nlohmann::detail Namespace Reference

detail namespace with internal helper functions More...

Namespaces
namespace	dtoa_impl
	implements the Grisu2 algorithm for binary to decimal floating-point conversion.

Classes
class	binary_reader
	deserialization of CBOR, MessagePack, and UBJSON values More...
class	binary_writer
	serialization to CBOR and MessagePack values More...
struct	conjunction
struct	conjunction< B1 >
struct	conjunction< B1, Bn... >
struct	detector
struct	detector< Default, void_t< Op< Args... > >, Op, Args... >
class	exception
	general exception of the basic_json class More...
struct	external_constructor
struct	external_constructor< value_t::array >
struct	external_constructor< value_t::boolean >
struct	external_constructor< value_t::number_float >
struct	external_constructor< value_t::number_integer >
struct	external_constructor< value_t::number_unsigned >
struct	external_constructor< value_t::object >
struct	external_constructor< value_t::string >
class	file_input_adapter
struct	from_json_fn
struct	has_from_json
struct	has_from_json< BasicJsonType, T, enable_if_t< not is_basic_json< T >::value > >
struct	has_non_default_from_json
struct	has_non_default_from_json< BasicJsonType, T, enable_if_t< not is_basic_json< T >::value > >
struct	has_to_json
struct	has_to_json< BasicJsonType, T, enable_if_t< not is_basic_json< T >::value > >
struct	index_sequence
class	input_adapter
struct	input_adapter_protocol
	abstract input adapter interface More...
class	input_buffer_adapter
	input adapter for buffer input More...
class	input_stream_adapter
struct	internal_iterator
	an iterator value More...
class	invalid_iterator
	exception indicating errors with iterators More...
struct	is_basic_json
struct	is_basic_json< NLOHMANN_BASIC_JSON_TPL >
struct	is_compatible_array_type
struct	is_compatible_array_type_impl
struct	is_compatible_array_type_impl< BasicJsonType, CompatibleArrayType, enable_if_t< is_detected< value_type_t, CompatibleArrayType >::value and is_detected< iterator_t, CompatibleArrayType >::value and not is_iterator_traits< iterator_traits< CompatibleArrayType > >::value > >
struct	is_compatible_integer_type
struct	is_compatible_integer_type_impl
struct	is_compatible_integer_type_impl< RealIntegerType, CompatibleNumberIntegerType, enable_if_t< std::is_integral< RealIntegerType >::value and std::is_integral< CompatibleNumberIntegerType >::value and not std::is_same< bool, CompatibleNumberIntegerType >::value > >
struct	is_compatible_object_type
struct	is_compatible_object_type_impl
struct	is_compatible_object_type_impl< BasicJsonType, CompatibleObjectType, enable_if_t< is_detected< mapped_type_t, CompatibleObjectType >::value and is_detected< key_type_t, CompatibleObjectType >::value > >
struct	is_compatible_string_type
struct	is_compatible_string_type_impl
struct	is_compatible_string_type_impl< BasicJsonType, CompatibleStringType, enable_if_t< is_detected_exact< typename BasicJsonType::string_t::value_type, value_type_t, CompatibleStringType >::value > >
struct	is_compatible_type
struct	is_compatible_type_impl
struct	is_compatible_type_impl< BasicJsonType, CompatibleType, enable_if_t< is_complete_type< CompatibleType >::value > >
struct	is_complete_type
struct	is_complete_type< T, decltype(void(sizeof(T)))>
struct	is_constructible_array_type
struct	is_constructible_array_type_impl
struct	is_constructible_array_type_impl< BasicJsonType, ConstructibleArrayType, enable_if_t< not std::is_same< ConstructibleArrayType, typename BasicJsonType::value_type >::value and std::is_default_constructible< ConstructibleArrayType >::value and(std::is_move_assignable< ConstructibleArrayType >::value or std::is_copy_assignable< ConstructibleArrayType >::value) andis_detected< value_type_t, ConstructibleArrayType >::value andis_detected< iterator_t, ConstructibleArrayType >::value andis_complete_type< detected_t< value_type_t, ConstructibleArrayType > >::value > >
struct	is_constructible_array_type_impl< BasicJsonType, ConstructibleArrayType, enable_if_t< std::is_same< ConstructibleArrayType, typename BasicJsonType::value_type >::value > >
struct	is_constructible_object_type
struct	is_constructible_object_type_impl
struct	is_constructible_object_type_impl< BasicJsonType, ConstructibleObjectType, enable_if_t< is_detected< mapped_type_t, ConstructibleObjectType >::value and is_detected< key_type_t, ConstructibleObjectType >::value > >
struct	is_constructible_string_type
struct	is_constructible_string_type_impl
struct	is_constructible_string_type_impl< BasicJsonType, ConstructibleStringType, enable_if_t< is_detected_exact< typename BasicJsonType::string_t::value_type, value_type_t, ConstructibleStringType >::value > >
struct	is_constructible_tuple
struct	is_constructible_tuple< T1, std::tuple< Args... > >
struct	is_iterator_traits
struct	is_iterator_traits< iterator_traits< T > >
struct	is_sax
struct	is_sax_static_asserts
class	iter_impl
	a template for a bidirectional iterator for the basic_json class This class implements a both iterators (iterator and const_iterator) for the basic_json class. More...
class	iteration_proxy
	proxy class for the items() function More...
class	iteration_proxy_value
struct	iterator_traits
struct	iterator_traits< T *, enable_if_t< std::is_object< T >::value > >
struct	iterator_traits< T, enable_if_t< !std::is_pointer< T >::value > >
struct	iterator_types
struct	iterator_types< It, void_t< typename It::difference_type, typename It::value_type, typename It::pointer, typename It::reference, typename It::iterator_category > >
class	json_ref
class	json_reverse_iterator
	a template for a reverse iterator class More...
class	json_sax_acceptor
class	json_sax_dom_callback_parser
class	json_sax_dom_parser
	SAX implementation to create a JSON value from SAX events. More...
class	lexer
	lexical analysis More...
struct	make_index_sequence
struct	make_index_sequence< 0 >
struct	make_index_sequence< 1 >
struct	make_void
struct	merge_and_renumber
struct	merge_and_renumber< index_sequence< I1... >, index_sequence< I2... > >
struct	nonesuch
class	other_error
	exception indicating other library errors More...
class	out_of_range
	exception indicating access out of the defined range More...
class	output_adapter
struct	output_adapter_protocol
	abstract output adapter interface More...
class	output_stream_adapter
	output adapter for output streams More...
class	output_string_adapter
	output adapter for basic_string More...
class	output_vector_adapter
	output adapter for byte vectors More...
class	parse_error
	exception indicating a parse error More...
class	parser
	syntax analysis More...
struct	position_t
	struct to capture the start position of the current token More...
class	primitive_iterator_t
struct	priority_tag
struct	priority_tag< 0 >
class	serializer
struct	static_const
struct	to_json_fn
class	type_error
	exception indicating executing a member function with a wrong type More...
class	wide_string_input_adapter
struct	wide_string_input_helper
struct	wide_string_input_helper< WideStringType, 2 >

Typedefs
template<bool B, typename T = void>
using	enable_if_t = typename std::enable_if<B, T>::type
template<typename T>
using	uncvref_t = typename std::remove_cv<typename std::remove_reference<T>::type>::type
template<typename... Ts>
using	index_sequence_for = make_index_sequence<sizeof...(Ts)>
template<typename ... Ts>
using	void_t = typename make_void<Ts...>::type
template<template< class... > class Op, class... Args>
using	is_detected = typename detector<nonesuch, void, Op, Args...>::value_t
template<template< class... > class Op, class... Args>
using	detected_t = typename detector<nonesuch, void, Op, Args...>::type
template<class Default, template< class... > class Op, class... Args>
using	detected_or = detector<Default, void, Op, Args...>
template<class Default, template< class... > class Op, class... Args>
using	detected_or_t = typename detected_or<Default, Op, Args...>::type
template<class Expected, template< class... > class Op, class... Args>
using	is_detected_exact = std::is_same<Expected, detected_t<Op, Args...>>
template<class To, template< class... > class Op, class... Args>
using	is_detected_convertible
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>
using	iterator_t = typename T::iterator
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>())
using	input_adapter_t = std::shared_ptr<input_adapter_protocol>
	a type to simplify interfaces
template<typename T>
using	null_function_t = decltype(std::declval<T&>().null())
template<typename T>
using	boolean_function_t
template<typename T, typename Integer>
using	number_integer_function_t
template<typename T, typename Unsigned>
using	number_unsigned_function_t
template<typename T, typename Float, typename String>
using	number_float_function_t
template<typename T, typename String>
using	string_function_t
template<typename T>
using	start_object_function_t
template<typename T, typename String>
using	key_function_t
template<typename T>
using	end_object_function_t = decltype(std::declval<T&>().end_object())
template<typename T>
using	start_array_function_t
template<typename T>
using	end_array_function_t = decltype(std::declval<T&>().end_array())
template<typename T, typename Exception>
using	parse_error_function_t
template<typename CharType>
using	output_adapter_t = std::shared_ptr<output_adapter_protocol<CharType>>
	a type to simplify interfaces

Enumerations
enum class	value_t : std::uint8_t {   null , object , array , string ,   boolean , number_integer , number_unsigned , number_float ,   discarded }
	the JSON type enumeration More...
enum class	input_format_t {   json , cbor , msgpack , ubjson ,   bson }
	the supported input formats
enum class	error_handler_t { strict , replace , ignore }
	how to treat decoding errors More...

Functions
bool	operator< (const value_t lhs, const value_t rhs) noexcept
	comparison operator for JSON types
template<typename BasicJsonType>
void	from_json (const BasicJsonType &j, typename std::nullptr_t &n)
template<typename BasicJsonType, typename ArithmeticType, enable_if_t< std::is_arithmetic< ArithmeticType >::value and not std::is_same< ArithmeticType, typename BasicJsonType::boolean_t >::value, int > = 0>
void	get_arithmetic_value (const BasicJsonType &j, ArithmeticType &val)
template<typename BasicJsonType>
void	from_json (const BasicJsonType &j, typename BasicJsonType::boolean_t &b)
template<typename BasicJsonType>
void	from_json (const BasicJsonType &j, typename BasicJsonType::string_t &s)
template<typename BasicJsonType, typename ConstructibleStringType, enable_if_t< is_constructible_string_type< BasicJsonType, ConstructibleStringType >::value and not std::is_same< typename BasicJsonType::string_t, ConstructibleStringType >::value, int > = 0>
void	from_json (const BasicJsonType &j, ConstructibleStringType &s)
template<typename BasicJsonType>
void	from_json (const BasicJsonType &j, typename BasicJsonType::number_float_t &val)
template<typename BasicJsonType>
void	from_json (const BasicJsonType &j, typename BasicJsonType::number_unsigned_t &val)
template<typename BasicJsonType>
void	from_json (const BasicJsonType &j, typename BasicJsonType::number_integer_t &val)
template<typename BasicJsonType, typename EnumType, enable_if_t< std::is_enum< EnumType >::value, int > = 0>
void	from_json (const BasicJsonType &j, EnumType &e)
template<typename BasicJsonType, typename T, typename Allocator, enable_if_t< std::is_convertible< BasicJsonType, T >::value, int > = 0>
void	from_json (const BasicJsonType &j, std::forward_list< T, Allocator > &l)
template<typename BasicJsonType, typename T, enable_if_t< std::is_convertible< BasicJsonType, T >::value, int > = 0>
void	from_json (const BasicJsonType &j, std::valarray< T > &l)
template<typename BasicJsonType, typename T, std::size_t N>
auto	from_json (const BasicJsonType &j, T(&arr)[N]) -> decltype(j.template get< T >(), void())
template<typename BasicJsonType>
void	from_json_array_impl (const BasicJsonType &j, typename BasicJsonType::array_t &arr, priority_tag< 3 >)
template<typename BasicJsonType, typename T, std::size_t N>
auto	from_json_array_impl (const BasicJsonType &j, std::array< T, N > &arr, priority_tag< 2 >) -> decltype(j.template get< T >(), void())
template<typename BasicJsonType, typename ConstructibleArrayType>
auto	from_json_array_impl (const BasicJsonType &j, ConstructibleArrayType &arr, priority_tag< 1 >) -> decltype(arr.reserve(std::declval< typename ConstructibleArrayType::size_type >()), j.template get< typename ConstructibleArrayType::value_type >(), void())
template<typename BasicJsonType, typename ConstructibleArrayType>
void	from_json_array_impl (const BasicJsonType &j, ConstructibleArrayType &arr, priority_tag< 0 >)
template<typename BasicJsonType, typename ConstructibleArrayType, enable_if_t< is_constructible_array_type< BasicJsonType, ConstructibleArrayType >::value and not is_constructible_object_type< BasicJsonType, ConstructibleArrayType >::value and not is_constructible_string_type< BasicJsonType, ConstructibleArrayType >::value and not is_basic_json< ConstructibleArrayType >::value, int > = 0>
auto	from_json (const BasicJsonType &j, ConstructibleArrayType &arr) -> decltype(from_json_array_impl(j, arr, priority_tag< 3 > {}), j.template get< typename ConstructibleArrayType::value_type >(), void())
template<typename BasicJsonType, typename ConstructibleObjectType, enable_if_t< is_constructible_object_type< BasicJsonType, ConstructibleObjectType >::value, int > = 0>
void	from_json (const BasicJsonType &j, ConstructibleObjectType &obj)
template<typename BasicJsonType, typename ArithmeticType, enable_if_t< std::is_arithmetic< ArithmeticType >::value and not std::is_same< ArithmeticType, typename BasicJsonType::number_unsigned_t >::value and not std::is_same< ArithmeticType, typename BasicJsonType::number_integer_t >::value and not std::is_same< ArithmeticType, typename BasicJsonType::number_float_t >::value and not std::is_same< ArithmeticType, typename BasicJsonType::boolean_t >::value, int > = 0>
void	from_json (const BasicJsonType &j, ArithmeticType &val)
template<typename BasicJsonType, typename A1, typename A2>
void	from_json (const BasicJsonType &j, std::pair< A1, A2 > &p)
template<typename BasicJsonType, typename Tuple, std::size_t... Idx>
void	from_json_tuple_impl (const BasicJsonType &j, Tuple &t, index_sequence< Idx... >)
template<typename BasicJsonType, typename... Args>
void	from_json (const BasicJsonType &j, std::tuple< Args... > &t)
template<typename BasicJsonType, typename Key, typename Value, typename Compare, typename Allocator, typename = enable_if_t<not std::is_constructible< typename BasicJsonType::string_t, Key>::value>>
void	from_json (const BasicJsonType &j, std::map< Key, Value, Compare, Allocator > &m)
template<typename BasicJsonType, typename Key, typename Value, typename Hash, typename KeyEqual, typename Allocator, typename = enable_if_t<not std::is_constructible< typename BasicJsonType::string_t, Key>::value>>
void	from_json (const BasicJsonType &j, std::unordered_map< Key, Value, Hash, KeyEqual, Allocator > &m)
template<typename string_type>
void	int_to_string (string_type &target, std::size_t value)
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())
template<typename BasicJsonType, typename T, enable_if_t< std::is_same< T, typename BasicJsonType::boolean_t >::value, int > = 0>
void	to_json (BasicJsonType &j, T b) noexcept
template<typename BasicJsonType, typename CompatibleString, enable_if_t< std::is_constructible< typename BasicJsonType::string_t, CompatibleString >::value, int > = 0>
void	to_json (BasicJsonType &j, const CompatibleString &s)
template<typename BasicJsonType>
void	to_json (BasicJsonType &j, typename BasicJsonType::string_t &&s)
template<typename BasicJsonType, typename FloatType, enable_if_t< std::is_floating_point< FloatType >::value, int > = 0>
void	to_json (BasicJsonType &j, FloatType val) noexcept
template<typename BasicJsonType, typename CompatibleNumberUnsignedType, enable_if_t< is_compatible_integer_type< typename BasicJsonType::number_unsigned_t, CompatibleNumberUnsignedType >::value, int > = 0>
void	to_json (BasicJsonType &j, CompatibleNumberUnsignedType val) noexcept
template<typename BasicJsonType, typename CompatibleNumberIntegerType, enable_if_t< is_compatible_integer_type< typename BasicJsonType::number_integer_t, CompatibleNumberIntegerType >::value, int > = 0>
void	to_json (BasicJsonType &j, CompatibleNumberIntegerType val) noexcept
template<typename BasicJsonType, typename EnumType, enable_if_t< std::is_enum< EnumType >::value, int > = 0>
void	to_json (BasicJsonType &j, EnumType e) noexcept
template<typename BasicJsonType>
void	to_json (BasicJsonType &j, const std::vector< bool > &e)
template<typename BasicJsonType, typename CompatibleArrayType, enable_if_t< is_compatible_array_type< BasicJsonType, CompatibleArrayType >::value and not is_compatible_object_type< BasicJsonType, CompatibleArrayType >::value and not is_compatible_string_type< BasicJsonType, CompatibleArrayType >::value and not is_basic_json< CompatibleArrayType >::value, int > = 0>
void	to_json (BasicJsonType &j, const CompatibleArrayType &arr)
template<typename BasicJsonType, typename T, enable_if_t< std::is_convertible< T, BasicJsonType >::value, int > = 0>
void	to_json (BasicJsonType &j, const std::valarray< T > &arr)
template<typename BasicJsonType>
void	to_json (BasicJsonType &j, typename BasicJsonType::array_t &&arr)
template<typename BasicJsonType, typename CompatibleObjectType, enable_if_t< is_compatible_object_type< BasicJsonType, CompatibleObjectType >::value and not is_basic_json< CompatibleObjectType >::value, int > = 0>
void	to_json (BasicJsonType &j, const CompatibleObjectType &obj)
template<typename BasicJsonType>
void	to_json (BasicJsonType &j, typename BasicJsonType::object_t &&obj)
template<typename BasicJsonType, typename T, std::size_t N, enable_if_t< not std::is_constructible< typename BasicJsonType::string_t, const T(&)[N]>::value, int > = 0>
void	to_json (BasicJsonType &j, const T(&arr)[N])
template<typename BasicJsonType, typename T1, typename T2, enable_if_t< std::is_constructible< BasicJsonType, T1 >::value &&std::is_constructible< BasicJsonType, T2 >::value, int > = 0>
void	to_json (BasicJsonType &j, const std::pair< T1, T2 > &p)
template<typename BasicJsonType, typename T, enable_if_t< std::is_same< T, iteration_proxy_value< typename BasicJsonType::iterator > >::value, int > = 0>
void	to_json (BasicJsonType &j, const T &b)
template<typename BasicJsonType, typename Tuple, std::size_t... Idx>
void	to_json_tuple_impl (BasicJsonType &j, const Tuple &t, index_sequence< Idx... >)
template<typename FloatType>
JSON_HEDLEY_RETURNS_NON_NULL char *	to_chars (char *first, const char *last, FloatType value)
	generates a decimal representation of the floating-point number value in [first, last).

Variables
template<typename T>
constexpr T	static_const< T >::value

Detailed Description

detail namespace with internal helper functions

This namespace collects functions that should not be exposed, implementations of some basic_json methods, and meta-programming helpers.

Since

version 2.1.0

Typedef Documentation

boolean_function_t

template<typename T>

using nlohmann::detail::boolean_function_t

Initial value:

 
    decltype(std::declval<T&>().boolean(std::declval<bool>()))

is_detected_convertible

template<class To, template< class... > class Op, class... Args>

using nlohmann::detail::is_detected_convertible

Initial value:

 
    std::is_convertible<detected_t<Op, Args...>, To>

key_function_t

template<typename T, typename String>

using nlohmann::detail::key_function_t

Initial value:

 
    decltype(std::declval<T&>().key(std::declval<String&>()))

number_float_function_t

template<typename T, typename Float, typename String>

using nlohmann::detail::number_float_function_t

Initial value:

 decltype(std::declval<T&>().number_float(
                                    std::declval<Float>(), std::declval<const String&>()))

number_integer_function_t

template<typename T, typename Integer>

using nlohmann::detail::number_integer_function_t

Initial value:

 
    decltype(std::declval<T&>().number_integer(std::declval<Integer>()))

number_unsigned_function_t

template<typename T, typename Unsigned>

using nlohmann::detail::number_unsigned_function_t

Initial value:

 
    decltype(std::declval<T&>().number_unsigned(std::declval<Unsigned>()))

parse_error_function_t

template<typename T, typename Exception>

using nlohmann::detail::parse_error_function_t

Initial value:

 decltype(std::declval<T&>().parse_error(
        std::declval<std::size_t>(), std::declval<const std::string&>(),
        std::declval<const Exception&>()))

start_array_function_t

template<typename T>

using nlohmann::detail::start_array_function_t

Initial value:

 
    decltype(std::declval<T&>().start_array(std::declval<std::size_t>()))

start_object_function_t

template<typename T>

using nlohmann::detail::start_object_function_t

Initial value:

 
    decltype(std::declval<T&>().start_object(std::declval<std::size_t>()))

string_function_t

template<typename T, typename String>

using nlohmann::detail::string_function_t

Initial value:

 
    decltype(std::declval<T&>().string(std::declval<String&>()))

Enumeration Type Documentation

error_handler_t

enum class nlohmann::detail::error_handler_t

strong

how to treat decoding errors

Enumerator
strict	throw a type_error exception in case of invalid UTF-8
replace	replace invalid UTF-8 sequences with U+FFFD
ignore	ignore invalid UTF-8 sequences

value_t

enum class nlohmann::detail::value_t : std::uint8_t

strong

the JSON type enumeration

This enumeration collects the different JSON types. It is internally used to distinguish the stored values, and the functions basic_json::is_null(), basic_json::is_object(), basic_json::is_array(), basic_json::is_string(), basic_json::is_boolean(), basic_json::is_number() (with basic_json::is_number_integer(), basic_json::is_number_unsigned(), and basic_json::is_number_float()), basic_json::is_discarded(), basic_json::is_primitive(), and basic_json::is_structured() rely on it.

Note

There are three enumeration entries (number_integer, number_unsigned, and number_float), because the library distinguishes these three types for numbers: basic_json::number_unsigned_t is used for unsigned integers, basic_json::number_integer_t is used for signed integers, and basic_json::number_float_t is used for floating-point numbers or to approximate integers which do not fit in the limits of their respective type.

See also

basic_json::basic_json(const value_t value_type) – create a JSON value with the default value for a given type

Since

version 1.0.0

Enumerator
null	null value
object	object (unordered set of name/value pairs)
array	array (ordered collection of values)
string	string value
boolean	boolean value
number_integer	number value (signed integer)
number_unsigned	number value (unsigned integer)
number_float	number value (floating-point)
discarded	discarded by the the parser callback function

Function Documentation

operator<()

bool nlohmann::detail::operator< ( const value_t lhs, const value_t rhs )

inlinenoexcept

comparison operator for JSON types

Returns an ordering that is similar to Python:

• order: null < boolean < number < object < array < string
• furthermore, each type is not smaller than itself
• discarded values are not comparable

Since

version 1.0.0

to_chars()

template<typename FloatType>

JSON_HEDLEY_RETURNS_NON_NULL char * nlohmann::detail::to_chars	(	char *	first,
		const char *	last,
		FloatType	value )

generates a decimal representation of the floating-point number value in [first, last).

The format of the resulting decimal representation is similar to printf's g format. Returns an iterator pointing past-the-end of the decimal representation.

Note

The input number must be finite, i.e. NaN's and Inf's are not supported.

The buffer must be large enough.

The result is NOT null-terminated.