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_STRING_H 11 #define _LIBCPP___FORMAT_FORMATTER_STRING_H 12 13 #include <__assert> 14 #include <__config> 15 #include <__format/format_error.h> 16 #include <__format/format_fwd.h> 17 #include <__format/format_string.h> 18 #include <__format/formatter.h> 19 #include <__format/parser_std_format_spec.h> 20 #include <string_view> 21 22 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 23 # pragma GCC system_header 24 #endif 25 26 _LIBCPP_BEGIN_NAMESPACE_STD 27 28 #if _LIBCPP_STD_VER > 17 29 30 // TODO FMT Remove this once we require compilers with proper C++20 support. 31 // If the compiler has no concepts support, the format header will be disabled. 32 // Without concepts support enable_if needs to be used and that too much effort 33 // to support compilers with partial C++20 support. 34 #if !defined(_LIBCPP_HAS_NO_CONCEPTS) 35 36 namespace __format_spec { 37 38 template <__formatter::__char_type _CharT> 39 class _LIBCPP_TEMPLATE_VIS __formatter_string : public __parser_string<_CharT> { 40 public: 41 _LIBCPP_HIDE_FROM_ABI auto format(basic_string_view<_CharT> __str, 42 auto& __ctx) -> decltype(__ctx.out()) { 43 44 _LIBCPP_ASSERT(this->__alignment != _Flags::_Alignment::__default, 45 "The parser should not use these defaults"); 46 47 if (this->__width_needs_substitution()) 48 this->__substitute_width_arg_id(__ctx.arg(this->__width)); 49 50 if (this->__precision_needs_substitution()) 51 this->__substitute_precision_arg_id(__ctx.arg(this->__precision)); 52 53 return __formatter::__write_unicode( 54 __ctx.out(), __str, this->__width, 55 this->__has_precision_field() ? this->__precision : -1, this->__fill, 56 this->__alignment); 57 } 58 }; 59 60 } //namespace __format_spec 61 62 // [format.formatter.spec]/2.2 For each charT, the string type specializations 63 64 // Formatter const char*. 65 template <__formatter::__char_type _CharT> 66 struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT 67 formatter<const _CharT*, _CharT> 68 : public __format_spec::__formatter_string<_CharT> { 69 using _Base = __format_spec::__formatter_string<_CharT>; 70 71 _LIBCPP_HIDE_FROM_ABI auto format(const _CharT* __str, auto& __ctx) 72 -> decltype(__ctx.out()) { 73 _LIBCPP_ASSERT(__str, "The basic_format_arg constructor should have " 74 "prevented an invalid pointer."); 75 76 // When using a center or right alignment and the width option the length 77 // of __str must be known to add the padding upfront. This case is handled 78 // by the base class by converting the argument to a basic_string_view. 79 // 80 // When using left alignment and the width option the padding is added 81 // after outputting __str so the length can be determined while outputting 82 // __str. The same holds true for the precision, during outputting __str it 83 // can be validated whether the precision threshold has been reached. For 84 // now these optimizations aren't implemented. Instead the base class 85 // handles these options. 86 // TODO FMT Implement these improvements. 87 if (this->__has_width_field() || this->__has_precision_field()) 88 return _Base::format(__str, __ctx); 89 90 // No formatting required, copy the string to the output. 91 auto __out_it = __ctx.out(); 92 while (*__str) 93 *__out_it++ = *__str++; 94 return __out_it; 95 } 96 }; 97 98 // Formatter char*. 99 template <__formatter::__char_type _CharT> 100 struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT 101 formatter<_CharT*, _CharT> : public formatter<const _CharT*, _CharT> { 102 using _Base = formatter<const _CharT*, _CharT>; 103 104 _LIBCPP_HIDE_FROM_ABI auto format(_CharT* __str, auto& __ctx) 105 -> decltype(__ctx.out()) { 106 return _Base::format(__str, __ctx); 107 } 108 }; 109 110 // Formatter const char[]. 111 template <__formatter::__char_type _CharT, size_t _Size> 112 struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT 113 formatter<const _CharT[_Size], _CharT> 114 : public __format_spec::__formatter_string<_CharT> { 115 using _Base = __format_spec::__formatter_string<_CharT>; 116 117 _LIBCPP_HIDE_FROM_ABI auto format(const _CharT __str[_Size], auto& __ctx) 118 -> decltype(__ctx.out()) { 119 return _Base::format(basic_string_view<_CharT>(__str, _Size), __ctx); 120 } 121 }; 122 123 // Formatter std::string. 124 template <__formatter::__char_type _CharT, class _Traits, class _Allocator> 125 struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT 126 formatter<basic_string<_CharT, _Traits, _Allocator>, _CharT> 127 : public __format_spec::__formatter_string<_CharT> { 128 using _Base = __format_spec::__formatter_string<_CharT>; 129 130 _LIBCPP_HIDE_FROM_ABI auto 131 format(const basic_string<_CharT, _Traits, _Allocator>& __str, auto& __ctx) 132 -> decltype(__ctx.out()) { 133 // drop _Traits and _Allocator 134 return _Base::format(basic_string_view<_CharT>(__str.data(), __str.size()), __ctx); 135 } 136 }; 137 138 // Formatter std::string_view. 139 template <__formatter::__char_type _CharT, class _Traits> 140 struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT formatter<basic_string_view<_CharT, _Traits>, _CharT> 141 : public __format_spec::__formatter_string<_CharT> { 142 using _Base = __format_spec::__formatter_string<_CharT>; 143 144 _LIBCPP_HIDE_FROM_ABI auto 145 format(basic_string_view<_CharT, _Traits> __str, auto& __ctx) 146 -> decltype(__ctx.out()) { 147 // drop _Traits 148 return _Base::format(basic_string_view<_CharT>(__str.data(), __str.size()), __ctx); 149 } 150 }; 151 152 #endif // !defined(_LIBCPP_HAS_NO_CONCEPTS) 153 154 #endif //_LIBCPP_STD_VER > 17 155 156 _LIBCPP_END_NAMESPACE_STD 157 158 #endif // _LIBCPP___FORMAT_FORMATTER_STRING_H 159