Modules/_weakref.c

   1 #include "Python.h"
   2
   3
   4 #define GET_WEAKREFS_LISTPTR(o) \
   5         ((PyWeakReference **) PyObject_GET_WEAKREFS_LISTPTR(o))
   6
   7
   8 PyDoc_STRVAR(weakref_getweakrefcount__doc__,
   9 "getweakrefcount(object) -- return the number of weak references\n"
  10 "to 'object'.");
  11
  12 static PyObject *
  13 weakref_getweakrefcount(PyObject *self, PyObject *object)
  14 {
  15     PyObject *result = NULL;
  16
  17     if (PyType_SUPPORTS_WEAKREFS(Py_TYPE(object))) {
  18         PyWeakReference **list = GET_WEAKREFS_LISTPTR(object);
  19
  20         result = PyInt_FromSsize_t(_PyWeakref_GetWeakrefCount(*list));
  21     }
  22     else
  23         result = PyInt_FromLong(0);
  24
  25     return result;
  26 }
  27
  28
  29 PyDoc_STRVAR(weakref_getweakrefs__doc__,
  30 "getweakrefs(object) -- return a list of all weak reference objects\n"
  31 "that point to 'object'.");
  32
  33 static PyObject *
  34 weakref_getweakrefs(PyObject *self, PyObject *object)
  35 {
  36     PyObject *result = NULL;
  37
  38     if (PyType_SUPPORTS_WEAKREFS(Py_TYPE(object))) {
  39         PyWeakReference **list = GET_WEAKREFS_LISTPTR(object);
  40         Py_ssize_t count = _PyWeakref_GetWeakrefCount(*list);
  41
  42         result = PyList_New(count);
  43         if (result != NULL) {
  44             PyWeakReference *current = *list;
  45             Py_ssize_t i;
  46             for (i = 0; i < count; ++i) {
  47                 PyList_SET_ITEM(result, i, (PyObject *) current);
  48                 Py_INCREF(current);
  49                 current = current->wr_next;
  50             }
  51         }
  52     }
  53     else {
  54         result = PyList_New(0);
  55     }
  56     return result;
  57 }
  58
  59
  60 PyDoc_STRVAR(weakref_proxy__doc__,
  61 "proxy(object[, callback]) -- create a proxy object that weakly\n"
  62 "references 'object'.  'callback', if given, is called with a\n"
  63 "reference to the proxy when 'object' is about to be finalized.");
  64
  65 static PyObject *
  66 weakref_proxy(PyObject *self, PyObject *args)
  67 {
  68     PyObject *object;
  69     PyObject *callback = NULL;
  70     PyObject *result = NULL;
  71
  72     if (PyArg_UnpackTuple(args, "proxy", 1, 2, &object, &callback)) {
  73         result = PyWeakref_NewProxy(object, callback);
  74     }
  75     return result;
  76 }
  77
  78
  79 static PyMethodDef
  80 weakref_functions[] =  {
  81     {"getweakrefcount", weakref_getweakrefcount,        METH_O,
  82      weakref_getweakrefcount__doc__},
  83     {"getweakrefs",     weakref_getweakrefs,            METH_O,
  84      weakref_getweakrefs__doc__},
  85     {"proxy",           weakref_proxy,                  METH_VARARGS,
  86      weakref_proxy__doc__},
  87     {NULL, NULL, 0, NULL}
  88 };
  89
  90
  91 PyMODINIT_FUNC
  92 init_weakref(void)
  93 {
  94     PyObject *m;
  95
  96     m = Py_InitModule3("_weakref", weakref_functions,
  97                        "Weak-reference support module.");
  98     if (m != NULL) {
  99         Py_INCREF(&_PyWeakref_RefType);
 100         PyModule_AddObject(m, "ref",
 101                            (PyObject *) &_PyWeakref_RefType);
 102         Py_INCREF(&_PyWeakref_RefType);
 103         PyModule_AddObject(m, "ReferenceType",
 104                            (PyObject *) &_PyWeakref_RefType);
 105         Py_INCREF(&_PyWeakref_ProxyType);
 106         PyModule_AddObject(m, "ProxyType",
 107                            (PyObject *) &_PyWeakref_ProxyType);
 108         Py_INCREF(&_PyWeakref_CallableProxyType);
 109         PyModule_AddObject(m, "CallableProxyType",
 110                            (PyObject *) &_PyWeakref_CallableProxyType);
 111     }
 112 }