1 // __ _____ _____ _____ 2 // __| | __| | | | JSON for Modern C++ 3 // | | |__ | | | | | | version 3.11.2 4 // |_____|_____|_____|_|___| https://github.com/nlohmann/json 5 // 6 // SPDX-FileCopyrightText: 2013-2022 Niels Lohmann <https://nlohmann.me> 7 // SPDX-License-Identifier: MIT 8 9 #pragma once 10 11 #include <cstddef> // ptrdiff_t 12 #include <iterator> // reverse_iterator 13 #include <utility> // declval 14 15 #include <nlohmann/detail/abi_macros.hpp> 16 17 NLOHMANN_JSON_NAMESPACE_BEGIN 18 namespace detail 19 { 20 21 ////////////////////// 22 // reverse_iterator // 23 ////////////////////// 24 25 /*! 26 @brief a template for a reverse iterator class 27 28 @tparam Base the base iterator type to reverse. Valid types are @ref 29 iterator (to create @ref reverse_iterator) and @ref const_iterator (to 30 create @ref const_reverse_iterator). 31 32 @requirement The class satisfies the following concept requirements: 33 - 34 [BidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator): 35 The iterator that can be moved can be moved in both directions (i.e. 36 incremented and decremented). 37 - [OutputIterator](https://en.cppreference.com/w/cpp/named_req/OutputIterator): 38 It is possible to write to the pointed-to element (only if @a Base is 39 @ref iterator). 40 41 @since version 1.0.0 42 */ 43 template<typename Base> 44 class json_reverse_iterator : public std::reverse_iterator<Base> 45 { 46 public: 47 using difference_type = std::ptrdiff_t; 48 /// shortcut to the reverse iterator adapter 49 using base_iterator = std::reverse_iterator<Base>; 50 /// the reference type for the pointed-to element 51 using reference = typename Base::reference; 52 53 /// create reverse iterator from iterator json_reverse_iterator(const typename base_iterator::iterator_type & it)54 explicit json_reverse_iterator(const typename base_iterator::iterator_type& it) noexcept 55 : base_iterator(it) {} 56 57 /// create reverse iterator from base class json_reverse_iterator(const base_iterator & it)58 explicit json_reverse_iterator(const base_iterator& it) noexcept : base_iterator(it) {} 59 60 /// post-increment (it++) operator ++(int)61 json_reverse_iterator operator++(int)& // NOLINT(cert-dcl21-cpp) 62 { 63 return static_cast<json_reverse_iterator>(base_iterator::operator++(1)); 64 } 65 66 /// pre-increment (++it) operator ++()67 json_reverse_iterator& operator++() 68 { 69 return static_cast<json_reverse_iterator&>(base_iterator::operator++()); 70 } 71 72 /// post-decrement (it--) operator --(int)73 json_reverse_iterator operator--(int)& // NOLINT(cert-dcl21-cpp) 74 { 75 return static_cast<json_reverse_iterator>(base_iterator::operator--(1)); 76 } 77 78 /// pre-decrement (--it) operator --()79 json_reverse_iterator& operator--() 80 { 81 return static_cast<json_reverse_iterator&>(base_iterator::operator--()); 82 } 83 84 /// add to iterator operator +=(difference_type i)85 json_reverse_iterator& operator+=(difference_type i) 86 { 87 return static_cast<json_reverse_iterator&>(base_iterator::operator+=(i)); 88 } 89 90 /// add to iterator operator +(difference_type i) const91 json_reverse_iterator operator+(difference_type i) const 92 { 93 return static_cast<json_reverse_iterator>(base_iterator::operator+(i)); 94 } 95 96 /// subtract from iterator operator -(difference_type i) const97 json_reverse_iterator operator-(difference_type i) const 98 { 99 return static_cast<json_reverse_iterator>(base_iterator::operator-(i)); 100 } 101 102 /// return difference operator -(const json_reverse_iterator & other) const103 difference_type operator-(const json_reverse_iterator& other) const 104 { 105 return base_iterator(*this) - base_iterator(other); 106 } 107 108 /// access to successor operator [](difference_type n) const109 reference operator[](difference_type n) const 110 { 111 return *(this->operator+(n)); 112 } 113 114 /// return the key of an object iterator key() const115 auto key() const -> decltype(std::declval<Base>().key()) 116 { 117 auto it = --this->base(); 118 return it.key(); 119 } 120 121 /// return the value of an iterator value() const122 reference value() const 123 { 124 auto it = --this->base(); 125 return it.operator * (); 126 } 127 }; 128 129 } // namespace detail 130 NLOHMANN_JSON_NAMESPACE_END 131