/* 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.

 */

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.

     */

    long 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;

};

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_TYPE(op) == &_PyWeakref_RefType)

#define PyWeakref_CheckProxy(op) \

        ((Py_TYPE(op) == &_PyWeakref_ProxyType) || \

         (Py_TYPE(op) == &_PyWeakref_CallableProxyType))

/* This macro calls PyWeakref_CheckRef() last since that can involve a

   function call; this makes it more likely that the function call

   will be avoided. */

#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);

PyAPI_FUNC(Py_ssize_t) _PyWeakref_GetWeakrefCount(PyWeakReference *head);

PyAPI_FUNC(void) _PyWeakref_ClearRef(PyWeakReference *self);

#define PyWeakref_GET_OBJECT(ref) (((PyWeakReference *)(ref))->wr_object)

#ifdef __cplusplus

}

#endif

#endif /* !Py_WEAKREFOBJECT_H */