Split C API docs in Py3k branch.
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+.. highlightlang:: c
+
+.. _setobjects:
+
+Set Objects
+-----------
+
+.. sectionauthor:: Raymond D. Hettinger <python@rcn.com>
+
+
+.. index::
+ object: set
+ object: frozenset
+
+This section details the public API for :class:`set` and :class:`frozenset`
+objects. Any functionality not listed below is best accessed using the either
+the abstract object protocol (including :cfunc:`PyObject_CallMethod`,
+:cfunc:`PyObject_RichCompareBool`, :cfunc:`PyObject_Hash`,
+:cfunc:`PyObject_Repr`, :cfunc:`PyObject_IsTrue`, :cfunc:`PyObject_Print`, and
+:cfunc:`PyObject_GetIter`) or the abstract number protocol (including
+:cfunc:`PyNumber_And`, :cfunc:`PyNumber_Subtract`, :cfunc:`PyNumber_Or`,
+:cfunc:`PyNumber_Xor`, :cfunc:`PyNumber_InPlaceAnd`,
+:cfunc:`PyNumber_InPlaceSubtract`, :cfunc:`PyNumber_InPlaceOr`, and
+:cfunc:`PyNumber_InPlaceXor`).
+
+
+.. ctype:: PySetObject
+
+ This subtype of :ctype:`PyObject` is used to hold the internal data for both
+ :class:`set` and :class:`frozenset` objects. It is like a :ctype:`PyDictObject`
+ in that it is a fixed size for small sets (much like tuple storage) and will
+ point to a separate, variable sized block of memory for medium and large sized
+ sets (much like list storage). None of the fields of this structure should be
+ considered public and are subject to change. All access should be done through
+ the documented API rather than by manipulating the values in the structure.
+
+
+.. cvar:: PyTypeObject PySet_Type
+
+ This is an instance of :ctype:`PyTypeObject` representing the Python
+ :class:`set` type.
+
+
+.. cvar:: PyTypeObject PyFrozenSet_Type
+
+ This is an instance of :ctype:`PyTypeObject` representing the Python
+ :class:`frozenset` type.
+
+The following type check macros work on pointers to any Python object. Likewise,
+the constructor functions work with any iterable Python object.
+
+
+.. cfunction:: int PyAnySet_Check(PyObject *p)
+
+ Return true if *p* is a :class:`set` object, a :class:`frozenset` object, or an
+ instance of a subtype.
+
+
+.. cfunction:: int PyAnySet_CheckExact(PyObject *p)
+
+ Return true if *p* is a :class:`set` object or a :class:`frozenset` object but
+ not an instance of a subtype.
+
+
+.. cfunction:: int PyFrozenSet_CheckExact(PyObject *p)
+
+ Return true if *p* is a :class:`frozenset` object but not an instance of a
+ subtype.
+
+
+.. cfunction:: PyObject* PySet_New(PyObject *iterable)
+
+ Return a new :class:`set` containing objects returned by the *iterable*. The
+ *iterable* may be *NULL* to create a new empty set. Return the new set on
+ success or *NULL* on failure. Raise :exc:`TypeError` if *iterable* is not
+ actually iterable. The constructor is also useful for copying a set
+ (``c=set(s)``).
+
+
+.. cfunction:: PyObject* PyFrozenSet_New(PyObject *iterable)
+
+ Return a new :class:`frozenset` containing objects returned by the *iterable*.
+ The *iterable* may be *NULL* to create a new empty frozenset. Return the new
+ set on success or *NULL* on failure. Raise :exc:`TypeError` if *iterable* is
+ not actually iterable.
+
+The following functions and macros are available for instances of :class:`set`
+or :class:`frozenset` or instances of their subtypes.
+
+
+.. cfunction:: Py_ssize_t PySet_Size(PyObject *anyset)
+
+ .. index:: builtin: len
+
+ Return the length of a :class:`set` or :class:`frozenset` object. Equivalent to
+ ``len(anyset)``. Raises a :exc:`PyExc_SystemError` if *anyset* is not a
+ :class:`set`, :class:`frozenset`, or an instance of a subtype.
+
+
+.. cfunction:: Py_ssize_t PySet_GET_SIZE(PyObject *anyset)
+
+ Macro form of :cfunc:`PySet_Size` without error checking.
+
+
+.. cfunction:: int PySet_Contains(PyObject *anyset, PyObject *key)
+
+ Return 1 if found, 0 if not found, and -1 if an error is encountered. Unlike
+ the Python :meth:`__contains__` method, this function does not automatically
+ convert unhashable sets into temporary frozensets. Raise a :exc:`TypeError` if
+ the *key* is unhashable. Raise :exc:`PyExc_SystemError` if *anyset* is not a
+ :class:`set`, :class:`frozenset`, or an instance of a subtype.
+
+The following functions are available for instances of :class:`set` or its
+subtypes but not for instances of :class:`frozenset` or its subtypes.
+
+
+.. cfunction:: int PySet_Add(PyObject *set, PyObject *key)
+
+ Add *key* to a :class:`set` instance. Does not apply to :class:`frozenset`
+ instances. Return 0 on success or -1 on failure. Raise a :exc:`TypeError` if
+ the *key* is unhashable. Raise a :exc:`MemoryError` if there is no room to grow.
+ Raise a :exc:`SystemError` if *set* is an not an instance of :class:`set` or its
+ subtype.
+
+
+.. cfunction:: int PySet_Discard(PyObject *set, PyObject *key)
+
+ Return 1 if found and removed, 0 if not found (no action taken), and -1 if an
+ error is encountered. Does not raise :exc:`KeyError` for missing keys. Raise a
+ :exc:`TypeError` if the *key* is unhashable. Unlike the Python :meth:`discard`
+ method, this function does not automatically convert unhashable sets into
+ temporary frozensets. Raise :exc:`PyExc_SystemError` if *set* is an not an
+ instance of :class:`set` or its subtype.
+
+
+.. cfunction:: PyObject* PySet_Pop(PyObject *set)
+
+ Return a new reference to an arbitrary object in the *set*, and removes the
+ object from the *set*. Return *NULL* on failure. Raise :exc:`KeyError` if the
+ set is empty. Raise a :exc:`SystemError` if *set* is an not an instance of
+ :class:`set` or its subtype.
+
+
+.. cfunction:: int PySet_Clear(PyObject *set)
+
+ Empty an existing set of all elements.