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#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
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