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