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_PARSE_CONTEXT_H 11 #define _LIBCPP___FORMAT_FORMAT_PARSE_CONTEXT_H 12 13 #include <__config> 14 #include <__format/format_error.h> 15 #include <__type_traits/is_constant_evaluated.h> 16 #include <string_view> 17 18 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 19 # pragma GCC system_header 20 #endif 21 22 _LIBCPP_BEGIN_NAMESPACE_STD 23 24 #if _LIBCPP_STD_VER >= 20 25 26 template <class _CharT> 27 class _LIBCPP_TEMPLATE_VIS basic_format_parse_context { 28 public: 29 using char_type = _CharT; 30 using const_iterator = typename basic_string_view<_CharT>::const_iterator; 31 using iterator = const_iterator; 32 33 _LIBCPP_HIDE_FROM_ABI constexpr explicit basic_format_parse_context( 34 basic_string_view<_CharT> __fmt, size_t __num_args = 0) noexcept 35 : __begin_(__fmt.begin()), 36 __end_(__fmt.end()), 37 __indexing_(__unknown), 38 __next_arg_id_(0), 39 __num_args_(__num_args) {} 40 41 basic_format_parse_context(const basic_format_parse_context&) = delete; 42 basic_format_parse_context& operator=(const basic_format_parse_context&) = delete; 43 44 _LIBCPP_HIDE_FROM_ABI constexpr const_iterator begin() const noexcept { return __begin_; } 45 _LIBCPP_HIDE_FROM_ABI constexpr const_iterator end() const noexcept { return __end_; } 46 _LIBCPP_HIDE_FROM_ABI constexpr void advance_to(const_iterator __it) { __begin_ = __it; } 47 48 _LIBCPP_HIDE_FROM_ABI constexpr size_t next_arg_id() { 49 if (__indexing_ == __manual) 50 std::__throw_format_error("Using automatic argument numbering in manual argument numbering mode"); 51 52 if (__indexing_ == __unknown) 53 __indexing_ = __automatic; 54 55 // Throws an exception to make the expression a non core constant 56 // expression as required by: 57 // [format.parse.ctx]/8 58 // Remarks: Let cur-arg-id be the value of next_arg_id_ prior to this 59 // call. Call expressions where cur-arg-id >= num_args_ is true are not 60 // core constant expressions (7.7 [expr.const]). 61 // Note: the Throws clause [format.parse.ctx]/9 doesn't specify the 62 // behavior when id >= num_args_. 63 if (is_constant_evaluated() && __next_arg_id_ >= __num_args_) 64 std::__throw_format_error("Argument index outside the valid range"); 65 66 return __next_arg_id_++; 67 } 68 _LIBCPP_HIDE_FROM_ABI constexpr void check_arg_id(size_t __id) { 69 if (__indexing_ == __automatic) 70 std::__throw_format_error("Using manual argument numbering in automatic argument numbering mode"); 71 72 if (__indexing_ == __unknown) 73 __indexing_ = __manual; 74 75 // Throws an exception to make the expression a non core constant 76 // expression as required by: 77 // [format.parse.ctx]/11 78 // Remarks: Call expressions where id >= num_args_ are not core constant 79 // expressions ([expr.const]). 80 // Note: the Throws clause [format.parse.ctx]/10 doesn't specify the 81 // behavior when id >= num_args_. 82 if (is_constant_evaluated() && __id >= __num_args_) 83 std::__throw_format_error("Argument index outside the valid range"); 84 } 85 86 private: 87 iterator __begin_; 88 iterator __end_; 89 enum _Indexing { __unknown, __manual, __automatic }; 90 _Indexing __indexing_; 91 size_t __next_arg_id_; 92 size_t __num_args_; 93 }; 94 _LIBCPP_CTAD_SUPPORTED_FOR_TYPE(basic_format_parse_context); 95 96 using format_parse_context = basic_format_parse_context<char>; 97 # ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS 98 using wformat_parse_context = basic_format_parse_context<wchar_t>; 99 # endif 100 101 #endif //_LIBCPP_STD_VER >= 20 102 103 _LIBCPP_END_NAMESPACE_STD 104 105 #endif // _LIBCPP___FORMAT_FORMAT_PARSE_CONTEXT_H 106