mirror of https://github.com/python/cpython
234 lines
7.4 KiB
ReStructuredText
234 lines
7.4 KiB
ReStructuredText
.. highlightlang:: c
|
|
|
|
.. _dictobjects:
|
|
|
|
Dictionary Objects
|
|
------------------
|
|
|
|
.. index:: object: dictionary
|
|
|
|
|
|
.. c:type:: PyDictObject
|
|
|
|
This subtype of :c:type:`PyObject` represents a Python dictionary object.
|
|
|
|
|
|
.. c:var:: PyTypeObject PyDict_Type
|
|
|
|
.. index::
|
|
single: DictType (in module types)
|
|
single: DictionaryType (in module types)
|
|
|
|
This instance of :c:type:`PyTypeObject` represents the Python dictionary
|
|
type. This is exposed to Python programs as ``dict`` and
|
|
``types.DictType``.
|
|
|
|
|
|
.. c:function:: int PyDict_Check(PyObject *p)
|
|
|
|
Return true if *p* is a dict object or an instance of a subtype of the dict
|
|
type.
|
|
|
|
.. versionchanged:: 2.2
|
|
Allowed subtypes to be accepted.
|
|
|
|
|
|
.. c:function:: int PyDict_CheckExact(PyObject *p)
|
|
|
|
Return true if *p* is a dict object, but not an instance of a subtype of
|
|
the dict type.
|
|
|
|
.. versionadded:: 2.4
|
|
|
|
|
|
.. c:function:: PyObject* PyDict_New()
|
|
|
|
Return a new empty dictionary, or *NULL* on failure.
|
|
|
|
|
|
.. c:function:: PyObject* PyDictProxy_New(PyObject *dict)
|
|
|
|
Return a proxy object for a mapping which enforces read-only behavior.
|
|
This is normally used to create a proxy to prevent modification of the
|
|
dictionary for non-dynamic class types.
|
|
|
|
.. versionadded:: 2.2
|
|
|
|
|
|
.. c:function:: void PyDict_Clear(PyObject *p)
|
|
|
|
Empty an existing dictionary of all key-value pairs.
|
|
|
|
|
|
.. c:function:: int PyDict_Contains(PyObject *p, PyObject *key)
|
|
|
|
Determine if dictionary *p* contains *key*. If an item in *p* is matches
|
|
*key*, return ``1``, otherwise return ``0``. On error, return ``-1``.
|
|
This is equivalent to the Python expression ``key in p``.
|
|
|
|
.. versionadded:: 2.4
|
|
|
|
|
|
.. c:function:: PyObject* PyDict_Copy(PyObject *p)
|
|
|
|
Return a new dictionary that contains the same key-value pairs as *p*.
|
|
|
|
.. versionadded:: 1.6
|
|
|
|
|
|
.. c:function:: int PyDict_SetItem(PyObject *p, PyObject *key, PyObject *val)
|
|
|
|
Insert *value* into the dictionary *p* with a key of *key*. *key* must be
|
|
:term:`hashable`; if it isn't, :exc:`TypeError` will be raised. Return
|
|
``0`` on success or ``-1`` on failure.
|
|
|
|
|
|
.. c:function:: int PyDict_SetItemString(PyObject *p, const char *key, PyObject *val)
|
|
|
|
.. index:: single: PyString_FromString()
|
|
|
|
Insert *value* into the dictionary *p* using *key* as a key. *key* should
|
|
be a :c:type:`char\*`. The key object is created using
|
|
``PyString_FromString(key)``. Return ``0`` on success or ``-1`` on
|
|
failure.
|
|
|
|
|
|
.. c:function:: int PyDict_DelItem(PyObject *p, PyObject *key)
|
|
|
|
Remove the entry in dictionary *p* with key *key*. *key* must be hashable;
|
|
if it isn't, :exc:`TypeError` is raised. Return ``0`` on success or ``-1``
|
|
on failure.
|
|
|
|
|
|
.. c:function:: int PyDict_DelItemString(PyObject *p, char *key)
|
|
|
|
Remove the entry in dictionary *p* which has a key specified by the string
|
|
*key*. Return ``0`` on success or ``-1`` on failure.
|
|
|
|
|
|
.. c:function:: PyObject* PyDict_GetItem(PyObject *p, PyObject *key)
|
|
|
|
Return the object from dictionary *p* which has a key *key*. Return *NULL*
|
|
if the key *key* is not present, but *without* setting an exception.
|
|
|
|
|
|
.. c:function:: PyObject* PyDict_GetItemString(PyObject *p, const char *key)
|
|
|
|
This is the same as :c:func:`PyDict_GetItem`, but *key* is specified as a
|
|
:c:type:`char\*`, rather than a :c:type:`PyObject\*`.
|
|
|
|
|
|
.. c:function:: PyObject* PyDict_Items(PyObject *p)
|
|
|
|
Return a :c:type:`PyListObject` containing all the items from the
|
|
dictionary, as in the dictionary method :meth:`dict.items`.
|
|
|
|
|
|
.. c:function:: PyObject* PyDict_Keys(PyObject *p)
|
|
|
|
Return a :c:type:`PyListObject` containing all the keys from the dictionary,
|
|
as in the dictionary method :meth:`dict.keys`.
|
|
|
|
|
|
.. c:function:: PyObject* PyDict_Values(PyObject *p)
|
|
|
|
Return a :c:type:`PyListObject` containing all the values from the
|
|
dictionary *p*, as in the dictionary method :meth:`dict.values`.
|
|
|
|
|
|
.. c:function:: Py_ssize_t PyDict_Size(PyObject *p)
|
|
|
|
.. index:: builtin: len
|
|
|
|
Return the number of items in the dictionary. This is equivalent to
|
|
``len(p)`` on a dictionary.
|
|
|
|
.. versionchanged:: 2.5
|
|
This function returned an :c:type:`int` type. This might require changes
|
|
in your code for properly supporting 64-bit systems.
|
|
|
|
|
|
.. c:function:: int PyDict_Next(PyObject *p, Py_ssize_t *ppos, PyObject **pkey, PyObject **pvalue)
|
|
|
|
Iterate over all key-value pairs in the dictionary *p*. The
|
|
:c:type:`Py_ssize_t` referred to by *ppos* must be initialized to ``0``
|
|
prior to the first call to this function to start the iteration; the
|
|
function returns true for each pair in the dictionary, and false once all
|
|
pairs have been reported. The parameters *pkey* and *pvalue* should either
|
|
point to :c:type:`PyObject\*` variables that will be filled in with each key
|
|
and value, respectively, or may be *NULL*. Any references returned through
|
|
them are borrowed. *ppos* should not be altered during iteration. Its
|
|
value represents offsets within the internal dictionary structure, and
|
|
since the structure is sparse, the offsets are not consecutive.
|
|
|
|
For example::
|
|
|
|
PyObject *key, *value;
|
|
Py_ssize_t pos = 0;
|
|
|
|
while (PyDict_Next(self->dict, &pos, &key, &value)) {
|
|
/* do something interesting with the values... */
|
|
...
|
|
}
|
|
|
|
The dictionary *p* should not be mutated during iteration. It is safe
|
|
(since Python 2.1) to modify the values of the keys as you iterate over the
|
|
dictionary, but only so long as the set of keys does not change. For
|
|
example::
|
|
|
|
PyObject *key, *value;
|
|
Py_ssize_t pos = 0;
|
|
|
|
while (PyDict_Next(self->dict, &pos, &key, &value)) {
|
|
int i = PyInt_AS_LONG(value) + 1;
|
|
PyObject *o = PyInt_FromLong(i);
|
|
if (o == NULL)
|
|
return -1;
|
|
if (PyDict_SetItem(self->dict, key, o) < 0) {
|
|
Py_DECREF(o);
|
|
return -1;
|
|
}
|
|
Py_DECREF(o);
|
|
}
|
|
|
|
.. versionchanged:: 2.5
|
|
This function used an :c:type:`int *` type for *ppos*. This might require
|
|
changes in your code for properly supporting 64-bit systems.
|
|
|
|
|
|
.. c:function:: int PyDict_Merge(PyObject *a, PyObject *b, int override)
|
|
|
|
Iterate over mapping object *b* adding key-value pairs to dictionary *a*.
|
|
*b* may be a dictionary, or any object supporting :c:func:`PyMapping_Keys`
|
|
and :c:func:`PyObject_GetItem`. If *override* is true, existing pairs in *a*
|
|
will be replaced if a matching key is found in *b*, otherwise pairs will
|
|
only be added if there is not a matching key in *a*. Return ``0`` on
|
|
success or ``-1`` if an exception was raised.
|
|
|
|
.. versionadded:: 2.2
|
|
|
|
|
|
.. c:function:: int PyDict_Update(PyObject *a, PyObject *b)
|
|
|
|
This is the same as ``PyDict_Merge(a, b, 1)`` in C, or ``a.update(b)`` in
|
|
Python. Return ``0`` on success or ``-1`` if an exception was raised.
|
|
|
|
.. versionadded:: 2.2
|
|
|
|
|
|
.. c:function:: int PyDict_MergeFromSeq2(PyObject *a, PyObject *seq2, int override)
|
|
|
|
Update or merge into dictionary *a*, from the key-value pairs in *seq2*.
|
|
*seq2* must be an iterable object producing iterable objects of length 2,
|
|
viewed as key-value pairs. In case of duplicate keys, the last wins if
|
|
*override* is true, else the first wins. Return ``0`` on success or ``-1``
|
|
if an exception was raised. Equivalent Python (except for the return
|
|
value)::
|
|
|
|
def PyDict_MergeFromSeq2(a, seq2, override):
|
|
for key, value in seq2:
|
|
if override or key not in a:
|
|
a[key] = value
|
|
|
|
.. versionadded:: 2.2
|