mirror of https://github.com/python/cpython
134 lines
4.6 KiB
ReStructuredText
134 lines
4.6 KiB
ReStructuredText
.. highlight:: c
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.. _mapping:
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Mapping Protocol
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================
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See also :c:func:`PyObject_GetItem`, :c:func:`PyObject_SetItem` and
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:c:func:`PyObject_DelItem`.
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.. c:function:: int PyMapping_Check(PyObject *o)
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Return ``1`` if the object provides the mapping protocol or supports slicing,
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and ``0`` otherwise. Note that it returns ``1`` for Python classes with
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a :meth:`~object.__getitem__` method, since in general it is impossible to
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determine what type of keys the class supports. This function always succeeds.
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.. c:function:: Py_ssize_t PyMapping_Size(PyObject *o)
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Py_ssize_t PyMapping_Length(PyObject *o)
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.. index:: pair: built-in function; len
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Returns the number of keys in object *o* on success, and ``-1`` on failure.
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This is equivalent to the Python expression ``len(o)``.
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.. c:function:: PyObject* PyMapping_GetItemString(PyObject *o, const char *key)
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Return element of *o* corresponding to the string *key* or ``NULL`` on failure.
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This is the equivalent of the Python expression ``o[key]``.
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See also :c:func:`PyObject_GetItem`.
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.. c:function:: int PyMapping_GetOptionalItem(PyObject *obj, PyObject *key, PyObject **result)
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Variant of :c:func:`PyObject_GetItem` which doesn't raise
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:exc:`KeyError` if the key is not found.
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If the key is found, return ``1`` and set *\*result* to a new
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:term:`strong reference` to the corresponding value.
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If the key is not found, return ``0`` and set *\*result* to ``NULL``;
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the :exc:`KeyError` is silenced.
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If an error other than :exc:`KeyError` is raised, return ``-1`` and
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set *\*result* to ``NULL``.
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.. versionadded:: 3.13
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.. c:function:: int PyMapping_GetOptionalItemString(PyObject *obj, const char *key, PyObject **result)
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Variant of :c:func:`PyMapping_GetItemString` which doesn't raise
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:exc:`KeyError` if the key is not found.
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If the key is found, return ``1`` and set *\*result* to a new
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:term:`strong reference` to the corresponding value.
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If the key is not found, return ``0`` and set *\*result* to ``NULL``;
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the :exc:`KeyError` is silenced.
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If an error other than :exc:`KeyError` is raised, return ``-1`` and
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set *\*result* to ``NULL``.
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.. versionadded:: 3.13
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.. c:function:: int PyMapping_SetItemString(PyObject *o, const char *key, PyObject *v)
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Map the string *key* to the value *v* in object *o*. Returns ``-1`` on
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failure. This is the equivalent of the Python statement ``o[key] = v``.
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See also :c:func:`PyObject_SetItem`. This function *does not* steal a
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reference to *v*.
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.. c:function:: int PyMapping_DelItem(PyObject *o, PyObject *key)
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Remove the mapping for the object *key* from the object *o*. Return ``-1``
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on failure. This is equivalent to the Python statement ``del o[key]``.
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This is an alias of :c:func:`PyObject_DelItem`.
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.. c:function:: int PyMapping_DelItemString(PyObject *o, const char *key)
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Remove the mapping for the string *key* from the object *o*. Return ``-1``
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on failure. This is equivalent to the Python statement ``del o[key]``.
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.. c:function:: int PyMapping_HasKey(PyObject *o, PyObject *key)
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Return ``1`` if the mapping object has the key *key* and ``0`` otherwise.
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This is equivalent to the Python expression ``key in o``.
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This function always succeeds.
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Note that exceptions which occur while calling the :meth:`~object.__getitem__`
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method will get suppressed.
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To get error reporting use :c:func:`PyObject_GetItem()` instead.
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.. c:function:: int PyMapping_HasKeyString(PyObject *o, const char *key)
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Return ``1`` if the mapping object has the key *key* and ``0`` otherwise.
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This is equivalent to the Python expression ``key in o``.
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This function always succeeds.
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Note that exceptions which occur while calling the :meth:`~object.__getitem__`
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method and creating a temporary string object will get suppressed.
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To get error reporting use :c:func:`PyMapping_GetItemString()` instead.
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.. c:function:: PyObject* PyMapping_Keys(PyObject *o)
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On success, return a list of the keys in object *o*. On failure, return
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``NULL``.
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.. versionchanged:: 3.7
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Previously, the function returned a list or a tuple.
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.. c:function:: PyObject* PyMapping_Values(PyObject *o)
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On success, return a list of the values in object *o*. On failure, return
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``NULL``.
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.. versionchanged:: 3.7
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Previously, the function returned a list or a tuple.
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.. c:function:: PyObject* PyMapping_Items(PyObject *o)
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On success, return a list of the items in object *o*, where each item is a
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tuple containing a key-value pair. On failure, return ``NULL``.
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.. versionchanged:: 3.7
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Previously, the function returned a list or a tuple.
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