# 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.

  This is the same as `PyObject_GetItem()`, but key is specified as a const char* UTF-8 encoded bytes string, rather than a PyObject*.

int PyMapping_GetOptionalItem(PyObject *obj, PyObject *key, PyObject **result)
  Part of the Stable ABI since version 3.13.

  Variant of `PyObject_GetItem()` which doesn’t raise `KeyError` if the key is not found.

  If the key is found, return `1` and set *result to a new strong reference to the corresponding value. If the key is not found, return `0` and set *result to `NULL`; the `KeyError` is silenced. If an error other than `KeyError` is raised, return `-1` and set *result to `NULL`.

  Added in version 3.13.

int PyMapping_GetOptionalItemString(PyObject *obj, const char *key, PyObject **result)
  Part of the Stable ABI since version 3.13.

  This is the same as `PyMapping_GetOptionalItem()`, but key is specified as a const char* UTF-8 encoded bytes string, rather than a PyObject*.

  Added in version 3.13.

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

  This is the same as `PyObject_SetItem()`, but key is specified as a const char* UTF-8 encoded bytes string, rather than a PyObject*.

int PyMapping_DelItem(PyObject *o, PyObject *key)

  This is an alias of `PyObject_DelItem()`.

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

  This is the same as `PyObject_DelItem()`, but key is specified as a const char* UTF-8 encoded bytes string, rather than a PyObject*.

int PyMapping_HasKeyWithError(PyObject *o, PyObject *key)
  Part of the Stable ABI since version 3.13.

  Return `1` if the mapping object has the key key and `0` otherwise. This is equivalent to the Python expression `key in o`. On failure, return `-1`.

  Added in version 3.13.

int PyMapping_HasKeyStringWithError(PyObject *o, const char *key)
  Part of the Stable ABI since version 3.13.

  This is the same as `PyMapping_HasKeyWithError()`, but key is specified as a const char* UTF-8 encoded bytes string, rather than a PyObject*.

  Added in version 3.13.

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

  Exceptions which occur when this calls the `__getitem__()` method are silently ignored. For proper error handling, use `PyMapping_HasKeyWithError()`, `PyMapping_GetOptionalItem()` or `PyObject_GetItem()` instead.

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

  This is the same as `PyMapping_HasKey()`, but key is specified as a const char* UTF-8 encoded bytes string, rather than a PyObject*.

  Note

  Exceptions that occur when this calls the `__getitem__()` method or while creating the temporary `str` object are silently ignored. For proper error handling, use `PyMapping_HasKeyStringWithError()`, `PyMapping_GetOptionalItemString()` or `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.