+.. _apiref:
+
*************
API Reference
*************
and false for values of other types and for *NULL*.
+.. _apiref-reference-count:
+
Reference Count
---------------
argument.
+Circular References
+-------------------
+
+A circular reference is created when an object or an array is,
+directly or indirectly, inserted inside itself. The direct case is
+simple::
+
+ json_t *obj = json_object();
+ json_object_set(obj, "foo", obj);
+
+Jansson will refuse to do this, and :cfunc:`json_object_set()` (and
+all the other such functions for objects and arrays) will return with
+an error status. The indirect case is the dangerous one::
+
+ json_t *arr1 = json_array(), *arr2 = json_array();
+ json_array_append(arr1, arr2);
+ json_array_append(arr2, arr1);
+
+In this example, the array ``arr2`` is contained in the array
+``arr1``, and vice versa. Jansson cannot check for this kind of
+indirect circular references without a performance hit, so it's up to
+the user to avoid them.
+
+If a circular reference is created, the memory consumed by the values
+cannot be freed by :cfunc:`json_decref()`. The reference counts never
+drops to zero because the values are keeping the circular reference to
+themselves. Moreover, trying to encode the values with any of the
+encoding functions will fail. The encoder detects circular references
+and returns an error status.
+
+
True, False and Null
====================
Returns a new JSON string, or *NULL* on error. *value* must be a
valid UTF-8 encoded Unicode string.
+.. cfunction:: json_t *json_string_nocheck(const char *value)
+
+ .. refcounting:: new
+
+ Like :cfunc:`json_string`, but doesn't check that *value* is valid
+ UTF-8. Use this function only if you are certain that this really
+ is the case (e.g. you have already checked it by other means).
+
+ .. versionadded:: 1.2
+
.. cfunction:: const char *json_string_value(const json_t *string)
Returns the associated value of *string* as a null terminated UTF-8
.. versionadded:: 1.1
+.. cfunction:: int json_string_set_nocheck(const json_t *string, const char *value)
+
+ Like :cfunc:`json_string_set`, but doesn't check that *value* is
+ valid UTF-8. Use this function only if you are certain that this
+ really is the case (e.g. you have already checked it by other
+ means).
+
+ .. versionadded:: 1.2
+
Number
======
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_nocheck(json_t *object, const char *key, json_t *value)
+
+ Like :cfunc:`json_object_set`, but doesn't check that *key* is
+ valid UTF-8. Use this function only if you are certain that this
+ really is the case (e.g. you have already checked it by other
+ means).
+
+ .. versionadded:: 1.2
+
.. cfunction:: int json_object_set_new(json_t *object, const char *key, json_t *value)
Like :cfunc:`json_object_set()` but steals the reference to
.. versionadded:: 1.1
+.. cfunction:: int json_object_set_new_nocheck(json_t *object, const char *key, json_t *value)
+
+ Like :cfunc:`json_object_set_new`, but doesn't check that *key* is
+ valid UTF-8. Use this function only if you are certain that this
+ really is the case (e.g. you have already checked it by other
+ means).
+
+ .. versionadded:: 1.2
+
.. cfunction:: int json_object_del(json_t *object, const char *key)
Delete *key* from *object* if it exists. Returns 0 on success, or
values to JSON. Only objects and arrays can be encoded, since they are
the only valid "root" values of a JSON text.
+By default, the output has no newlines, and spaces are used between
+array and object elements for a readable output. This behavior can be
+altered by using the ``JSON_INDENT`` and ``JSON_COMPACT`` flags
+described below. A newline is never appended to the end of the encoded
+JSON data.
+
Each function takes a *flags* parameter that controls some aspects of
how the data is encoded. Its default value is 0. The following macros
can be ORed together to obtain *flags*.
``JSON_INDENT(n)``
- Pretty-print the result, indenting arrays and objects by *n*
- spaces. The valid range for *n* is between 0 and 255, other values
- result in an undefined output. If ``JSON_INDENT`` is not used or
- *n* is 0, no pretty-printing is done and the result is a compact
- representation.
+ Pretty-print the result, using newlines between array and object
+ items, and indenting with *n* spaces. The valid range for *n* is
+ between 0 and 255, other values result in an undefined output. If
+ ``JSON_INDENT`` is not used or *n* is 0, no newlines are inserted
+ between array and object items.
+
+``JSON_COMPACT``
+ This flag enables a compact representation, i.e. sets the separator
+ between array and object items to ``","`` and between object keys
+ and values to ``":"``. Without this flag, the corresponding
+ separators are ``", "`` and ``": "`` for more readable output.
+
+ .. versionadded:: 1.2
+
+``JSON_ENSURE_ASCII``
+ If this flag is used, the output is guaranteed to consist only of
+ ASCII characters. This is achived by escaping all Unicode
+ characters outside the ASCII range.
+
+ .. versionadded:: 1.2
+
+``JSON_SORT_KEYS``
+ If this flag is used, all the objects in output are sorted by key.
+ This is useful e.g. if two JSON texts are diffed or visually
+ compared.
+
+ .. versionadded:: 1.2
The following functions perform the actual JSON encoding. The result
is in UTF-8.
Write the JSON representation of *root* to the stream *output*.
*flags* is described above. Returns 0 on success and -1 on error.
+ If an error occurs, something may have already been written to
+ *output*. In this case, the output is undefined and most likely not
+ valid JSON.
.. cfunction:: int json_dump_file(const json_t *json, const char *path, unsigned long flags)
object it contains, or *NULL* on error, in which case *error* is
filled with information about the error. See above for discussion
on the *error* parameter.
+
+
+Equality
+========
+
+Testing for equality of two JSON values cannot, in general, be
+achieved using the ``==`` operator. Equality in the terms of the
+``==`` operator states that the two :ctype:`json_t` pointers point to
+exactly the same JSON value. However, two JSON values can be equal not
+only if they are exactly the same value, but also if they have equal
+"contents":
+
+* Two integer or real values are equal if their contained numeric
+ values are equal. An integer value is never equal to a real value,
+ though.
+
+* Two strings are equal if their contained UTF-8 strings are equal.
+
+* Two arrays are equal if they have the same number of elements and
+ each element in the first array is equal to the corresponding
+ element in the second array.
+
+* Two objects are equal if they have exactly the same keys and the
+ value for each key in the first object is equal to the value of the
+ corresponding key in the second object.
+
+* Two true, false or null values have no "contents", so they are equal
+ if their types are equal. (Because these values are singletons,
+ their equality can actually be tested with ``==``.)
+
+The following function can be used to test whether two JSON values are
+equal.
+
+.. cfunction:: int json_equal(json_t *value1, json_t *value2)
+
+ Returns 1 if *value1* and *value2* are equal, as defined above.
+ Returns 0 if they are inequal or one or both of the pointers are
+ *NULL*.
+
+ .. versionadded:: 1.2