diff --git a/src/json.hpp b/src/json.hpp index 1e75b5e2..7ecbe91d 100644 --- a/src/json.hpp +++ b/src/json.hpp @@ -4459,6 +4459,111 @@ template class iteration_proxy return iteration_proxy_internal(container.end()); } }; + +/*! +@brief a template for a reverse iterator class + +@tparam Base the base iterator type to reverse. Valid types are @ref +iterator (to create @ref reverse_iterator) and @ref const_iterator (to +create @ref const_reverse_iterator). + +@requirement The class satisfies the following concept requirements: +- +[RandomAccessIterator](http://en.cppreference.com/w/cpp/concept/RandomAccessIterator): + The iterator that can be moved to point (forward and backward) to any + element in constant time. +- [OutputIterator](http://en.cppreference.com/w/cpp/concept/OutputIterator): + It is possible to write to the pointed-to element (only if @a Base is + @ref iterator). + +@since version 1.0.0 +*/ +template +class json_reverse_iterator : public std::reverse_iterator +{ + public: + using difference_type = std::ptrdiff_t; + /// shortcut to the reverse iterator adaptor + using base_iterator = std::reverse_iterator; + /// the reference type for the pointed-to element + using reference = typename Base::reference; + + /// create reverse iterator from iterator + json_reverse_iterator( + const typename base_iterator::iterator_type& it) noexcept + : base_iterator(it) {} + + /// create reverse iterator from base class + json_reverse_iterator(const base_iterator& it) noexcept : base_iterator(it) {} + + /// post-increment (it++) + json_reverse_iterator operator++(int) + { + return static_cast(base_iterator::operator++(1)); + } + + /// pre-increment (++it) + json_reverse_iterator& operator++() + { + return static_cast(base_iterator::operator++()); + } + + /// post-decrement (it--) + json_reverse_iterator operator--(int) + { + return static_cast(base_iterator::operator--(1)); + } + + /// pre-decrement (--it) + json_reverse_iterator& operator--() + { + return static_cast(base_iterator::operator--()); + } + + /// add to iterator + json_reverse_iterator& operator+=(difference_type i) + { + return static_cast(base_iterator::operator+=(i)); + } + + /// add to iterator + json_reverse_iterator operator+(difference_type i) const + { + return static_cast(base_iterator::operator+(i)); + } + + /// subtract from iterator + json_reverse_iterator operator-(difference_type i) const + { + return static_cast(base_iterator::operator-(i)); + } + + /// return difference + difference_type operator-(const json_reverse_iterator& other) const + { + return base_iterator(*this) - base_iterator(other); + } + + /// access to successor + reference operator[](difference_type n) const + { + return *(this->operator+(n)); + } + + /// return the key of an object iterator + auto key() const -> decltype(std::declval().key()) + { + auto it = --this->base(); + return it.key(); + } + + /// return the value of an iterator + reference value() const + { + auto it = --this->base(); + return it.operator * (); + } +}; } // namespace detail /// namespace to hold default `to_json` / `from_json` functions @@ -4946,11 +5051,11 @@ class basic_json using iter_impl = ::nlohmann::detail::iter_impl; template using iteration_proxy = ::nlohmann::detail::iteration_proxy; + template using json_reverse_iterator = ::nlohmann::detail::json_reverse_iterator; public: using value_t = detail::value_t; // forward declarations - template class json_reverse_iterator; using json_pointer = ::nlohmann::json_pointer; template using json_serializer = JSONSerializer; @@ -11298,114 +11403,6 @@ class basic_json /// the value of the current element json_value m_value = {}; - public: - /*! - @brief a template for a reverse iterator class - - @tparam Base the base iterator type to reverse. Valid types are @ref - iterator (to create @ref reverse_iterator) and @ref const_iterator (to - create @ref const_reverse_iterator). - - @requirement The class satisfies the following concept requirements: - - [RandomAccessIterator](http://en.cppreference.com/w/cpp/concept/RandomAccessIterator): - The iterator that can be moved to point (forward and backward) to any - element in constant time. - - [OutputIterator](http://en.cppreference.com/w/cpp/concept/OutputIterator): - It is possible to write to the pointed-to element (only if @a Base is - @ref iterator). - - @since version 1.0.0 - */ - template - class json_reverse_iterator : public std::reverse_iterator - { - public: - /// shortcut to the reverse iterator adaptor - using base_iterator = std::reverse_iterator; - /// the reference type for the pointed-to element - using reference = typename Base::reference; - - /// create reverse iterator from iterator - json_reverse_iterator(const typename base_iterator::iterator_type& it) noexcept - : base_iterator(it) - {} - - /// create reverse iterator from base class - json_reverse_iterator(const base_iterator& it) noexcept - : base_iterator(it) - {} - - /// post-increment (it++) - json_reverse_iterator operator++(int) - { - return static_cast(base_iterator::operator++(1)); - } - - /// pre-increment (++it) - json_reverse_iterator& operator++() - { - return static_cast(base_iterator::operator++()); - } - - /// post-decrement (it--) - json_reverse_iterator operator--(int) - { - return static_cast(base_iterator::operator--(1)); - } - - /// pre-decrement (--it) - json_reverse_iterator& operator--() - { - return static_cast(base_iterator::operator--()); - } - - /// add to iterator - json_reverse_iterator& operator+=(difference_type i) - { - return static_cast(base_iterator::operator+=(i)); - } - - /// add to iterator - json_reverse_iterator operator+(difference_type i) const - { - return static_cast(base_iterator::operator+(i)); - } - - /// subtract from iterator - json_reverse_iterator operator-(difference_type i) const - { - return static_cast(base_iterator::operator-(i)); - } - - /// return difference - difference_type operator-(const json_reverse_iterator& other) const - { - return base_iterator(*this) - base_iterator(other); - } - - /// access to successor - reference operator[](difference_type n) const - { - return *(this->operator+(n)); - } - - /// return the key of an object iterator - typename object_t::key_type key() const - { - auto it = --this->base(); - return it.key(); - } - - /// return the value of an iterator - reference value() const - { - auto it = --this->base(); - return it.operator * (); - } - }; - - - private: ////////////////////////////////////////// // binary serialization/deserialization // //////////////////////////////////////////