Include/weakrefobject.h

   1 /* Weak references objects for Python. */
   2
   3 #ifndef Py_WEAKREFOBJECT_H
   4 #define Py_WEAKREFOBJECT_H
   5 #ifdef __cplusplus
   6 extern "C" {
   7 #endif
   8
   9
  10 typedef struct _PyWeakReference PyWeakReference;
  11
  12 /* PyWeakReference is the base struct for the Python ReferenceType, ProxyType,
  13  * and CallableProxyType.
  14  */
  15 struct _PyWeakReference {
  16     PyObject_HEAD
  17
  18     /* The object to which this is a weak reference, or Py_None if none.
  19      * Note that this is a stealth reference:  wr_object's refcount is
  20      * not incremented to reflect this pointer.
  21      */
  22     PyObject *wr_object;
  23
  24     /* A callable to invoke when wr_object dies, or NULL if none. */
  25     PyObject *wr_callback;
  26
  27     /* A cache for wr_object's hash code.  As usual for hashes, this is -1
  28      * if the hash code isn't known yet.
  29      */
  30     long hash;
  31
  32     /* If wr_object is weakly referenced, wr_object has a doubly-linked NULL-
  33      * terminated list of weak references to it.  These are the list pointers.
  34      * If wr_object goes away, wr_object is set to Py_None, and these pointers
  35      * have no meaning then.
  36      */
  37     PyWeakReference *wr_prev;
  38     PyWeakReference *wr_next;
  39 };
  40
  41 PyAPI_DATA(PyTypeObject) _PyWeakref_RefType;
  42 PyAPI_DATA(PyTypeObject) _PyWeakref_ProxyType;
  43 PyAPI_DATA(PyTypeObject) _PyWeakref_CallableProxyType;
  44
  45 #define PyWeakref_CheckRef(op) PyObject_TypeCheck(op, &_PyWeakref_RefType)
  46 #define PyWeakref_CheckRefExact(op) \
  47         (Py_TYPE(op) == &_PyWeakref_RefType)
  48 #define PyWeakref_CheckProxy(op) \
  49         ((Py_TYPE(op) == &_PyWeakref_ProxyType) || \
  50          (Py_TYPE(op) == &_PyWeakref_CallableProxyType))
  51
  52 /* This macro calls PyWeakref_CheckRef() last since that can involve a
  53    function call; this makes it more likely that the function call
  54    will be avoided. */
  55 #define PyWeakref_Check(op) \
  56         (PyWeakref_CheckRef(op) || PyWeakref_CheckProxy(op))
  57
  58
  59 PyAPI_FUNC(PyObject *) PyWeakref_NewRef(PyObject *ob,
  60                                               PyObject *callback);
  61 PyAPI_FUNC(PyObject *) PyWeakref_NewProxy(PyObject *ob,
  62                                                 PyObject *callback);
  63 PyAPI_FUNC(PyObject *) PyWeakref_GetObject(PyObject *ref);
  64
  65 PyAPI_FUNC(Py_ssize_t) _PyWeakref_GetWeakrefCount(PyWeakReference *head);
  66
  67 PyAPI_FUNC(void) _PyWeakref_ClearRef(PyWeakReference *self);
  68
  69 #define PyWeakref_GET_OBJECT(ref) (((PyWeakReference *)(ref))->wr_object)
  70
  71
  72 #ifdef __cplusplus
  73 }
  74 #endif
  75 #endif /* !Py_WEAKREFOBJECT_H */