python-3.6.zip added from Github

README.cosmo contains the necessary links.

third_party/python/Modules/_weakref.c

@@ -0,0 +1,174 @@
+#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;
+}