basic_json¶
Defined in header <json.hpp>
template<
template<typename U, typename V, typename... Args> class ObjectType = std::map,
template<typename U, typename... Args> class ArrayType = std::vector,
class StringType = std::string,
class BooleanType = bool,
class NumberIntegerType = std::int64_t,
class NumberUnsignedType = std::uint64_t,
class NumberFloatType = double,
template<typename U> class AllocatorType = std::allocator,
template<typename T, typename SFINAE = void> class JSONSerializer = adl_serializer,
class BinaryType = std::vector<std::uint8_t>
>
class basic_json;
Specializations¶
- json - default specialization
- ordered_json - specialization that maintains the insertion order of object keys
Template parameters¶
Template parameter | Description | Derived type |
---|---|---|
ObjectType | type for JSON objects | object_t |
ArrayType | type for JSON arrays | array_t |
StringType | type for JSON strings and object keys | string_t |
BooleanType | type for JSON booleans | boolean_t |
NumberIntegerType | type for JSON integer numbers | number_integer_t |
NumberUnsignedType | type for JSON unsigned integer numbers | number_unsigned_t |
NumberFloatType | type for JSON floating-point numbers | number_float_t |
AllocatorType | type of the allocator to use | |
JSONSerializer | the serializer to resolve internal calls to to_json() and from_json() | json_serializer |
BinaryType | type for binary arrays | binary_t |
Iterator invalidation¶
Todo
Member types¶
- adl_serializer - the default serializer
- value_t - the JSON type enumeration
- json_pointer - JSON Pointer implementation
- json_serializer - type of the serializer to for conversions from/to JSON
- error_handler_t - type to choose behavior on decoding errors
- cbor_tag_handler_t - type to choose how to handle CBOR tags
- initializer_list_t
- input_format_t - type to choose the format to parse
- json_sax_t
Exceptions¶
- exception - general exception of the
basic_json
class- parse_error - exception indicating a parse error
- invalid_iterator - exception indicating errors with iterators
- type_error - exception indicating executing a member function with a wrong type
- out_of_range - exception indicating access out of the defined range
- other_error - exception indicating other library errors
Container types¶
Type | Definition |
---|---|
value_type | basic_json |
reference | value_type& |
const_reference | const value_type& |
difference_type | std::ptrdiff_t |
size_type | std::size_t |
allocator_type | AllocatorType<basic_json> |
pointer | std::allocator_traits<allocator_type>::pointer |
const_pointer | std::allocator_traits<allocator_type>::const_pointer |
iterator | LegacyBidirectionalIterator |
const_iterator | constant LegacyBidirectionalIterator |
reverse_iterator | reverse iterator, derived from iterator |
const_reverse_iterator | reverse iterator, derived from const_iterator |
iteration_proxy | helper type for items function |
JSON value data types¶
- array_t - type for arrays
- binary_t - type for binary arrays
- boolean_t - type for booleans
- number_float_t - type for numbers (floating-point)
- number_integer_t - type for numbers (integer)
- number_unsigned_t - type for numbers (unsigned)
- object_comparator_t - comparator for objects
- object_t - type for objects
- string_t - type for strings
Parser callback¶
- parse_event_t - parser event types
- parser_callback_t - per-element parser callback type
Member functions¶
- (constructor)
- (destructor)
- operator= - copy assignment
- array (static) - explicitly create an array
- binary (static) - explicitly create a binary array
- object (static) - explicitly create an object
Object inspection¶
Functions to inspect the type of a JSON value.
- type - return the type of the JSON value
- operator value_t - return the type of the JSON value
- type_name - return the type as string
- is_primitive - return whether type is primitive
- is_structured - return whether type is structured
- is_null - return whether value is null
- is_boolean - return whether value is a boolean
- is_number - return whether value is a number
- is_number_integer - return whether value is an integer number
- is_number_unsigned - return whether value is an unsigned integer number
- is_number_float - return whether value is a floating-point number
- is_object - return whether value is an object
- is_array - return whether value is an array
- is_string - return whether value is a string
- is_binary - return whether value is a binary array
- is_discarded - return whether value is discarded
Value access¶
Direct access to the stored value of a JSON value.
- get - get a value
- get_to - get a value and write it to a destination
- get_ptr - get a pointer value
- get_ref - get a reference value
- operator ValueType - get a value
- get_binary - get a binary value
Element access¶
Access to the JSON value
- at - access specified element with bounds checking
- operator[] - access specified element
- value - access specified object element with default value
- front - access the first element
- back - access the last element
Lookup¶
- find - find an element in a JSON object
- count - returns the number of occurrences of a key in a JSON object
- contains - check the existence of an element in a JSON object
Iterators¶
- begin - returns an iterator to the first element
- cbegin - returns a const iterator to the first element
- end - returns an iterator to one past the last element
- cend - returns a const iterator to one past the last element
- rbegin - returns an iterator to the reverse-beginning
- rend - returns an iterator to the reverse-end
- crbegin - returns a const iterator to the reverse-beginning
- crend - returns a const iterator to the reverse-end
- items - wrapper to access iterator member functions in range-based for
Capacity¶
- empty - checks whether the container is empty
- size - returns the number of elements
- max_size - returns the maximum possible number of elements
Modifiers¶
- clear - clears the contents
- push_back - add a value to an array/object
- operator+= - add a value to an array/object
- emplace_back - add a value to an array
- emplace - add a value to an object if key does not exist
- erase - remove elements
- insert - inserts elements
- update - updates a JSON object from another object, overwriting existing keys
- swap - exchanges the values
Lexicographical comparison operators¶
- operator== - comparison: equal
- operator!= - comparison: not equal
- operator< - comparison: less than
- operator<= - comparison: less than or equal
- operator> - comparison: greater than
- operator>= - comparison: greater than or equal
Serialization / Dumping¶
- dump - serialization
- to_string - user-defined to_string function for JSON values
Deserialization / Parsing¶
- parse (static) - deserialize from a compatible input
- accept (static) - check if the input is valid JSON
- sax_parse (static) - generate SAX events
JSON Pointer functions¶
JSON Patch functions¶
JSON Merge Patch functions¶
- merge_patch - applies a JSON Merge Patch
Static functions¶
- meta - returns version information on the library
- get_allocator - returns the allocator associated with the container
Binary formats¶
- from_bson (static) - create a JSON value from an input in BSON format
- from_cbor (static) - create a JSON value from an input in CBOR format
- from_msgpack (static) - create a JSON value from an input in MessagePack format
- from_ubjson (static) - create a JSON value from an input in UBJSON format
- to_bson (static) - create a BSON serialization of a given JSON value
- to_cbor (static) - create a CBOR serialization of a given JSON value
- to_msgpack (static) - create a MessagePack serialization of a given JSON value
- to_ubjson (static) - create a UBJSON serialization of a given JSON value
Non-member functions¶
- operator<<(std::ostream&) - serialize to stream
- operator>>(std::istream&) - deserialize from stream
Literals¶
- operator""_json - user-defined string literal for JSON values
- operator""_json_pointer - user-defined string literal for JSON pointers
Helper classes¶
- std::hash<nlohmann::json>
- std::less<nlohmann::value_t>
- std::swap<nlohmann::json>