mirror of
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201 lines
7.6 KiB
C++
201 lines
7.6 KiB
C++
#pragma once
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#include <ciso646> // not
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#include <limits> // numeric_limits
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#include <type_traits> // false_type, is_constructible, is_integral, is_same, true_type
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#include <utility> // declval
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#include <nlohmann/json_fwd.hpp>
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#include <nlohmann/detail/meta/cpp_future.hpp>
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#include <nlohmann/detail/macro_scope.hpp>
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namespace nlohmann
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{
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/*!
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@brief detail namespace with internal helper functions
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This namespace collects functions that should not be exposed,
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implementations of some @ref basic_json methods, and meta-programming helpers.
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@since version 2.1.0
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*/
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namespace detail
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{
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/////////////
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// helpers //
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/////////////
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template<typename> struct is_basic_json : std::false_type {};
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NLOHMANN_BASIC_JSON_TPL_DECLARATION
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struct is_basic_json<NLOHMANN_BASIC_JSON_TPL> : std::true_type {};
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////////////////////////
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// has_/is_ functions //
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////////////////////////
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// source: https://stackoverflow.com/a/37193089/4116453
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template <typename T, typename = void>
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struct is_complete_type : std::false_type {};
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template <typename T>
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struct is_complete_type<T, decltype(void(sizeof(T)))> : std::true_type {};
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NLOHMANN_JSON_HAS_HELPER(mapped_type);
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NLOHMANN_JSON_HAS_HELPER(key_type);
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NLOHMANN_JSON_HAS_HELPER(value_type);
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NLOHMANN_JSON_HAS_HELPER(iterator);
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template<bool B, class RealType, class CompatibleObjectType>
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struct is_compatible_object_type_impl : std::false_type {};
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template<class RealType, class CompatibleObjectType>
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struct is_compatible_object_type_impl<true, RealType, CompatibleObjectType>
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{
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static constexpr auto value =
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std::is_constructible<typename RealType::key_type, typename CompatibleObjectType::key_type>::value and
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std::is_constructible<typename RealType::mapped_type, typename CompatibleObjectType::mapped_type>::value;
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};
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template<bool B, class RealType, class CompatibleStringType>
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struct is_compatible_string_type_impl : std::false_type {};
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template<class RealType, class CompatibleStringType>
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struct is_compatible_string_type_impl<true, RealType, CompatibleStringType>
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{
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static constexpr auto value =
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std::is_same<typename RealType::value_type, typename CompatibleStringType::value_type>::value and
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std::is_constructible<RealType, CompatibleStringType>::value;
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};
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template<class BasicJsonType, class CompatibleObjectType>
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struct is_compatible_object_type
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{
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static auto constexpr value = is_compatible_object_type_impl <
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conjunction<negation<std::is_same<void, CompatibleObjectType>>,
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has_mapped_type<CompatibleObjectType>,
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has_key_type<CompatibleObjectType>>::value,
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typename BasicJsonType::object_t, CompatibleObjectType >::value;
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};
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template<class BasicJsonType, class CompatibleStringType>
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struct is_compatible_string_type
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{
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static auto constexpr value = is_compatible_string_type_impl <
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conjunction<negation<std::is_same<void, CompatibleStringType>>,
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has_value_type<CompatibleStringType>>::value,
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typename BasicJsonType::string_t, CompatibleStringType >::value;
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};
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template<typename BasicJsonType, typename T>
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struct is_basic_json_nested_type
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{
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static auto constexpr value = std::is_same<T, typename BasicJsonType::iterator>::value or
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std::is_same<T, typename BasicJsonType::const_iterator>::value or
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std::is_same<T, typename BasicJsonType::reverse_iterator>::value or
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std::is_same<T, typename BasicJsonType::const_reverse_iterator>::value;
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};
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template<class BasicJsonType, class CompatibleArrayType>
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struct is_compatible_array_type
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{
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static auto constexpr value =
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conjunction<negation<std::is_same<void, CompatibleArrayType>>,
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negation<is_compatible_object_type<
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BasicJsonType, CompatibleArrayType>>,
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negation<std::is_constructible<typename BasicJsonType::string_t,
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CompatibleArrayType>>,
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negation<is_basic_json_nested_type<BasicJsonType, CompatibleArrayType>>,
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has_value_type<CompatibleArrayType>,
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has_iterator<CompatibleArrayType>>::value;
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};
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template<bool, typename, typename>
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struct is_compatible_integer_type_impl : std::false_type {};
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template<typename RealIntegerType, typename CompatibleNumberIntegerType>
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struct is_compatible_integer_type_impl<true, RealIntegerType, CompatibleNumberIntegerType>
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{
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// is there an assert somewhere on overflows?
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using RealLimits = std::numeric_limits<RealIntegerType>;
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using CompatibleLimits = std::numeric_limits<CompatibleNumberIntegerType>;
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static constexpr auto value =
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std::is_constructible<RealIntegerType, CompatibleNumberIntegerType>::value and
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CompatibleLimits::is_integer and
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RealLimits::is_signed == CompatibleLimits::is_signed;
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};
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template<typename RealIntegerType, typename CompatibleNumberIntegerType>
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struct is_compatible_integer_type
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{
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static constexpr auto value =
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is_compatible_integer_type_impl <
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std::is_integral<CompatibleNumberIntegerType>::value and
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not std::is_same<bool, CompatibleNumberIntegerType>::value,
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RealIntegerType, CompatibleNumberIntegerType > ::value;
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};
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// trait checking if JSONSerializer<T>::from_json(json const&, udt&) exists
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template<typename BasicJsonType, typename T>
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struct has_from_json
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{
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// also check the return type of from_json
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template<typename U, typename = enable_if_t<std::is_same<void, decltype(uncvref_t<U>::from_json(
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std::declval<BasicJsonType>(), std::declval<T&>()))>::value>>
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static int detect(U&&);
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static void detect(...);
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static constexpr bool value = std::is_integral<decltype(
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detect(std::declval<typename BasicJsonType::template json_serializer<T, void>>()))>::value;
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};
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// This trait checks if JSONSerializer<T>::from_json(json const&) exists
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// this overload is used for non-default-constructible user-defined-types
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template<typename BasicJsonType, typename T>
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struct has_non_default_from_json
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{
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template <
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typename U,
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typename = enable_if_t<std::is_same<
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T, decltype(uncvref_t<U>::from_json(std::declval<BasicJsonType>()))>::value >>
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static int detect(U&&);
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static void detect(...);
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static constexpr bool value = std::is_integral<decltype(detect(
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std::declval<typename BasicJsonType::template json_serializer<T, void>>()))>::value;
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};
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// This trait checks if BasicJsonType::json_serializer<T>::to_json exists
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template<typename BasicJsonType, typename T>
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struct has_to_json
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{
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template<typename U, typename = decltype(uncvref_t<U>::to_json(
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std::declval<BasicJsonType&>(), std::declval<T>()))>
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static int detect(U&&);
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static void detect(...);
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static constexpr bool value = std::is_integral<decltype(detect(
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std::declval<typename BasicJsonType::template json_serializer<T, void>>()))>::value;
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};
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template <typename BasicJsonType, typename CompatibleCompleteType>
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struct is_compatible_complete_type
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{
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static constexpr bool value =
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not std::is_base_of<std::istream, CompatibleCompleteType>::value and
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not is_basic_json<CompatibleCompleteType>::value and
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not is_basic_json_nested_type<BasicJsonType, CompatibleCompleteType>::value and
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has_to_json<BasicJsonType, CompatibleCompleteType>::value;
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};
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template <typename BasicJsonType, typename CompatibleType>
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struct is_compatible_type
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: conjunction<is_complete_type<CompatibleType>,
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is_compatible_complete_type<BasicJsonType, CompatibleType>>
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{
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};
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}
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}
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