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