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// __ _____ _____ _____
// __| | __| | | | JSON for Modern C++
// | | |__ | | | | | | version 3.12.0
// |_____|_____|_____|_|___| https://github.com/nlohmann/json
//
// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
// SPDX-License-Identifier: MIT
#pragma once
#include <cstddef> // size_t
#include <iterator> // forward_iterator_tag
#include <tuple> // tuple_size, get, tuple_element
#include <utility> // move
#if JSON_HAS_RANGES
#include <ranges> // enable_borrowed_range
#endif
#include <nlohmann/detail/abi_macros.hpp>
#include <nlohmann/detail/meta/type_traits.hpp>
#include <nlohmann/detail/string_utils.hpp>
#include <nlohmann/detail/value_t.hpp>
NLOHMANN_JSON_NAMESPACE_BEGIN
namespace detail
{
template<typename IteratorType> class iteration_proxy_value
{
public:
using difference_type = std::ptrdiff_t;
using value_type = iteration_proxy_value;
using pointer = value_type *;
using reference = value_type &;
using iterator_category = std::forward_iterator_tag;
using string_type = typename std::remove_cv< typename std::remove_reference<decltype( std::declval<IteratorType>().key() ) >::type >::type;
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 string_type array_index_str = "0";
/// an empty string (to return a reference for primitive values)
string_type empty_str{};
public:
explicit iteration_proxy_value() = default;
explicit iteration_proxy_value(IteratorType it, std::size_t array_index_ = 0)
noexcept(std::is_nothrow_move_constructible<IteratorType>::value
&& std::is_nothrow_default_constructible<string_type>::value)
: anchor(std::move(it))
, array_index(array_index_)
{}
iteration_proxy_value(iteration_proxy_value const&) = default;
iteration_proxy_value& operator=(iteration_proxy_value const&) = default;
// older GCCs are a bit fussy and require explicit noexcept specifiers on defaulted functions
iteration_proxy_value(iteration_proxy_value&&)
noexcept(std::is_nothrow_move_constructible<IteratorType>::value
&& std::is_nothrow_move_constructible<string_type>::value) = default; // NOLINT(hicpp-noexcept-move,performance-noexcept-move-constructor,cppcoreguidelines-noexcept-move-operations)
iteration_proxy_value& operator=(iteration_proxy_value&&)
noexcept(std::is_nothrow_move_assignable<IteratorType>::value
&& std::is_nothrow_move_assignable<string_type>::value) = default; // NOLINT(hicpp-noexcept-move,performance-noexcept-move-constructor,cppcoreguidelines-noexcept-move-operations)
~iteration_proxy_value() = default;
/// dereference operator (needed for range-based for)
const iteration_proxy_value& operator*() const
{
return *this;
}
/// increment operator (needed for range-based for)
iteration_proxy_value& operator++()
{
++anchor;
++array_index;
return *this;
}
iteration_proxy_value operator++(int)& // NOLINT(cert-dcl21-cpp)
{
auto tmp = iteration_proxy_value(anchor, array_index);
++anchor;
++array_index;
return tmp;
}
/// equality operator (needed for InputIterator)
bool operator==(const iteration_proxy_value& o) const
{
return anchor == o.anchor;
}
/// inequality operator (needed for range-based for)
bool operator!=(const iteration_proxy_value& o) const
{
return anchor != o.anchor;
}
/// return key of the iterator
const string_type& key() const
{
JSON_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)
{
int_to_string( array_index_str, 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
case value_t::null:
case value_t::string:
case value_t::boolean:
case value_t::number_integer:
case value_t::number_unsigned:
case value_t::number_float:
case value_t::binary:
case value_t::discarded:
default:
return empty_str;
}
}
/// return value of the iterator
typename IteratorType::reference value() const
{
return anchor.value();
}
};
/// proxy class for the items() function
template<typename IteratorType> class iteration_proxy
{
private:
/// the container to iterate
typename IteratorType::pointer container = nullptr;
public:
explicit iteration_proxy() = default;
/// construct iteration proxy from a container
explicit iteration_proxy(typename IteratorType::reference cont) noexcept
: container(&cont) {}
iteration_proxy(iteration_proxy const&) = default;
iteration_proxy& operator=(iteration_proxy const&) = default;
iteration_proxy(iteration_proxy&&) noexcept = default;
iteration_proxy& operator=(iteration_proxy&&) noexcept = default;
~iteration_proxy() = default;
/// return iterator begin (needed for range-based for)
iteration_proxy_value<IteratorType> begin() const noexcept
{
return iteration_proxy_value<IteratorType>(container->begin());
}
/// return iterator end (needed for range-based for)
iteration_proxy_value<IteratorType> end() const noexcept
{
return iteration_proxy_value<IteratorType>(container->end());
}
};
// Structured Bindings Support
// For further reference see https://blog.tartanllama.xyz/structured-bindings/
// And see https://github.com/nlohmann/json/pull/1391
template<std::size_t N, typename IteratorType, enable_if_t<N == 0, int> = 0>
auto get(const nlohmann::detail::iteration_proxy_value<IteratorType>& i) -> decltype(i.key())
{
return i.key();
}
// Structured Bindings Support
// For further reference see https://blog.tartanllama.xyz/structured-bindings/
// And see https://github.com/nlohmann/json/pull/1391
template<std::size_t N, typename IteratorType, enable_if_t<N == 1, int> = 0>
auto get(const nlohmann::detail::iteration_proxy_value<IteratorType>& i) -> decltype(i.value())
{
return i.value();
}
} // namespace detail
NLOHMANN_JSON_NAMESPACE_END
// The Addition to the STD Namespace is required to add
// Structured Bindings Support to the iteration_proxy_value class
// For further reference see https://blog.tartanllama.xyz/structured-bindings/
// And see https://github.com/nlohmann/json/pull/1391
namespace std
{
#if defined(__clang__)
// Fix: https://github.com/nlohmann/json/issues/1401
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wmismatched-tags"
#endif
template<typename IteratorType>
class tuple_size<::nlohmann::detail::iteration_proxy_value<IteratorType>> // NOLINT(cert-dcl58-cpp)
: public std::integral_constant<std::size_t, 2> {};
template<std::size_t N, typename IteratorType>
class tuple_element<N, ::nlohmann::detail::iteration_proxy_value<IteratorType >> // NOLINT(cert-dcl58-cpp)
{
public:
using type = decltype(
get<N>(std::declval <
::nlohmann::detail::iteration_proxy_value<IteratorType >> ()));
};
#if defined(__clang__)
#pragma clang diagnostic pop
#endif
} // namespace std
#if JSON_HAS_RANGES
template <typename IteratorType>
inline constexpr bool ::std::ranges::enable_borrowed_range<::nlohmann::detail::iteration_proxy<IteratorType>> = true;
#endif
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