#include "Python.h"


#define GET_WEAKREFS_LISTPTR(o) \
 ((PyWeakReference **) PyObject_GET_WEAKREFS_LISTPTR(o))

/*[clinic input]
module _weakref
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=ffec73b85846596d]*/

#include "clinic/_weakref.c.h"

/*[clinic input]

_weakref.getweakrefcount -> Py_ssize_t

 object: object
 /

Return the number of weak references to 'object'.
[clinic start generated code]*/

static Py_ssize_t
_weakref_getweakrefcount_impl(PyObject *module, PyObject *object)
/*[clinic end generated code: output=301806d59558ff3e input=cedb69711b6a2507]*/
{
 PyWeakReference **list;

 if (!PyType_SUPPORTS_WEAKREFS(Py_TYPE(object)))
 return 0;

 list = GET_WEAKREFS_LISTPTR(object);
 return _PyWeakref_GetWeakrefCount(*list);
}


static int
is_dead_weakref(PyObject *value)
{
 if (!PyWeakref_Check(value)) {
 PyErr_SetString(PyExc_TypeError, "not a weakref");
 return -1;
 }
 return PyWeakref_GET_OBJECT(value) == Py_None;
}

/*[clinic input]

_weakref._remove_dead_weakref -> object

 dct: object(subclass_of='&PyDict_Type')
 key: object
 /

Atomically remove key from dict if it points to a dead weakref.
[clinic start generated code]*/

static PyObject *
_weakref__remove_dead_weakref_impl(PyObject *module, PyObject *dct,
 PyObject *key)
/*[clinic end generated code: output=d9ff53061fcb875c input=19fc91f257f96a1d]*/
{
 if (_PyDict_DelItemIf(dct, key, is_dead_weakref) < 0) {
 if (PyErr_ExceptionMatches(PyExc_KeyError))
 /* This function is meant to allow safe weak-value dicts
 with GC in another thread (see issue #28427), so it's
 ok if the key doesn't exist anymore.
 */
 PyErr_Clear();
 else
 return NULL;
 }
 Py_RETURN_NONE;
}


PyDoc_STRVAR(weakref_getweakrefs__doc__,
"getweakrefs(object) -- return a list of all weak reference objects\n"
"that point to 'object'.");

static PyObject *
weakref_getweakrefs(PyObject *self, PyObject *object)
{
 PyObject *result = NULL;

 if (PyType_SUPPORTS_WEAKREFS(Py_TYPE(object))) {
 PyWeakReference **list = GET_WEAKREFS_LISTPTR(object);
 Py_ssize_t count = _PyWeakref_GetWeakrefCount(*list);

 result = PyList_New(count);
 if (result != NULL) {
 PyWeakReference *current = *list;
 Py_ssize_t i;
 for (i = 0; i < count; ++i) {
 PyList_SET_ITEM(result, i, (PyObject *) current);
 Py_INCREF(current);
 current = current->wr_next;
 }
 }
 }
 else {
 result = PyList_New(0);
 }
 return result;
}


PyDoc_STRVAR(weakref_proxy__doc__,
"proxy(object[, callback]) -- create a proxy object that weakly\n"
"references 'object'. 'callback', if given, is called with a\n"
"reference to the proxy when 'object' is about to be finalized.");

static PyObject *
weakref_proxy(PyObject *self, PyObject *args)
{
 PyObject *object;
 PyObject *callback = NULL;
 PyObject *result = NULL;

 if (PyArg_UnpackTuple(args, "proxy", 1, 2, &object, &callback)) {
 result = PyWeakref_NewProxy(object, callback);
 }
 return result;
}


static PyMethodDef
weakref_functions[] = {
 _WEAKREF_GETWEAKREFCOUNT_METHODDEF
 _WEAKREF__REMOVE_DEAD_WEAKREF_METHODDEF
 {"getweakrefs", weakref_getweakrefs, METH_O,
 weakref_getweakrefs__doc__},
 {"proxy", weakref_proxy, METH_VARARGS,
 weakref_proxy__doc__},
 {NULL, NULL, 0, NULL}
};


static struct PyModuleDef weakrefmodule = {
 PyModuleDef_HEAD_INIT,
 "_weakref",
 "Weak-reference support module.",
 -1,
 weakref_functions,
 NULL,
 NULL,
 NULL,
 NULL
};

PyMODINIT_FUNC
PyInit__weakref(void)
{
 PyObject *m;

 m = PyModule_Create(&weakrefmodule);

 if (m != NULL) {
 Py_INCREF(&_PyWeakref_RefType);
 PyModule_AddObject(m, "ref",
 (PyObject *) &_PyWeakref_RefType);
 Py_INCREF(&_PyWeakref_RefType);
 PyModule_AddObject(m, "ReferenceType",
 (PyObject *) &_PyWeakref_RefType);
 Py_INCREF(&_PyWeakref_ProxyType);
 PyModule_AddObject(m, "ProxyType",
 (PyObject *) &_PyWeakref_ProxyType);
 Py_INCREF(&_PyWeakref_CallableProxyType);
 PyModule_AddObject(m, "CallableProxyType",
 (PyObject *) &_PyWeakref_CallableProxyType);
 }
 return m;
}