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 */