167 lines
6.0 KiB
ReStructuredText
167 lines
6.0 KiB
ReStructuredText
.. highlight:: c
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.. _setobjects:
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Set Objects
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-----------
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.. sectionauthor:: Raymond D. Hettinger <python@rcn.com>
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.. index::
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object: set
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object: frozenset
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This section details the public API for :class:`set` and :class:`frozenset`
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objects. Any functionality not listed below is best accessed using the either
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the abstract object protocol (including :c:func:`PyObject_CallMethod`,
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:c:func:`PyObject_RichCompareBool`, :c:func:`PyObject_Hash`,
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:c:func:`PyObject_Repr`, :c:func:`PyObject_IsTrue`, :c:func:`PyObject_Print`, and
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:c:func:`PyObject_GetIter`) or the abstract number protocol (including
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:c:func:`PyNumber_And`, :c:func:`PyNumber_Subtract`, :c:func:`PyNumber_Or`,
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:c:func:`PyNumber_Xor`, :c:func:`PyNumber_InPlaceAnd`,
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:c:func:`PyNumber_InPlaceSubtract`, :c:func:`PyNumber_InPlaceOr`, and
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:c:func:`PyNumber_InPlaceXor`).
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.. c:type:: PySetObject
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This subtype of :c:type:`PyObject` is used to hold the internal data for both
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:class:`set` and :class:`frozenset` objects. It is like a :c:type:`PyDictObject`
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in that it is a fixed size for small sets (much like tuple storage) and will
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point to a separate, variable sized block of memory for medium and large sized
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sets (much like list storage). None of the fields of this structure should be
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considered public and are subject to change. All access should be done through
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the documented API rather than by manipulating the values in the structure.
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.. c:var:: PyTypeObject PySet_Type
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This is an instance of :c:type:`PyTypeObject` representing the Python
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:class:`set` type.
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.. c:var:: PyTypeObject PyFrozenSet_Type
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This is an instance of :c:type:`PyTypeObject` representing the Python
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:class:`frozenset` type.
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The following type check macros work on pointers to any Python object. Likewise,
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the constructor functions work with any iterable Python object.
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.. c:function:: int PySet_Check(PyObject *p)
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Return true if *p* is a :class:`set` object or an instance of a subtype.
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.. c:function:: int PyFrozenSet_Check(PyObject *p)
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Return true if *p* is a :class:`frozenset` object or an instance of a
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subtype.
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.. c:function:: int PyAnySet_Check(PyObject *p)
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Return true if *p* is a :class:`set` object, a :class:`frozenset` object, or an
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instance of a subtype.
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.. c:function:: int PyAnySet_CheckExact(PyObject *p)
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Return true if *p* is a :class:`set` object or a :class:`frozenset` object but
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not an instance of a subtype.
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.. c:function:: int PyFrozenSet_CheckExact(PyObject *p)
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Return true if *p* is a :class:`frozenset` object but not an instance of a
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subtype.
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.. c:function:: PyObject* PySet_New(PyObject *iterable)
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Return a new :class:`set` containing objects returned by the *iterable*. The
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*iterable* may be *NULL* to create a new empty set. Return the new set on
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success or *NULL* on failure. Raise :exc:`TypeError` if *iterable* is not
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actually iterable. The constructor is also useful for copying a set
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(``c=set(s)``).
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.. c:function:: PyObject* PyFrozenSet_New(PyObject *iterable)
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Return a new :class:`frozenset` containing objects returned by the *iterable*.
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The *iterable* may be *NULL* to create a new empty frozenset. Return the new
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set on success or *NULL* on failure. Raise :exc:`TypeError` if *iterable* is
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not actually iterable.
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The following functions and macros are available for instances of :class:`set`
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or :class:`frozenset` or instances of their subtypes.
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.. c:function:: Py_ssize_t PySet_Size(PyObject *anyset)
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.. index:: builtin: len
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Return the length of a :class:`set` or :class:`frozenset` object. Equivalent to
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``len(anyset)``. Raises a :exc:`PyExc_SystemError` if *anyset* is not a
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:class:`set`, :class:`frozenset`, or an instance of a subtype.
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.. c:function:: Py_ssize_t PySet_GET_SIZE(PyObject *anyset)
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Macro form of :c:func:`PySet_Size` without error checking.
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.. c:function:: int PySet_Contains(PyObject *anyset, PyObject *key)
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Return ``1`` if found, ``0`` if not found, and ``-1`` if an error is encountered. Unlike
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the Python :meth:`__contains__` method, this function does not automatically
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convert unhashable sets into temporary frozensets. Raise a :exc:`TypeError` if
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the *key* is unhashable. Raise :exc:`PyExc_SystemError` if *anyset* is not a
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:class:`set`, :class:`frozenset`, or an instance of a subtype.
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.. c:function:: int PySet_Add(PyObject *set, PyObject *key)
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Add *key* to a :class:`set` instance. Also works with :class:`frozenset`
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instances (like :c:func:`PyTuple_SetItem` it can be used to fill-in the values
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of brand new frozensets before they are exposed to other code). Return ``0`` on
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success or ``-1`` on failure. Raise a :exc:`TypeError` if the *key* is
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unhashable. Raise a :exc:`MemoryError` if there is no room to grow. Raise a
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:exc:`SystemError` if *set* is not an instance of :class:`set` or its
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subtype.
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The following functions are available for instances of :class:`set` or its
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subtypes but not for instances of :class:`frozenset` or its subtypes.
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.. c:function:: int PySet_Discard(PyObject *set, PyObject *key)
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Return ``1`` if found and removed, ``0`` if not found (no action taken), and ``-1`` if an
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error is encountered. Does not raise :exc:`KeyError` for missing keys. Raise a
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:exc:`TypeError` if the *key* is unhashable. Unlike the Python :meth:`~set.discard`
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method, this function does not automatically convert unhashable sets into
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temporary frozensets. Raise :exc:`PyExc_SystemError` if *set* is not an
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instance of :class:`set` or its subtype.
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.. c:function:: PyObject* PySet_Pop(PyObject *set)
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Return a new reference to an arbitrary object in the *set*, and removes the
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object from the *set*. Return *NULL* on failure. Raise :exc:`KeyError` if the
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set is empty. Raise a :exc:`SystemError` if *set* is not an instance of
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:class:`set` or its subtype.
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.. c:function:: int PySet_Clear(PyObject *set)
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Empty an existing set of all elements.
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.. c:function:: int PySet_ClearFreeList()
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Clear the free list. Return the total number of freed items.
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.. versionadded:: 3.3
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