Represents a JSON value. More...

#include <value.h>

Public Member Functions
	Value (ValueType type=nullValue)
	Create a default Value of the given type.
	Value (const char *value)
	Copy til first 0. (NULL causes to seg-fault.)
	Value (const char begin, const char end)
	Copy all, incl zeroes.
	Value (const StaticString &value)
	Constructs a value from a static string.
	Value (const JSONCPP_STRING &value)
	Copy data() til size(). Embedded zeroes too.
	Value (const Value &other)
	Deep copy.
	Value (Value &&other)
	Move constructor.
Value &	operator= (Value other)
	Deep copy, then swap(other).
void	swap (Value &other)
	Swap everything.
void	swapPayload (Value &other)
	Swap values but leave comments and source offsets in place.
void	copy (const Value &other)
	copy everything.
void	copyPayload (const Value &other)
	copy values but leave comments and source offsets in place.
bool	operator< (const Value &other) const
	Compare payload only, not comments etc.
const char *	asCString () const
	Embedded zeroes could cause you trouble!
JSONCPP_STRING	asString () const
	Embedded zeroes are possible.
bool	getString (char const begin, char const end) const
	Get raw char* of string-value.
ArrayIndex	size () const
	Number of values in array or object.
bool	empty () const
	Return true if empty array, empty object, or null; otherwise, false.
	operator bool () const
	Return !isNull()
void	clear ()
	Remove all object members and array elements.
void	resize (ArrayIndex size)
	Resize the array to size elements.
Value &	operator[] (ArrayIndex index)
	Access an array element (zero based index ).
Value &	operator[] (int index)
	Access an array element (zero based index ).
const Value &	operator[] (ArrayIndex index) const
	Access an array element (zero based index ) (You may need to say 'value[0u]' to get your compiler to distinguish this from the operator[] which takes a string.)
const Value &	operator[] (int index) const
	Access an array element (zero based index ) (You may need to say 'value[0u]' to get your compiler to distinguish this from the operator[] which takes a string.)
Value	get (ArrayIndex index, const Value &defaultValue) const
	If the array contains at least index+1 elements, returns the element value, otherwise returns defaultValue.
bool	isValidIndex (ArrayIndex index) const
	Return true if index < size().
Value &	append (const Value &value)
	Append value to array at the end.
Value &	operator[] (const char *key)
	Access an object value by name, create a null member if it does not exist.
const Value &	operator[] (const char *key) const
	Access an object value by name, returns null if there is no member with that name.
Value &	operator[] (const JSONCPP_STRING &key)
	Access an object value by name, create a null member if it does not exist.
const Value &	operator[] (const JSONCPP_STRING &key) const
	Access an object value by name, returns null if there is no member with that name.
Value &	operator[] (const StaticString &key)
	Access an object value by name, create a null member if it does not exist.
Value &	operator[] (const CppTL::ConstString &key)
	Access an object value by name, create a null member if it does not exist.
const Value &	operator[] (const CppTL::ConstString &key) const
	Access an object value by name, returns null if there is no member with that name.
Value	get (const char *key, const Value &defaultValue) const
	Return the member named key if it exist, defaultValue otherwise.
Value	get (const char begin, const char end, const Value &defaultValue) const
	Return the member named key if it exist, defaultValue otherwise.
Value	get (const JSONCPP_STRING &key, const Value &defaultValue) const
	Return the member named key if it exist, defaultValue otherwise.
Value	get (const CppTL::ConstString &key, const Value &defaultValue) const
	Return the member named key if it exist, defaultValue otherwise.
Value const *	find (char const begin, char const end) const
	Most general and efficient version of isMember()const, get()const, and operator[]const.
Value const *	demand (char const begin, char const end)
	Most general and efficient version of object-mutators.
void	removeMember (const char *key)
	Remove and return the named member.
void	removeMember (const JSONCPP_STRING &key)
	Same as removeMember(const char*)
bool	removeMember (const char key, Value removed)
	Same as removeMember(const char* begin, const char* end, Value* removed), but 'key' is null-terminated.
bool	removeMember (JSONCPP_STRING const &key, Value *removed)
	Remove the named map member.
bool	removeMember (const char begin, const char end, Value *removed)
	Same as removeMember(JSONCPP_STRING const& key, Value* removed)
bool	removeIndex (ArrayIndex i, Value *removed)
	Remove the indexed array element.
bool	isMember (const char *key) const
	Return true if the object has a member named key.
bool	isMember (const JSONCPP_STRING &key) const
	Return true if the object has a member named key.
bool	isMember (const char begin, const char end) const
	Same as isMember(JSONCPP_STRING const& key)const.
bool	isMember (const CppTL::ConstString &key) const
	Return true if the object has a member named key.
Members	getMemberNames () const
	Return a list of the member names.
	JSONCPP_DEPRECATED ("Use setComment(JSONCPP_STRING const&) instead.") void setComment(const char *comment
void	setComment (const char *comment, size_t len, CommentPlacement placement)
	Comments must be //... or /* ... */.
void	setComment (const JSONCPP_STRING &comment, CommentPlacement placement)
	Comments must be //... or /* ... */.
JSONCPP_STRING	getComment (CommentPlacement placement) const
	Include delimiters and embedded newlines.
Static Public Member Functions
static Value const &	nullSingleton ()
	Prefer this to null or nullRef.
Static Public Attributes
static const Value &	null = Value::nullSingleton()
	We regret this reference to a global instance; prefer the simpler Value().
static const Value &	nullRef = Value::nullSingleton()
	just a kludge for binary-compatibility; same as null
static const LargestInt	minLargestInt = LargestInt(~(LargestUInt(-1) / 2))
	Minimum signed integer value that can be stored in a Json::Value.
static const LargestInt	maxLargestInt = LargestInt(LargestUInt(-1) / 2)
	Maximum signed integer value that can be stored in a Json::Value.
static const LargestUInt	maxLargestUInt = LargestUInt(-1)
	Maximum unsigned integer value that can be stored in a Json::Value.
static const Int	minInt = Int(~(UInt(-1) / 2))
	Minimum signed int value that can be stored in a Json::Value.
static const Int	maxInt = Int(UInt(-1) / 2)
	Maximum signed int value that can be stored in a Json::Value.
static const UInt	maxUInt = UInt(-1)
	Maximum unsigned int value that can be stored in a Json::Value.
static const Int64	minInt64 = Int64(~(UInt64(-1) / 2))
	Minimum signed 64 bits int value that can be stored in a Json::Value.
static const Int64	maxInt64 = Int64(UInt64(-1) / 2)
	Maximum signed 64 bits int value that can be stored in a Json::Value.
static const UInt64	maxUInt64 = UInt64(-1)
	Maximum unsigned 64 bits int value that can be stored in a Json::Value.

Detailed Description

Represents a JSON value.

This class is a discriminated union wrapper that can represents a:

signed integer [range: Value::minInt - Value::maxInt]
unsigned integer (range: 0 - Value::maxUInt)
double
UTF-8 string
boolean
'null'
an ordered list of Value
collection of name/value pairs (javascript object)

The type of the held value is represented by a ValueType and can be obtained using type().

Values of an objectValue or arrayValue can be accessed using operator[]() methods. Non-const methods will automatically create the a nullValue element if it does not exist. The sequence of an arrayValue will be automatically resized and initialized with nullValue. resize() can be used to enlarge or truncate an arrayValue.

The get() methods can be used to obtain default value in the case the required element does not exist.

It is possible to iterate over the list of a objectValue values using the getMemberNames() method.

Note:: Value string-length fit in size_t, but keys must be < 2^30. (The reason is an implementation detail.) A CharReader will raise an exception if a bound is exceeded to avoid security holes in your app, but the Value API does *not* check bounds. That is the responsibility of the caller.

Definition at line 177 of file value.h.

Constructor & Destructor Documentation

Value ( ValueType type = nullValue )

Create a default Value of the given type.

This is a very useful constructor. To create an empty array, pass arrayValue. To create an empty object, pass objectValue. Another Value can then be set to this one by assignment. This is useful since clear() and resize() will not alter types.

Examples:

Json::Value null_value; // null
Json::Value arr_value(Json::arrayValue); // []
Json::Value obj_value(Json::objectValue); // {}

Definition at line 355 of file json_value.cpp.

Value ( const char * value )

Copy til first 0. (NULL causes to seg-fault.)

Definition at line 409 of file json_value.cpp.

Value	(	const char *	begin,
		const char *	end
	)

Copy all, incl zeroes.

Definition at line 415 of file json_value.cpp.

Value ( const StaticString & value )

Constructs a value from a static string.

Like other value string constructor but do not duplicate the string for internal storage. The given string must remain alive after the call to this constructor.

Note:: This works only for null-terminated strings. (We cannot change the size of this class, so we have nowhere to store the length, which might be computed later for various operations.)

Example of usage:

 static StaticString foo("some text");
 Json::Value aValue(foo);

Definition at line 427 of file json_value.cpp.

Value ( const JSONCPP_STRING & value )

Copy data() til size(). Embedded zeroes too.

Definition at line 421 of file json_value.cpp.

Value ( const Value & other )

Deep copy.

Definition at line 444 of file json_value.cpp.

Value ( Value && other )

Move constructor.

Definition at line 490 of file json_value.cpp.

Member Function Documentation

Value & append ( const Value & value )

Append value to array at the end.

Equivalent to jsonvalue[jsonvalue.size()] = value;

Definition at line 1148 of file json_value.cpp.

const char * asCString ( ) const

Embedded zeroes could cause you trouble!

Definition at line 666 of file json_value.cpp.

JSONCPP_STRING asString ( ) const

Embedded zeroes are possible.

Definition at line 697 of file json_value.cpp.

void clear ( )

Remove all object members and array elements.

Precondition:: type() is arrayValue, objectValue, or nullValue

Postcondition:: type() is unchanged

Definition at line 967 of file json_value.cpp.

void copy ( const Value & other )

copy everything.

Definition at line 549 of file json_value.cpp.

void copyPayload ( const Value & other )

copy values but leave comments and source offsets in place.

Definition at line 536 of file json_value.cpp.

Value const* demand	(	char const *	begin,
		char const *	end
	)

Most general and efficient version of object-mutators.

Note:: As stated elsewhere, behavior is undefined if (end-begin) >= 2^30

Returns:: non-zero, but JSON_ASSERT if this is neither object nor nullValue.

bool empty ( ) const

Return true if empty array, empty object, or null; otherwise, false.

Definition at line 958 of file json_value.cpp.

Value const * find	(	char const *	begin,
		char const *	end
	)		const

Most general and efficient version of isMember()const, get()const, and operator[]const.

Note:: As stated elsewhere, behavior is undefined if (end-begin) >= 2^30

Definition at line 1100 of file json_value.cpp.

Value get	(	const JSONCPP_STRING &	key,
		const Value &	defaultValue
	)		const

Return the member named key if it exist, defaultValue otherwise.

Note:: deep copy

Parameters:

key	may contain embedded nulls.

Definition at line 1163 of file json_value.cpp.

Value get	(	const CppTL::ConstString &	key,
		const Value &	defaultValue
	)		const

Return the member named key if it exist, defaultValue otherwise.

Note:: deep copy

Definition at line 1229 of file json_value.cpp.

Value get	(	ArrayIndex	index,
		const Value &	defaultValue
	)		const

If the array contains at least index+1 elements, returns the element value, otherwise returns defaultValue.

Definition at line 1093 of file json_value.cpp.

Value get	(	const char *	key,
		const Value &	defaultValue
	)		const

Return the member named key if it exist, defaultValue otherwise.

Note:: deep copy

Definition at line 1159 of file json_value.cpp.

Value get	(	const char *	begin,
		const char *	end,
		const Value &	defaultValue
	)		const

Return the member named key if it exist, defaultValue otherwise.

Note:: deep copy; key may contain embedded nulls.

Definition at line 1154 of file json_value.cpp.

JSONCPP_STRING getComment ( CommentPlacement placement ) const

Include delimiters and embedded newlines.

Definition at line 1440 of file json_value.cpp.

Value::Members getMemberNames ( ) const

Return a list of the member names.

If null, return an empty list.

Precondition:: type() is objectValue or nullValue

Postcondition:: if type() was nullValue, it remains nullValue

Definition at line 1255 of file json_value.cpp.

bool getString	(	char const **	begin,
		char const **	end
	)		const

Get raw char* of string-value.

Returns:: false if !string. (Seg-fault if str or end are NULL.)

Definition at line 688 of file json_value.cpp.

bool isMember ( const CppTL::ConstString & key ) const

Return true if the object has a member named key.

Definition at line 1250 of file json_value.cpp.

bool isMember ( const char * key ) const

Return true if the object has a member named key.

Note:: 'key' must be null-terminated.

Definition at line 1240 of file json_value.cpp.

bool isMember	(	const char *	begin,
		const char *	end
	)		const

Same as isMember(JSONCPP_STRING const& key)const.

Definition at line 1235 of file json_value.cpp.

bool isMember ( const JSONCPP_STRING & key ) const

Return true if the object has a member named key.

Parameters:

key	may contain embedded nulls.

Definition at line 1244 of file json_value.cpp.

bool isValidIndex ( ArrayIndex index ) const

Return true if index < size().

Definition at line 1098 of file json_value.cpp.

JSONCPP_DEPRECATED ( "Use setComment(JSONCPP_STRING const&) instead." ) const

Value const & nullSingleton ( ) [static]

Prefer this to null or nullRef.

Definition at line 40 of file json_value.cpp.

operator bool ( ) const [explicit]

Return !isNull()

Definition at line 965 of file json_value.cpp.

bool operator< ( const Value & other ) const

Compare payload only, not comments etc.

Definition at line 566 of file json_value.cpp.

Value & operator= ( Value other )

Deep copy, then swap(other).

Note:: Over-write existing comments. To preserve comments, use swapPayload().

Definition at line 521 of file json_value.cpp.

const Value & operator[] ( ArrayIndex index ) const

Access an array element (zero based index ) (You may need to say 'value[0u]' to get your compiler to distinguish this from the operator[] which takes a string.)

Definition at line 1024 of file json_value.cpp.

Value & operator[] ( const StaticString & key )

Access an object value by name, create a null member if it does not exist.

If the object has no entry for that name, then the member name used to store the new entry is not duplicated. Example of use:

 Json::Value object;
 static const StaticString code("code");
 object[code] = 1234;

Definition at line 1132 of file json_value.cpp.

const Value & operator[] ( int index ) const

Access an array element (zero based index ) (You may need to say 'value[0u]' to get your compiler to distinguish this from the operator[] which takes a string.)

Definition at line 1037 of file json_value.cpp.

Value & operator[] ( const JSONCPP_STRING & key )

Access an object value by name, create a null member if it does not exist.

Parameters:

key	may contain embedded nulls.

Definition at line 1128 of file json_value.cpp.

Value const & operator[] ( const CppTL::ConstString & key ) const

Access an object value by name, returns null if there is no member with that name.

Definition at line 1140 of file json_value.cpp.

Value & operator[] ( ArrayIndex index )

Access an array element (zero based index ).

If the array contains less than index element, then null value are inserted in the array so that its size is index+1. (You may need to say 'value[0u]' to get your compiler to distinguish this from the operator[] which takes a string.)

Definition at line 1001 of file json_value.cpp.

Value & operator[] ( int index )

Access an array element (zero based index ).

If the array contains less than index element, then null value are inserted in the array so that its size is index+1. (You may need to say 'value[0u]' to get your compiler to distinguish this from the operator[] which takes a string.)

Definition at line 1017 of file json_value.cpp.

Value & operator[] ( const char * key )

Access an object value by name, create a null member if it does not exist.

Note:: Because of our implementation, keys are limited to 2^30 -1 chars. Exceeding that will cause an exception.

Definition at line 1124 of file json_value.cpp.

const Value & operator[] ( const char * key ) const

Access an object value by name, returns null if there is no member with that name.

Definition at line 1111 of file json_value.cpp.

Value const & operator[] ( const JSONCPP_STRING & key ) const

Access an object value by name, returns null if there is no member with that name.

Parameters:

key	may contain embedded nulls.

Definition at line 1117 of file json_value.cpp.

Value & operator[] ( const CppTL::ConstString & key )

Access an object value by name, create a null member if it does not exist.

Definition at line 1137 of file json_value.cpp.

bool removeIndex	(	ArrayIndex	i,
		Value *	removed
	)

Remove the indexed array element.

O(n) expensive operations. Update 'removed' iff removed.

Returns:: true iff removed (no exceptions)

Definition at line 1205 of file json_value.cpp.

bool removeMember	(	const char *	key,
		Value *	removed
	)

Same as removeMember(const char* begin, const char* end, Value* removed), but 'key' is null-terminated.

Definition at line 1182 of file json_value.cpp.

bool removeMember	(	const char *	begin,
		const char *	end,
		Value *	removed
	)

Same as removeMember(JSONCPP_STRING const& key, Value* removed)

Definition at line 1169 of file json_value.cpp.

void removeMember ( const JSONCPP_STRING & key )

Same as removeMember(const char*)

Parameters:

key	may contain embedded nulls.

Definition at line 1200 of file json_value.cpp.

bool removeMember	(	JSONCPP_STRING const &	key,
		Value *	removed
	)

Remove the named map member.

Update 'removed' iff removed.

Parameters:

key	may contain embedded nulls.

Returns:: true iff removed (no exceptions)

Definition at line 1186 of file json_value.cpp.

void removeMember ( const char * key )

Remove and return the named member.

Do nothing if it did not exist.

Returns:: the removed Value, or null.

Precondition:: type() is objectValue or nullValue

Postcondition:: type() is unchanged

Definition at line 1190 of file json_value.cpp.

void resize ( ArrayIndex size )

Resize the array to size elements.

New elements are initialized to null. May only be called on nullValue or arrayValue.

Precondition:: type() is arrayValue or nullValue

Postcondition:: type() is arrayValue

Definition at line 983 of file json_value.cpp.

void setComment	(	const char *	comment,
		size_t	len,
		CommentPlacement	placement
	)

Comments must be //... or /* ... */.

Definition at line 1418 of file json_value.cpp.

void setComment	(	const JSONCPP_STRING &	comment,
		CommentPlacement	placement
	)

Comments must be //... or /* ... */.

Definition at line 1432 of file json_value.cpp.

ArrayIndex size ( ) const

Number of values in array or object.

Definition at line 935 of file json_value.cpp.

void swap ( Value & other )

Swap everything.

Definition at line 542 of file json_value.cpp.

void swapPayload ( Value & other )

Swap values but leave comments and source offsets in place.

Definition at line 526 of file json_value.cpp.

Field Documentation

const Int maxInt = Int(UInt(-1) / 2) [static]

Maximum signed int value that can be stored in a Json::Value.

Definition at line 210 of file value.h.

const Int64 maxInt64 = Int64(UInt64(-1) / 2) [static]

Maximum signed 64 bits int value that can be stored in a Json::Value.

Definition at line 218 of file value.h.

const LargestInt maxLargestInt = LargestInt(LargestUInt(-1) / 2) [static]

Maximum signed integer value that can be stored in a Json::Value.

Definition at line 203 of file value.h.

const LargestUInt maxLargestUInt = LargestUInt(-1) [static]

Maximum unsigned integer value that can be stored in a Json::Value.

Definition at line 205 of file value.h.

const UInt maxUInt = UInt(-1) [static]

Maximum unsigned int value that can be stored in a Json::Value.

Definition at line 212 of file value.h.

const UInt64 maxUInt64 = UInt64(-1) [static]

Maximum unsigned 64 bits int value that can be stored in a Json::Value.

Definition at line 220 of file value.h.

const Int minInt = Int(~(UInt(-1) / 2)) [static]

Minimum signed int value that can be stored in a Json::Value.

Definition at line 208 of file value.h.

const Int64 minInt64 = Int64(~(UInt64(-1) / 2)) [static]

Minimum signed 64 bits int value that can be stored in a Json::Value.

Definition at line 216 of file value.h.

const LargestInt minLargestInt = LargestInt(~(LargestUInt(-1) / 2)) [static]

Minimum signed integer value that can be stored in a Json::Value.

Definition at line 201 of file value.h.

Value const & null = Value::nullSingleton() [static]

We regret this reference to a global instance; prefer the simpler Value().

Definition at line 196 of file value.h.

Value const & nullRef = Value::nullSingleton() [static]

just a kludge for binary-compatibility; same as null

Definition at line 197 of file value.h.

Type:	Program
Mbed OS support:	Mbed OS
Created:	26 Jan 2018
Imports:	25
Forks:	0
Commits:	1
Dependents:	0
Dependencies:	0
Followers:	1

Value Class Reference

Public Member Functions

Static Public Member Functions

Static Public Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Field Documentation

Repository toolbox

Repository details

Important Information for this Arm website

Value Class Reference

Public Member Functions

Static Public Member Functions

Static Public Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Field Documentation

Repository toolbox

Repository details

Important Information for this Arm website

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