1 #include "Python.h"
2 #include "pycore_object.h" // _PyObject_GET_WEAKREFS_LISTPTR
3
4
5 #define GET_WEAKREFS_LISTPTR(o) \
6 ((PyWeakReference **) _PyObject_GET_WEAKREFS_LISTPTR(o))
7
8 /*[clinic input]
9 module _weakref
10 [clinic start generated code]*/
11 /*[clinic end generated code: output=da39a3ee5e6b4b0d input=ffec73b85846596d]*/
12
13 #include "clinic/_weakref.c.h"
14
15 /*[clinic input]
16
17 _weakref.getweakrefcount -> Py_ssize_t
18
19 object: object
20 /
21
22 Return the number of weak references to 'object'.
23 [clinic start generated code]*/
24
25 static Py_ssize_t
26 _weakref_getweakrefcount_impl(PyObject *module, PyObject *object)
27 /*[clinic end generated code: output=301806d59558ff3e input=cedb69711b6a2507]*/
28 {
29 PyWeakReference **list;
30
31 if (!_PyType_SUPPORTS_WEAKREFS(Py_TYPE(object)))
32 return 0;
33
34 list = GET_WEAKREFS_LISTPTR(object);
35 return _PyWeakref_GetWeakrefCount(*list);
36 }
37
38
39 static int
40 is_dead_weakref(PyObject *value)
41 {
42 if (!PyWeakref_Check(value)) {
43 PyErr_SetString(PyExc_TypeError, "not a weakref");
44 return -1;
45 }
46 return PyWeakref_GET_OBJECT(value) == Py_None;
47 }
48
49 /*[clinic input]
50
51 _weakref._remove_dead_weakref -> object
52
53 dct: object(subclass_of='&PyDict_Type')
54 key: object
55 /
56
57 Atomically remove key from dict if it points to a dead weakref.
58 [clinic start generated code]*/
59
60 static PyObject *
61 _weakref__remove_dead_weakref_impl(PyObject *module, PyObject *dct,
62 PyObject *key)
63 /*[clinic end generated code: output=d9ff53061fcb875c input=19fc91f257f96a1d]*/
64 {
65 if (_PyDict_DelItemIf(dct, key, is_dead_weakref) < 0) {
66 if (PyErr_ExceptionMatches(PyExc_KeyError))
67 /* This function is meant to allow safe weak-value dicts
68 with GC in another thread (see issue #28427), so it's
69 ok if the key doesn't exist anymore.
70 */
71 PyErr_Clear();
72 else
73 return NULL;
74 }
75 Py_RETURN_NONE;
76 }
77
78
79 /*[clinic input]
80 _weakref.getweakrefs
81 object: object
82 /
83
84 Return a list of all weak reference objects pointing to 'object'.
85 [clinic start generated code]*/
86
87 static PyObject *
88 _weakref_getweakrefs(PyObject *module, PyObject *object)
89 /*[clinic end generated code: output=25c7731d8e011824 input=00c6d0e5d3206693]*/
90 {
91 PyObject *result = NULL;
92
93 if (_PyType_SUPPORTS_WEAKREFS(Py_TYPE(object))) {
94 PyWeakReference **list = GET_WEAKREFS_LISTPTR(object);
95 Py_ssize_t count = _PyWeakref_GetWeakrefCount(*list);
96
97 result = PyList_New(count);
98 if (result != NULL) {
99 PyWeakReference *current = *list;
100 Py_ssize_t i;
101 for (i = 0; i < count; ++i) {
102 PyList_SET_ITEM(result, i, (PyObject *) current);
103 Py_INCREF(current);
104 current = current->wr_next;
105 }
106 }
107 }
108 else {
109 result = PyList_New(0);
110 }
111 return result;
112 }
113
114
115 /*[clinic input]
116
117 _weakref.proxy
118 object: object
119 callback: object(c_default="NULL") = None
120 /
121
122 Create a proxy object that weakly references 'object'.
123
124 'callback', if given, is called with a reference to the
125 proxy when 'object' is about to be finalized.
126 [clinic start generated code]*/
127
128 static PyObject *
129 _weakref_proxy_impl(PyObject *module, PyObject *object, PyObject *callback)
130 /*[clinic end generated code: output=d68fa4ad9ea40519 input=4808adf22fd137e7]*/
131 {
132 return PyWeakref_NewProxy(object, callback);
133 }
134
135
136 static PyMethodDef
137 weakref_functions[] = {
138 _WEAKREF_GETWEAKREFCOUNT_METHODDEF
139 _WEAKREF__REMOVE_DEAD_WEAKREF_METHODDEF
140 _WEAKREF_GETWEAKREFS_METHODDEF
141 _WEAKREF_PROXY_METHODDEF
142 {NULL, NULL, 0, NULL}
143 };
144
145 static int
146 weakref_exec(PyObject *module)
147 {
148 Py_INCREF(&_PyWeakref_RefType);
149 if (PyModule_AddObject(module, "ref", (PyObject *) &_PyWeakref_RefType) < 0) {
150 Py_DECREF(&_PyWeakref_RefType);
151 return -1;
152 }
153 Py_INCREF(&_PyWeakref_RefType);
154 if (PyModule_AddObject(module, "ReferenceType",
155 (PyObject *) &_PyWeakref_RefType) < 0) {
156 Py_DECREF(&_PyWeakref_RefType);
157 return -1;
158 }
159 Py_INCREF(&_PyWeakref_ProxyType);
160 if (PyModule_AddObject(module, "ProxyType",
161 (PyObject *) &_PyWeakref_ProxyType) < 0) {
162 Py_DECREF(&_PyWeakref_ProxyType);
163 return -1;
164 }
165 Py_INCREF(&_PyWeakref_CallableProxyType);
166 if (PyModule_AddObject(module, "CallableProxyType",
167 (PyObject *) &_PyWeakref_CallableProxyType) < 0) {
168 Py_DECREF(&_PyWeakref_CallableProxyType);
169 return -1;
170 }
171
172 return 0;
173 }
174
175 static struct PyModuleDef_Slot weakref_slots[] = {
176 {Py_mod_exec, weakref_exec},
177 {Py_mod_multiple_interpreters, Py_MOD_PER_INTERPRETER_GIL_SUPPORTED},
178 {0, NULL}
179 };
180
181 static struct PyModuleDef weakrefmodule = {
182 PyModuleDef_HEAD_INIT,
183 "_weakref",
184 "Weak-reference support module.",
185 0,
186 weakref_functions,
187 weakref_slots,
188 NULL,
189 NULL,
190 NULL
191 };
192
193 PyMODINIT_FUNC
194 PyInit__weakref(void)
195 {
196 return PyModuleDef_Init(&weakrefmodule);
197 }