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#pragma once
#include <cstddef> // size_t
#include <string> // string, to_string
#include <iterator> // input_iterator_tag
#include <lib/modernjson/detail/value_t.hpp>
namespace nlohmann
{
namespace detail
{
/// proxy class for the items() function
template<typename IteratorType> class iteration_proxy
{
private:
/// helper class for iteration
class iteration_proxy_internal
{
public:
using difference_type = std::ptrdiff_t;
using value_type = iteration_proxy_internal;
using pointer = iteration_proxy_internal*;
using reference = iteration_proxy_internal&;
using iterator_category = std::input_iterator_tag;
private:
/// the iterator
IteratorType anchor;
/// an index for arrays (used to create key names)
std::size_t array_index = 0;
/// last stringified array index
mutable std::size_t array_index_last = 0;
/// a string representation of the array index
mutable std::string array_index_str = "0";
/// an empty string (to return a reference for primitive values)
const std::string empty_str = "";
public:
explicit iteration_proxy_internal(IteratorType it) noexcept : anchor(it) {}
iteration_proxy_internal(const iteration_proxy_internal&) = default;
iteration_proxy_internal& operator=(const iteration_proxy_internal&) = default;
/// dereference operator (needed for range-based for)
iteration_proxy_internal& operator*()
{
return *this;
}
/// increment operator (needed for range-based for)
iteration_proxy_internal& operator++()
{
++anchor;
++array_index;
return *this;
}
/// equality operator (needed for InputIterator)
bool operator==(const iteration_proxy_internal& o) const noexcept
{
return anchor == o.anchor;
}
/// inequality operator (needed for range-based for)
bool operator!=(const iteration_proxy_internal& o) const noexcept
{
return anchor != o.anchor;
}
/// return key of the iterator
const std::string& key() const
{
assert(anchor.m_object != nullptr);
switch (anchor.m_object->type())
{
// use integer array index as key
case value_t::array:
{
if (array_index != array_index_last)
{
array_index_str = std::to_string(array_index);
array_index_last = array_index;
}
return array_index_str;
}
// use key from the object
case value_t::object:
return anchor.key();
// use an empty key for all primitive types
default:
return empty_str;
}
}
/// return value of the iterator
typename IteratorType::reference value() const
{
return anchor.value();
}
};
/// the container to iterate
typename IteratorType::reference container;
public:
/// construct iteration proxy from a container
explicit iteration_proxy(typename IteratorType::reference cont) noexcept
: container(cont) {}
/// return iterator begin (needed for range-based for)
iteration_proxy_internal begin() noexcept
{
return iteration_proxy_internal(container.begin());
}
/// return iterator end (needed for range-based for)
iteration_proxy_internal end() noexcept
{
return iteration_proxy_internal(container.end());
}
};
}
}
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