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Value Class Reference

Represents a JSON value. More...

#include <value.h>

Public Types

typedef std::vector< std::string > Members
 
typedef ValueIterator iterator
 
typedef ValueConstIterator const_iterator
 
typedef Json::UInt UInt
 
typedef Json::Int Int
 
typedef UInt ArrayIndex
 
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 (double value)
 
 Value (const char *value)
 
 Value (const char *beginValue, const char *endValue)
 
 Value (const StaticString &value)
 Constructs a value from a static string. More...
 
 Value (const std::string &value)
 
 Value (bool value)
 
 Value (const Value &other)
 
 ~Value ()
 
Valueoperator= (const Value &other)
 
void swap (Value &other)
 
ValueType type () 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
 
bool operator== (const Value &other) const
 
bool operator!= (const Value &other) const
 
int compare (const Value &other)
 
const char * asCString () const
 
std::string asString () const
 
Int asInt () const
 
UInt asUInt () const
 
double asDouble () const
 
bool asBool () const
 
bool isNull () const
 
bool isBool () const
 
bool isInt () const
 
bool isUInt () const
 
bool isIntegral () const
 
bool isDouble () const
 
bool isNumeric () const
 
bool isString () const
 
bool isArray () const
 
bool isObject () const
 
bool isConvertibleTo (ValueType other) const
 
UInt size () const
 Number of values in array or object. More...
 
bool empty () const
 Return true if empty array, empty object, or null; otherwise, false. More...
 
bool operator! () const
 Return isNull() More...
 
void clear ()
 
void resize (UInt size)
 
Valueoperator[] (UInt index)
 
const Valueoperator[] (UInt index) const
 
Value get (UInt index, const Value &defaultValue) const
 
bool isValidIndex (UInt index) const
 Return true if index < size(). More...
 
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. More...
 
Valueoperator[] (const std::string &key)
 Access an object value by name, create a null member if it does not exist. More...
 
const Valueoperator[] (const std::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 std::string &key, const Value &defaultValue) const
 Return the member named key if it exist, defaultValue otherwise. More...
 
Value removeMember (const char *key)
 Remove and return the named member. More...
 
Value removeMember (const std::string &key)
 Same as removeMember(const char*) More...
 
bool isMember (const char *key) const
 Return true if the object has a member named key. More...
 
bool isMember (const std::string &key) const
 Return true if the object has a member named key. More...
 
Members getMemberNames () const
 Return a list of the member names. More...
 
void setComment (const char *comment, CommentPlacement placement)
 Comments must be //... or /* ... */. More...
 
void setComment (const std::string &comment, CommentPlacement placement)
 Comments must be //... or /* ... */. More...
 
bool hasComment (CommentPlacement placement) const
 
std::string getComment (CommentPlacement placement) const
 Include delimiters and embedded newlines. More...
 
std::string toStyledString () const
 
const_iterator begin () const
 
const_iterator end () const
 
iterator begin ()
 
iterator end ()
 

Static Public Attributes

static const Value null
 
static const Int minInt = Int( ~(UInt(-1)/2) )
 
static const Int maxInt = Int( UInt(-1)/2 )
 
static const UInt maxUInt = UInt(-1)
 

Friends

class ValueIteratorBase
 

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 resize and initialized with nullValue. resize() can be used to enlarge or truncate an arrayValue.

The get() methods can be used to obtanis 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.

Member Typedef Documentation

typedef UInt ArrayIndex
typedef Json::Int Int
typedef std::vector<std::string> Members
typedef std::map<CZString, Value> ObjectValues
typedef Json::UInt UInt

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); // {}
Value ( Int  value)
Value ( UInt  value)
Value ( double  value)
Value ( const char *  value)
Value ( const char *  beginValue,
const char *  endValue 
)
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. Example of usage:

Json::Value aValue( StaticString("some text") );
Value ( const std::string &  value)
Value ( bool  value)
Value ( const Value other)
~Value ( )

Member Function Documentation

Value & append ( const Value value)

Append value to array at the end.

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

bool asBool ( ) const
const char * asCString ( ) const
double asDouble ( ) const
Value::Int asInt ( ) const
std::string asString ( ) const
Value::UInt asUInt ( ) const
Value::const_iterator begin ( ) const
Value::iterator begin ( )
void clear ( void  )

Remove all object members and array elements.

Precondition
type() is arrayValue, objectValue, or nullValue
Postcondition
type() is unchanged
int compare ( const Value other)
bool empty ( ) const

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

Value::const_iterator end ( void  ) const
Value::iterator end ( void  )
Value get ( UInt  index,
const Value defaultValue 
) const

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

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

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

Value get ( const std::string &  key,
const Value defaultValue 
) const

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

std::string getComment ( CommentPlacement  placement) const

Include delimiters and embedded newlines.

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
bool hasComment ( CommentPlacement  placement) const
bool isArray ( ) const
bool isBool ( ) const
bool isConvertibleTo ( ValueType  other) const
bool isDouble ( ) const
bool isInt ( ) const
bool isIntegral ( ) const
bool isMember ( const char *  key) const

Return true if the object has a member named key.

bool isMember ( const std::string &  key) const

Return true if the object has a member named key.

bool isNull ( void  ) const
bool isNumeric ( ) const
bool isObject ( ) const
bool isString ( ) const
bool isUInt ( ) const
bool isValidIndex ( UInt  index) const

Return true if index < size().

bool operator! ( ) const

Return isNull()

bool operator!= ( const Value other) const
bool operator< ( const Value other) const
bool operator<= ( const Value other) const
Value & operator= ( const Value other)
bool operator== ( const Value other) const
bool operator> ( const Value other) const
bool operator>= ( const Value other) const
Value & operator[] ( UInt  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.)

const Value & operator[] ( UInt  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 & 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 std::string &  key)

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

const Value & operator[] ( const std::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.

If the object as 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;
Value 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
Value removeMember ( const std::string &  key)
void resize ( UInt  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
void setComment ( const char *  comment,
CommentPlacement  placement 
)

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

void setComment ( const std::string &  comment,
CommentPlacement  placement 
)

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

Value::UInt size ( void  ) const

Number of values in array or object.

void swap ( Value other)

Swap values.

Note
Currently, comments are intentionally not swapped, for both logic and efficiency.
std::string toStyledString ( ) const
ValueType type ( ) const

Friends And Related Function Documentation

friend class ValueIteratorBase
friend

Member Data Documentation

const Int maxInt = Int( UInt(-1)/2 )
static
const UInt maxUInt = UInt(-1)
static
const Int minInt = Int( ~(UInt(-1)/2) )
static
const Value null
static

The documentation for this class was generated from the following files: