALLY_WIDEN(_CharT, ", "); 134 basic_string_view<_CharT> __opening_bracket_ = _LIBCPP_STATICALLY_WIDEN(_CharT, "("); 135 basic_string_view<_CharT> __closing_bracket_ = _LIBCPP_STATICALLY_WIDEN(_CharT, ")"); 136 }; 137 138 template <__fmt_char_type _CharT, formattable<_CharT>... _Args> 139 struct _LIBCPP_TEMPLATE_VIS formatter<pair<_Args...>, _CharT> 140 : public __formatter_tuple<_CharT, pair<_Args...>, _Args...> {}; 141 142 template <__fmt_char_type _CharT, formattable<_CharT>... _Args> 143 struct _LIBCPP_TEMPLATE_VIS formatter<tuple<_Args...>, _CharT> 144 : public __formatter_tuple<_CharT, tuple<_Args...>, _Args...> {}; 145 146 #endif //_LIBCPP_STD_VER >= 23 147 148 _LIBCPP_END_NAMESPACE_STD 149 150 #endif // _LIBCPP___FORMAT_FORMATTER_TUPLE_H 151