/* Set object interface */

#ifndef Py_SETOBJECT_H
#define Py_SETOBJECT_H
#ifdef __cplusplus
extern "C" {
#endif

#ifndef Py_LIMITED_API

/* There are three kinds of entries in the table:

1. Unused: key == NULL and hash == 0
2. Dummy: key == dummy and hash == -1
3. Active: key != NULL and key != dummy and hash != -1

The hash field of Unused slots is always zero.

The hash field of Dummy slots are set to -1
meaning that dummy entries can be detected by
either entry->key==dummy or by entry->hash==-1.
*/

#define PySet_MINSIZE 8

typedef struct {
 PyObject *key;
 Py_hash_t hash; /* Cached hash code of the key */
} setentry;

/* The SetObject data structure is shared by set and frozenset objects.

Invariant for sets:
 - hash is -1

Invariants for frozensets:
 - data is immutable.
 - hash is the hash of the frozenset or -1 if not computed yet.

*/

typedef struct {
 PyObject_HEAD

 Py_ssize_t fill; /* Number active and dummy entries*/
 Py_ssize_t used; /* Number active entries */

 /* The table contains mask + 1 slots, and that's a power of 2.
 * We store the mask instead of the size because the mask is more
 * frequently needed.
 */
 Py_ssize_t mask;

 /* The table points to a fixed-size smalltable for small tables
 * or to additional malloc'ed memory for bigger tables.
 * The table pointer is never NULL which saves us from repeated
 * runtime null-tests.
 */
 setentry *table;
 Py_hash_t hash; /* Only used by frozenset objects */
 Py_ssize_t finger; /* Search finger for pop() */

 setentry smalltable[PySet_MINSIZE];
 PyObject *weakreflist; /* List of weak references */
} PySetObject;

#define PySet_GET_SIZE(so) (assert(PyAnySet_Check(so)),(((PySetObject *)(so))->used))

PyAPI_DATA(PyObject *) _PySet_Dummy;

PyAPI_FUNC(int) _PySet_NextEntry(PyObject *set, Py_ssize_t *pos, PyObject **key, Py_hash_t *hash);
PyAPI_FUNC(int) _PySet_Update(PyObject *set, PyObject *iterable);
PyAPI_FUNC(int) PySet_ClearFreeList(void);

#endif /* Section excluded by Py_LIMITED_API */

PyAPI_DATA(PyTypeObject) PySet_Type;
PyAPI_DATA(PyTypeObject) PyFrozenSet_Type;
PyAPI_DATA(PyTypeObject) PySetIter_Type;

PyAPI_FUNC(PyObject *) PySet_New(PyObject *);
PyAPI_FUNC(PyObject *) PyFrozenSet_New(PyObject *);

PyAPI_FUNC(int) PySet_Add(PyObject *set, PyObject *key);
PyAPI_FUNC(int) PySet_Clear(PyObject *set);
PyAPI_FUNC(int) PySet_Contains(PyObject *anyset, PyObject *key);
PyAPI_FUNC(int) PySet_Discard(PyObject *set, PyObject *key);
PyAPI_FUNC(PyObject *) PySet_Pop(PyObject *set);
PyAPI_FUNC(Py_ssize_t) PySet_Size(PyObject *anyset);

#define PyFrozenSet_CheckExact(ob) (Py_TYPE(ob) == &PyFrozenSet_Type)
#define PyAnySet_CheckExact(ob) \
 (Py_TYPE(ob) == &PySet_Type || Py_TYPE(ob) == &PyFrozenSet_Type)
#define PyAnySet_Check(ob) \
 (Py_TYPE(ob) == &PySet_Type || Py_TYPE(ob) == &PyFrozenSet_Type || \
 PyType_IsSubtype(Py_TYPE(ob), &PySet_Type) || \
 PyType_IsSubtype(Py_TYPE(ob), &PyFrozenSet_Type))
#define PySet_Check(ob) \
 (Py_TYPE(ob) == &PySet_Type || \
 PyType_IsSubtype(Py_TYPE(ob), &PySet_Type))
#define PyFrozenSet_Check(ob) \
 (Py_TYPE(ob) == &PyFrozenSet_Type || \
 PyType_IsSubtype(Py_TYPE(ob), &PyFrozenSet_Type))

#ifdef __cplusplus
}
#endif
#endif /* !Py_SETOBJECT_H */