ADTF: Value

Represents a JSON value. More...

Classes
struct	CommentInfo

class	CZString

union	ValueHolder

Public Types
typedef std::vector< JSONCPP_STRING >	Members

typedef ValueIterator	iterator

typedef ValueConstIterator	const_iterator

typedef Json::UInt	UInt

typedef Json::Int	Int

typedef Json::UInt64	UInt64

typedef Json::Int64	Int64

typedef Json::LargestInt	LargestInt

typedef Json::LargestUInt	LargestUInt

typedef Json::ArrayIndex	ArrayIndex

typedef std::string	value_type

typedef std::map< CZString, Value >	ObjectValues

Public Member Functions
	Value (ValueType type=nullValue)
	Create a default Value of the given type. More...

	Value (Int value)

	Value (UInt value)

	Value (Int64 value)

	Value (UInt64 value)

	Value (double value)

	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. More...

	Value (const JSONCPP_STRING &value)
	Copy data() til size(). Embedded zeroes too.

	Value (bool value)

	Value (const Value &other)
	Deep copy.

Value &	operator= (Value other)
	Deep copy, then swap(other). More...

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.

ValueType	type () const

bool	operator< (const Value &other) const
	Compare payload only, not comments etc.

bool	operator<= (const Value &other) const

bool	operator>= (const Value &other) const

bool	operator> (const Value &other) const

bool	operator== (const Value &other) const

bool	operator!= (const Value &other) const

int	compare (const Value &other) const

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. More...

Int	asInt () const

UInt	asUInt () const

Int64	asInt64 () const

UInt64	asUInt64 () const

LargestInt	asLargestInt () const

LargestUInt	asLargestUInt () const

float	asFloat () const

double	asDouble () const

bool	asBool () const

bool	isNull () const

bool	isBool () const

bool	isInt () const

bool	isInt64 () const

bool	isUInt () const

bool	isUInt64 () const

bool	isIntegral () const

bool	isDouble () const

bool	isNumeric () const

bool	isString () const

bool	isArray () const

bool	isObject () const

bool	isConvertibleTo (ValueType other) const

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. More...

void	resize (ArrayIndex size)
	Resize the array to size elements. More...

Value &	operator[] (ArrayIndex index)
	Access an array element (zero based index ). More...

Value &	operator[] (int index)
	Access an array element (zero based index ). More...

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. More...

Value &	operator[] (const char *key)
	Access an object value by name, create a null member if it does not exist. More...

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. More...

const Value &	operator[] (const JSONCPP_STRING &key) const
	Access an object value by name, returns null if there is no member with that name. More...

Value &	operator[] (const StaticString &key)
	Access an object value by name, create a null member if it does not exist. More...

Value	get (const char *key, const Value &defaultValue) const
	Return the member named key if it exist, defaultValue otherwise. More...

Value	get (const char begin, const char end, const Value &defaultValue) const
	Return the member named key if it exist, defaultValue otherwise. More...

Value	get (const JSONCPP_STRING &key, const Value &defaultValue) const
	Return the member named key if it exist, defaultValue otherwise. More...

Value const *	find (char const begin, char const end) const
	Most general and efficient version of isMember()const, get()const, and operator[]const. More...

Value const *	demand (char const begin, char const end)
	Most general and efficient version of object-mutators. More...

void	removeMember (const char *key)
	Remove and return the named member. More...

void	removeMember (const JSONCPP_STRING &key)
	Same as removeMember(const char*) More...

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. More...

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. More...

bool	isMember (const char *key) const
	Return true if the object has a member named key. More...

bool	isMember (const JSONCPP_STRING &key) const
	Return true if the object has a member named key. More...

bool	isMember (const char begin, const char end) const
	Same as isMember(JSONCPP_STRING const& key)const.

Members	getMemberNames () const
	Return a list of the member names. More...

void	setComment (const char *comment, CommentPlacement placement)

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 /* ... *‍/.

bool	hasComment (CommentPlacement placement) const

JSONCPP_STRING	getComment (CommentPlacement placement) const
	Include delimiters and embedded newlines.

JSONCPP_STRING	toStyledString () const

const_iterator	begin () const

const_iterator	end () const

iterator	begin ()

iterator	end ()

void	setOffsetStart (ptrdiff_t start)

void	setOffsetLimit (ptrdiff_t limit)

ptrdiff_t	getOffsetStart () const

ptrdiff_t	getOffsetLimit () const

Static Public Member Functions
static Value const &	nullSingleton ()
	Prefer this to null or nullRef.

Static Public Attributes
static const Value &	null
	We regret this reference to a global instance; prefer the simpler Value().

static const Value &	nullRef
	just a kludge for binary-compatibility; same as null

static const LargestInt	minLargestInt
	Minimum signed integer value that can be stored in a Json::Value.

static const LargestInt	maxLargestInt
	Maximum signed integer value that can be stored in a Json::Value.

static const LargestUInt	maxLargestUInt
	Maximum unsigned integer value that can be stored in a Json::Value.

static const Int	minInt
	Minimum signed int value that can be stored in a Json::Value.

static const Int	maxInt
	Maximum signed int value that can be stored in a Json::Value.

static const UInt	maxUInt
	Maximum unsigned int value that can be stored in a Json::Value.

static const Int64	minInt64
	Minimum signed 64 bits int value that can be stored in a Json::Value.

static const Int64	maxInt64
	Maximum signed 64 bits int value that can be stored in a Json::Value.

static const UInt64	maxUInt64
	Maximum unsigned 64 bits int value that can be stored in a Json::Value.

Private Member Functions
void	initBasic (ValueType type, bool allocated=false)

Value &	resolveReference (const char *key)

Value &	resolveReference (const char key, const char end)

Private Attributes
union Json::Value::ValueHolder	value_

ValueType	type_: 8

unsigned int	allocated_: 1

CommentInfo *	comments_

ptrdiff_t	start_

ptrdiff_t	limit_

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() [1/2]

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); // {}

◆ Value() [2/2]

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);

Member Function Documentation

◆ append()

Value& append ( const Value & value )

Append value to array at the end.

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

◆ clear()

void clear ( )

Remove all object members and array elements.

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

Postcondition: type() is unchanged

◆ demand()

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.

◆ find()

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

◆ get() [1/3]

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.

◆ get() [2/3]

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

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

Note: deep copy

◆ get() [3/3]

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.

◆ getMemberNames()

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

◆ getString()

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.)

◆ isMember() [1/2]

bool isMember ( const char * key ) const

Return true if the object has a member named key.

Note: 'key' must be null-terminated.

◆ isMember() [2/2]

bool isMember ( const JSONCPP_STRING & key ) const

Return true if the object has a member named key.

Parameters

key	may contain embedded nulls.

◆ operator=()

Value& operator= ( Value other )

Deep copy, then swap(other).

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

◆ operator[]() [1/6]

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.)

◆ operator[]() [2/6]

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.

◆ operator[]() [3/6]

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.

◆ operator[]() [4/6]

const Value& 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.

◆ operator[]() [5/6]

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;

◆ operator[]() [6/6]

Value& operator[] ( int index )

Access an array element (zero based index ).

◆ removeIndex()

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)

◆ removeMember() [1/3]

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

Deprecated:

◆ removeMember() [2/3]

void removeMember ( const JSONCPP_STRING & key )

Same as removeMember(const char*)

Parameters

key	may contain embedded nulls.

Deprecated:

◆ removeMember() [3/3]

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)

◆ resize()

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

◆ setComment()

void setComment	(	const char *	comment,
		CommentPlacement	placement
	)

Deprecated:: Always pass len.

Classes

Public Types

Public Member Functions

Static Public Member Functions

Static Public Attributes

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ Value() [1/2]

◆ Value() [2/2]

Member Function Documentation

◆ append()

◆ clear()

◆ demand()

◆ find()

◆ get() [1/3]

◆ get() [2/3]

◆ get() [3/3]

◆ getMemberNames()

◆ getString()

◆ isMember() [1/2]

◆ isMember() [2/2]

◆ operator=()

◆ operator[]() [1/6]

◆ operator[]() [2/6]

◆ operator[]() [3/6]

◆ operator[]() [4/6]

◆ operator[]() [5/6]

◆ operator[]() [6/6]

◆ removeIndex()

◆ removeMember() [1/3]

◆ removeMember() [2/3]

◆ removeMember() [3/3]

◆ resize()

◆ setComment()