--- /dev/null
+#pragma once
+
+#include <limits> // numeric_limits
+#include <type_traits> // false_type, is_constructible, is_integral, is_same, true_type
+#include <utility> // declval
+#include <tuple> // tuple
+
+#include <nlohmann/detail/macro_scope.hpp>
+
+#include <nlohmann/detail/iterators/iterator_traits.hpp>
+#include <nlohmann/detail/meta/call_std/begin.hpp>
+#include <nlohmann/detail/meta/call_std/end.hpp>
+#include <nlohmann/detail/meta/cpp_future.hpp>
+#include <nlohmann/detail/meta/detected.hpp>
+#include <nlohmann/json_fwd.hpp>
+
+namespace nlohmann
+{
+/*!
+@brief detail namespace with internal helper functions
+
+This namespace collects functions that should not be exposed,
+implementations of some @ref basic_json methods, and meta-programming helpers.
+
+@since version 2.1.0
+*/
+namespace detail
+{
+/////////////
+// helpers //
+/////////////
+
+// Note to maintainers:
+//
+// Every trait in this file expects a non CV-qualified type.
+// The only exceptions are in the 'aliases for detected' section
+// (i.e. those of the form: decltype(T::member_function(std::declval<T>())))
+//
+// In this case, T has to be properly CV-qualified to constraint the function arguments
+// (e.g. to_json(BasicJsonType&, const T&))
+
+template<typename> struct is_basic_json : std::false_type {};
+
+NLOHMANN_BASIC_JSON_TPL_DECLARATION
+struct is_basic_json<NLOHMANN_BASIC_JSON_TPL> : std::true_type {};
+
+//////////////////////
+// json_ref helpers //
+//////////////////////
+
+template<typename>
+class json_ref;
+
+template<typename>
+struct is_json_ref : std::false_type {};
+
+template<typename T>
+struct is_json_ref<json_ref<T>> : std::true_type {};
+
+//////////////////////////
+// aliases for detected //
+//////////////////////////
+
+template<typename T>
+using mapped_type_t = typename T::mapped_type;
+
+template<typename T>
+using key_type_t = typename T::key_type;
+
+template<typename T>
+using value_type_t = typename T::value_type;
+
+template<typename T>
+using difference_type_t = typename T::difference_type;
+
+template<typename T>
+using pointer_t = typename T::pointer;
+
+template<typename T>
+using reference_t = typename T::reference;
+
+template<typename T>
+using iterator_category_t = typename T::iterator_category;
+
+template<typename T, typename... Args>
+using to_json_function = decltype(T::to_json(std::declval<Args>()...));
+
+template<typename T, typename... Args>
+using from_json_function = decltype(T::from_json(std::declval<Args>()...));
+
+template<typename T, typename U>
+using get_template_function = decltype(std::declval<T>().template get<U>());
+
+// trait checking if JSONSerializer<T>::from_json(json const&, udt&) exists
+template<typename BasicJsonType, typename T, typename = void>
+struct has_from_json : std::false_type {};
+
+// trait checking if j.get<T> is valid
+// use this trait instead of std::is_constructible or std::is_convertible,
+// both rely on, or make use of implicit conversions, and thus fail when T
+// has several constructors/operator= (see https://github.com/nlohmann/json/issues/958)
+template <typename BasicJsonType, typename T>
+struct is_getable
+{
+ static constexpr bool value = is_detected<get_template_function, const BasicJsonType&, T>::value;
+};
+
+template<typename BasicJsonType, typename T>
+struct has_from_json < BasicJsonType, T, enable_if_t < !is_basic_json<T>::value >>
+{
+ using serializer = typename BasicJsonType::template json_serializer<T, void>;
+
+ static constexpr bool value =
+ is_detected_exact<void, from_json_function, serializer,
+ const BasicJsonType&, T&>::value;
+};
+
+// This trait checks if JSONSerializer<T>::from_json(json const&) exists
+// this overload is used for non-default-constructible user-defined-types
+template<typename BasicJsonType, typename T, typename = void>
+struct has_non_default_from_json : std::false_type {};
+
+template<typename BasicJsonType, typename T>
+struct has_non_default_from_json < BasicJsonType, T, enable_if_t < !is_basic_json<T>::value >>
+{
+ using serializer = typename BasicJsonType::template json_serializer<T, void>;
+
+ static constexpr bool value =
+ is_detected_exact<T, from_json_function, serializer,
+ const BasicJsonType&>::value;
+};
+
+// This trait checks if BasicJsonType::json_serializer<T>::to_json exists
+// Do not evaluate the trait when T is a basic_json type, to avoid template instantiation infinite recursion.
+template<typename BasicJsonType, typename T, typename = void>
+struct has_to_json : std::false_type {};
+
+template<typename BasicJsonType, typename T>
+struct has_to_json < BasicJsonType, T, enable_if_t < !is_basic_json<T>::value >>
+{
+ using serializer = typename BasicJsonType::template json_serializer<T, void>;
+
+ static constexpr bool value =
+ is_detected_exact<void, to_json_function, serializer, BasicJsonType&,
+ T>::value;
+};
+
+
+///////////////////
+// is_ functions //
+///////////////////
+
+// https://en.cppreference.com/w/cpp/types/conjunction
+template<class...> struct conjunction : std::true_type { };
+template<class B1> struct conjunction<B1> : B1 { };
+template<class B1, class... Bn>
+struct conjunction<B1, Bn...>
+: std::conditional<bool(B1::value), conjunction<Bn...>, B1>::type {};
+
+// https://en.cppreference.com/w/cpp/types/negation
+template<class B> struct negation : std::integral_constant < bool, !B::value > { };
+
+// Reimplementation of is_constructible and is_default_constructible, due to them being broken for
+// std::pair and std::tuple until LWG 2367 fix (see https://cplusplus.github.io/LWG/lwg-defects.html#2367).
+// This causes compile errors in e.g. clang 3.5 or gcc 4.9.
+template <typename T>
+struct is_default_constructible : std::is_default_constructible<T> {};
+
+template <typename T1, typename T2>
+struct is_default_constructible<std::pair<T1, T2>>
+ : conjunction<is_default_constructible<T1>, is_default_constructible<T2>> {};
+
+template <typename T1, typename T2>
+struct is_default_constructible<const std::pair<T1, T2>>
+ : conjunction<is_default_constructible<T1>, is_default_constructible<T2>> {};
+
+template <typename... Ts>
+struct is_default_constructible<std::tuple<Ts...>>
+ : conjunction<is_default_constructible<Ts>...> {};
+
+template <typename... Ts>
+struct is_default_constructible<const std::tuple<Ts...>>
+ : conjunction<is_default_constructible<Ts>...> {};
+
+
+template <typename T, typename... Args>
+struct is_constructible : std::is_constructible<T, Args...> {};
+
+template <typename T1, typename T2>
+struct is_constructible<std::pair<T1, T2>> : is_default_constructible<std::pair<T1, T2>> {};
+
+template <typename T1, typename T2>
+struct is_constructible<const std::pair<T1, T2>> : is_default_constructible<const std::pair<T1, T2>> {};
+
+template <typename... Ts>
+struct is_constructible<std::tuple<Ts...>> : is_default_constructible<std::tuple<Ts...>> {};
+
+template <typename... Ts>
+struct is_constructible<const std::tuple<Ts...>> : is_default_constructible<const std::tuple<Ts...>> {};
+
+
+template<typename T, typename = void>
+struct is_iterator_traits : std::false_type {};
+
+template<typename T>
+struct is_iterator_traits<iterator_traits<T>>
+{
+ private:
+ using traits = iterator_traits<T>;
+
+ public:
+ static constexpr auto value =
+ is_detected<value_type_t, traits>::value &&
+ is_detected<difference_type_t, traits>::value &&
+ is_detected<pointer_t, traits>::value &&
+ is_detected<iterator_category_t, traits>::value &&
+ is_detected<reference_t, traits>::value;
+};
+
+template<typename T>
+struct is_range
+{
+ private:
+ using t_ref = typename std::add_lvalue_reference<T>::type;
+
+ using iterator = detected_t<result_of_begin, t_ref>;
+ using sentinel = detected_t<result_of_end, t_ref>;
+
+ // to be 100% correct, it should use https://en.cppreference.com/w/cpp/iterator/input_or_output_iterator
+ // and https://en.cppreference.com/w/cpp/iterator/sentinel_for
+ // but reimplementing these would be too much work, as a lot of other concepts are used underneath
+ static constexpr auto is_iterator_begin =
+ is_iterator_traits<iterator_traits<iterator>>::value;
+
+ public:
+ static constexpr bool value = !std::is_same<iterator, nonesuch>::value && !std::is_same<sentinel, nonesuch>::value && is_iterator_begin;
+};
+
+template<typename R>
+using iterator_t = enable_if_t<is_range<R>::value, result_of_begin<decltype(std::declval<R&>())>>;
+
+template<typename T>
+using range_value_t = value_type_t<iterator_traits<iterator_t<T>>>;
+
+// The following implementation of is_complete_type is taken from
+// https://blogs.msdn.microsoft.com/vcblog/2015/12/02/partial-support-for-expression-sfinae-in-vs-2015-update-1/
+// and is written by Xiang Fan who agreed to using it in this library.
+
+template<typename T, typename = void>
+struct is_complete_type : std::false_type {};
+
+template<typename T>
+struct is_complete_type<T, decltype(void(sizeof(T)))> : std::true_type {};
+
+template<typename BasicJsonType, typename CompatibleObjectType,
+ typename = void>
+struct is_compatible_object_type_impl : std::false_type {};
+
+template<typename BasicJsonType, typename CompatibleObjectType>
+struct is_compatible_object_type_impl <
+ BasicJsonType, CompatibleObjectType,
+ enable_if_t < is_detected<mapped_type_t, CompatibleObjectType>::value&&
+ is_detected<key_type_t, CompatibleObjectType>::value >>
+{
+ using object_t = typename BasicJsonType::object_t;
+
+ // macOS's is_constructible does not play well with nonesuch...
+ static constexpr bool value =
+ is_constructible<typename object_t::key_type,
+ typename CompatibleObjectType::key_type>::value &&
+ is_constructible<typename object_t::mapped_type,
+ typename CompatibleObjectType::mapped_type>::value;
+};
+
+template<typename BasicJsonType, typename CompatibleObjectType>
+struct is_compatible_object_type
+ : is_compatible_object_type_impl<BasicJsonType, CompatibleObjectType> {};
+
+template<typename BasicJsonType, typename ConstructibleObjectType,
+ typename = void>
+struct is_constructible_object_type_impl : std::false_type {};
+
+template<typename BasicJsonType, typename ConstructibleObjectType>
+struct is_constructible_object_type_impl <
+ BasicJsonType, ConstructibleObjectType,
+ enable_if_t < is_detected<mapped_type_t, ConstructibleObjectType>::value&&
+ is_detected<key_type_t, ConstructibleObjectType>::value >>
+{
+ using object_t = typename BasicJsonType::object_t;
+
+ static constexpr bool value =
+ (is_default_constructible<ConstructibleObjectType>::value &&
+ (std::is_move_assignable<ConstructibleObjectType>::value ||
+ std::is_copy_assignable<ConstructibleObjectType>::value) &&
+ (is_constructible<typename ConstructibleObjectType::key_type,
+ typename object_t::key_type>::value &&
+ std::is_same <
+ typename object_t::mapped_type,
+ typename ConstructibleObjectType::mapped_type >::value)) ||
+ (has_from_json<BasicJsonType,
+ typename ConstructibleObjectType::mapped_type>::value ||
+ has_non_default_from_json <
+ BasicJsonType,
+ typename ConstructibleObjectType::mapped_type >::value);
+};
+
+template<typename BasicJsonType, typename ConstructibleObjectType>
+struct is_constructible_object_type
+ : is_constructible_object_type_impl<BasicJsonType,
+ ConstructibleObjectType> {};
+
+template<typename BasicJsonType, typename CompatibleStringType>
+struct is_compatible_string_type
+{
+ static constexpr auto value =
+ is_constructible<typename BasicJsonType::string_t, CompatibleStringType>::value;
+};
+
+template<typename BasicJsonType, typename ConstructibleStringType>
+struct is_constructible_string_type
+{
+ static constexpr auto value =
+ is_constructible<ConstructibleStringType,
+ typename BasicJsonType::string_t>::value;
+};
+
+template<typename BasicJsonType, typename CompatibleArrayType, typename = void>
+struct is_compatible_array_type_impl : std::false_type {};
+
+template<typename BasicJsonType, typename CompatibleArrayType>
+struct is_compatible_array_type_impl <
+ BasicJsonType, CompatibleArrayType,
+ enable_if_t <
+ is_detected<iterator_t, CompatibleArrayType>::value&&
+ is_iterator_traits<iterator_traits<detected_t<iterator_t, CompatibleArrayType>>>::value&&
+// special case for types like std::filesystem::path whose iterator's value_type are themselves
+// c.f. https://github.com/nlohmann/json/pull/3073
+ !std::is_same<CompatibleArrayType, detected_t<range_value_t, CompatibleArrayType>>::value >>
+{
+ static constexpr bool value =
+ is_constructible<BasicJsonType,
+ range_value_t<CompatibleArrayType>>::value;
+};
+
+template<typename BasicJsonType, typename CompatibleArrayType>
+struct is_compatible_array_type
+ : is_compatible_array_type_impl<BasicJsonType, CompatibleArrayType> {};
+
+template<typename BasicJsonType, typename ConstructibleArrayType, typename = void>
+struct is_constructible_array_type_impl : std::false_type {};
+
+template<typename BasicJsonType, typename ConstructibleArrayType>
+struct is_constructible_array_type_impl <
+ BasicJsonType, ConstructibleArrayType,
+ enable_if_t<std::is_same<ConstructibleArrayType,
+ typename BasicJsonType::value_type>::value >>
+ : std::true_type {};
+
+template<typename BasicJsonType, typename ConstructibleArrayType>
+struct is_constructible_array_type_impl <
+ BasicJsonType, ConstructibleArrayType,
+ enable_if_t < !std::is_same<ConstructibleArrayType,
+ typename BasicJsonType::value_type>::value&&
+ !is_compatible_string_type<BasicJsonType, ConstructibleArrayType>::value&&
+ is_default_constructible<ConstructibleArrayType>::value&&
+(std::is_move_assignable<ConstructibleArrayType>::value ||
+ std::is_copy_assignable<ConstructibleArrayType>::value)&&
+is_detected<iterator_t, ConstructibleArrayType>::value&&
+is_iterator_traits<iterator_traits<detected_t<iterator_t, ConstructibleArrayType>>>::value&&
+is_detected<range_value_t, ConstructibleArrayType>::value&&
+// special case for types like std::filesystem::path whose iterator's value_type are themselves
+// c.f. https://github.com/nlohmann/json/pull/3073
+!std::is_same<ConstructibleArrayType, detected_t<range_value_t, ConstructibleArrayType>>::value&&
+ is_complete_type <
+ detected_t<range_value_t, ConstructibleArrayType >>::value >>
+{
+ using value_type = range_value_t<ConstructibleArrayType>;
+
+ static constexpr bool value =
+ std::is_same<value_type,
+ typename BasicJsonType::array_t::value_type>::value ||
+ has_from_json<BasicJsonType,
+ value_type>::value ||
+ has_non_default_from_json <
+ BasicJsonType,
+ value_type >::value;
+};
+
+template<typename BasicJsonType, typename ConstructibleArrayType>
+struct is_constructible_array_type
+ : is_constructible_array_type_impl<BasicJsonType, ConstructibleArrayType> {};
+
+template<typename RealIntegerType, typename CompatibleNumberIntegerType,
+ typename = void>
+struct is_compatible_integer_type_impl : std::false_type {};
+
+template<typename RealIntegerType, typename CompatibleNumberIntegerType>
+struct is_compatible_integer_type_impl <
+ RealIntegerType, CompatibleNumberIntegerType,
+ enable_if_t < std::is_integral<RealIntegerType>::value&&
+ std::is_integral<CompatibleNumberIntegerType>::value&&
+ !std::is_same<bool, CompatibleNumberIntegerType>::value >>
+{
+ // is there an assert somewhere on overflows?
+ using RealLimits = std::numeric_limits<RealIntegerType>;
+ using CompatibleLimits = std::numeric_limits<CompatibleNumberIntegerType>;
+
+ static constexpr auto value =
+ is_constructible<RealIntegerType,
+ CompatibleNumberIntegerType>::value &&
+ CompatibleLimits::is_integer &&
+ RealLimits::is_signed == CompatibleLimits::is_signed;
+};
+
+template<typename RealIntegerType, typename CompatibleNumberIntegerType>
+struct is_compatible_integer_type
+ : is_compatible_integer_type_impl<RealIntegerType,
+ CompatibleNumberIntegerType> {};
+
+template<typename BasicJsonType, typename CompatibleType, typename = void>
+struct is_compatible_type_impl: std::false_type {};
+
+template<typename BasicJsonType, typename CompatibleType>
+struct is_compatible_type_impl <
+ BasicJsonType, CompatibleType,
+ enable_if_t<is_complete_type<CompatibleType>::value >>
+{
+ static constexpr bool value =
+ has_to_json<BasicJsonType, CompatibleType>::value;
+};
+
+template<typename BasicJsonType, typename CompatibleType>
+struct is_compatible_type
+ : is_compatible_type_impl<BasicJsonType, CompatibleType> {};
+
+template<typename T1, typename T2>
+struct is_constructible_tuple : std::false_type {};
+
+template<typename T1, typename... Args>
+struct is_constructible_tuple<T1, std::tuple<Args...>> : conjunction<is_constructible<T1, Args>...> {};
+
+// a naive helper to check if a type is an ordered_map (exploits the fact that
+// ordered_map inherits capacity() from std::vector)
+template <typename T>
+struct is_ordered_map
+{
+ using one = char;
+
+ struct two
+ {
+ char x[2]; // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
+ };
+
+ template <typename C> static one test( decltype(&C::capacity) ) ;
+ template <typename C> static two test(...);
+
+ enum { value = sizeof(test<T>(nullptr)) == sizeof(char) }; // NOLINT(cppcoreguidelines-pro-type-vararg,hicpp-vararg)
+};
+
+// to avoid useless casts (see https://github.com/nlohmann/json/issues/2893#issuecomment-889152324)
+template < typename T, typename U, enable_if_t < !std::is_same<T, U>::value, int > = 0 >
+T conditional_static_cast(U value)
+{
+ return static_cast<T>(value);
+}
+
+template<typename T, typename U, enable_if_t<std::is_same<T, U>::value, int> = 0>
+T conditional_static_cast(U value)
+{
+ return value;
+}
+
+} // namespace detail
+} // namespace nlohmann
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