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- /* Weak references objects for Python. */
- #ifndef Py_WEAKREFOBJECT_H
- #define Py_WEAKREFOBJECT_H
- #ifdef __cplusplus
- extern "C" {
- #endif
- typedef struct _PyWeakReference PyWeakReference;
- /* PyWeakReference is the base struct for the Python ReferenceType, ProxyType,
- * and CallableProxyType.
- */
- #ifndef Py_LIMITED_API
- struct _PyWeakReference {
- PyObject_HEAD
- /* The object to which this is a weak reference, or Py_None if none.
- * Note that this is a stealth reference: wr_object's refcount is
- * not incremented to reflect this pointer.
- */
- PyObject *wr_object;
- /* A callable to invoke when wr_object dies, or NULL if none. */
- PyObject *wr_callback;
- /* A cache for wr_object's hash code. As usual for hashes, this is -1
- * if the hash code isn't known yet.
- */
- Py_hash_t hash;
- /* If wr_object is weakly referenced, wr_object has a doubly-linked NULL-
- * terminated list of weak references to it. These are the list pointers.
- * If wr_object goes away, wr_object is set to Py_None, and these pointers
- * have no meaning then.
- */
- PyWeakReference *wr_prev;
- PyWeakReference *wr_next;
- };
- #endif
- PyAPI_DATA(PyTypeObject) _PyWeakref_RefType;
- PyAPI_DATA(PyTypeObject) _PyWeakref_ProxyType;
- PyAPI_DATA(PyTypeObject) _PyWeakref_CallableProxyType;
- #define PyWeakref_CheckRef(op) PyObject_TypeCheck(op, &_PyWeakref_RefType)
- #define PyWeakref_CheckRefExact(op) \
- Py_IS_TYPE(op, &_PyWeakref_RefType)
- #define PyWeakref_CheckProxy(op) \
- (Py_IS_TYPE(op, &_PyWeakref_ProxyType) || \
- Py_IS_TYPE(op, &_PyWeakref_CallableProxyType))
- #define PyWeakref_Check(op) \
- (PyWeakref_CheckRef(op) || PyWeakref_CheckProxy(op))
- PyAPI_FUNC(PyObject *) PyWeakref_NewRef(PyObject *ob,
- PyObject *callback);
- PyAPI_FUNC(PyObject *) PyWeakref_NewProxy(PyObject *ob,
- PyObject *callback);
- PyAPI_FUNC(PyObject *) PyWeakref_GetObject(PyObject *ref);
- #ifndef Py_LIMITED_API
- PyAPI_FUNC(Py_ssize_t) _PyWeakref_GetWeakrefCount(PyWeakReference *head);
- PyAPI_FUNC(void) _PyWeakref_ClearRef(PyWeakReference *self);
- #endif
- /* Explanation for the Py_REFCNT() check: when a weakref's target is part
- of a long chain of deallocations which triggers the trashcan mechanism,
- clearing the weakrefs can be delayed long after the target's refcount
- has dropped to zero. In the meantime, code accessing the weakref will
- be able to "see" the target object even though it is supposed to be
- unreachable. See issue #16602. */
- #define PyWeakref_GET_OBJECT(ref) \
- (Py_REFCNT(((PyWeakReference *)(ref))->wr_object) > 0 \
- ? ((PyWeakReference *)(ref))->wr_object \
- : Py_None)
- #ifdef __cplusplus
- }
- #endif
- #endif /* !Py_WEAKREFOBJECT_H */
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