are APIs for querying the type, manipulating the reference count, and
for constructing and manipulating values of different types.
+Unless noted otherwise, all API functions return an error value if an
+error occurs. Depending on the function's signature, the error value
+is either *NULL* or -1. Invalid arguments or invalid input are
+apparent sources for errors. Memory allocation and I/O operations may
+also cause errors.
+
Type
----
.. cfunction:: int json_typeof(const json_t *json)
Return the type of the JSON value (a :ctype:`json_type` cast to
- :ctype:`int`). This function is actually implemented as a macro for
- speed.
+ :ctype:`int`). *json* MUST NOT be *NULL*. This function is actually
+ implemented as a macro for speed.
.. cfunction:: json_is_object(const json_t *json)
json_is_array(const json_t *json)
json_is_null(const json_t *json)
These functions (actually macros) return true (non-zero) for values
- of the given type, and false (zero) for values of other types.
+ of the given type, and false (zero) for values of other types and
+ for *NULL*.
.. cfunction:: json_is_number(const json_t *json)
Returns true for values of types :const:`JSON_INTEGER` and
- :const:`JSON_REAL`, and false for other types.
+ :const:`JSON_REAL`, and false for other types and for *NULL*.
.. cfunction:: json_is_boolean(const json_t *json)
Returns true for types :const:`JSON_TRUE` and :const:`JSON_FALSE`,
- and false for values of other types.
+ and false for values of other types and for *NULL*.
Reference Count
.. cfunction:: json_t *json_incref(json_t *json)
- Increment the reference count of *json*.
+ Increment the reference count of *json* if it's not non-*NULL*.
+ Returns *json*.
.. cfunction:: void json_decref(json_t *json)
to release the reference.
Normally, all functions accepting a JSON value as an argument will
-manage the reference, i.e. increase and decrease the reference count
+nmanage the reference, i.e. increase and decrease the reference count
as needed. However, some functions **steal** the reference, i.e. they
have the same result as if the user called :cfunc:`json_decref()` on
the argument right after calling the function. These are usually
True, False and Null
====================
+These values are implemented as singletons, so each of these functions
+returns the same value each time.
+
.. cfunction:: json_t *json_true(void)
.. refcounting:: new
- Returns a value of the type :const:`JSON_TRUE`, or *NULL* on
- error.
+ Returns the JSON true value.
.. cfunction:: json_t *json_false(void)
.. refcounting:: new
- Returns a value of the type :const:`JSON_FALSE`, or *NULL* on
- error.
+ Returns the JSON false value.
.. cfunction:: json_t *json_null(void)
.. refcounting:: new
- Returns a value of the type :const:`JSON_NULL`, or *NULL* on
- error.
+ Returns the JSON null value.
String
.. refcounting:: new
- Returns a new value of the type :const:`JSON_STRING`, or *NULL* on
- error. *value* must be a valid UTF-8 encoded Unicode string.
+ Returns a new JSON string, or *NULL* on error. *value* must be a
+ valid UTF-8 encoded Unicode string.
.. cfunction:: const char *json_string_value(const json_t *json)
- Returns the associated value of a :const:`JSON_STRING` value as a
- null terminated UTF-8 encoded string.
+ Returns the associated value of the JSON string *json* as a null
+ terminated UTF-8 encoded string, or *NULL* if *json* is not a JSON
+ string.
Number
.. refcounting:: new
- Returns a new value of the type :const:`JSON_INTEGER`, or *NULL* on
- error.
+ Returns a new JSON integer, or *NULL* on error.
.. cfunction:: int json_integer_value(const json_t *json)
- Returns the associated integer value of values of the type
- :const:`JSON_INTEGER`, or 0 for values of other types.
+ Returns the associated value the JSON integer *json*. If *json* is
+ *NULL* or not a JSON integer, 0 is returned.
.. cfunction:: json_t *json_real(double value)
.. refcounting:: new
- Returns a new value of the type :const:`JSON_REAL`, or *NULL* on
- error.
+ Returns a new JSON real, or *NULL* on error.
.. cfunction:: double json_real_value(const json_t *json)
- Returns the associated real value of values of the type
- :const:`JSON_INTEGER`, or 0 for values of other types.
+ Returns the associated value of the JSON real *json*. If *json* is
+ *NULL* or not a JSON real, 0.0 is returned.
In addition to the functions above, there's a common query function
for integers and reals:
.. cfunction:: double json_number_value(const json_t *json)
- Returns the value of either ``JSON_INTEGER`` or ``JSON_REAL``, cast
- to double regardless of the actual type.
+ Returns the associated value of the JSON integer or JSON real
+ *json*, cast to double regardless of the actual type. If *json* is
+ neither JSON real nor JSON integer, 0.0 is returned.
Array
.. refcounting:: new
- Returns a new value of the type :const:`JSON_ARRAY`, or *NULL* on
- error. Initially, the array is empty.
+ Returns a new JSON array, or *NULL* on error. Initially, the array
+ is empty.
.. cfunction:: unsigned int json_array_size(const json_t *array)
- Returns the number of elements in *array*.
+ Returns the number of elements in *array*, or 0 if *array* is NULL
+ or not a JSON array.
.. cfunction:: json_t *json_array_get(const json_t *array, unsigned int index)
.. refcounting:: borrow
- Returns the element in *array* at position *index*, or *NULL* if
- *index* is out of range. The valid range for *index* is from 0 to
- the return value of :cfunc:`json_array_size()` minus 1.
+ Returns the element in *array* at position *index*. The valid range
+ for *index* is from 0 to the return value of
+ :cfunc:`json_array_size()` minus 1. If *array* is not a JSON array,
+ if *array* is *NULL*, or if *index* is out of range, *NULL* is
+ returned.
.. cfunction:: int json_array_set(json_t *array, unsigned int index, json_t *value)
Replaces the element in *array* at position *index* with *value*.
- Returns 0 on success, or -1 if *index* is out of range. The valid
- range for *index* is from 0 to the return value of
- :cfunc:`json_array_size()` minus 1.
+ The valid range for *index* is from 0 to the return value of
+ :cfunc:`json_array_size()` minus 1. Returns 0 on success and -1 on
+ error.
.. cfunction:: int json_array_set_new(json_t *array, unsigned int index, json_t *value)
.. versionadded:: 1.1
+.. cfunction:: int json_array_insert(json_t *array, unsigned int index, json_t *value)
+
+ Inserts *value* to *array* at position *index*, shifting the
+ elements at *index* and after it one position towards the end of
+ the array. Returns 0 on success and -1 on error.
+
+ .. versionadded:: 1.1
+
+.. cfunction:: int json_array_insert_new(json_t *array, unsigned int index, json_t *value)
+
+ Like :cfunc:`json_array_insert()` but steals the reference to
+ *value*. This is useful when *value* is newly created and not used
+ after the call.
+
+ .. versionadded:: 1.1
+
+.. cfunction:: int json_array_remove(json_t *array, unsigned int index)
+
+ Removes the element in *array* at position *index*, shifting the
+ elements after *index* one position towards the start of the array.
+ Returns 0 on success and -1 on error.
+
+ .. versionadded:: 1.1
+
+.. cfunction:: int json_array_clear(json_t *array)
+
+ Removes all elements from *array*. Returns 0 on sucess and -1 on
+ error.
+
+ .. versionadded:: 1.1
+
+.. cfunction:: int json_array_extend(json_t *array, json_t *other_array)
+
+ Appends all elements in *other_array* to the end of *array*.
+ Returns 0 on success and -1 on error.
+
+ .. versionadded:: 1.1
+
Object
======
.. refcounting:: new
- Returns a new value of the type :const:`JSON_OBJECT`, or *NULL* on
- error. Initially, the object is empty.
+ Returns a new JSON object, or *NULL* on error. Initially, the
+ object is empty.
.. cfunction:: json_t *json_object_get(const json_t *object, const char *key)
.. cfunction:: int json_object_set(json_t *object, const char *key, json_t *value)
Set the value of *key* to *value* in *object*. *key* must be a
- valid terminated UTF-8 encoded Unicode string. If there already is
- a value for *key*, it is replaced by the new value. Returns 0 on
- success and -1 on error.
+ valid null terminated UTF-8 encoded Unicode string. If there
+ already is a value for *key*, it is replaced by the new value.
+ Returns 0 on success and -1 on error.
.. cfunction:: int json_object_set_new(json_t *object, const char *key, json_t *value)
Extract the associated value from *iter*.
+The iteration protocol can be used for example as follows::
+
+ /* obj is a JSON object */
+ const char *key;
+ json_t *value;
+ void *iter = json_object_iter(obj);
+ while(iter)
+ {
+ key = json_object_iter_key(iter);
+ value = json_object_iter_value(iter);
+ /* use key and value ... */
+ iter = json_object_iter_next(obj, iter);
+ }
+
Encoding
========
The following functions perform the actual JSON encoding. The result
is in UTF-8.
-.. cfunction:: char *json_dumps(const json_t *root, uint32_t flags)
+.. cfunction:: char *json_dumps(const json_t *root, unsigned long flags)
Returns the JSON representation of *root* as a string, or *NULL* on
error. *flags* is described above. The return value must be freed
by the caller using :cfunc:`free()`.
-.. cfunction:: int json_dumpf(const json_t *root, FILE *output, uint32_t flags)
+.. cfunction:: int json_dumpf(const json_t *root, FILE *output, unsigned long flags)
Write the JSON representation of *root* to the stream *output*.
*flags* is described above. Returns 0 on success and -1 on error.
-.. cfunction:: int json_dump_file(const json_t *json, const char *path, uint32_t flags)
+.. cfunction:: int json_dump_file(const json_t *json, const char *path, unsigned long flags)
Write the JSON representation of *root* to the file *path*. If
*path* already exists, it is overwritten. *flags* is described
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