1.. highlight:: c 2 3.. _mapping: 4 5Mapping Protocol 6================ 7 8See also :c:func:`PyObject_GetItem`, :c:func:`PyObject_SetItem` and 9:c:func:`PyObject_DelItem`. 10 11 12.. c:function:: int PyMapping_Check(PyObject *o) 13 14 Return ``1`` if the object provides the mapping protocol or supports slicing, 15 and ``0`` otherwise. Note that it returns ``1`` for Python classes with 16 a :meth:`~object.__getitem__` method, since in general it is impossible to 17 determine what type of keys the class supports. This function always succeeds. 18 19 20.. c:function:: Py_ssize_t PyMapping_Size(PyObject *o) 21 Py_ssize_t PyMapping_Length(PyObject *o) 22 23 .. index:: pair: built-in function; len 24 25 Returns the number of keys in object *o* on success, and ``-1`` on failure. 26 This is equivalent to the Python expression ``len(o)``. 27 28 29.. c:function:: PyObject* PyMapping_GetItemString(PyObject *o, const char *key) 30 31 This is the same as :c:func:`PyObject_GetItem`, but *key* is 32 specified as a :c:expr:`const char*` UTF-8 encoded bytes string, 33 rather than a :c:expr:`PyObject*`. 34 35 36.. c:function:: int PyMapping_GetOptionalItem(PyObject *obj, PyObject *key, PyObject **result) 37 38 Variant of :c:func:`PyObject_GetItem` which doesn't raise 39 :exc:`KeyError` if the key is not found. 40 41 If the key is found, return ``1`` and set *\*result* to a new 42 :term:`strong reference` to the corresponding value. 43 If the key is not found, return ``0`` and set *\*result* to ``NULL``; 44 the :exc:`KeyError` is silenced. 45 If an error other than :exc:`KeyError` is raised, return ``-1`` and 46 set *\*result* to ``NULL``. 47 48 .. versionadded:: 3.13 49 50 51.. c:function:: int PyMapping_GetOptionalItemString(PyObject *obj, const char *key, PyObject **result) 52 53 This is the same as :c:func:`PyMapping_GetOptionalItem`, but *key* is 54 specified as a :c:expr:`const char*` UTF-8 encoded bytes string, 55 rather than a :c:expr:`PyObject*`. 56 57 .. versionadded:: 3.13 58 59 60.. c:function:: int PyMapping_SetItemString(PyObject *o, const char *key, PyObject *v) 61 62 This is the same as :c:func:`PyObject_SetItem`, but *key* is 63 specified as a :c:expr:`const char*` UTF-8 encoded bytes string, 64 rather than a :c:expr:`PyObject*`. 65 66 67.. c:function:: int PyMapping_DelItem(PyObject *o, PyObject *key) 68 69 This is an alias of :c:func:`PyObject_DelItem`. 70 71 72.. c:function:: int PyMapping_DelItemString(PyObject *o, const char *key) 73 74 This is the same as :c:func:`PyObject_DelItem`, but *key* is 75 specified as a :c:expr:`const char*` UTF-8 encoded bytes string, 76 rather than a :c:expr:`PyObject*`. 77 78 79.. c:function:: int PyMapping_HasKeyWithError(PyObject *o, PyObject *key) 80 81 Return ``1`` if the mapping object has the key *key* and ``0`` otherwise. 82 This is equivalent to the Python expression ``key in o``. 83 On failure, return ``-1``. 84 85 .. versionadded:: 3.13 86 87 88.. c:function:: int PyMapping_HasKeyStringWithError(PyObject *o, const char *key) 89 90 This is the same as :c:func:`PyMapping_HasKeyWithError`, but *key* is 91 specified as a :c:expr:`const char*` UTF-8 encoded bytes string, 92 rather than a :c:expr:`PyObject*`. 93 94 .. versionadded:: 3.13 95 96 97.. c:function:: int PyMapping_HasKey(PyObject *o, PyObject *key) 98 99 Return ``1`` if the mapping object has the key *key* and ``0`` otherwise. 100 This is equivalent to the Python expression ``key in o``. 101 This function always succeeds. 102 103 .. note:: 104 105 Exceptions which occur when this calls :meth:`~object.__getitem__` 106 method are silently ignored. 107 For proper error handling, use :c:func:`PyMapping_HasKeyWithError`, 108 :c:func:`PyMapping_GetOptionalItem` or :c:func:`PyObject_GetItem()` instead. 109 110 111.. c:function:: int PyMapping_HasKeyString(PyObject *o, const char *key) 112 113 This is the same as :c:func:`PyMapping_HasKey`, but *key* is 114 specified as a :c:expr:`const char*` UTF-8 encoded bytes string, 115 rather than a :c:expr:`PyObject*`. 116 117 .. note:: 118 119 Exceptions that occur when this calls :meth:`~object.__getitem__` 120 method or while creating the temporary :class:`str` 121 object are silently ignored. 122 For proper error handling, use :c:func:`PyMapping_HasKeyStringWithError`, 123 :c:func:`PyMapping_GetOptionalItemString` or 124 :c:func:`PyMapping_GetItemString` instead. 125 126 127.. c:function:: PyObject* PyMapping_Keys(PyObject *o) 128 129 On success, return a list of the keys in object *o*. On failure, return 130 ``NULL``. 131 132 .. versionchanged:: 3.7 133 Previously, the function returned a list or a tuple. 134 135 136.. c:function:: PyObject* PyMapping_Values(PyObject *o) 137 138 On success, return a list of the values in object *o*. On failure, return 139 ``NULL``. 140 141 .. versionchanged:: 3.7 142 Previously, the function returned a list or a tuple. 143 144 145.. c:function:: PyObject* PyMapping_Items(PyObject *o) 146 147 On success, return a list of the items in object *o*, where each item is a 148 tuple containing a key-value pair. On failure, return ``NULL``. 149 150 .. versionchanged:: 3.7 151 Previously, the function returned a list or a tuple. 152