Dendro in Greek language means tree. The Dendro library is a large scale (262K cores on ORNL's Titan) distributed memory adaptive octree framework. The main goal of Dendro is to perform large scale multiphysics simulations efficeiently in mordern supercomputers. Dendro consists of efficient parallel data structures and algorithms to perform variational ( finite element) methods and finite difference mthods on 2:1 balanced arbitary adaptive octrees which enables the users to perform simulations raning from black holes (binary black hole mergers) to blood flow in human body, where applications ranging from relativity, astrophysics to biomedical engineering.
template<typename ValueType , typename std::enable_if< not std::is_pointer< ValueType >::value and not std::is_same< ValueType, detail::json_ref< basic_json >>::value and not std::is_same< ValueType, typename string_t::value_type >::value and not detail::is_basic_json< ValueType >::value and not std::is_same< ValueType, std::initializer_list< typename string_t::value_type >>::value, int >::type = 0>
StandardLayoutType: JSON values have standard layout: All non-static data members are private and standard layout types, the class has no virtual functions or (virtual) base classes.
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>
An implementation may set limits on the maximum depth of nesting.
In this class, the array's limit of nesting is not explicitly constrained. However, a maximum depth of nesting may be introduced by the compiler or runtime environment. A theoretical limit can be queried by calling the max_size function of a JSON array.
Storage
Arrays are stored as pointers in a basic_json type. That is, for any access to array values, a pointer of type array_t* must be dereferenced.
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>
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>
This class is an extension of std::exception objects with a member id for exception ids. It is used as the base class for all exceptions thrown by the basic_json class. This class can hence be used as "wildcard" to catch exceptions.
Subclasses:
parse_error for exceptions indicating a parse error
invalid_iterator for exceptions indicating errors with iterators
type_error for exceptions indicating executing a member function with a wrong type
out_of_range for exceptions indicating access out of the defined range
other_error for exceptions indicating other library errors
{The following code shows how arbitrary library exceptions can be caught.,exception}
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>
This exception is thrown if iterators passed to a library function do not match the expected semantics.
Exceptions have ids 2xx.
name / id
example message
description
json.exception.invalid_iterator.201
iterators are not compatible
The iterators passed to constructor basic_json(InputIT first, InputIT last) are not compatible, meaning they do not belong to the same container. Therefore, the range (first, last) is invalid.
json.exception.invalid_iterator.202
iterator does not fit current value
In an erase or insert function, the passed iterator pos does not belong to the JSON value for which the function was called. It hence does not define a valid position for the deletion/insertion.
json.exception.invalid_iterator.203
iterators do not fit current value
Either iterator passed to function erase(IteratorType first, IteratorType last) does not belong to the JSON value from which values shall be erased. It hence does not define a valid range to delete values from.
json.exception.invalid_iterator.204
iterators out of range
When an iterator range for a primitive type (number, boolean, or string) is passed to a constructor or an erase function, this range has to be exactly (begin(), end()), because this is the only way the single stored value is expressed. All other ranges are invalid.
json.exception.invalid_iterator.205
iterator out of range
When an iterator for a primitive type (number, boolean, or string) is passed to an erase function, the iterator has to be the begin() iterator, because it is the only way to address the stored value. All other iterators are invalid.
The key() member function can only be used on iterators belonging to a JSON object, because other types do not have a concept of a key.
json.exception.invalid_iterator.208
cannot use operator[] for object iterators
The operator[] to specify a concrete offset cannot be used on iterators belonging to a JSON object, because JSON objects are unordered.
json.exception.invalid_iterator.209
cannot use offsets with object iterators
The offset operators (+, -, +=, -=) cannot be used on iterators belonging to a JSON object, because JSON objects are unordered.
json.exception.invalid_iterator.210
iterators do not fit
The iterator range passed to the insert function are not compatible, meaning they do not belong to the same container. Therefore, the range (first, last) is invalid.
json.exception.invalid_iterator.211
passed iterators may not belong to container
The iterator range passed to the insert function must not be a subrange of the container to insert to.
json.exception.invalid_iterator.212
cannot compare iterators of different containers
When two iterators are compared, they must belong to the same container.
json.exception.invalid_iterator.213
cannot compare order of object iterators
The order of object iterators cannot be compared, because JSON objects are unordered.
json.exception.invalid_iterator.214
cannot get value
Cannot get value for iterator: Either the iterator belongs to a null value or it is an iterator to a primitive type (number, boolean, or string), but the iterator is different to begin().
{The following code shows how an invalid_iterator exception can be caught.,invalid_iterator}
See also
exception for the base class of the library exceptions
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>
A JSON pointer defines a string syntax for identifying a specific value within a JSON document. It can be used with functions at and operator[]. Furthermore, JSON pointers are the base for JSON patches.
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>
The representation of numbers is similar to that used in most programming languages. A number is represented in base 10 using decimal digits. It contains an integer component that may be prefixed with an optional minus sign, which may be followed by a fraction part and/or an exponent part. Leading zeros are not allowed. (...) Numeric values that cannot be represented in the grammar below (such as Infinity and NaN) are not permitted.
This description includes both integer and floating-point numbers. However, C++ allows more precise storage if it is known whether the number is a signed integer, an unsigned integer or a floating-point number. Therefore, three different types, number_integer_t, number_unsigned_t and number_float_t are used.
To store floating-point numbers in C++, a type is defined by the template parameter NumberFloatType which chooses the type to use.
Default type
With the default values for NumberFloatType (double), the default value for number_float_t is:
double
Default behavior
The restrictions about leading zeros is not enforced in C++. Instead, leading zeros in floating-point literals will be ignored. Internally, the value will be stored as decimal number. For instance, the C++ floating-point literal 01.2 will be serialized to 1.2. During deserialization, leading zeros yield an error.
Not-a-number (NaN) values will be serialized to null.
This specification allows implementations to set limits on the range and precision of numbers accepted. Since software that implements IEEE 754-2008 binary64 (double precision) numbers is generally available and widely used, good interoperability can be achieved by implementations that expect no more precision or range than these provide, in the sense that implementations will approximate JSON numbers within the expected precision.
This implementation does exactly follow this approach, as it uses double precision floating-point numbers. Note values smaller than -1.79769313486232e+308 and values greater than 1.79769313486232e+308 will be stored as NaN internally and be serialized to null.
Storage
Floating-point number values are stored directly inside a basic_json type.
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>
The representation of numbers is similar to that used in most programming languages. A number is represented in base 10 using decimal digits. It contains an integer component that may be prefixed with an optional minus sign, which may be followed by a fraction part and/or an exponent part. Leading zeros are not allowed. (...) Numeric values that cannot be represented in the grammar below (such as Infinity and NaN) are not permitted.
This description includes both integer and floating-point numbers. However, C++ allows more precise storage if it is known whether the number is a signed integer, an unsigned integer or a floating-point number. Therefore, three different types, number_integer_t, number_unsigned_t and number_float_t are used.
To store integer numbers in C++, a type is defined by the template parameter NumberIntegerType which chooses the type to use.
Default type
With the default values for NumberIntegerType (int64_t), the default value for number_integer_t is:
int64_t
Default behavior
The restrictions about leading zeros is not enforced in C++. Instead, leading zeros in integer literals lead to an interpretation as octal number. Internally, the value will be stored as decimal number. For instance, the C++ integer literal 010 will be serialized to 8. During deserialization, leading zeros yield an error.
Not-a-number (NaN) values will be serialized to null.
An implementation may set limits on the range and precision of numbers.
When the default type is used, the maximal integer number that can be stored is 9223372036854775807 (INT64_MAX) and the minimal integer number that can be stored is -9223372036854775808 (INT64_MIN). Integer numbers that are out of range will yield over/underflow when used in a constructor. During deserialization, too large or small integer numbers will be automatically be stored as number_unsigned_t or number_float_t.
Note that when such software is used, numbers that are integers and are in the range are interoperable in the sense that implementations will agree exactly on their numeric values.
As this range is a subrange of the exactly supported range [INT64_MIN, INT64_MAX], this class's integer type is interoperable.
Storage
Integer number values are stored directly inside a basic_json type.
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>
The representation of numbers is similar to that used in most programming languages. A number is represented in base 10 using decimal digits. It contains an integer component that may be prefixed with an optional minus sign, which may be followed by a fraction part and/or an exponent part. Leading zeros are not allowed. (...) Numeric values that cannot be represented in the grammar below (such as Infinity and NaN) are not permitted.
This description includes both integer and floating-point numbers. However, C++ allows more precise storage if it is known whether the number is a signed integer, an unsigned integer or a floating-point number. Therefore, three different types, number_integer_t, number_unsigned_t and number_float_t are used.
To store unsigned integer numbers in C++, a type is defined by the template parameter NumberUnsignedType which chooses the type to use.
Default type
With the default values for NumberUnsignedType (uint64_t), the default value for number_unsigned_t is:
uint64_t
Default behavior
The restrictions about leading zeros is not enforced in C++. Instead, leading zeros in integer literals lead to an interpretation as octal number. Internally, the value will be stored as decimal number. For instance, the C++ integer literal 010 will be serialized to 8. During deserialization, leading zeros yield an error.
Not-a-number (NaN) values will be serialized to null.
An implementation may set limits on the range and precision of numbers.
When the default type is used, the maximal integer number that can be stored is 18446744073709551615 (UINT64_MAX) and the minimal integer number that can be stored is 0. Integer numbers that are out of range will yield over/underflow when used in a constructor. During deserialization, too large or small integer numbers will be automatically be stored as number_integer_t or number_float_t.
Note that when such software is used, numbers that are integers and are in the range are interoperable in the sense that implementations will agree exactly on their numeric values.
As this range is a subrange (when considered in conjunction with the number_integer_t type) of the exactly supported range [0, UINT64_MAX], this class's integer type is interoperable.
Storage
Integer number values are stored directly inside a basic_json type.
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>
An object is an unordered collection of zero or more name/value pairs, where a name is a string and a value is a string, number, boolean, null, object, or array.
To store objects in C++, a type is defined by the template parameters described below.
Template Parameters
ObjectType
the container to store objects (e.g., std::map or std::unordered_map)
StringType
the type of the keys or names (e.g., std::string). The comparison function std::less<StringType> is used to order elements inside the container.
AllocatorType
the allocator to use for objects (e.g., std::allocator)
Default type
With the default values for ObjectType (std::map), StringType (std::string), and AllocatorType (std::allocator), the default value for object_t is:
The choice of object_t influences the behavior of the JSON class. With the default type, objects have the following behavior:
When all names are unique, objects will be interoperable in the sense that all software implementations receiving that object will agree on the name-value mappings.
When the names within an object are not unique, it is unspecified which one of the values for a given key will be chosen. For instance, {"key": 2, "key": 1} could be equal to either {"key": 1} or {"key": 2}.
Internally, name/value pairs are stored in lexicographical order of the names. Objects will also be serialized (see dump) in this order. For instance, {"b": 1, "a": 2} and {"a": 2, "b": 1} will be stored and serialized as {"a": 2, "b": 1}.
When comparing objects, the order of the name/value pairs is irrelevant. This makes objects interoperable in the sense that they will not be affected by these differences. For instance, {"b": 1, "a": 2} and {"a": 2, "b": 1} will be treated as equal.
An implementation may set limits on the maximum depth of nesting.
In this class, the object's limit of nesting is not explicitly constrained. However, a maximum depth of nesting may be introduced by the compiler or runtime environment. A theoretical limit can be queried by calling the max_size function of a JSON object.
Storage
Objects are stored as pointers in a basic_json type. That is, for any access to object values, a pointer of type object_t* must be dereferenced.
The order name/value pairs are added to the object is not preserved by the library. Therefore, iterating an object may return name/value pairs in a different order than they were originally stored. In fact, keys will be traversed in alphabetical order as std::map with std::less is used by default. Please note this behavior conforms to RFC 7159, because any order implements the specified "unordered" nature of JSON objects.
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>
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>
exception indicating access out of the defined range
This exception is thrown in case a library function is called on an input parameter that exceeds the expected range, for instance in case of array indices or nonexisting object keys.
Exceptions have ids 4xx.
name / id
example message
description
json.exception.out_of_range.401
array index 3 is out of range
The provided array index i is larger than size-1.
json.exception.out_of_range.402
array index '-' (3) is out of range
The special array index - in a JSON Pointer never describes a valid element of the array, but the index past the end. That is, it can only be used to add elements at this position, but not to read it.
json.exception.out_of_range.403
key 'foo' not found
The provided key was not found in the JSON object.
json.exception.out_of_range.404
unresolved reference token 'foo'
A reference token in a JSON Pointer could not be resolved.
json.exception.out_of_range.405
JSON pointer has no parent
The JSON Patch operations 'remove' and 'add' can not be applied to the root element of the JSON value.
json.exception.out_of_range.406
number overflow parsing '10E1000'
A parsed number could not be stored as without changing it to NaN or INF.
json.exception.out_of_range.407
number overflow serializing '9223372036854775808'
UBJSON only supports integers numbers up to 9223372036854775807.
json.exception.out_of_range.408
excessive array size: 8658170730974374167
The size (following #) of an UBJSON array or object exceeds the maximal capacity.
{The following code shows how an out_of_range exception can be caught.,out_of_range}
See also
exception for the base class of the library exceptions
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>
This exception is thrown by the library when a parse error occurs. Parse errors can occur during the deserialization of JSON text, CBOR, MessagePack, as well as when using JSON Patch.
Member byte holds the byte index of the last read character in the input file.
Exceptions have ids 1xx.
name / id
example message
description
json.exception.parse_error.101
parse error at 2: unexpected end of input; expected string literal
This error indicates a syntax error while deserializing a JSON text. The error message describes that an unexpected token (character) was encountered, and the member byte indicates the error position.
json.exception.parse_error.102
parse error at 14: missing or wrong low surrogate
JSON uses the \uxxxx format to describe Unicode characters. Code points above above 0xFFFF are split into two \uxxxx entries ("surrogate pairs"). This error indicates that the surrogate pair is incomplete or contains an invalid code point.
json.exception.parse_error.103
parse error: code points above 0x10FFFF are invalid
Unicode supports code points up to 0x10FFFF. Code points above 0x10FFFF are invalid.
json.exception.parse_error.104
parse error: JSON patch must be an array of objects
RFC 6902 requires a JSON Patch document to be a JSON document that represents an array of objects.
json.exception.parse_error.105
parse error: operation must have string member 'op'
An operation of a JSON Patch document must contain exactly one "op" member, whose value indicates the operation to perform. Its value must be one of "add", "remove", "replace", "move", "copy", or "test"; other values are errors.
json.exception.parse_error.106
parse error: array index '01' must not begin with '0'
An array index in a JSON Pointer (RFC 6901) may be 0 or any number without a leading 0.
json.exception.parse_error.107
parse error: JSON pointer must be empty or begin with '/' - was: 'foo'
A JSON Pointer must be a Unicode string containing a sequence of zero or more reference tokens, each prefixed by a / character.
json.exception.parse_error.108
parse error: escape character '~' must be followed with '0' or '1'
In a JSON Pointer, only ~0 and ~1 are valid escape sequences.
json.exception.parse_error.109
parse error: array index 'one' is not a number
A JSON Pointer array index must be a number.
json.exception.parse_error.110
parse error at 1: cannot read 2 bytes from vector
When parsing CBOR or MessagePack, the byte vector ends before the complete value has been read.
json.exception.parse_error.112
parse error at 1: error reading CBOR; last byte: 0xF8
Not all types of CBOR or MessagePack are supported. This exception occurs if an unsupported byte was read.
json.exception.parse_error.113
parse error at 2: expected a CBOR string; last byte: 0x98
While parsing a map key, a value that is not a string has been read.
Note
For an input with n bytes, 1 is the index of the first character and n+1 is the index of the terminating null byte or the end of file. This also holds true when reading a byte vector (CBOR or MessagePack).
{The following code shows how a parse_error exception can be caught.,parse_error}
See also
exception for the base class of the library exceptions
invalid_iterator for exceptions indicating errors with iterators
type_error for exceptions indicating executing a member function with a wrong type
out_of_range for exceptions indicating access out of the defined range
other_error for exceptions indicating other library errors
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>
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>
With a parser callback function, the result of parsing a JSON text can be influenced. When passed to parse, it is called on certain events (passed as parse_event_t via parameter event) with a set recursion depth depth and context JSON value parsed. The return value of the callback function is a boolean indicating whether the element that emitted the callback shall be kept or not.
We distinguish six scenarios (determined by the event type) in which the callback function can be called. The following table describes the values of the parameters depth, event, and parsed.
parameter event
description
parameter depth
parameter parsed
parse_event_t::object_start
the parser read { and started to process a JSON object
depth of the parent of the JSON object
a JSON value with type discarded
parse_event_t::key
the parser read a key of a value in an object
depth of the currently parsed JSON object
a JSON string containing the key
parse_event_t::object_end
the parser read } and finished processing a JSON object
depth of the parent of the JSON object
the parsed JSON object
parse_event_t::array_start
the parser read [ and started to process a JSON array
depth of the parent of the JSON array
a JSON value with type discarded
parse_event_t::array_end
the parser read ] and finished processing a JSON array
depth of the parent of the JSON array
the parsed JSON array
parse_event_t::value
the parser finished reading a JSON value
depth of the value
the parsed JSON value
Example when certain parse events are triggered
Discarding a value (i.e., returning false) has different effects depending on the context in which function was called:
Discarded values in structured types are skipped. That is, the parser will behave as if the discarded value was never read.
In case a value outside a structured type is skipped, it is replaced with null. This case happens if the top-level element is skipped.
Parameters
[in]
depth
the depth of the recursion during parsing
[in]
event
an event of type parse_event_t indicating the context in the callback function has been called
[in,out]
parsed
the current intermediate parse result; note that writing to this value has no effect for parse_event_t::key events
Returns
Whether the JSON value which called the function during parsing should be kept (true) or not (false). In the latter case, it is either skipped completely or replaced by an empty discarded object.
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>
A string is a sequence of zero or more Unicode characters.
To store objects in C++, a type is defined by the template parameter described below. Unicode values are split by the JSON class into byte-sized characters during deserialization.
Template Parameters
StringType
the container to store strings (e.g., std::string). Note this container is used for keys/names in objects, see object_t.
Default type
With the default values for StringType (std::string), the default value for string_t is:
std::string
Encoding
Strings are stored in UTF-8 encoding. Therefore, functions like std::string::size() or std::string::length() return the number of bytes in the string rather than the number of characters or glyphs.
Software implementations are typically required to test names of object members for equality. Implementations that transform the textual representation into sequences of Unicode code units and then perform the comparison numerically, code unit by code unit, are interoperable in the sense that implementations will agree in all cases on equality or inequality of two strings. For example, implementations that compare strings with escaped characters unconverted may incorrectly find that "a\\b" and "a\u005Cb" are not equal.
This implementation is interoperable as it does compare strings code unit by code unit.
Storage
String values are stored as pointers in a basic_json type. That is, for any access to string values, a pointer of type string_t* must be dereferenced.
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>
exception indicating executing a member function with a wrong type
This exception is thrown in case of a type error; that is, a library function is executed on a JSON value whose type does not match the expected semantics.
Exceptions have ids 3xx.
name / id
example message
description
json.exception.type_error.301
cannot create object from initializer list
To create an object from an initializer list, the initializer list must consist only of a list of pairs whose first element is a string. When this constraint is violated, an array is created instead.
json.exception.type_error.302
type must be object, but is array
During implicit or explicit value conversion, the JSON type must be compatible to the target type. For instance, a JSON string can only be converted into string types, but not into numbers or boolean types.
json.exception.type_error.303
incompatible ReferenceType for get_ref, actual type is object
To retrieve a reference to a value stored in a basic_json object with get_ref, the type of the reference must match the value type. For instance, for a JSON array, the ReferenceType must be array_t&.
The update() member functions can only be executed for certain JSON types.
json.exception.type_error.313
invalid value to unflatten
The unflatten function converts an object whose keys are JSON Pointers back into an arbitrary nested JSON value. The JSON Pointers must not overlap, because then the resulting value would not be well defined.
json.exception.type_error.314
only objects can be unflattened
The unflatten function only works for an object whose keys are JSON Pointers.
json.exception.type_error.315
values in object must be primitive
The unflatten function only works for an object whose keys are JSON Pointers and whose values are primitive.
json.exception.type_error.316
invalid UTF-8 byte at index 10: 0x7E
The dump function only works with UTF-8 encoded strings; that is, if you assign a std::string to a JSON value, make sure it is UTF-8 encoded.
{The following code shows how a type_error exception can be caught.,type_error}
See also
exception for the base class of the library exceptions
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>
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>
Create a null JSON value. It either takes a null pointer as parameter (explicitly creating null) or no parameter (implicitly creating null). The passed null pointer itself is not read – it is only used to choose the right constructor.
Constant.
No-throw guarantee: this constructor never throws exceptions.
{The following code shows the constructor with and without a null pointer parameter.,basic_json__nullptr_t}
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>
template<typename CompatibleType , typename U = detail::uncvref_t<CompatibleType>, detail::enable_if_t< detail::is_compatible_type< basic_json_t, U >::value, int > = 0>
This is a "catch all" constructor for all compatible JSON types; that is, types for which a to_json() method exists. The constructor forwards the parameter val to that method (to json_serializer<U>::to_json method with U = uncvref_t<CompatibleType>, to be exact).
Template type CompatibleType includes, but is not limited to, the following types:
arrays: array_t and all kinds of compatible containers such as std::vector, std::deque, std::list, std::forward_list, std::array, std::valarray, std::set, std::unordered_set, std::multiset, and std::unordered_multiset with a value_type from which a basic_json value can be constructed.
objects: object_t and all kinds of compatible associative containers such as std::map, std::unordered_map, std::multimap, and std::unordered_multimap with a key_type compatible to string_t and a value_type from which a basic_json value can be constructed.
strings: string_t, string literals, and all compatible string containers can be used.
json_serializer<U> has a to_json(basic_json_t&, CompatibleType&&) method
U
= uncvref_t<CompatibleType>
Parameters
[in]
val
the value to be forwarded to the respective constructor
Usually linear in the size of the passed val, also depending on the implementation of the called to_json() method.
Depends on the called constructor. For types directly supported by the library (i.e., all types for which no to_json() function was provided), strong guarantee holds: if an exception is thrown, there are no changes to any JSON value.
{The following code shows the constructor with several compatible types.,basic_json__CompatibleType}
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>
template<typename BasicJsonType , detail::enable_if_t< detail::is_basic_json< BasicJsonType >::value and not std::is_same< basic_json, BasicJsonType >::value, int > = 0>
This is a constructor for existing basic_json types. It does not hijack copy/move constructors, since the parameter has different template arguments than the current ones.
The constructor tries to convert the internal m_value of the parameter.
Usually linear in the size of the passed val, also depending on the implementation of the called to_json() method.
Depends on the called constructor. For types directly supported by the library (i.e., all types for which no to_json() function was provided), strong guarantee holds: if an exception is thrown, there are no changes to any JSON value.
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>
create a container (array or object) from an initializer list
Creates a JSON value of type array or object from the passed initializer list init. In case type_deduction is true (default), the type of the JSON value to be created is deducted from the initializer list init according to the following rules:
If the list is empty, an empty JSON object value {} is created.
If the list consists of pairs whose first element is a string, a JSON object value is created where the first elements of the pairs are treated as keys and the second elements are as values.
In all other cases, an array is created.
The rules aim to create the best fit between a C++ initializer list and JSON values. The rationale is as follows:
The empty initializer list is written as {} which is exactly an empty JSON object.
C++ has no way of describing mapped types other than to list a list of pairs. As JSON requires that keys must be of type string, rule 2 is the weakest constraint one can pose on initializer lists to interpret them as an object.
In all other cases, the initializer list could not be interpreted as JSON object type, so interpreting it as JSON array type is safe.
With the rules described above, the following JSON values cannot be expressed by an initializer list:
arrays whose elements satisfy rule 2: use array(initializer_list_t) with the same initializer list in this case
Note
When used without parentheses around an empty initializer list, basic_json() is called instead of this function, yielding the JSON null value.
Parameters
[in]
init
initializer list with JSON values
[in]
type_deduction
internal parameter; when set to true, the type of the JSON value is deducted from the initializer list init; when set to false, the type provided via manual_type is forced. This mode is used by the functions array(initializer_list_t) and object(initializer_list_t).
[in]
manual_type
internal parameter; when type_deduction is set to false, the created JSON value will use the provided type (only value_t::array and value_t::object are valid); when type_deduction is set to true, this parameter has no effect
Exceptions
type_error.301
if type_deduction is false, manual_type is value_t::object, but init contains an element which is not a pair whose first element is a string. In this case, the constructor could not create an object. If type_deduction would have be true, an array would have been created. See object(initializer_list_t) for an example.
Linear in the size of the initializer list init.
Strong guarantee: if an exception is thrown, there are no changes to any JSON value.
{The example below shows how JSON values are created from initializer lists.,basic_json__list_init_t}
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>
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>
template<class InputIT , typename std::enable_if< std::is_same< InputIT, typename basic_json_t::iterator >::value or std::is_same< InputIT, typename basic_json_t::const_iterator >::value, int >::type = 0>
construct a JSON container given an iterator range
Constructs the JSON value with the contents of the range [first, last). The semantics depends on the different types a JSON value can have:
In case of a null type, invalid_iterator.206 is thrown.
In case of other primitive types (number, boolean, or string), first must be begin() and last must be end(). In this case, the value is copied. Otherwise, invalid_iterator.204 is thrown.
In case of structured types (array, object), the constructor behaves as similar versions for std::vector or std::map; that is, a JSON array or object is constructed from the values in the range.
Iterators first and last must be initialized. This precondition is enforced with an assertion (see warning). If assertions are switched off, a violation of this precondition yields undefined behavior.
Range [first, last) is valid. Usually, this precondition cannot be checked efficiently. Only certain edge cases are detected; see the description of the exceptions below. A violation of this precondition yields undefined behavior.
Warning
A precondition is enforced with a runtime assertion that will result in calling std::abort if this precondition is not met. Assertions can be disabled by defining NDEBUG at compile time. See http://en.cppreference.com/w/cpp/error/assert for more information.
Exceptions
invalid_iterator.201
if iterators first and last are not compatible (i.e., do not belong to the same JSON value). In this case, the range [first, last) is undefined.
invalid_iterator.204
if iterators first and last belong to a primitive type (number, boolean, or string), but first does not point to the first element any more. In this case, the range [first, last) is undefined. See example code below.
invalid_iterator.206
if iterators first and last belong to a null value. In this case, the range [first, last) is undefined.
Linear in distance between first and last.
Strong guarantee: if an exception is thrown, there are no changes to any JSON value.
{The example below shows several ways to create JSON values by specifying a subrange with iterators.,basic_json__InputIt_InputIt}
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>
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>
Move constructor. Constructs a JSON value with the contents of the given value other using move semantics. It "steals" the resources from other and leaves it as JSON null value.
Parameters
[in,out]
other
value to move to this object
Postcondition
*this has the same value as other before the call.
other is a JSON null value.
Constant.
No-throw guarantee: this constructor never throws exceptions.
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>
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>
explicitly create an array from an initializer list
Creates a JSON array value from a given initializer list. That is, given a list of values a, b, c, creates the JSON value [a, b, c]. If the initializer list is empty, the empty array [] is created.
Note
This function is only needed to express two edge cases that cannot be realized with the initializer list constructor (basic_json(initializer_list_t, bool, value_t)). These cases are:
creating an array whose elements are all pairs whose first element is a string – in this case, the initializer list constructor would create an object, taking the first elements as keys
creating an empty array – passing the empty initializer list to the initializer list constructor yields an empty object
Parameters
[in]
init
initializer list with JSON values to create an array from (optional)
Returns
JSON array value
Linear in the size of init.
Strong guarantee: if an exception is thrown, there are no changes to any JSON value.
{The following code shows an example for the array function.,array}
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>
access specified array element with bounds checking
Returns a reference to the element at specified location idx, with bounds checking.
Parameters
[in]
idx
index of the element to access
Returns
reference to the element at index idx
Exceptions
type_error.304
if the JSON value is not an array; in this case, calling at with an index makes no sense. See example below.
out_of_range.401
if the index idx is out of range of the array; that is, idx >= size(). See example below.
Strong guarantee: if an exception is thrown, there are no changes in the JSON value.
Constant.
Since
version 1.0.0
{The example below shows how array elements can be read and written using at(). It also demonstrates the different exceptions that can be thrown.,at__size_type}
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>
access specified array element with bounds checking
Returns a const reference to the element at specified location idx, with bounds checking.
Parameters
[in]
idx
index of the element to access
Returns
const reference to the element at index idx
Exceptions
type_error.304
if the JSON value is not an array; in this case, calling at with an index makes no sense. See example below.
out_of_range.401
if the index idx is out of range of the array; that is, idx >= size(). See example below.
Strong guarantee: if an exception is thrown, there are no changes in the JSON value.
Constant.
Since
version 1.0.0
{The example below shows how array elements can be read using at(). It also demonstrates the different exceptions that can be thrown., at__size_type_const}
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>
{The example below shows how object elements can be read and written using at(). It also demonstrates the different exceptions that can be thrown.,at__object_t_key_type}
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>
{The example below shows how object elements can be read using at(). It also demonstrates the different exceptions that can be thrown., at__object_t_key_type_const}
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>
Returns a reference to the element at with specified JSON pointer ptr, with bounds checking.
Parameters
[in]
ptr
JSON pointer to the desired element
Returns
reference to the element pointed to by ptr
Exceptions
parse_error.106
if an array index in the passed JSON pointer ptr begins with '0'. See example below.
parse_error.109
if an array index in the passed JSON pointer ptr is not a number. See example below.
out_of_range.401
if an array index in the passed JSON pointer ptr is out of range. See example below.
out_of_range.402
if the array index '-' is used in the passed JSON pointer ptr. As at provides checked access (and no elements are implicitly inserted), the index '-' is always invalid. See example below.
out_of_range.403
if the JSON pointer describes a key of an object which cannot be found. See example below.
out_of_range.404
if the JSON pointer ptr can not be resolved. See example below.
Strong guarantee: if an exception is thrown, there are no changes in the JSON value.
Constant.
Since
version 2.0.0
{The behavior is shown in the example.,at_json_pointer}
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>
Returns a const reference to the element at with specified JSON pointer ptr, with bounds checking.
Parameters
[in]
ptr
JSON pointer to the desired element
Returns
reference to the element pointed to by ptr
Exceptions
parse_error.106
if an array index in the passed JSON pointer ptr begins with '0'. See example below.
parse_error.109
if an array index in the passed JSON pointer ptr is not a number. See example below.
out_of_range.401
if an array index in the passed JSON pointer ptr is out of range. See example below.
out_of_range.402
if the array index '-' is used in the passed JSON pointer ptr. As at provides checked access (and no elements are implicitly inserted), the index '-' is always invalid. See example below.
out_of_range.403
if the JSON pointer describes a key of an object which cannot be found. See example below.
out_of_range.404
if the JSON pointer ptr can not be resolved. See example below.
Strong guarantee: if an exception is thrown, there are no changes in the JSON value.
Constant.
Since
version 2.0.0
{The behavior is shown in the example.,at_json_pointer_const}
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>
Returns a reference to the last element in the container. For a JSON container c, the expression c.back() is equivalent to
auto tmp = c.end();
--tmp;
return *tmp;
Returns
In case of a structured type (array or object), a reference to the last element is returned. In case of number, string, or boolean values, a reference to the value is returned.
Constant.
Precondition
The JSON value must not be null (would throw std::out_of_range) or an empty array or object (undefined behavior, guarded by assertions).
Postcondition
The JSON value remains unchanged.
Exceptions
invalid_iterator.214
when called on a null value. See example below.
{The following code shows an example for back().,back}
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>
Returns a reference to the last element in the container. For a JSON container c, the expression c.back() is equivalent to
auto tmp = c.end();
--tmp;
return *tmp;
Returns
In case of a structured type (array or object), a reference to the last element is returned. In case of number, string, or boolean values, a reference to the value is returned.
Constant.
Precondition
The JSON value must not be null (would throw std::out_of_range) or an empty array or object (undefined behavior, guarded by assertions).
Postcondition
The JSON value remains unchanged.
Exceptions
invalid_iterator.214
when called on a null value. See example below.
{The following code shows an example for back().,back}
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>
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>
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>
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>
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>
Clears the content of a JSON value and resets it to the default value as if basic_json(value_t) would have been called with the current value type from type():
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>
returns the number of occurrences of a key in a JSON object
Returns the number of elements with key key. If ObjectType is the default std::map type, the return value will always be 0 (key was not found) or 1 (key was found).
Note
This method always returns 0 when executed on a JSON type that is not an object.
Parameters
[in]
key
key value of the element to count
Returns
Number of elements with key key. If the JSON value is not an object, the return value will be 0.
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>
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>
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>
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>
Serialization function for JSON values. The function tries to mimic Python's json.dumps() function, and currently supports its indent and ensure_ascii parameters.
Parameters
[in]
indent
If indent is nonnegative, then array elements and object members will be pretty-printed with that indent level. An indent level of 0 will only insert newlines. -1 (the default) selects the most compact representation.
[in]
indent_char
The character to use for indentation if indent is greater than 0. The default is (space).
[in]
ensure_ascii
If ensure_ascii is true, all non-ASCII characters in the output are escaped with \uXXXX sequences, and the result consists of ASCII characters only.
Returns
string containing the serialization of the JSON value
Exceptions
type_error.316
if a string stored inside the JSON value is not UTF-8 encoded
Linear.
Strong guarantee: if an exception is thrown, there are no changes in the JSON value.
{The following example shows the effect of different indent\, indent_char\, and ensure_ascii parameters to the result of the serialization.,dump}
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>
Inserts a new element into a JSON object constructed in-place with the given args if there is no element with the key in the container. If the function is called on a JSON null value, an empty object is created before appending the value created from args.
Parameters
[in]
args
arguments to forward to a constructor of basic_json
a pair consisting of an iterator to the inserted element, or the already-existing element if no insertion happened, and a bool denoting whether the insertion took place.
Exceptions
type_error.311
when called on a type other than JSON object or null; example: "cannot use emplace() with number"
Logarithmic in the size of the container, O(log(size())).
{The example shows how emplace() can be used to add elements to a JSON object. Note how the null value was silently converted to a JSON object. Further note how no value is added if there was already one value stored with the same key.,emplace}
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>
Creates a JSON value from the passed parameters args to the end of the JSON value. If the function is called on a JSON null value, an empty array is created before appending the value created from args.
Parameters
[in]
args
arguments to forward to a constructor of basic_json
when called on a type other than JSON array or null; example: "cannot use emplace_back() with number"
Amortized constant.
{The example shows how push_back() can be used to add elements to a JSON array. Note how the null value was silently converted to a JSON array.,emplace_back}
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>
Checks if a JSON value has no elements (i.e. whether its size is 0).
Returns
The return value depends on the different types and is defined as follows:
Value type
return value
null
true
boolean
false
string
false
number
false
object
result of function object_t::empty()
array
result of function array_t::empty()
{The following code uses empty() to check if a JSON object contains any elements.,empty}
Constant, as long as array_t and object_t satisfy the Container concept; that is, their empty() functions have constant complexity.
No changes.
No-throw guarantee: this function never throws exceptions.
Note
This function does not return whether a string stored as JSON value is empty - it returns whether the JSON container itself is empty which is false in the case of a string.
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>
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>
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>
template<class IteratorType , typename std::enable_if< std::is_same< IteratorType, typename basic_json_t::iterator >::value or std::is_same< IteratorType, typename basic_json_t::const_iterator >::value, int >::type = 0>
Removes the element specified by iterator pos. The iterator pos must be valid and dereferenceable. Thus the end() iterator (which is valid, but is not dereferenceable) cannot be used as a value for pos.
If called on a primitive type other than null, the resulting JSON value will be null.
Parameters
[in]
pos
iterator to the element to remove
Returns
Iterator following the last removed element. If the iterator pos refers to the last element, the end() iterator is returned.
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>
template<class IteratorType , typename std::enable_if< std::is_same< IteratorType, typename basic_json_t::iterator >::value or std::is_same< IteratorType, typename basic_json_t::const_iterator >::value, int >::type = 0>
Removes the element specified by the range [first; last). The iterator first does not need to be dereferenceable if first == last: erasing an empty range is a no-op.
If called on a primitive type other than null, the resulting JSON value will be null.
Parameters
[in]
first
iterator to the beginning of the range to remove
[in]
last
iterator past the end of the range to remove
Returns
Iterator following the last removed element. If the iterator second refers to the last element, the end() iterator is returned.
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>
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>
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>
Finds an element in a JSON object with key equivalent to key. If the element is not found or the JSON value is not an object, end() is returned.
Note
This method always returns end() when executed on a JSON type that is not an object.
Parameters
[in]
key
key value of the element to search for.
Returns
Iterator to an element with key equivalent to key. If no such element is found or the JSON value is not an object, past-the-end (see end()) iterator is returned.
Logarithmic in the size of the JSON object.
{The example shows how find() is used.,find__key_type}
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>
find an element in a JSON object Finds an element in a JSON object with key equivalent to key. If the element is not found or the JSON value is not an object, end() is returned.
Note
This method always returns end() when executed on a JSON type that is not an object.
Parameters
[in]
key
key value of the element to search for.
Returns
Iterator to an element with key equivalent to key. If no such element is found or the JSON value is not an object, past-the-end (see end()) iterator is returned.
Logarithmic in the size of the JSON object.
{The example shows how find() is used.,find__key_type}
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>
The function creates a JSON object whose keys are JSON pointers (see RFC 6901) and whose values are all primitive. The original JSON value can be restored using the unflatten() function.
Returns
an object that maps JSON pointers to primitive values
Note
Empty objects and arrays are flattened to null and will not be reconstructed correctly by the unflatten() function.
Linear in the size the JSON value.
{The following code shows how a JSON object is flattened to an object whose keys consist of JSON pointers.,flatten}
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>
Deserializes a given input i to a JSON value using the CBOR (Concise Binary Object Representation) serialization format.
The library maps CBOR types to JSON value types as follows:
CBOR type
JSON value type
first byte
Integer
number_unsigned
0x00..0x17
Unsigned integer
number_unsigned
0x18
Unsigned integer
number_unsigned
0x19
Unsigned integer
number_unsigned
0x1A
Unsigned integer
number_unsigned
0x1B
Negative integer
number_integer
0x20..0x37
Negative integer
number_integer
0x38
Negative integer
number_integer
0x39
Negative integer
number_integer
0x3A
Negative integer
number_integer
0x3B
Negative integer
number_integer
0x40..0x57
UTF-8 string
string
0x60..0x77
UTF-8 string
string
0x78
UTF-8 string
string
0x79
UTF-8 string
string
0x7A
UTF-8 string
string
0x7B
UTF-8 string
string
0x7F
array
array
0x80..0x97
array
array
0x98
array
array
0x99
array
array
0x9A
array
array
0x9B
array
array
0x9F
map
object
0xA0..0xB7
map
object
0xB8
map
object
0xB9
map
object
0xBA
map
object
0xBB
map
object
0xBF
False
false
0xF4
True
true
0xF5
Nill
null
0xF6
Half-Precision Float
number_float
0xF9
Single-Precision Float
number_float
0xFA
Double-Precision Float
number_float
0xFB
Warning
The mapping is incomplete in the sense that not all CBOR types can be converted to a JSON value. The following CBOR types are not supported and will yield parse errors (parse_error.112):
byte strings (0x40..0x5F)
date/time (0xC0..0xC1)
bignum (0xC2..0xC3)
decimal fraction (0xC4)
bigfloat (0xC5)
tagged items (0xC6..0xD4, 0xD8..0xDB)
expected conversions (0xD5..0xD7)
simple values (0xE0..0xF3, 0xF8)
undefined (0xF7)
CBOR allows map keys of any type, whereas JSON only allows strings as keys in object values. Therefore, CBOR maps with keys other than UTF-8 strings are rejected (parse_error.113).
Note
Any CBOR output created to_cbor can be successfully parsed by from_cbor.
Parameters
[in]
i
an input in CBOR format convertible to an input adapter
[in]
strict
whether to expect the input to be consumed until EOF (true by default)
Returns
deserialized JSON value
Exceptions
parse_error.110
if the given input ends prematurely or the end of file was not reached when strict was set to true
parse_error.112
if unsupported features from CBOR were used in the given input v or if the input is not valid CBOR
parse_error.113
if a string was expected as map key, but not found
Linear in the size of the input i.
{The example shows the deserialization of a byte vector in CBOR format to a JSON value.,from_cbor}
version 2.0.9; parameter start_index since 2.1.1; changed to consume input adapters, removed start_index parameter, and added strict parameter since 3.0.0
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>
Deserializes a given input i to a JSON value using the CBOR (Concise Binary Object Representation) serialization format.
The library maps CBOR types to JSON value types as follows:
CBOR type
JSON value type
first byte
Integer
number_unsigned
0x00..0x17
Unsigned integer
number_unsigned
0x18
Unsigned integer
number_unsigned
0x19
Unsigned integer
number_unsigned
0x1A
Unsigned integer
number_unsigned
0x1B
Negative integer
number_integer
0x20..0x37
Negative integer
number_integer
0x38
Negative integer
number_integer
0x39
Negative integer
number_integer
0x3A
Negative integer
number_integer
0x3B
Negative integer
number_integer
0x40..0x57
UTF-8 string
string
0x60..0x77
UTF-8 string
string
0x78
UTF-8 string
string
0x79
UTF-8 string
string
0x7A
UTF-8 string
string
0x7B
UTF-8 string
string
0x7F
array
array
0x80..0x97
array
array
0x98
array
array
0x99
array
array
0x9A
array
array
0x9B
array
array
0x9F
map
object
0xA0..0xB7
map
object
0xB8
map
object
0xB9
map
object
0xBA
map
object
0xBB
map
object
0xBF
False
false
0xF4
True
true
0xF5
Nill
null
0xF6
Half-Precision Float
number_float
0xF9
Single-Precision Float
number_float
0xFA
Double-Precision Float
number_float
0xFB
Warning
The mapping is incomplete in the sense that not all CBOR types can be converted to a JSON value. The following CBOR types are not supported and will yield parse errors (parse_error.112):
byte strings (0x40..0x5F)
date/time (0xC0..0xC1)
bignum (0xC2..0xC3)
decimal fraction (0xC4)
bigfloat (0xC5)
tagged items (0xC6..0xD4, 0xD8..0xDB)
expected conversions (0xD5..0xD7)
simple values (0xE0..0xF3, 0xF8)
undefined (0xF7)
CBOR allows map keys of any type, whereas JSON only allows strings as keys in object values. Therefore, CBOR maps with keys other than UTF-8 strings are rejected (parse_error.113).
Note
Any CBOR output created to_cbor can be successfully parsed by from_cbor.
Parameters
[in]
i
an input in CBOR format convertible to an input adapter
[in]
strict
whether to expect the input to be consumed until EOF (true by default)
Returns
deserialized JSON value
Exceptions
parse_error.110
if the given input ends prematurely or the end of file was not reached when strict was set to true
parse_error.112
if unsupported features from CBOR were used in the given input v or if the input is not valid CBOR
parse_error.113
if a string was expected as map key, but not found
Linear in the size of the input i.
{The example shows the deserialization of a byte vector in CBOR format to a JSON value.,from_cbor}
version 2.0.9; parameter start_index since 2.1.1; changed to consume input adapters, removed start_index parameter, and added strict parameter since 3.0.0
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>
create a JSON value from an input in MessagePack format
Deserializes a given input i to a JSON value using the MessagePack serialization format.
The library maps MessagePack types to JSON value types as follows:
MessagePack type
JSON value type
first byte
positive fixint
number_unsigned
0x00..0x7F
fixmap
object
0x80..0x8F
fixarray
array
0x90..0x9F
fixstr
string
0xA0..0xBF
nil
null
0xC0
false
false
0xC2
true
true
0xC3
float 32
number_float
0xCA
float 64
number_float
0xCB
uint 8
number_unsigned
0xCC
uint 16
number_unsigned
0xCD
uint 32
number_unsigned
0xCE
uint 64
number_unsigned
0xCF
int 8
number_integer
0xD0
int 16
number_integer
0xD1
int 32
number_integer
0xD2
int 64
number_integer
0xD3
str 8
string
0xD9
str 16
string
0xDA
str 32
string
0xDB
array 16
array
0xDC
array 32
array
0xDD
map 16
object
0xDE
map 32
object
0xDF
negative fixint
number_integer
0xE0-0xFF
Warning
The mapping is incomplete in the sense that not all MessagePack types can be converted to a JSON value. The following MessagePack types are not supported and will yield parse errors:
version 2.0.9; parameter start_index since 2.1.1; changed to consume input adapters, removed start_index parameter, and added strict parameter since 3.0.0
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>
create a JSON value from an input in MessagePack format
Deserializes a given input i to a JSON value using the MessagePack serialization format.
The library maps MessagePack types to JSON value types as follows:
MessagePack type
JSON value type
first byte
positive fixint
number_unsigned
0x00..0x7F
fixmap
object
0x80..0x8F
fixarray
array
0x90..0x9F
fixstr
string
0xA0..0xBF
nil
null
0xC0
false
false
0xC2
true
true
0xC3
float 32
number_float
0xCA
float 64
number_float
0xCB
uint 8
number_unsigned
0xCC
uint 16
number_unsigned
0xCD
uint 32
number_unsigned
0xCE
uint 64
number_unsigned
0xCF
int 8
number_integer
0xD0
int 16
number_integer
0xD1
int 32
number_integer
0xD2
int 64
number_integer
0xD3
str 8
string
0xD9
str 16
string
0xDA
str 32
string
0xDB
array 16
array
0xDC
array 32
array
0xDD
map 16
object
0xDE
map 32
object
0xDF
negative fixint
number_integer
0xE0-0xFF
Warning
The mapping is incomplete in the sense that not all MessagePack types can be converted to a JSON value. The following MessagePack types are not supported and will yield parse errors:
version 2.0.9; parameter start_index since 2.1.1; changed to consume input adapters, removed start_index parameter, and added strict parameter since 3.0.0
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>
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>
Returns a reference to the first element in the container. For a JSON container c, the expression c.front() is equivalent to *c.begin().
Returns
In case of a structured type (array or object), a reference to the first element is returned. In case of number, string, or boolean values, a reference to the value is returned.
Constant.
Precondition
The JSON value must not be null (would throw std::out_of_range) or an empty array or object (undefined behavior, guarded by assertions).
Postcondition
The JSON value remains unchanged.
Exceptions
invalid_iterator.214
when called on null value
{The following code shows an example for front().,front}
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>
Returns a reference to the first element in the container. For a JSON container c, the expression c.front() is equivalent to *c.begin().
Returns
In case of a structured type (array or object), a reference to the first element is returned. In case of number, string, or boolean values, a reference to the value is returned.
Constant.
Precondition
The JSON value must not be null (would throw std::out_of_range) or an empty array or object (undefined behavior, guarded by assertions).
Postcondition
The JSON value remains unchanged.
Exceptions
invalid_iterator.214
when called on null value
{The following code shows an example for front().,front}
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>
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>
template<typename BasicJsonType , detail::enable_if_t< not std::is_same< BasicJsonType, basic_json >::value and detail::is_basic_json< BasicJsonType >::value, int > = 0>
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>
template<typename ValueTypeCV , typename ValueType = detail::uncvref_t<ValueTypeCV>, detail::enable_if_t< not detail::is_basic_json< ValueType >::value and detail::has_from_json< basic_json_t, ValueType >::value and not detail::has_non_default_from_json< basic_json_t, ValueType >::value, int > = 0>
Explicit type conversion between the JSON value and a compatible value which is CopyConstructible and DefaultConstructible. The value is converted by calling the json_serializer<ValueType> from_json() method.
{The example below shows several conversions from JSON values to other types. There a few things to note: (1) Floating-point numbers can be converted to integers\, (2) A JSON array can be converted to a standard std::vector<short>\, (3) A JSON object can be converted to C++ associative containers such as std::unordered_map<std::string\, json>.,get__ValueType_const}
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>
template<typename ValueTypeCV , typename ValueType = detail::uncvref_t<ValueTypeCV>, detail::enable_if_t< not std::is_same< basic_json_t, ValueType >::value and detail::has_non_default_from_json< basic_json_t, ValueType >::value, int > = 0>
Explicit type conversion between the JSON value and a compatible value which is notCopyConstructible and notDefaultConstructible. The value is converted by calling the json_serializer<ValueType> from_json() method.
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>
pointer to the internally stored JSON value if the requested pointer type PointerType fits to the JSON value; nullptr otherwise
Constant.
{The example below shows how pointers to internal values of a JSON value can be requested. Note that no type conversions are made and a nullptr is returned if the value and the requested pointer type does not match.,get__PointerType}
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>
pointer to the internally stored JSON value if the requested pointer type PointerType fits to the JSON value; nullptr otherwise
Constant.
{The example below shows how pointers to internal values of a JSON value can be requested. Note that no type conversions are made and a nullptr is returned if the value and the requested pointer type does not match.,get__PointerType}
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>
pointer to the internally stored JSON value if the requested pointer type PointerType fits to the JSON value; nullptr otherwise
Constant.
{The example below shows how pointers to internal values of a JSON value can be requested. Note that no type conversions are made and a nullptr is returned if the value and the requested pointer type does not match.,get_ptr}
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>
template<typename PointerType , typename std::enable_if< std::is_pointer< PointerType >::value and std::is_const< typename std::remove_pointer< PointerType >::type >::value, int >::type = 0>
pointer to the internally stored JSON value if the requested pointer type PointerType fits to the JSON value; nullptr otherwise
Constant.
{The example below shows how pointers to internal values of a JSON value can be requested. Note that no type conversions are made and a nullptr is returned if the value and the requested pointer type does not match.,get_ptr}
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>
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>
template<typename ReferenceType , typename std::enable_if< std::is_reference< ReferenceType >::value and std::is_const< typename std::remove_reference< ReferenceType >::type >::value, int >::type = 0>
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>
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>
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>
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>
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>
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>
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>
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>
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>
This function returns true if and only if the JSON value was discarded during parsing with a callback function (see parser_callback_t).
Note
This function will always be false for JSON values after parsing. That is, discarded values can only occur during parsing, but will be removed when inside a structured value or replaced by null in other cases.
Returns
true if type is discarded, false otherwise.
Constant.
No-throw guarantee: this member function never throws exceptions.
{The following code exemplifies is_discarded() for all JSON types.,is_discarded}
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
helper to access iterator member functions in range-based for
This function allows to access iterator::key() and iterator::value() during range-based for loops. In these loops, a reference to the JSON values is returned, so there is no access to the underlying iterator.
When iterating over an array, key() will return the index of the element as string (see example). For primitive types (e.g., numbers), key() returns an empty string.
Returns
iteration proxy object wrapping ref with an interface to use in range-based for loops
{The following code shows how the function is used.,items}
Strong guarantee: if an exception is thrown, there are no changes in the JSON value.
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>
helper to access iterator member functions in range-based for
This function allows to access iterator::key() and iterator::value() during range-based for loops. In these loops, a reference to the JSON values is returned, so there is no access to the underlying iterator.
When iterating over an array, key() will return the index of the element as string (see example). For primitive types (e.g., numbers), key() returns an empty string.
Returns
iteration proxy object wrapping ref with an interface to use in range-based for loops
{The following code shows how the function is used.,items}
Strong guarantee: if an exception is thrown, there are no changes in the JSON value.
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>
wrapper to access iterator member functions in range-based for
This function allows to access iterator::key() and iterator::value() during range-based for loops. In these loops, a reference to the JSON values is returned, so there is no access to the underlying iterator.
For loop without iterator_wrapper:
for (auto it = j_object.begin(); it != j_object.end(); ++it)
This stream operator is deprecated and will be removed in future 4.0.0 of the library. Please use items() instead; that is, replace json::iterator_wrapper(j) with j.items().
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>
wrapper to access iterator member functions in range-based for
This function allows to access iterator::key() and iterator::value() during range-based for loops. In these loops, a reference to the JSON values is returned, so there is no access to the underlying iterator.
For loop without iterator_wrapper:
for (auto it = j_object.begin(); it != j_object.end(); ++it)
This stream operator is deprecated and will be removed in future 4.0.0 of the library. Please use items() instead; that is, replace json::iterator_wrapper(j) with j.items().
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>
Returns the maximum number of elements a JSON value is able to hold due to system or library implementation limitations, i.e. std::distance(begin(), end()) for the JSON value.
Returns
The return value depends on the different types and is defined as follows:
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>
The merge patch format is primarily intended for use with the HTTP PATCH method as a means of describing a set of modifications to a target resource's content. This function applies a merge patch to the current JSON value.
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>
This function returns a JSON object with information about the library, including the version number and information on the platform and compiler.
Returns
JSON object holding version information
key
description
compiler
Information on the used compiler. It is an object with the following keys: c++ (the used C++ standard), family (the compiler family; possible values are clang, icc, gcc, ilecpp, msvc, pgcpp, sunpro, and unknown), and version (the compiler version).
copyright
The copyright line for the library as string.
name
The name of the library as string.
platform
The used platform as string. Possible values are win32, linux, apple, unix, and unknown.
url
The URL of the project as string.
version
The version of the library. It is an object with the following keys: major, minor, and patch as defined by Semantic Versioning, and string (the version string).
{The following code shows an example output of the meta() function.,meta}
Strong guarantee: if an exception is thrown, there are no changes to any JSON value.
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>
explicitly create an object from an initializer list
Creates a JSON object value from a given initializer list. The initializer lists elements must be pairs, and their first elements must be strings. If the initializer list is empty, the empty object {} is created.
Note
This function is only added for symmetry reasons. In contrast to the related function array(initializer_list_t), there are no cases which can only be expressed by this function. That is, any initializer list init can also be passed to the initializer list constructor basic_json(initializer_list_t, bool, value_t).
Parameters
[in]
init
initializer list to create an object from (optional)
Returns
JSON object value
Exceptions
type_error.301
if init is not a list of pairs whose first elements are strings. In this case, no object can be created. When such a value is passed to basic_json(initializer_list_t, bool, value_t), an array would have been created from the passed initializer list init. See example below.
Linear in the size of init.
Strong guarantee: if an exception is thrown, there are no changes to any JSON value.
{The following code shows an example for the object function.,object}
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>
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>
template<typename ValueType , typename std::enable_if< not std::is_pointer< ValueType >::value and not std::is_same< ValueType, detail::json_ref< basic_json >>::value and not std::is_same< ValueType, typename string_t::value_type >::value and not detail::is_basic_json< ValueType >::value and not std::is_same< ValueType, std::initializer_list< typename string_t::value_type >>::value, int >::type = 0>
Implicit type conversion between the JSON value and a compatible value. The call is realized by calling get() const.
Template Parameters
ValueType
non-pointer type compatible to the JSON value, for instance int for JSON integer numbers, bool for JSON booleans, or std::vector types for JSON arrays. The character type of string_t as well as an initializer list of this type is excluded to avoid ambiguities as these types implicitly convert to std::string.
Returns
copy of the JSON value, converted to type ValueType
Exceptions
type_error.302
in case passed type ValueType is incompatible to the JSON value type (e.g., the JSON value is of type boolean, but a string is requested); see example below
Linear in the size of the JSON value.
{The example below shows several conversions from JSON values to other types. There a few things to note: (1) Floating-point numbers can be converted to integers\, (2) A JSON array can be converted to a standard std::vector<short>\, (3) A JSON object can be converted to C++ associative containers such as std::unordered_map<std::string\, json>.,operator__ValueType}
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>
add an object to an array Appends the given element val to the end of the JSON value. If the function is called on a JSON null value, an empty array is created before appending val.
Parameters
[in]
val
the value to add to the JSON array
Exceptions
type_error.308
when called on a type other than JSON array or null; example: "cannot use push_back() with number"
Amortized constant.
{The example shows how push_back() and += can be used to add elements to a JSON array. Note how the null value was silently converted to a JSON array.,push_back}
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>
add an object to an array Appends the given element val to the end of the JSON value. If the function is called on a JSON null value, an empty array is created before appending val.
Parameters
[in]
val
the value to add to the JSON array
Exceptions
type_error.308
when called on a type other than JSON array or null; example: "cannot use push_back() with number"
Amortized constant.
{The example shows how push_back() and += can be used to add elements to a JSON array. Note how the null value was silently converted to a JSON array.,push_back}
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>
add an object to an object Inserts the given element val to the JSON object. If the function is called on a JSON null value, an empty object is created before inserting val.
Parameters
[in]
val
the value to add to the JSON object
Exceptions
type_error.308
when called on a type other than JSON object or null; example: "cannot use push_back() with number"
Logarithmic in the size of the container, O(log(size())).
{The example shows how push_back() and += can be used to add elements to a JSON object. Note how the null value was silently converted to a JSON object.,push_back__object_t__value}
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>
This function is required to resolve an ambiguous overload error, because pairs like {"key", "value"} can be both interpreted as object_t::value_type or std::initializer_list<basic_json>, see https://github.com/nlohmann/json/issues/235 for more information.
{The example shows how initializer lists are treated as objects when possible.,push_back__initializer_list}
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>
Copy assignment operator. Copies a JSON value via the "copy and swap" strategy: It is expressed in terms of the copy constructor, destructor, and the swap() member function.
{The code below shows and example for the copy assignment. It creates a copy of value a which is then swapped with b. Finally\, the copy of a (which is the null value after the swap) is destroyed.,basic_json__copyassignment}
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>
Returns a reference to the element at specified location idx.
Note
If idx is beyond the range of the array (i.e., idx >= size()), then the array is silently filled up with null values to make idx a valid reference to the last stored element.
Parameters
[in]
idx
index of the element to access
Returns
reference to the element at index idx
Exceptions
type_error.305
if the JSON value is not an array or null; in that cases, using the [] operator with an index makes no sense.
Constant if idx is in the range of the array. Otherwise linear in idx - size().
{The example below shows how array elements can be read and written using [] operator. Note the addition of null values.,operatorarray__size_type}
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>
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>
Returns a reference to the element at with specified key key.
Note
If key is not found in the object, then it is silently added to the object and filled with a null value to make key a valid reference. In case the value was null before, it is converted to an object.
Parameters
[in]
key
key of the element to access
Returns
reference to the element at key key
Exceptions
type_error.305
if the JSON value is not an object or null; in that cases, using the [] operator with a key makes no sense.
Logarithmic in the size of the container.
{The example below shows how object elements can be read and written using the [] operator.,operatorarray__key_type}
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>
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>
Returns a reference to the element at with specified key key.
Note
If key is not found in the object, then it is silently added to the object and filled with a null value to make key a valid reference. In case the value was null before, it is converted to an object.
Parameters
[in]
key
key of the element to access
Returns
reference to the element at key key
Exceptions
type_error.305
if the JSON value is not an object or null; in that cases, using the [] operator with a key makes no sense.
Logarithmic in the size of the container.
{The example below shows how object elements can be read and written using the [] operator.,operatorarray__key_type}
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>
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>
Uses a JSON pointer to retrieve a reference to the respective JSON value. No bound checking is performed. Similar to operator[](const typename object_t::key_type&), null values are created in arrays and objects if necessary.
In particular:
If the JSON pointer points to an object key that does not exist, it is created an filled with a null value before a reference to it is returned.
If the JSON pointer points to an array index that does not exist, it is created an filled with a null value before a reference to it is returned. All indices between the current maximum and the given index are also filled with null.
The special value - is treated as a synonym for the index past the end.
Parameters
[in]
ptr
a JSON pointer
Returns
reference to the element pointed to by ptr
Constant.
Exceptions
parse_error.106
if an array index begins with '0'
parse_error.109
if an array index was not a number
out_of_range.404
if the JSON pointer can not be resolved
{The behavior is shown in the example.,operatorjson_pointer}
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>
Uses a JSON pointer to retrieve a reference to the respective JSON value. No bound checking is performed. The function does not change the JSON value; no null values are created. In particular, the the special value - yields an exception.
Parameters
[in]
ptr
JSON pointer to the desired element
Returns
const reference to the element pointed to by ptr
Constant.
Exceptions
parse_error.106
if an array index begins with '0'
parse_error.109
if an array index was not a number
out_of_range.402
if the array index '-' is used
out_of_range.404
if the JSON pointer can not be resolved
{The behavior is shown in the example.,operatorjson_pointer_const}
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>
This function reads from a compatible input. Examples are:
an array of 1-byte values
strings with character/literal type with size of 1 byte
input streams
container with contiguous storage of 1-byte values. Compatible container types include std::vector, std::string, std::array, std::valarray, and std::initializer_list. Furthermore, C-style arrays can be used with std::begin()/std::end(). User-defined containers can be used as long as they implement random-access iterators and a contiguous storage.
Precondition
Each element of the container has a size of 1 byte. Violating this precondition yields undefined behavior. This precondition is enforced with a static assertion.
The container storage is contiguous. Violating this precondition yields undefined behavior. This precondition is enforced with an assertion.
Each element of the container has a size of 1 byte. Violating this precondition yields undefined behavior. This precondition is enforced with a static assertion.
Warning
There is no way to enforce all preconditions at compile-time. If the function is called with a noncompliant container and with assertions switched off, the behavior is undefined and will most likely yield segmentation violation.
Parameters
[in]
i
input to read from
[in]
cb
a parser callback function of type parser_callback_t which is used to control the deserialization by filtering unwanted values (optional)
Returns
result of the deserialization
Exceptions
parse_error.101
if a parse error occurs; example: ""unexpected end of input; expected string literal""
parse_error.102
if to_unicode fails or surrogate error
parse_error.103
if to_unicode fails
Linear in the length of the input. The parser is a predictive LL(1) parser. The complexity can be higher if the parser callback function cb has a super-linear complexity.
Note
A UTF-8 byte order mark is silently ignored.
{The example below demonstrates the parse() function reading from an array.,parse__array__parser_callback_t}
{The example below demonstrates the parse() function with and without callback function.,parse__string__parser_callback_t}
{The example below demonstrates the parse() function with and without callback function.,parse__istream__parser_callback_t}
{The example below demonstrates the parse() function reading from a contiguous container.,parse__contiguouscontainer__parser_callback_t}
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>
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>
deserialize from an iterator range with contiguous storage
This function reads from an iterator range of a container with contiguous storage of 1-byte values. Compatible container types include std::vector, std::string, std::array, std::valarray, and std::initializer_list. Furthermore, C-style arrays can be used with std::begin()/std::end(). User-defined containers can be used as long as they implement random-access iterators and a contiguous storage.
Precondition
The iterator range is contiguous. Violating this precondition yields undefined behavior. This precondition is enforced with an assertion.
Each element in the range has a size of 1 byte. Violating this precondition yields undefined behavior. This precondition is enforced with a static assertion.
Warning
There is no way to enforce all preconditions at compile-time. If the function is called with noncompliant iterators and with assertions switched off, the behavior is undefined and will most likely yield segmentation violation.
Template Parameters
IteratorType
iterator of container with contiguous storage
Parameters
[in]
first
begin of the range to parse (included)
[in]
last
end of the range to parse (excluded)
[in]
cb
a parser callback function of type parser_callback_t which is used to control the deserialization by filtering unwanted values (optional)
[in]
allow_exceptions
whether to throw exceptions in case of a parse error (optional, true by default)
Returns
result of the deserialization
Exceptions
parse_error.101
in case of an unexpected token
parse_error.102
if to_unicode fails or surrogate error
parse_error.103
if to_unicode fails
Linear in the length of the input. The parser is a predictive LL(1) parser. The complexity can be higher if the parser callback function cb has a super-linear complexity.
Note
A UTF-8 byte order mark is silently ignored.
{The example below demonstrates the parse() function reading from an iterator range.,parse__iteratortype__parser_callback_t}
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>
JSON Patch defines a JSON document structure for expressing a sequence of operations to apply to a JSON) document. With this function, a JSON Patch is applied to the current JSON value by executing all operations from the patch.
Parameters
[in]
json_patch
JSON patch document
Returns
patched document
Note
The application of a patch is atomic: Either all operations succeed and the patched document is returned or an exception is thrown. In any case, the original value is not changed: the patch is applied to a copy of the value.
Exceptions
parse_error.104
if the JSON patch does not consist of an array of objects
parse_error.105
if the JSON patch is malformed (e.g., mandatory attributes are missing); example: "operation add must have member path"
out_of_range.401
if an array index is out of range.
out_of_range.403
if a JSON pointer inside the patch could not be resolved successfully in the current JSON value; example: "key baz not
found"
out_of_range.405
if JSON pointer has no parent ("add", "remove", "move")
other_error.501
if "test" operation was unsuccessful
Linear in the size of the JSON value and the length of the JSON patch. As usually only a fraction of the JSON value is affected by the patch, the complexity can usually be neglected.
{The following code shows how a JSON patch is applied to a value.,patch}
See also
diff – create a JSON patch by comparing two JSON values
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>
Appends the given element val to the end of the JSON value. If the function is called on a JSON null value, an empty array is created before appending val.
Parameters
[in]
val
the value to add to the JSON array
Exceptions
type_error.308
when called on a type other than JSON array or null; example: "cannot use push_back() with number"
Amortized constant.
{The example shows how push_back() and += can be used to add elements to a JSON array. Note how the null value was silently converted to a JSON array.,push_back}
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>
add an object to an array Appends the given element val to the end of the JSON value. If the function is called on a JSON null value, an empty array is created before appending val.
Parameters
[in]
val
the value to add to the JSON array
Exceptions
type_error.308
when called on a type other than JSON array or null; example: "cannot use push_back() with number"
Amortized constant.
{The example shows how push_back() and += can be used to add elements to a JSON array. Note how the null value was silently converted to a JSON array.,push_back}
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>
Inserts the given element val to the JSON object. If the function is called on a JSON null value, an empty object is created before inserting val.
Parameters
[in]
val
the value to add to the JSON object
Exceptions
type_error.308
when called on a type other than JSON object or null; example: "cannot use push_back() with number"
Logarithmic in the size of the container, O(log(size())).
{The example shows how push_back() and += can be used to add elements to a JSON object. Note how the null value was silently converted to a JSON object.,push_back__object_t__value}
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>
This function is required to resolve an ambiguous overload error, because pairs like {"key", "value"} can be both interpreted as object_t::value_type or std::initializer_list<basic_json>, see https://github.com/nlohmann/json/issues/235 for more information.
{The example shows how initializer lists are treated as objects when possible.,push_back__initializer_list}
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>
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>
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>
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>
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>
The return value depends on the different types and is defined as follows:
Value type
return value
null
0
boolean
1
string
1
number
1
object
result of function object_t::size()
array
result of function array_t::size()
{The following code calls size() on the different value types.,size}
Constant, as long as array_t and object_t satisfy the Container concept; that is, their size() functions have constant complexity.
No changes.
No-throw guarantee: this function never throws exceptions.
Note
This function does not return the length of a string stored as JSON value - it returns the number of elements in the JSON value which is 1 in the case of a string.
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>
Exchanges the contents of the JSON value with those of other. Does not invoke any move, copy, or swap operations on individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated.
Parameters
[in,out]
other
JSON value to exchange the contents with
Constant.
{The example below shows how JSON values can be swapped with swap().,swap__reference}
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>
Exchanges the contents of a JSON array with those of other. Does not invoke any move, copy, or swap operations on individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated.
Parameters
[in,out]
other
array to exchange the contents with
Exceptions
type_error.310
when JSON value is not an array; example: "cannot
use swap() with string"
Constant.
{The example below shows how arrays can be swapped with swap().,swap__array_t}
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>
Exchanges the contents of a JSON object with those of other. Does not invoke any move, copy, or swap operations on individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated.
Parameters
[in,out]
other
object to exchange the contents with
Exceptions
type_error.310
when JSON value is not an object; example: "cannot use swap() with string"
Constant.
{The example below shows how objects can be swapped with swap().,swap__object_t}
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>
Exchanges the contents of a JSON string with those of other. Does not invoke any move, copy, or swap operations on individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated.
Parameters
[in,out]
other
string to exchange the contents with
Exceptions
type_error.310
when JSON value is not a string; example: "cannot
use swap() with boolean"
Constant.
{The example below shows how strings can be swapped with swap().,swap__string_t}
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>
Serializes a given JSON value j to a byte vector using the CBOR (Concise Binary Object Representation) serialization format. CBOR is a binary serialization format which aims to be more compact than JSON itself, yet more efficient to parse.
The library uses the following mapping from JSON values types to CBOR types according to the CBOR specification (RFC 7049):
JSON value type
value/range
CBOR type
first byte
null
null
Null
0xF6
boolean
true
True
0xF5
boolean
false
False
0xF4
number_integer
-9223372036854775808..-2147483649
Negative integer (8 bytes follow)
0x3B
number_integer
-2147483648..-32769
Negative integer (4 bytes follow)
0x3A
number_integer
-32768..-129
Negative integer (2 bytes follow)
0x39
number_integer
-128..-25
Negative integer (1 byte follow)
0x38
number_integer
-24..-1
Negative integer
0x20..0x37
number_integer
0..23
Integer
0x00..0x17
number_integer
24..255
Unsigned integer (1 byte follow)
0x18
number_integer
256..65535
Unsigned integer (2 bytes follow)
0x19
number_integer
65536..4294967295
Unsigned integer (4 bytes follow)
0x1A
number_integer
4294967296..18446744073709551615
Unsigned integer (8 bytes follow)
0x1B
number_unsigned
0..23
Integer
0x00..0x17
number_unsigned
24..255
Unsigned integer (1 byte follow)
0x18
number_unsigned
256..65535
Unsigned integer (2 bytes follow)
0x19
number_unsigned
65536..4294967295
Unsigned integer (4 bytes follow)
0x1A
number_unsigned
4294967296..18446744073709551615
Unsigned integer (8 bytes follow)
0x1B
number_float
any value
Double-Precision Float
0xFB
string
length: 0..23
UTF-8 string
0x60..0x77
string
length: 23..255
UTF-8 string (1 byte follow)
0x78
string
length: 256..65535
UTF-8 string (2 bytes follow)
0x79
string
length: 65536..4294967295
UTF-8 string (4 bytes follow)
0x7A
string
length: 4294967296..18446744073709551615
UTF-8 string (8 bytes follow)
0x7B
array
size: 0..23
array
0x80..0x97
array
size: 23..255
array (1 byte follow)
0x98
array
size: 256..65535
array (2 bytes follow)
0x99
array
size: 65536..4294967295
array (4 bytes follow)
0x9A
array
size: 4294967296..18446744073709551615
array (8 bytes follow)
0x9B
object
size: 0..23
map
0xA0..0xB7
object
size: 23..255
map (1 byte follow)
0xB8
object
size: 256..65535
map (2 bytes follow)
0xB9
object
size: 65536..4294967295
map (4 bytes follow)
0xBA
object
size: 4294967296..18446744073709551615
map (8 bytes follow)
0xBB
Note
The mapping is complete in the sense that any JSON value type can be converted to a CBOR value.
If NaN or Infinity are stored inside a JSON number, they are serialized properly. This behavior differs from the dump() function which serializes NaN or Infinity to null.
The following CBOR types are not used in the conversion:
byte strings (0x40..0x5F)
UTF-8 strings terminated by "break" (0x7F)
arrays terminated by "break" (0x9F)
maps terminated by "break" (0xBF)
date/time (0xC0..0xC1)
bignum (0xC2..0xC3)
decimal fraction (0xC4)
bigfloat (0xC5)
tagged items (0xC6..0xD4, 0xD8..0xDB)
expected conversions (0xD5..0xD7)
simple values (0xE0..0xF3, 0xF8)
undefined (0xF7)
half and single-precision floats (0xF9-0xFA)
break (0xFF)
Parameters
[in]
j
JSON value to serialize
Returns
MessagePack serialization as byte vector
Linear in the size of the JSON value j.
{The example shows the serialization of a JSON value to a byte vector in CBOR format.,to_cbor}
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>
create a MessagePack serialization of a given JSON value
Serializes a given JSON value j to a byte vector using the MessagePack serialization format. MessagePack is a binary serialization format which aims to be more compact than JSON itself, yet more efficient to parse.
The library uses the following mapping from JSON values types to MessagePack types according to the MessagePack specification:
JSON value type
value/range
MessagePack type
first byte
null
null
nil
0xC0
boolean
true
true
0xC3
boolean
false
false
0xC2
number_integer
-9223372036854775808..-2147483649
int64
0xD3
number_integer
-2147483648..-32769
int32
0xD2
number_integer
-32768..-129
int16
0xD1
number_integer
-128..-33
int8
0xD0
number_integer
-32..-1
negative fixint
0xE0..0xFF
number_integer
0..127
positive fixint
0x00..0x7F
number_integer
128..255
uint 8
0xCC
number_integer
256..65535
uint 16
0xCD
number_integer
65536..4294967295
uint 32
0xCE
number_integer
4294967296..18446744073709551615
uint 64
0xCF
number_unsigned
0..127
positive fixint
0x00..0x7F
number_unsigned
128..255
uint 8
0xCC
number_unsigned
256..65535
uint 16
0xCD
number_unsigned
65536..4294967295
uint 32
0xCE
number_unsigned
4294967296..18446744073709551615
uint 64
0xCF
number_float
any value
float 64
0xCB
string
length: 0..31
fixstr
0xA0..0xBF
string
length: 32..255
str 8
0xD9
string
length: 256..65535
str 16
0xDA
string
length: 65536..4294967295
str 32
0xDB
array
size: 0..15
fixarray
0x90..0x9F
array
size: 16..65535
array 16
0xDC
array
size: 65536..4294967295
array 32
0xDD
object
size: 0..15
fix map
0x80..0x8F
object
size: 16..65535
map 16
0xDE
object
size: 65536..4294967295
map 32
0xDF
Note
The mapping is complete in the sense that any JSON value type can be converted to a MessagePack value.
The following values can not be converted to a MessagePack value:
strings with more than 4294967295 bytes
arrays with more than 4294967295 elements
objects with more than 4294967295 elements
The following MessagePack types are not used in the conversion:
If NaN or Infinity are stored inside a JSON number, they are serialized properly. This behavior differs from the dump() function which serializes NaN or Infinity to null.
Parameters
[in]
j
JSON value to serialize
Returns
MessagePack serialization as byte vector
Linear in the size of the JSON value j.
{The example shows the serialization of a JSON value to a byte vector in MessagePack format.,to_msgpack}
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>
create a UBJSON serialization of a given JSON value
Serializes a given JSON value j to a byte vector using the UBJSON (Universal Binary JSON) serialization format. UBJSON aims to be more compact than JSON itself, yet more efficient to parse.
The library uses the following mapping from JSON values types to UBJSON types according to the UBJSON specification:
JSON value type
value/range
UBJSON type
marker
null
null
null
Z
boolean
true
true
T
boolean
false
false
F
number_integer
-9223372036854775808..-2147483649
int64
L
number_integer
-2147483648..-32769
int32
l
number_integer
-32768..-129
int16
I
number_integer
-128..127
int8
i
number_integer
128..255
uint8
U
number_integer
256..32767
int16
I
number_integer
32768..2147483647
int32
l
number_integer
2147483648..9223372036854775807
int64
L
number_unsigned
0..127
int8
i
number_unsigned
128..255
uint8
U
number_unsigned
256..32767
int16
I
number_unsigned
32768..2147483647
int32
l
number_unsigned
2147483648..9223372036854775807
int64
L
number_float
any value
float64
D
string
with shortest length indicator
string
S
array
see notes on optimized format
array
[
object
see notes on optimized format
map
{
Note
The mapping is complete in the sense that any JSON value type can be converted to a UBJSON value.
The following values can not be converted to a UBJSON value:
strings with more than 9223372036854775807 bytes (theoretical)
If NaN or Infinity are stored inside a JSON number, they are serialized properly. This behavior differs from the dump() function which serializes NaN or Infinity to null.
The optimized formats for containers are supported: Parameter use_size adds size information to the beginning of a container and removes the closing marker. Parameter use_type further checks whether all elements of a container have the same type and adds the type marker to the beginning of the container. The use_type parameter must only be used together with use_size = true. Note that use_size = true alone may result in larger representations - the benefit of this parameter is that the receiving side is immediately informed on the number of elements of the container.
Parameters
[in]
j
JSON value to serialize
[in]
use_size
whether to add size annotations to container types
[in]
use_type
whether to add type annotations to container types (must be combined with use_size = true)
Returns
UBJSON serialization as byte vector
Linear in the size of the JSON value j.
{The example shows the serialization of a JSON value to a byte vector in UBJSON format.,to_ubjson}
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>
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>
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>
The function restores the arbitrary nesting of a JSON value that has been flattened before using the flatten() function. The JSON value must meet certain constraints:
Empty objects and arrays are flattened by flatten() to null values and can not unflattened to their original type. Apart from this example, for a JSON value j, the following is always true: j == j.flatten().unflatten().
Linear in the size the JSON value.
Exceptions
type_error.314
if value is not an object
type_error.315
if object values are not primitive
{The following code shows how a flattened JSON object is unflattened into the original nested JSON object.,unflatten}
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>
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>
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>
Unlike operator[](const typename object_t::key_type& key), this function does not implicitly add an element to the position defined by key. This function is furthermore also applicable to const objects.
Parameters
[in]
key
key of the element to access
[in]
default_value
the value to return if key is not found
Template Parameters
ValueType
type compatible to JSON values, for instance int for JSON integer numbers, bool for JSON booleans, or std::vector types for JSON arrays. Note the type of the expected value at key and the default value default_value must be compatible.
Returns
copy of the element at key key or default_value if key is not found
Exceptions
type_error.306
if the JSON value is not an object; in that case, using value() with a key makes no sense.
Logarithmic in the size of the container.
{The example below shows how object elements can be queried with a default value.,basic_json__value}
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>
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>
Unlike at(const json_pointer&), this function does not throw if the given key key was not found.
Parameters
[in]
ptr
a JSON pointer to the element to access
[in]
default_value
the value to return if ptr found no value
Template Parameters
ValueType
type compatible to JSON values, for instance int for JSON integer numbers, bool for JSON booleans, or std::vector types for JSON arrays. Note the type of the expected value at key and the default value default_value must be compatible.
Returns
copy of the element at key key or default_value if key is not found
Exceptions
type_error.306
if the JSON value is not an objec; in that case, using value() with a key makes no sense.
Logarithmic in the size of the container.
{The example below shows how object elements can be queried with a default value.,basic_json__value_ptr}
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>
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>
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>
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>
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>
Compares whether one JSON value lhs is less than another JSON value rhs according to the following rules:
If lhs and rhs have the same type, the values are compared using the default < operator.
Integer and floating-point numbers are automatically converted before comparison
In case lhs and rhs have different types, the values are ignored and the order of the types is considered, see operator<(const value_t, const value_t).
Parameters
[in]
lhs
first JSON value to consider
[in]
rhs
second JSON value to consider
Returns
whether lhs is less than rhs
Linear.
No-throw guarantee: this function never throws exceptions.
{The example demonstrates comparing several JSON types.,operator__less}
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>
comparison: less than Compares whether one JSON value lhs is less than another JSON value rhs according to the following rules:
If lhs and rhs have the same type, the values are compared using the default < operator.
Integer and floating-point numbers are automatically converted before comparison
In case lhs and rhs have different types, the values are ignored and the order of the types is considered, see operator<(const value_t, const value_t).
Parameters
[in]
lhs
first JSON value to consider
[in]
rhs
second JSON value to consider
Returns
whether lhs is less than rhs
Linear.
No-throw guarantee: this function never throws exceptions.
{The example demonstrates comparing several JSON types.,operator__less}
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>
comparison: less than Compares whether one JSON value lhs is less than another JSON value rhs according to the following rules:
If lhs and rhs have the same type, the values are compared using the default < operator.
Integer and floating-point numbers are automatically converted before comparison
In case lhs and rhs have different types, the values are ignored and the order of the types is considered, see operator<(const value_t, const value_t).
Parameters
[in]
lhs
first JSON value to consider
[in]
rhs
second JSON value to consider
Returns
whether lhs is less than rhs
Linear.
No-throw guarantee: this function never throws exceptions.
{The example demonstrates comparing several JSON types.,operator__less}
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>
Serialize the given JSON value j to the output stream o. The JSON value will be serialized using the dump member function.
The indentation of the output can be controlled with the member variable width of the output stream o. For instance, using the manipulator std::setw(4) on o sets the indentation level to 4 and the serialization result is the same as calling dump(4).
The indentation character can be controlled with the member variable fill of the output stream o. For instance, the manipulator `std::setfill('\t')` sets indentation to use a tab character rather than the default space character.
Parameters
[in,out]
o
stream to serialize to
[in]
j
JSON value to serialize
Returns
the stream o
Exceptions
type_error.316
if a string stored inside the JSON value is not UTF-8 encoded
Linear.
{The example below shows the serialization with different parameters to width to adjust the indentation level.,operator_serialize}
Since
version 1.0.0; indentation character added in version 3.0.0
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>
This stream operator is deprecated and will be removed in version 4.0.0 of the library. Please use operator>>(std::istream&, basic_json&) instead; that is, replace calls like j << i; with i >> j;.
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>
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>
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>
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>
Compares two JSON values for equality according to the following rules:
Two JSON values are equal if (1) they are from the same type and (2) their stored values are the same according to their respective operator==.
Integer and floating-point numbers are automatically converted before comparison. Note than two NaN values are always treated as unequal.
Two JSON null values are equal.
Note
Floating-point inside JSON values numbers are compared with json::number_float_t::operator== which is double::operator== by default. To compare floating-point while respecting an epsilon, an alternative comparison function could be used, for instance
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>
comparison: equal Compares two JSON values for equality according to the following rules:
Two JSON values are equal if (1) they are from the same type and (2) their stored values are the same according to their respective operator==.
Integer and floating-point numbers are automatically converted before comparison. Note than two NaN values are always treated as unequal.
Two JSON null values are equal.
Note
Floating-point inside JSON values numbers are compared with json::number_float_t::operator== which is double::operator== by default. To compare floating-point while respecting an epsilon, an alternative comparison function could be used, for instance
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>
comparison: equal Compares two JSON values for equality according to the following rules:
Two JSON values are equal if (1) they are from the same type and (2) their stored values are the same according to their respective operator==.
Integer and floating-point numbers are automatically converted before comparison. Note than two NaN values are always treated as unequal.
Two JSON null values are equal.
Note
Floating-point inside JSON values numbers are compared with json::number_float_t::operator== which is double::operator== by default. To compare floating-point while respecting an epsilon, an alternative comparison function could be used, for instance
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>
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>
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>
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>
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>
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>
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>
This stream operator is deprecated and will be removed in future 4.0.0 of the library. Please use operator<<(std::ostream&, const basic_json&) instead; that is, replace calls like j >> o; with o << j;.
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>
![$[-2^{53}+1, 2^{53}-1]$](form_3.png)
are interoperable in the sense that implementations will agree exactly on their numeric values. 
