# Mapping Protocol

See also `PyObject_GetItem()`, `PyObject_SetItem()` and `PyObject_DelItem()`.

int PyMapping_Check(PyObject *o)
  Part of the Stable ABI.

  Return `1` if the object provides the mapping protocol or supports slicing, and `0` otherwise. Note that it returns `1` for Python classes with a `__getitem__()` method, since in general it is impossible to determine what type of keys the class supports. This function always succeeds.

Py_ssize_t PyMapping_Size(PyObject *o)
Py_ssize_t PyMapping_Length(PyObject *o)
  Part of the Stable ABI.

  Returns the number of keys in object o on success, and `-1` on failure. This is equivalent to the Python expression `len(o)`.

PyObject *PyMapping_GetItemString(PyObject *o, const char *key)
  Return value: New reference. Part of the Stable ABI.

  Return element of o corresponding to the string key or `NULL` on failure. This is the equivalent of the Python expression `o[key]`. See also `PyObject_GetItem()`.

int PyMapping_SetItemString(PyObject *o, const char *key, PyObject *v)
  Part of the Stable ABI.

  Map the string key to the value v in object o. Returns `-1` on failure. This is the equivalent of the Python statement `o[key] = v`. See also `PyObject_SetItem()`. This function does not steal a reference to v.

int PyMapping_DelItem(PyObject *o, PyObject *key)

  Remove the mapping for the object key from the object o. Return `-1` on failure. This is equivalent to the Python statement `del o[key]`. This is an alias of `PyObject_DelItem()`.

int PyMapping_DelItemString(PyObject *o, const char *key)

  Remove the mapping for the string key from the object o. Return `-1` on failure. This is equivalent to the Python statement `del o[key]`.

int PyMapping_HasKey(PyObject *o, PyObject *key)
  Part of the Stable ABI.

  Return `1` if the mapping object has the key key and `0` otherwise. This is equivalent to the Python expression `key in o`. This function always succeeds.

  Note that exceptions which occur while calling the `__getitem__()` method will get suppressed. To get error reporting use `PyObject_GetItem()` instead.

int PyMapping_HasKeyString(PyObject *o, const char *key)
  Part of the Stable ABI.

  Return `1` if the mapping object has the key key and `0` otherwise. This is equivalent to the Python expression `key in o`. This function always succeeds.

  Note that exceptions which occur while calling the `__getitem__()` method and creating a temporary string object will get suppressed. To get error reporting use `PyMapping_GetItemString()` instead.

PyObject *PyMapping_Keys(PyObject *o)
  Return value: New reference. Part of the Stable ABI.

  On success, return a list of the keys in object o. On failure, return `NULL`.

  Changed in version 3.7: Previously, the function returned a list or a tuple.

PyObject *PyMapping_Values(PyObject *o)
  Return value: New reference. Part of the Stable ABI.

  On success, return a list of the values in object o. On failure, return `NULL`.

  Changed in version 3.7: Previously, the function returned a list or a tuple.

PyObject *PyMapping_Items(PyObject *o)
  Return value: New reference. Part of the Stable ABI.

  On success, return a list of the items in object o, where each item is a tuple containing a key-value pair. On failure, return `NULL`.

  Changed in version 3.7: Previously, the function returned a list or a tuple.