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_FORMAT_CONTEXT_H 11 #define _LIBCPP___FORMAT_FORMAT_CONTEXT_H 12 13 #include <__availability> 14 #include <__config> 15 #include <__format/format_args.h> 16 #include <__format/format_fwd.h> 17 #include <__iterator/back_insert_iterator.h> 18 #include <__iterator/concepts.h> 19 #include <concepts> 20 21 #ifndef _LIBCPP_HAS_NO_LOCALIZATION 22 #include <locale> 23 #include <optional> 24 #endif 25 26 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 27 # pragma GCC system_header 28 #endif 29 30 _LIBCPP_BEGIN_NAMESPACE_STD 31 32 #if _LIBCPP_STD_VER > 17 33 34 template <class _OutIt, class _CharT> 35 requires output_iterator<_OutIt, const _CharT&> 36 class _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT basic_format_context; 37 38 #ifndef _LIBCPP_HAS_NO_LOCALIZATION 39 /** 40 * Helper to create a basic_format_context. 41 * 42 * This is needed since the constructor is private. 43 */ 44 template <class _OutIt, class _CharT> 45 _LIBCPP_HIDE_FROM_ABI basic_format_context<_OutIt, _CharT> 46 __format_context_create( 47 _OutIt __out_it, 48 basic_format_args<basic_format_context<_OutIt, _CharT>> __args, 49 optional<_VSTD::locale>&& __loc = nullopt) { 50 return _VSTD::basic_format_context(_VSTD::move(__out_it), __args, 51 _VSTD::move(__loc)); 52 } 53 #else 54 template <class _OutIt, class _CharT> 55 _LIBCPP_HIDE_FROM_ABI basic_format_context<_OutIt, _CharT> 56 __format_context_create( 57 _OutIt __out_it, 58 basic_format_args<basic_format_context<_OutIt, _CharT>> __args) { 59 return _VSTD::basic_format_context(_VSTD::move(__out_it), __args); 60 } 61 #endif 62 63 // TODO FMT Implement [format.context]/4 64 // [Note 1: For a given type charT, implementations are encouraged to provide a 65 // single instantiation of basic_format_context for appending to 66 // basic_string<charT>, vector<charT>, or any other container with contiguous 67 // storage by wrapping those in temporary objects with a uniform interface 68 // (such as a span<charT>) and polymorphic reallocation. - end note] 69 70 using format_context = basic_format_context<back_insert_iterator<string>, char>; 71 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS 72 using wformat_context = basic_format_context<back_insert_iterator<wstring>, wchar_t>; 73 #endif 74 75 template <class _OutIt, class _CharT> 76 requires output_iterator<_OutIt, const _CharT&> 77 class 78 // clang-format off 79 _LIBCPP_TEMPLATE_VIS 80 _LIBCPP_AVAILABILITY_FORMAT 81 _LIBCPP_PREFERRED_NAME(format_context) 82 _LIBCPP_IF_WIDE_CHARACTERS(_LIBCPP_PREFERRED_NAME(wformat_context)) 83 // clang-format on 84 basic_format_context { 85 public: 86 using iterator = _OutIt; 87 using char_type = _CharT; 88 template <class _Tp> 89 using formatter_type = formatter<_Tp, _CharT>; 90 91 basic_format_context(const basic_format_context&) = delete; 92 basic_format_context& operator=(const basic_format_context&) = delete; 93 94 _LIBCPP_HIDE_FROM_ABI basic_format_arg<basic_format_context> 95 arg(size_t __id) const noexcept { 96 return __args_.get(__id); 97 } 98 #ifndef _LIBCPP_HAS_NO_LOCALIZATION 99 _LIBCPP_HIDE_FROM_ABI _VSTD::locale locale() { 100 if (!__loc_) 101 __loc_ = _VSTD::locale{}; 102 return *__loc_; 103 } 104 #endif 105 _LIBCPP_HIDE_FROM_ABI iterator out() { return __out_it_; } 106 _LIBCPP_HIDE_FROM_ABI void advance_to(iterator __it) { __out_it_ = __it; } 107 108 private: 109 iterator __out_it_; 110 basic_format_args<basic_format_context> __args_; 111 #ifndef _LIBCPP_HAS_NO_LOCALIZATION 112 113 // The Standard doesn't specify how the locale is stored. 114 // [format.context]/6 115 // std::locale locale(); 116 // Returns: The locale passed to the formatting function if the latter 117 // takes one, and std::locale() otherwise. 118 // This is done by storing the locale of the constructor in this optional. If 119 // locale() is called and the optional has no value the value will be created. 120 // This allows the implementation to lazily create the locale. 121 // TODO FMT Validate whether lazy creation is the best solution. 122 optional<_VSTD::locale> __loc_; 123 124 template <class __OutIt, class __CharT> 125 friend _LIBCPP_HIDE_FROM_ABI basic_format_context<__OutIt, __CharT> 126 __format_context_create(__OutIt, basic_format_args<basic_format_context<__OutIt, __CharT>>, 127 optional<_VSTD::locale>&&); 128 129 // Note: the Standard doesn't specify the required constructors. 130 _LIBCPP_HIDE_FROM_ABI 131 explicit basic_format_context(_OutIt __out_it, 132 basic_format_args<basic_format_context> __args, 133 optional<_VSTD::locale>&& __loc) 134 : __out_it_(_VSTD::move(__out_it)), __args_(__args), 135 __loc_(_VSTD::move(__loc)) {} 136 #else 137 template <class __OutIt, class __CharT> 138 friend _LIBCPP_HIDE_FROM_ABI basic_format_context<__OutIt, __CharT> 139 __format_context_create(__OutIt, basic_format_args<basic_format_context<__OutIt, __CharT>>); 140 141 _LIBCPP_HIDE_FROM_ABI 142 explicit basic_format_context(_OutIt __out_it, 143 basic_format_args<basic_format_context> __args) 144 : __out_it_(_VSTD::move(__out_it)), __args_(__args) {} 145 #endif 146 }; 147 148 #endif //_LIBCPP_STD_VER > 17 149 150 _LIBCPP_END_NAMESPACE_STD 151 152 #endif // _LIBCPP___FORMAT_FORMAT_CONTEXT_H 153