ADTF  3.18.2
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, ValueObjectValues
 

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.
 
Valueoperator= (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...
 
Valueoperator[] (ArrayIndex index)
 Access an array element (zero based index ). More...
 
Valueoperator[] (int index)
 Access an array element (zero based index ). More...
 
const Valueoperator[] (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 Valueoperator[] (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().
 
Valueappend (const Value &value)
 Append value to array at the end. More...
 
Valueoperator[] (const char *key)
 Access an object value by name, create a null member if it does not exist. More...
 
const Valueoperator[] (const char *key) const
 Access an object value by name, returns null if there is no member with that name.
 
Valueoperator[] (const JSONCPP_STRING &key)
 Access an object value by name, create a null member if it does not exist. More...
 
const Valueoperator[] (const JSONCPP_STRING &key) const
 Access an object value by name, returns null if there is no member with that name. More...
 
Valueoperator[] (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 Valuenull
 We regret this reference to a global instance; prefer the simpler Value().
 
static const ValuenullRef
 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)
 
ValueresolveReference (const char *key)
 
ValueresolveReference (const char *key, const char *end)
 

Private Attributes

union Json::Value::ValueHolder value_
 
ValueType type_: 8
 
unsigned int allocated_: 1
 
CommentInfocomments_
 
ptrdiff_t start_
 
ptrdiff_t limit_
 

Detailed Description

Represents a JSON value.

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

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); // {}
Represents a JSON value.
Definition: value.h:177
@ arrayValue
array value (ordered list)
Definition: value.h:100
@ objectValue
object value (collection of name/value pairs).
Definition: value.h:101

◆ 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
keymay 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
keymay 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
keymay 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
keymay 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 ).

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.)

◆ 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
keymay 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
keymay 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.