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Diffstat (limited to 'include/lib/modernjson/detail/iterators/json_reverse_iterator.hpp')
-rw-r--r-- | include/lib/modernjson/detail/iterators/json_reverse_iterator.hpp | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/include/lib/modernjson/detail/iterators/json_reverse_iterator.hpp b/include/lib/modernjson/detail/iterators/json_reverse_iterator.hpp new file mode 100644 index 0000000..f3b5b5d --- /dev/null +++ b/include/lib/modernjson/detail/iterators/json_reverse_iterator.hpp @@ -0,0 +1,119 @@ +#pragma once + +#include <cstddef> // ptrdiff_t +#include <iterator> // reverse_iterator +#include <utility> // declval + +namespace nlohmann +{ +namespace detail +{ +////////////////////// +// reverse_iterator // +////////////////////// + +/*! +@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: +- +[BidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator): + The iterator that can be moved can be moved in both directions (i.e. + incremented and decremented). +- [OutputIterator](https://en.cppreference.com/w/cpp/named_req/OutputIterator): + It is possible to write to the pointed-to element (only if @a Base is + @ref iterator). + +@since version 1.0.0 +*/ +template<typename Base> +class json_reverse_iterator : public std::reverse_iterator<Base> +{ + public: + using difference_type = std::ptrdiff_t; + /// shortcut to the reverse iterator adapter + using base_iterator = std::reverse_iterator<Base>; + /// the reference type for the pointed-to element + using reference = typename Base::reference; + + /// create reverse iterator from iterator + explicit json_reverse_iterator(const typename base_iterator::iterator_type& it) noexcept + : base_iterator(it) {} + + /// create reverse iterator from base class + explicit json_reverse_iterator(const base_iterator& it) noexcept : base_iterator(it) {} + + /// post-increment (it++) + json_reverse_iterator const operator++(int) + { + return static_cast<json_reverse_iterator>(base_iterator::operator++(1)); + } + + /// pre-increment (++it) + json_reverse_iterator& operator++() + { + return static_cast<json_reverse_iterator&>(base_iterator::operator++()); + } + + /// post-decrement (it--) + json_reverse_iterator const operator--(int) + { + return static_cast<json_reverse_iterator>(base_iterator::operator--(1)); + } + + /// pre-decrement (--it) + json_reverse_iterator& operator--() + { + return static_cast<json_reverse_iterator&>(base_iterator::operator--()); + } + + /// add to iterator + json_reverse_iterator& operator+=(difference_type i) + { + return static_cast<json_reverse_iterator&>(base_iterator::operator+=(i)); + } + + /// add to iterator + json_reverse_iterator operator+(difference_type i) const + { + return static_cast<json_reverse_iterator>(base_iterator::operator+(i)); + } + + /// subtract from iterator + json_reverse_iterator operator-(difference_type i) const + { + return static_cast<json_reverse_iterator>(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<Base>().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 nlohmann |