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 <__config> 14 #include <__format/format_error.h> 15 #include <__format/format_fwd.h> 16 #include <__format/format_string.h> 17 #include <__format/formatter.h> 18 #include <__format/parser_std_format_spec.h> 19 #include <string_view> 20 21 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 22 #pragma GCC system_header 23 #endif 24 25 _LIBCPP_PUSH_MACROS 26 #include <__undef_macros> 27 28 _LIBCPP_BEGIN_NAMESPACE_STD 29 30 #if _LIBCPP_STD_VER > 17 31 32 // TODO FMT Remove this once we require compilers with proper C++20 support. 33 // If the compiler has no concepts support, the format header will be disabled. 34 // Without concepts support enable_if needs to be used and that too much effort 35 // to support compilers with partial C++20 support. 36 #if !defined(_LIBCPP_HAS_NO_CONCEPTS) 37 38 namespace __format_spec { 39 40 template <__formatter::__char_type _CharT> 41 class _LIBCPP_TEMPLATE_VIS __formatter_string : public __parser_string<_CharT> { 42 public: 43 _LIBCPP_HIDE_FROM_ABI auto format(basic_string_view<_CharT> __str, 44 auto& __ctx) -> decltype(__ctx.out()) { 45 46 _LIBCPP_ASSERT(this->__alignment != _Flags::_Alignment::__default, 47 "The parser should not use these defaults"); 48 49 if (this->__width_needs_substitution()) 50 this->__substitute_width_arg_id(__ctx.arg(this->__width)); 51 52 if (this->__precision_needs_substitution()) 53 this->__substitute_precision_arg_id(__ctx.arg(this->__precision)); 54 55 return __formatter::__write_unicode( 56 __ctx.out(), __str, this->__width, 57 this->__has_precision_field() ? this->__precision : -1, this->__fill, 58 this->__alignment); 59 } 60 }; 61 62 } //namespace __format_spec 63 64 // [format.formatter.spec]/2.2 For each charT, the string type specializations 65 66 // Formatter const char*. 67 template <__formatter::__char_type _CharT> 68 struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT 69 formatter<const _CharT*, _CharT> 70 : public __format_spec::__formatter_string<_CharT> { 71 using _Base = __format_spec::__formatter_string<_CharT>; 72 73 _LIBCPP_HIDE_FROM_ABI auto format(const _CharT* __str, auto& __ctx) 74 -> decltype(__ctx.out()) { 75 _LIBCPP_ASSERT(__str, "The basic_format_arg constructor should have " 76 "prevented an invalid pointer."); 77 78 // When using a center or right alignment and the width option the length 79 // of __str must be known to add the padding upfront. This case is handled 80 // by the base class by converting the argument to a basic_string_view. 81 // 82 // When using left alignment and the width option the padding is added 83 // after outputting __str so the length can be determined while outputting 84 // __str. The same holds true for the precision, during outputting __str it 85 // can be validated whether the precision threshold has been reached. For 86 // now these optimizations aren't implemented. Instead the base class 87 // handles these options. 88 // TODO FMT Implement these improvements. 89 if (this->__has_width_field() || this->__has_precision_field()) 90 return _Base::format(__str, __ctx); 91 92 // No formatting required, copy the string to the output. 93 auto __out_it = __ctx.out(); 94 while (*__str) 95 *__out_it++ = *__str++; 96 return __out_it; 97 } 98 }; 99 100 // Formatter char*. 101 template <__formatter::__char_type _CharT> 102 struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT 103 formatter<_CharT*, _CharT> : public formatter<const _CharT*, _CharT> { 104 using _Base = formatter<const _CharT*, _CharT>; 105 106 _LIBCPP_HIDE_FROM_ABI auto format(_CharT* __str, auto& __ctx) 107 -> decltype(__ctx.out()) { 108 return _Base::format(__str, __ctx); 109 } 110 }; 111 112 // Formatter const char[]. 113 template <__formatter::__char_type _CharT, size_t _Size> 114 struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT 115 formatter<const _CharT[_Size], _CharT> 116 : public __format_spec::__formatter_string<_CharT> { 117 using _Base = __format_spec::__formatter_string<_CharT>; 118 119 _LIBCPP_HIDE_FROM_ABI auto format(const _CharT __str[_Size], auto& __ctx) 120 -> decltype(__ctx.out()) { 121 return _Base::format(basic_string_view<_CharT>(__str, _Size), __ctx); 122 } 123 }; 124 125 // Formatter std::string. 126 template <__formatter::__char_type _CharT, class _Traits, class _Allocator> 127 struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT 128 formatter<basic_string<_CharT, _Traits, _Allocator>, _CharT> 129 : public __format_spec::__formatter_string<_CharT> { 130 using _Base = __format_spec::__formatter_string<_CharT>; 131 132 _LIBCPP_HIDE_FROM_ABI auto 133 format(const basic_string<_CharT, _Traits, _Allocator>& __str, auto& __ctx) 134 -> decltype(__ctx.out()) { 135 // drop _Traits and _Allocator 136 return _Base::format(basic_string_view<_CharT>(__str.data(), __str.size()), __ctx); 137 } 138 }; 139 140 // Formatter std::string_view. 141 template <__formatter::__char_type _CharT, class _Traits> 142 struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT formatter<basic_string_view<_CharT, _Traits>, _CharT> 143 : public __format_spec::__formatter_string<_CharT> { 144 using _Base = __format_spec::__formatter_string<_CharT>; 145 146 _LIBCPP_HIDE_FROM_ABI auto 147 format(basic_string_view<_CharT, _Traits> __str, auto& __ctx) 148 -> decltype(__ctx.out()) { 149 // drop _Traits 150 return _Base::format(basic_string_view<_CharT>(__str.data(), __str.size()), __ctx); 151 } 152 }; 153 154 #endif // !defined(_LIBCPP_HAS_NO_CONCEPTS) 155 156 #endif //_LIBCPP_STD_VER > 17 157 158 _LIBCPP_END_NAMESPACE_STD 159 160 _LIBCPP_POP_MACROS 161 162 #endif // _LIBCPP___FORMAT_FORMATTER_STRING_H 163