diff options
Diffstat (limited to 'Modules/_weakref.c')
| -rw-r--r-- | Modules/_weakref.c | 757 |
1 files changed, 757 insertions, 0 deletions
diff --git a/Modules/_weakref.c b/Modules/_weakref.c new file mode 100644 index 0000000..3c03c3c --- /dev/null +++ b/Modules/_weakref.c @@ -0,0 +1,757 @@ +#include "Python.h" +#include "structmember.h" + + +typedef struct _PyWeakReference PyWeakReference; + +struct _PyWeakReference { + PyObject_HEAD + PyObject *wr_object; + PyObject *wr_callback; + PyWeakReference *wr_prev; + PyWeakReference *wr_next; +}; + + +#define GET_WEAKREFS_LISTPTR(o) \ + ((PyWeakReference **) PyObject_GET_WEAKREFS_LISTPTR(o)) + +static PyObject * +ReferenceError; + +static PyWeakReference * +free_list = NULL; + +staticforward PyTypeObject +PyWeakReference_Type; + +static PyWeakReference * +new_weakref(void) +{ + PyWeakReference *result; + + if (free_list != NULL) { + result = free_list; + free_list = result->wr_next; + result->ob_type = &PyWeakReference_Type; + _Py_NewReference(result); + } + else { + result = PyObject_NEW(PyWeakReference, &PyWeakReference_Type); + } + return result; +} + + +/* This function clears the passed-in reference and removes it from the + * list of weak references for the referent. This is the only code that + * removes an item from the doubly-linked list of weak references for an + * object; it is also responsible for clearing the callback slot. + */ +static void +clear_weakref(PyWeakReference *self) +{ + PyObject *callback = self->wr_callback; + + if (self->wr_object != Py_None) { + PyWeakReference **list = GET_WEAKREFS_LISTPTR(self->wr_object); + + if (*list == self) + *list = self->wr_next; + self->wr_object = Py_None; + self->wr_callback = NULL; + if (self->wr_prev != NULL) + self->wr_prev->wr_next = self->wr_next; + if (self->wr_next != NULL) + self->wr_next->wr_prev = self->wr_prev; + self->wr_prev = NULL; + self->wr_next = NULL; + Py_XDECREF(callback); + } +} + + +static void +weakref_dealloc(PyWeakReference *self) +{ + clear_weakref(self); + PyObject_GC_Fini((PyObject *)self); + self->wr_next = free_list; + free_list = self; +} + + +static int +gc_traverse(PyWeakReference *self, visitproc visit, void *arg) +{ + if (self->wr_callback != NULL) + return visit(self->wr_callback, arg); + return 0; +} + + +static int +gc_clear(PyWeakReference *self) +{ + clear_weakref(self); + return 0; +} + + +static PyObject * +weakref_call(PyWeakReference *self, PyObject *args, PyObject *kw) +{ + static char *argnames[] = {NULL}; + + if (PyArg_ParseTupleAndKeywords(args, kw, ":__call__", argnames)) { + PyObject *object = self->wr_object; + Py_INCREF(object); + return (object); + } + return NULL; +} + + +static PyObject * +weakref_repr(PyWeakReference *self) +{ + char buffer[256]; + if (self->wr_object == Py_None) { + sprintf(buffer, "<weakref at %lx; dead>", + (long)(self)); + } + else { + sprintf(buffer, "<weakref at %#lx; to '%s' at %#lx>", + (long)(self), self->wr_object->ob_type->tp_name, + (long)(self->wr_object)); + } + return PyString_FromString(buffer); +} + + +statichere PyTypeObject +PyWeakReference_Type = { + PyObject_HEAD_INIT(NULL) + 0, + "weakref", + sizeof(PyWeakReference) + PyGC_HEAD_SIZE, + 0, + (destructor)weakref_dealloc,/*tp_dealloc*/ + 0, /*tp_print*/ + 0, /*tp_getattr*/ + 0, /*tp_setattr*/ + 0, /*tp_compare*/ + (reprfunc)weakref_repr, /*tp_repr*/ + 0, /*tp_as_number*/ + 0, /*tp_as_sequence*/ + 0, /*tp_as_mapping*/ + 0, /*tp_hash*/ + (ternaryfunc)weakref_call, /*tp_call*/ + 0, /*tp_str*/ + 0, /*tp_getattro*/ + 0, /*tp_setattro*/ + 0, /*tp_as_buffer*/ + Py_TPFLAGS_DEFAULT | Py_TPFLAGS_GC, + 0, /*tp_doc*/ + (traverseproc)gc_traverse, /*tp_traverse*/ + (inquiry)gc_clear, /*tp_clear*/ +}; + + +static int +proxy_checkref(PyWeakReference *proxy) +{ + if (proxy->wr_object == Py_None) { + PyErr_SetString(ReferenceError, + "weakly-referenced object no longer exists"); + return 0; + } + return 1; +} + + +#define WRAP_UNARY(method, generic) \ + static PyObject * \ + method(PyWeakReference *proxy) { \ + if (!proxy_checkref(proxy)) { \ + return NULL; \ + } \ + return generic(proxy->wr_object); \ + } + +#define WRAP_BINARY(method, generic) \ + static PyObject * \ + method(PyWeakReference *proxy, PyObject *v) { \ + if (!proxy_checkref(proxy)) { \ + return NULL; \ + } \ + return generic(proxy->wr_object, v); \ + } + +#define WRAP_TERNARY(method, generic) \ + static PyObject * \ + method(PyWeakReference *proxy, PyObject *v, PyObject *w) { \ + if (!proxy_checkref(proxy)) { \ + return NULL; \ + } \ + return generic(proxy->wr_object, v, w); \ + } + + +/* direct slots */ + +WRAP_BINARY(proxy_getattr, PyObject_GetAttr) +WRAP_UNARY(proxy_str, PyObject_Str) +WRAP_TERNARY(proxy_call, PyEval_CallObjectWithKeywords) + +static int +proxy_print(PyWeakReference *proxy, FILE *fp, int flags) +{ + if (!proxy_checkref(proxy)) + return -1; + return PyObject_Print(proxy->wr_object, fp, flags); +} + +static PyObject * +proxy_repr(PyWeakReference *proxy) +{ + char buf[160]; + sprintf(buf, "<weakref at %p to %.100s at %p>", proxy, + proxy->wr_object->ob_type->tp_name, proxy->wr_object); + return PyString_FromString(buf); +} + + +static int +proxy_setattr(PyWeakReference *proxy, PyObject *name, PyObject *value) +{ + if (!proxy_checkref(proxy)) + return -1; + return PyObject_SetAttr(proxy->wr_object, name, value); +} + +static int +proxy_compare(PyWeakReference *proxy, PyObject *v) +{ + if (!proxy_checkref(proxy)) + return -1; + return PyObject_Compare(proxy->wr_object, v); +} + +/* number slots */ +WRAP_BINARY(proxy_add, PyNumber_Add) +WRAP_BINARY(proxy_sub, PyNumber_Subtract) +WRAP_BINARY(proxy_mul, PyNumber_Multiply) +WRAP_BINARY(proxy_div, PyNumber_Divide) +WRAP_BINARY(proxy_mod, PyNumber_Remainder) +WRAP_BINARY(proxy_divmod, PyNumber_Divmod) +WRAP_TERNARY(proxy_pow, PyNumber_Power) +WRAP_UNARY(proxy_neg, PyNumber_Negative) +WRAP_UNARY(proxy_pos, PyNumber_Positive) +WRAP_UNARY(proxy_abs, PyNumber_Absolute) +WRAP_UNARY(proxy_invert, PyNumber_Invert) +WRAP_BINARY(proxy_lshift, PyNumber_Lshift) +WRAP_BINARY(proxy_rshift, PyNumber_Rshift) +WRAP_BINARY(proxy_and, PyNumber_And) +WRAP_BINARY(proxy_xor, PyNumber_Xor) +WRAP_BINARY(proxy_or, PyNumber_Or) +WRAP_UNARY(proxy_int, PyNumber_Int) +WRAP_UNARY(proxy_long, PyNumber_Long) +WRAP_UNARY(proxy_float, PyNumber_Float) +WRAP_BINARY(proxy_iadd, PyNumber_InPlaceAdd) +WRAP_BINARY(proxy_isub, PyNumber_InPlaceSubtract) +WRAP_BINARY(proxy_imul, PyNumber_InPlaceMultiply) +WRAP_BINARY(proxy_idiv, PyNumber_InPlaceDivide) +WRAP_BINARY(proxy_imod, PyNumber_InPlaceRemainder) +WRAP_TERNARY(proxy_ipow, PyNumber_InPlacePower) +WRAP_BINARY(proxy_ilshift, PyNumber_InPlaceLshift) +WRAP_BINARY(proxy_irshift, PyNumber_InPlaceRshift) +WRAP_BINARY(proxy_iand, PyNumber_InPlaceAnd) +WRAP_BINARY(proxy_ixor, PyNumber_InPlaceXor) +WRAP_BINARY(proxy_ior, PyNumber_InPlaceOr) + +static int +proxy_nonzero(PyWeakReference *proxy) +{ + PyObject *o = proxy->wr_object; + if (!proxy_checkref(proxy)) + return 1; + if (o->ob_type->tp_as_number && + o->ob_type->tp_as_number->nb_nonzero) + return (*o->ob_type->tp_as_number->nb_nonzero)(o); + else + return 1; +} + +/* sequence slots */ + +static PyObject * +proxy_slice(PyWeakReference *proxy, int i, int j) +{ + if (!proxy_checkref(proxy)) + return NULL; + return PySequence_GetSlice(proxy->wr_object, i, j); +} + +static int +proxy_ass_slice(PyWeakReference *proxy, int i, int j, PyObject *value) +{ + if (!proxy_checkref(proxy)) + return -1; + return PySequence_SetSlice(proxy->wr_object, i, j, value); +} + +static int +proxy_contains(PyWeakReference *proxy, PyObject *value) +{ + if (!proxy_checkref(proxy)) + return -1; + return PySequence_Contains(proxy->wr_object, value); +} + + +/* mapping slots */ + +static int +proxy_length(PyWeakReference *proxy) +{ + if (!proxy_checkref(proxy)) + return -1; + return PyObject_Length(proxy->wr_object); +} + +WRAP_BINARY(proxy_getitem, PyObject_GetItem) + +static int +proxy_setitem(PyWeakReference *proxy, PyObject *key, PyObject *value) +{ + if (!proxy_checkref(proxy)) + return -1; + return PyObject_SetItem(proxy->wr_object, key, value); +} + + +static PyNumberMethods proxy_as_number = { + (binaryfunc)proxy_add, /*nb_add*/ + (binaryfunc)proxy_sub, /*nb_subtract*/ + (binaryfunc)proxy_mul, /*nb_multiply*/ + (binaryfunc)proxy_div, /*nb_divide*/ + (binaryfunc)proxy_mod, /*nb_remainder*/ + (binaryfunc)proxy_divmod, /*nb_divmod*/ + (ternaryfunc)proxy_pow, /*nb_power*/ + (unaryfunc)proxy_neg, /*nb_negative*/ + (unaryfunc)proxy_pos, /*nb_positive*/ + (unaryfunc)proxy_abs, /*nb_absolute*/ + (inquiry)proxy_nonzero, /*nb_nonzero*/ + (unaryfunc)proxy_invert, /*nb_invert*/ + (binaryfunc)proxy_lshift, /*nb_lshift*/ + (binaryfunc)proxy_rshift, /*nb_rshift*/ + (binaryfunc)proxy_and, /*nb_and*/ + (binaryfunc)proxy_xor, /*nb_xor*/ + (binaryfunc)proxy_or, /*nb_or*/ + (coercion)0, /*nb_coerce*/ + (unaryfunc)proxy_int, /*nb_int*/ + (unaryfunc)proxy_long, /*nb_long*/ + (unaryfunc)proxy_float, /*nb_float*/ + (unaryfunc)0, /*nb_oct*/ + (unaryfunc)0, /*nb_hex*/ + (binaryfunc)proxy_iadd, /*nb_inplace_add*/ + (binaryfunc)proxy_isub, /*nb_inplace_subtract*/ + (binaryfunc)proxy_imul, /*nb_inplace_multiply*/ + (binaryfunc)proxy_idiv, /*nb_inplace_divide*/ + (binaryfunc)proxy_imod, /*nb_inplace_remainder*/ + (ternaryfunc)proxy_ipow, /*nb_inplace_power*/ + (binaryfunc)proxy_ilshift, /*nb_inplace_lshift*/ + (binaryfunc)proxy_irshift, /*nb_inplace_rshift*/ + (binaryfunc)proxy_iand, /*nb_inplace_and*/ + (binaryfunc)proxy_ixor, /*nb_inplace_xor*/ + (binaryfunc)proxy_ior, /*nb_inplace_or*/ +}; + +static PySequenceMethods proxy_as_sequence = { + (inquiry)proxy_length, /*sq_length*/ + 0, /*sq_concat*/ + 0, /*sq_repeat*/ + 0, /*sq_item*/ + (intintargfunc)proxy_slice, /*sq_slice*/ + 0, /*sq_ass_item*/ + (intintobjargproc)proxy_ass_slice, /*sq_ass_slice*/ + (objobjproc)proxy_contains, /* sq_contains */ +}; + +static PyMappingMethods proxy_as_mapping = { + (inquiry)proxy_length, /*mp_length*/ + (binaryfunc)proxy_getitem, /*mp_subscript*/ + (objobjargproc)proxy_setitem, /*mp_ass_subscript*/ +}; + + +static PyTypeObject +PyWeakProxy_Type = { + PyObject_HEAD_INIT(NULL) + 0, + "weakproxy", + sizeof(PyWeakReference) + PyGC_HEAD_SIZE, + 0, + /* methods */ + (destructor)weakref_dealloc,/*tp_dealloc*/ + (printfunc)proxy_print, /*tp_print*/ + 0, /*tp_getattr*/ + 0, /*tp_setattr*/ + (cmpfunc)proxy_compare, /*tp_compare*/ + (unaryfunc)proxy_repr, /*tp_repr*/ + &proxy_as_number, /*tp_as_number*/ + &proxy_as_sequence, /*tp_as_sequence*/ + &proxy_as_mapping, /*tp_as_mapping*/ + 0, /*tp_hash*/ + (ternaryfunc)0, /*tp_call*/ + (unaryfunc)proxy_str, /*tp_str*/ + (getattrofunc)proxy_getattr,/*tp_getattro*/ + (setattrofunc)proxy_setattr,/*tp_setattro*/ + 0, /*tp_as_buffer*/ + Py_TPFLAGS_DEFAULT | Py_TPFLAGS_GC + |Py_TPFLAGS_CHECKTYPES, /*tp_flags*/ + 0, /*tp_doc*/ + (traverseproc)gc_traverse, /*tp_traverse*/ + (inquiry)gc_clear, /*tp_clear*/ +}; + + +static PyTypeObject +PyWeakCallableProxy_Type = { + PyObject_HEAD_INIT(NULL) + 0, + "weakcallableproxy", + sizeof(PyWeakReference) + PyGC_HEAD_SIZE, + 0, + /* methods */ + (destructor)weakref_dealloc,/*tp_dealloc*/ + (printfunc)proxy_print, /*tp_print*/ + 0, /*tp_getattr*/ + 0, /*tp_setattr*/ + (cmpfunc)proxy_compare, /*tp_compare*/ + (unaryfunc)proxy_repr, /*tp_repr*/ + &proxy_as_number, /*tp_as_number*/ + &proxy_as_sequence, /*tp_as_sequence*/ + &proxy_as_mapping, /*tp_as_mapping*/ + 0, /*tp_hash*/ + (ternaryfunc)proxy_call, /*tp_call*/ + (unaryfunc)proxy_str, /*tp_str*/ + (getattrofunc)proxy_getattr,/*tp_getattro*/ + (setattrofunc)proxy_setattr,/*tp_setattro*/ + 0, /*tp_as_buffer*/ + Py_TPFLAGS_DEFAULT | Py_TPFLAGS_GC + |Py_TPFLAGS_CHECKTYPES, /*tp_flags*/ + 0, /*tp_doc*/ + (traverseproc)gc_traverse, /*tp_traverse*/ + (inquiry)gc_clear, /*tp_clear*/ +}; + + +static long +getweakrefcount(PyWeakReference *head) +{ + long count = 0; + + while (head != NULL) { + ++count; + head = head->wr_next; + } + return count; +} + + +static PyObject * +weakref_getweakrefcount(PyObject *self, PyObject *args) +{ + PyObject *result = NULL; + PyObject *object; + + if (PyArg_ParseTuple(args, "O:getweakrefcount", &object)) { + if (PyType_SUPPORTS_WEAKREFS(object->ob_type)) { + PyWeakReference **list = GET_WEAKREFS_LISTPTR(object); + + result = PyInt_FromLong(getweakrefcount(*list)); + } + else + result = PyInt_FromLong(0); + } + return result; +} + + +static PyObject * +weakref_getweakrefs(PyObject *self, PyObject *args) +{ + PyObject *result = NULL; + PyObject *object; + + if (PyArg_ParseTuple(args, "O:getweakrefs", &object)) { + if (PyType_SUPPORTS_WEAKREFS(object->ob_type)) { + PyWeakReference **list = GET_WEAKREFS_LISTPTR(object); + long count = getweakrefcount(*list); + + result = PyList_New(count); + if (result != NULL) { + PyWeakReference *current = *list; + long 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; +} + + +/* Given the head of an object's list of weak references, extract the + * two callback-less refs (ref and proxy). Used to determine if the + * shared references exist and to determine the back link for newly + * inserted references. + */ +static void +get_basic_refs(PyWeakReference *head, + PyWeakReference **refp, PyWeakReference **proxyp) +{ + *refp = NULL; + *proxyp = NULL; + + if (head != NULL && head->wr_callback == NULL) { + if (head->ob_type == &PyWeakReference_Type) { + *refp = head; + head = head->wr_next; + } + if (head != NULL && head->wr_callback == NULL) { + *proxyp = head; + head = head->wr_next; + } + } +} + +/* Insert 'newref' in the list after 'prev'. Both must be non-NULL. */ +static void +insert_after(PyWeakReference *newref, PyWeakReference *prev) +{ + newref->wr_prev = prev; + newref->wr_next = prev->wr_next; + if (prev->wr_next != NULL) + prev->wr_next->wr_prev = newref; + prev->wr_next = newref; +} + +/* Insert 'newref' at the head of the list; 'list' points to the variable + * that stores the head. + */ +static void +insert_head(PyWeakReference *newref, PyWeakReference **list) +{ + PyWeakReference *next = *list; + + newref->wr_prev = NULL; + newref->wr_next = next; + if (next != NULL) + next->wr_prev = newref; + *list = newref; +} + + +static PyObject * +weakref_ref(PyObject *self, PyObject *args) +{ + PyObject *object; + PyObject *callback = NULL; + PyWeakReference *result = NULL; + + if (PyArg_ParseTuple(args, "O|O:new", &object, &callback)) { + PyWeakReference **list; + PyWeakReference *ref, *proxy; + + if (!PyType_SUPPORTS_WEAKREFS(object->ob_type)) { + PyErr_Format(PyExc_TypeError, + "'%s' objects are not weakly referencable", + object->ob_type->tp_name); + return NULL; + } + list = GET_WEAKREFS_LISTPTR(object); + get_basic_refs(*list, &ref, &proxy); + if (callback == NULL) { + /* return existing weak reference if it exists */ + result = ref; + Py_XINCREF(result); + } + if (result == NULL) { + result = new_weakref(); + if (result != NULL) { + Py_XINCREF(callback); + result->wr_callback = callback; + result->wr_object = object; + if (callback == NULL) { + insert_head(result, list); + } + else { + PyWeakReference *prev = (proxy == NULL) ? ref : proxy; + + if (prev == NULL) + insert_head(result, list); + else + insert_after(result, prev); + } + PyObject_GC_Init((PyObject *) result); + } + } + } + return (PyObject *) result; +} + + +static PyObject * +weakref_proxy(PyObject *self, PyObject *args) +{ + PyObject *object; + PyObject *callback = NULL; + PyWeakReference *result = NULL; + + if (PyArg_ParseTuple(args, "O|O:new", &object, &callback)) { + PyWeakReference **list; + PyWeakReference *ref, *proxy; + + if (!PyType_SUPPORTS_WEAKREFS(object->ob_type)) { + PyErr_Format(PyExc_TypeError, + "'%s' objects are not weakly referencable", + object->ob_type->tp_name); + return NULL; + } + list = GET_WEAKREFS_LISTPTR(object); + get_basic_refs(*list, &ref, &proxy); + if (callback == NULL) { + /* attempt to return an existing weak reference if it exists */ + result = proxy; + Py_XINCREF(result); + } + if (result == NULL) { + result = new_weakref(); + if (result != NULL) { + PyWeakReference *prev; + + if (PyCallable_Check(object)) + result->ob_type = &PyWeakCallableProxy_Type; + else + result->ob_type = &PyWeakProxy_Type; + result->wr_object = object; + Py_XINCREF(callback); + result->wr_callback = callback; + if (callback == NULL) + prev = ref; + else + prev = (proxy == NULL) ? ref : proxy; + + if (prev == NULL) + insert_head(result, list); + else + insert_after(result, prev); + PyObject_GC_Init((PyObject *) result); + } + } + } + return (PyObject *) result; +} + + +/* This is the implementation of the PyObject_ClearWeakRefs() function; it + * is installed in the init_weakref() function. It is called by the + * tp_dealloc handler to clear weak references. + * + * This returns true if the object should be deallocated, and false if the + * object is resurrected and deallocation should be aborted. + * + * This iterates through the weak references for 'object' and calls callbacks + * until one resurrects the object, at which point it stops invalidating + * weak references and returns false. + */ +static int +cleanup_helper(PyObject *object) +{ + PyWeakReference **list; + + if (object == NULL + || !PyType_SUPPORTS_WEAKREFS(object->ob_type) + || object->ob_refcnt != 0) { + PyErr_BadInternalCall(); + /* not sure what we should return here */ + return 1; + } + list = GET_WEAKREFS_LISTPTR(object); + while (*list != NULL) { + PyWeakReference *current = *list; + PyObject *callback = current->wr_callback; + + Py_XINCREF(callback); + clear_weakref(current); + if (callback != NULL) { + PyObject *cbresult; + + cbresult = PyObject_CallFunction(callback, "O", current); + if (cbresult == NULL) + PyErr_WriteUnraisable(callback); + else + Py_DECREF(cbresult); + Py_DECREF(callback); + } + } + return (object->ob_refcnt > 0 ? 0 : 1); +} + + +static PyMethodDef +weakref_functions[] = { + {"getweakrefcount", weakref_getweakrefcount, METH_VARARGS, + "getweakrefcount(object) -- return the number of weak references\n" + "to 'object'."}, + {"getweakrefs", weakref_getweakrefs, METH_VARARGS, + "getweakrefs(object) -- return a list of all weak reference objects\n" + "that point to 'object'."}, + {"proxy", weakref_proxy, METH_VARARGS, + "proxy(object[, callback]) -- create a proxy object that weakly\n" + "references 'object'. 'callback', if given, is called with a\n" + "reference to 'object' when it is about to be finalized."}, + {"ref", weakref_ref, METH_VARARGS, + "new(object[, callback]) -- create a weak reference to 'object';\n" + "when 'object' is finalized, 'callback' will be called and passed\n" + "a reference to 'object'."}, + {NULL, NULL, 0, NULL} +}; + + +void +init_weakref(void) +{ + PyObject *m; + + PyWeakReference_Type.ob_type = &PyType_Type; + PyWeakProxy_Type.ob_type = &PyType_Type; + PyWeakCallableProxy_Type.ob_type = &PyType_Type; + m = Py_InitModule3("_weakref", weakref_functions, + "Weak-reference support module."); + if (m != NULL) { + PyObject_ClearWeakRefs = cleanup_helper; + Py_INCREF(&PyWeakReference_Type); + PyModule_AddObject(m, "ReferenceType", + (PyObject *) &PyWeakReference_Type); + Py_INCREF(&PyWeakProxy_Type); + PyModule_AddObject(m, "ProxyType", + (PyObject *) &PyWeakProxy_Type); + Py_INCREF(&PyWeakCallableProxy_Type); + PyModule_AddObject(m, "CallableProxyType", + (PyObject *) &PyWeakCallableProxy_Type); + ReferenceError = PyErr_NewException("weakref.ReferenceError", + PyExc_RuntimeError, NULL); + if (ReferenceError != NULL) + PyModule_AddObject(m, "ReferenceError", ReferenceError); + } +} |