JSON API

The JSON library provides JSON parsing, serialization and query capabilities. The library can parse strings and read files containing JSON text.

JSON can be read and serialized in strict JSON or in the more human readable JSON/5 format. When parsed, JSON is stored in-memory in a binary search tree for efficient querying. The library supports searching, querying and updating JSON values using dot and array notation.

The library supports the JSON and JSON/5 formats. JSON/5 is an extension of JSON that makes it easier to create, read and maintain configuration files in JSON. JSON/5 supports the following features to JSON:

• Object keys may be JavaScript identifiers without quotes.
• Objects or arrays may have a trailing comma.
• Strings may be single quoted.
• Strings may span multiple lines (single, double or back-tick quotes).
• Numbers may have a leading or trailing decimal point, be hexadecimal, may begin with a plus
• Values may be regular expressions.
• Undefined is a valid value.
• Single and multiline comments are allowed and preserved.

Extensions

Json	JSON Object.

Functions

Json *	jsonAlloc(int flags)
	Allocate a json object.
int	jsonBlend(Json *dest, int did, cchar *dkey, Json *src, int sid, cchar *skey, int flags)
	Blend nodes by copying from one Json to another.
Json *	jsonClone(Json *src, int flags)
	Clone a json object.
void	jsonFree(Json *json)
	Free a json object.
char *	jsonGet(Json *json, int nid, cchar *key, cchar *defaultValue)
	Get a json node value as an allocated string.
bool	jsonGetBool(Json *json, int nid, cchar *key, bool defaultValue)
	Get a json node value as a boolean.
JsonNode *	jsonGetChildNode(Json *json, int nid, int nth)
	Get the Nth child node for a json node.
int	jsonGetId(Json *json, int nid, cchar *key)
	Get a json node ID.
int	jsonGetInt(Json *json, int nid, cchar *key, int defaultValue)
	Get a json node value as an integer.
JsonNode *	jsonGetNode(Json *json, int nid, cchar *key)
	Get a json node object.
int64	jsonGetNum(Json *json, int nid, cchar *key, int64 defaultValue)
	Get a json node value as a 64-bit integer.
cchar *	jsonGetRef(Json *json, int nid, cchar *key, cchar *defaultValue)
	Get a json node value as a string.
int	jsonGetType(Json *json, int nid, cchar *key)
	Get the value type for a node.
void	jsonLock(Json *json)
	Lock a json object from further updates.
Json *	jsonParse(cchar *text, int flags)
	Parse a json string into a json object.
Json *	jsonParseFile(cchar *path, char **errorMsg, int flags)
	Load a JSON object from a filename.
Json *	jsonParseString(cchar *text, char **errorMsg, int flags)
	Parse a JSON string into an object tree and return any errors.
void	jsonPrint(Json *json)
	Print a JSON object.
int	jsonRemove(Json *obj, int nid, cchar *key)
	Remove a Property from a JSON object.
int	jsonSave(Json *obj, int nid, cchar *key, cchar *path, int mode, int flags)
	Save a JSON object to a filename.
int	jsonSet(Json *obj, int nid, cchar *key, cchar *value, int type)
	Update a key/value in the JSON object with a string value.
int	jsonSetBool(Json *obj, int nid, cchar *key, bool value)
	Update a property in the JSON object with a boolean value.
int	jsonSetDate(Json *json, int nid, cchar *key, Time value)
	Update a property in the JSON object with date value.
int	jsonSetDouble(Json *json, int nid, cchar *key, double value)
	Update a property with a floating point number value.
int	jsonSetFmt(Json *obj, int nid, cchar *key, cchar *fmt, ...)
	Update a key/value in the JSON object with a formatted string value.
void	jsonSetNodeType(JsonNode *node, int type)
	Update a node type.
void	jsonSetNodeValue(JsonNode *node, cchar *value, int type, int flags)
	Directly update a node value.
int	jsonSetNumber(Json *json, int nid, cchar *key, int64 value)
	Update a property in the JSON object with a numeric value.
cchar *	jsonString(Json *json)
	Serialize an entire JSON object into a string using a human readable format (JSON_PRETTY).
char *	jsonTemplate(Json *json, cchar *str)
	Expand a string template with ${prop.prop...} references.
void	jsonToBuf(RBuf *buf, cchar *value, int flags)
	Convert a json value to serialized JSON representation and save in the given buffer.
char *	jsonToString(Json *json, int nid, cchar *key, int flags)
	Serialize a JSON object into a string.
void	jsonUnlock(Json *json)
	Unlock a json object to allow updates.

Typedefs

JsonNode

JSON Node.

Defines

#define	ITERATE_JSON    nid = (int) ((parent ? parent : json->nodes) - json->nodes + 1); \ (json->count > 0) && json->nodes && (nid < (parent ? parent : json->nodes)->last) && \ ((child = &json->nodes[nid]) != 0); \ nid = child->last
	This iterates over the children under the "parent" id.
#define	JSON_APPEND   0x4
	Default to append to existing '+' (default).
#define	JSON_CCREATE   0x10
	Conditional create if not already existing '?'.
#define	JSON_COMBINE   0x1
	Combine properies using '+' '-' '=' '?' prefixes.
#define	JSON_LOCK   0x1
	Lock JSON object from further object.
#define	JSON_OVERWRITE   0x2
	Default to overwrite existing properies '='.
#define	JSON_PASS_TEXT   0x40
	Transfer ownership of the parsed text to json.
#define	JSON_PRETTY   0x100
	Save in Json6 format without quotes arounds keys.
#define	JSON_PRIMITIVE   0x10
	True, false, null, undefined, number.
#define	JSON_QUOTES   0x200
	Save in strict JSON format.
#define	JSON_REGEXP   0x20
	Regular expressions.
#define	JSON_REMOVE_UNDEF   0x20
	Remove undefined (NULL) properties.
#define	JSON_REPLACE   0x8
	Replace existing properies '-'.
#define	JSON_SINGLE   0x20
	Save objects on a sinle line where possible.
#define	JSON_STRICT   0x10
	Expect strict JSON format.
#define	JSON_STRING   0x8
	Strings including dates encoded as ISO strings.
#define	JSON_USER_ALLOC   0x2
	User flag.

Json

Json

JSON Object.

Description:

The JSON library parses JSON strings into an in-memory JSON tree that can be queried and modified and saved. Some APIs such as jsonGetRef return direct references into the JSON tree for performance as (const char*) references. Others, such as jsonGet will return an allocated string that must be freed by the caller.
When a JSON object is allocated or parsed, the JSON tree may be locked via the JSON_LOCK flag. A locked JSON object is useful as it will not permit further updates via (jsonSet or jsonBlend) and the internal node structure will be stable such that references returned via jsonGetRef and jsonGetNode will remain valid.

API Stability:

Evolving.

Fields:

uint		count	Number of allocated nodes (count <= size).
char *		end	End of text + 1.
char *		errorMsg	Parsing error details.
REvent		event	Saving event.
uint		flags	Use defined bits.
uint		lineNumber	Current parse line number.
char *		next	Pointer to next token.
char *		path	Filename being parsed.
uint		size	Size of Json.nodes in elements (includes spare).
uint		strict	Strict JSON standard mode.
char *		text	Text being parsed.
char *		value	Result from jsonString.

Json * * jsonAlloc (int flags)

Allocate a json object.

Parameters:

flags

Set to one JSON_STRICT for strict JSON parsing. Otherwise permits JSON/5.

Returns:

A json object.

API Stability:

Evolving.

int jsonBlend (Json *dest, int did, cchar *dkey, Json *src, int sid, cchar *skey, int flags)

Blend nodes by copying from one Json to another.

Description:

This performs an N-level deep clone of the source JSON nodes to be blended into the destination object. By default, this add new object properies and overwrite arrays and string values. The Property combination prefixes: '+', '=', '-' and '?' to append, overwrite, replace and conditionally overwrite are supported if the JSON_COMBINE flag is present.

Parameters:

dest	Destination json.
did	Base node ID from which to store the copied nodes.
dkey	Destination property name to search for.
src	Source json.
sid	Base node ID from which to copy nodes.
skey	Source property name to search for.
flags	The JSON_COMBINE flag enables Property name prefixes: '+', '=', '-', '?' to append, overwrite, replace and conditionally overwrite key values if not already present. When adding string properies, values will be appended using a space separator. Extra spaces will not be removed on replacement. Without JSON_COMBINE or for properies without a prefix, the default is to blend objects by creating new properies if not already existing in the destination, and to treat overwrite arrays and strings. Use the JSON_OVERWRITE flag to override the default appending of objects and rather overwrite existing properies. Use the JSON_APPEND flag to override the default of overwriting arrays and strings and rather append to existing properies.

Returns:

Zero if successful.

API Stability:

Evolving.

Json * * jsonClone (Json *src, int flags)

Clone a json object.

Parameters:

src	Input json object.
flags	Reserved, set to zero.

Returns:

The copied JSON tree. Caller must free with jsonFree

API Stability:

Evolving.

void jsonFree (Json *json)

Free a json object.

Parameters:

json	A json object.

API Stability:

Evolving.

char * * jsonGet (Json *json, int nid, cchar *key, cchar *defaultValue)

Get a json node value as an allocated string.

Description:

This call returns an allocated string as the result. Use jsonGetRef as a higher performance API if you do not need to retain the queried value.

Parameters:

json	Source json.
nid	Base node ID from which to examine. Set to zero for the top level.
key	Property name to search for. This may include ".". For example: "settings.mode".
defaultValue	If the key is not defined, return a copy of the defaultValue. The defaultValue can be NULL in which case the return value will be an allocated empty string.

Returns:

An allocated string copy of the key value or defaultValue if not defined. Caller must free.

API Stability:

Evolving.

bool jsonGetBool (Json *json, int nid, cchar *key, bool defaultValue)

Get a json node value as a boolean.

Parameters:

json	Source json.
nid	Base node ID from which to examine. Set to zero for the top level.
key	Property name to search for. This may include ".". For example: "settings.mode".
defaultValue	If the key is not defined, return the defaultValue.

Returns:

The key value as a boolean or defaultValue if not defined.

API Stability:

Evolving.

JsonNode * * jsonGetChildNode (Json *json, int nid, int nth)

Get the Nth child node for a json node.

Parameters:

json	Source json.
nid	Base node ID to examine.
nth	Specify which child to return.

Returns:

The Nth child node object for the specified node.

API Stability:

Evolving.

int jsonGetId (Json *json, int nid, cchar *key)

Get a json node ID.

Parameters:

json	Source json.
nid	Base node ID from which to start the search. Set to zero for the top level.
key	Property name to search for. This may include ".". For example: "settings.mode".

Returns:

The node ID for the specified key.

API Stability:

Evolving.

int jsonGetInt (Json *json, int nid, cchar *key, int defaultValue)

Get a json node value as an integer.

Parameters:

json	Source json.
nid	Base node ID from which to examine. Set to zero for the top level.
key	Property name to search for. This may include ".". For example: "settings.mode".
defaultValue	If the key is not defined, return the defaultValue.

Returns:

The key value as an integer or defaultValue if not defined.

API Stability:

Evolving.

JsonNode * * jsonGetNode (Json *json, int nid, cchar *key)

Get a json node object.

Description:

This call returns a reference into the JSON storage. Such references are not persistent if other modifications are made to the JSON tree.

Parameters:

json	Source json.
nid	Base node ID from which to start the search. Set to zero for the top level.
key	Property name to search for. This may include ".". For example: "settings.mode".

Returns:

The node object for the specified key. Returns NULL if not found.

API Stability:

Evolving.

int64 jsonGetNum (Json *json, int nid, cchar *key, int64 defaultValue)

Get a json node value as a 64-bit integer.

Parameters:

json	Source json.
nid	Base node ID from which to examine. Set to zero for the top level.
key	Property name to search for. This may include ".". For example: "settings.mode".
defaultValue	If the key is not defined, return the defaultValue.

Returns:

The key value as a 64-bit integer or defaultValue if not defined.

API Stability:

Evolving.

cchar * * jsonGetRef (Json *json, int nid, cchar *key, cchar *defaultValue)

Get a json node value as a string.

Description:

This call returns a reference into the JSON storage. Such references are short-term and may not remain valid if other modifications are made to the JSON tree. Only use the result of this API while no other changes are made to the JSON object. Use jsonGet if you need to retain the queried value.

Parameters:

json	Source json.
nid	Base node ID from which to examine. Set to zero for the top level.
key	Property name to search for. This may include ".". For example: "settings.mode".
defaultValue	If the key is not defined, return the defaultValue.

Returns:

The key value as a string or defaultValue if not defined. This is a reference into the JSON store. Caller must NOT free.

API Stability:

Evolving.

int jsonGetType (Json *json, int nid, cchar *key)

Get the value type for a node.

Parameters:

json	Source json.
nid	Base node ID from which to start the search.
key	Property name to search for. This may include ".". For example: "settings.mode".

Returns:

The data type. Set to JSON_OBJECT, JSON_ARRAY, JSON_COMMENT, JSON_STRING, JSON_PRIMITIVE or JSON_REGEXP.

API Stability:

Evolving.

void jsonLock (Json *json)

Lock a json object from further updates.

Description:

This call is useful to block all further updates via jsonSet. The jsonGet API returns a references into the JSON tree. Subsequent updates can grow the internal JSON structures and thus move references returned earlier.

Parameters:

json	A json object.

API Stability:

Evolving.

Json * * jsonParse (cchar *text, int flags)

Parse a json string into a json object.

Description:

Use this method if you are sure the supplied JSON text is valid. Use jsonParseString if you need to receive notification of parse errors.

Parameters:

text	Json string to parse.
flags	Set to JSON_STRICT to parse json, otherwise a relaxed json6 syntax is supported. Set JSON_PASS_TEXT to transfer ownership of the text to json which will free when jsonFree is called. Set to JSON_LOCK to lock the JSON tree to prevent further modification via jsonSet or jsonBlend. This will make returned references via jsonGetRef and jsonGetNode stable.

Returns:

Json object if successful. Caller must free via jsonFree. Returns null if the text will not parse.

API Stability:

Evolving.

Json * * jsonParseFile (cchar *path, char **errorMsg, int flags)

Load a JSON object from a filename.

Parameters:

path	Filename path containing a JSON string to load.
errorMsg	Error message string set if the parse fails. Caller must not free.
flags	Set to JSON_STRICT to parse json, otherwise a relaxed json6 syntax is supported.

Returns:

JSON object tree. Caller must free errorMsg via rFree on errors.

API Stability:

Evolving.

Json * * jsonParseString (cchar *text, char **errorMsg, int flags)

Parse a JSON string into an object tree and return any errors.

Description:

Deserializes a JSON string created into an object. The top level of the JSON string must be an object, array, string, number or boolean value.

Parameters:

text	JSON string to deserialize.
errorMsg	Error message string set if the parse fails. Caller must not free.
flags	Set to JSON_STRICT to parse json, otherwise a relaxed json6 syntax is supported. Set JSON_PASS_TEXT to transfer ownership of the text to json which will free when jsonFree is called.

Returns:

Returns a tree of Json objects. Each object represents a level in the JSON input stream. Caller must free errorMsg via rFree on errors.

API Stability:

Evolving.

void jsonPrint (Json *json)

Print a JSON object.

Description:

Prints a JSON object in pretty format.

Parameters:

json	Source json.

API Stability:

Evolving.

int jsonRemove (Json *obj, int nid, cchar *key)

Remove a Property from a JSON object.

Parameters:

obj	Parsed JSON object returned by jsonParse.
nid	Base node ID from which to start searching for key. Set to zero for the top level.
key	Property name to remove for. This may include ".". For example: "settings.mode".

Returns:

Returns a JSON object array of all removed properies. Array will be empty if not qualifying properies were found and removed.

API Stability:

Evolving.

int jsonSave (Json *obj, int nid, cchar *key, cchar *path, int mode, int flags)

Save a JSON object to a filename.

Parameters:

obj	Parsed JSON object returned by jsonParse.
nid	Base node ID from which to start searching for key. Set to zero for the top level.
key	Property name to add/update. This may include ".". For example: "settings.mode".
path	Filename path to contain the saved JSON string.
flags	Same flags as for jsonToString: JSON_PRETTY, JSON_QUOTES.
mode	Permissions mode.

Returns:

Zero if successful, otherwise a negative RT error code.

API Stability:

Evolving.

int jsonSet (Json *obj, int nid, cchar *key, cchar *value, int type)

Update a key/value in the JSON object with a string value.

Description:

This call takes a multipart Property name and will operate at any level of depth in the JSON object.

Parameters:

obj	Parsed JSON object returned by jsonParse.
nid	Base node ID from which to start search for key. Set to zero for the top level.
key	Property name to add/update. This may include ".". For example: "settings.mode".
value	Character string value.
type	Set to JSON_ARRAY, JSON_OBJECT, JSON_PRIMITIVE or JSON_STRING.

Returns:

Positive node id if updated successfully. Otherwise a negative error code.

API Stability:

Evolving.

int jsonSetBool (Json *obj, int nid, cchar *key, bool value)

Update a property in the JSON object with a boolean value.

Description:

This call takes a multipart Property name and will operate at any level of depth in the JSON object.

Parameters:

obj	Parsed JSON object returned by jsonParse.
nid	Base node ID from which to start search for key. Set to zero for the top level.
key	Property name to add/update. This may include ".". For example: "settings.mode".
value	Boolean string value.

Returns:

Positive node id if updated successfully. Otherwise a negative error code.

API Stability:

Evolving.

int jsonSetDate (Json *json, int nid, cchar *key, Time value)

Update a property in the JSON object with date value.

Description:

This call takes a multipart Property name and will operate at any level of depth in the JSON object.

Parameters:

json	Parsed JSON object returned by jsonParse.
nid	Base node ID from which to start search for key. Set to zero for the top level.
key	Property name to add/update. This may include ".". For example: "settings.mode".
value	Date value expressed as a Time (Elapsed milliseconds since Jan 1, 1970).

Returns:

Positive node id if updated successfully. Otherwise a negative error code.

API Stability:

Evolving.

int jsonSetDouble (Json *json, int nid, cchar *key, double value)

Update a property with a floating point number value.

Description:

This call takes a multipart Property name and will operate at any level of depth in the JSON object.

Parameters:

json	Parsed JSON object returned by jsonParse.
nid	Base node ID from which to start search for key. Set to zero for the top level.
key	Property name to add/update. This may include ".". For example: "settings.mode".
value	Double floating point value.

Returns:

Positive node id if updated successfully. Otherwise a negative error code.

API Stability:

Evolving.

int jsonSetFmt (Json *obj, int nid, cchar *key, cchar *fmt, ...)

Update a key/value in the JSON object with a formatted string value.

Description:

The type of the inserted value is determined from the contents. This call takes a multipart property name and will operate at any level of depth in the JSON object.

Parameters:

obj	Parsed JSON object returned by jsonParse.
nid	Base node ID from which to start search for key. Set to zero for the top level.
key	Property name to add/update. This may include ".". For example: "settings.mode".
fmt	Printf style format string.
...	Args for format.

Returns:

Positive node id if updated successfully. Otherwise a negative error code.

API Stability:

Evolving.

void jsonSetNodeType (JsonNode *node, int type)

Update a node type.

Description:

This is an internal API and is subject to change without notice. It offers a higher performance path to update node types.

Parameters:

node	Json node.
type	Json node type.

API Stability:

Internal.

void jsonSetNodeValue (JsonNode *node, cchar *value, int type, int flags)

Directly update a node value.

Description:

This is an internal API and is subject to change without notice. It offers a higher performance path to update node values.

Parameters:

node	Json node.
value	String value to update with.
type	Json node type.
flags	Set to JSON_PASS_TEXT to transfer ownership of a string. JSON will then free.

API Stability:

Internal.

int jsonSetNumber (Json *json, int nid, cchar *key, int64 value)

Update a property in the JSON object with a numeric value.

Description:

This call takes a multipart Property name and will operate at any level of depth in the JSON object.

Parameters:

json	Parsed JSON object returned by jsonParse.
nid	Base node ID from which to start search for key. Set to zero for the top level.
key	Property name to add/update. This may include ".". For example: "settings.mode".
value	Number to update.

Returns:

Positive node id if updated successfully. Otherwise a negative error code.

API Stability:

Evolving.

cchar * * jsonString (Json *json)

Serialize an entire JSON object into a string using a human readable format (JSON_PRETTY).

Parameters:

json	Source json.

Returns:

Returns a serialized JSON character string. Caller must NOT free.

API Stability:

Evolving.

char * * jsonTemplate (Json *json, cchar *str)

Expand a string template with ${prop.prop...} references.

Parameters:

json	Json object.
str	String template to expand.

Returns:

An allocated expanded string. Caller must free.

API Stability:

Evolving.

void jsonToBuf (RBuf *buf, cchar *value, int flags)

Convert a json value to serialized JSON representation and save in the given buffer.

Parameters:

buf	Destination buffer.
value	Value to convert.
flags	Json flags.

API Stability:

Evolving.

char * * jsonToString (Json *json, int nid, cchar *key, int flags)

Serialize a JSON object into a string.

Description:

Serializes a top level JSON object created via jsonParse into a characters string in JSON format.

Parameters:

json	Source json.
nid	Base node ID from which to convert. Set to zero for the top level.
key	Property name to serialize below. This may include ".". For example: "settings.mode".
flags	Serialization flags. Supported flags include JSON_PRETTY for a human-readable multiline format. JSON_QUOTES to wrap Property names in quotes. Use JSON_QUOTES to emit all Property values as quoted strings.

Returns:

Returns a serialized JSON character string. Caller must free.

API Stability:

Evolving.

void jsonUnlock (Json *json)

Unlock a json object to allow updates.

Parameters:

json	A json object.

API Stability:

Evolving.

Typedefs

JsonNode

JSON Node.

API Stability:

Evolving.

Fields:

uint		allocatedName	True if the node text was allocated and must be freed.
uint		allocatedValue	True if the node text was allocated and must be freed.
int		last	Index +1 of last node for which this node is parent.
char *		name	Property name - null terminated.
uint		type	Primitive type of the node (object, array, string or primitive).
char *		value	Property value - null terminated.