typeobject.c

python s60 1.4.5版本的源代码

	   it's possible that its instances are not types. */
	nbases = PyTuple_GET_SIZE(bases);
	winner = metatype;
	for (i = 0; i < nbases; i++) {
		tmp = PyTuple_GET_ITEM(bases, i);
		tmptype = tmp->ob_type;
		if (tmptype == &PyClass_Type)
			continue; /* Special case classic classes */
		if (PyType_IsSubtype(winner, tmptype))
			continue;
		if (PyType_IsSubtype(tmptype, winner)) {
			winner = tmptype;
			continue;
		}
		PyErr_SetString(PyExc_TypeError,
				"metatype conflict among bases");
		return NULL;
	}
	if (winner != metatype) {
		if (winner->tp_new != type_new) /* Pass it to the winner */
			return winner->tp_new(winner, args, kwds);
		metatype = winner;
	}

	/* Adjust for empty tuple bases */
	if (nbases == 0) {
		bases = Py_BuildValue("(O)", &PyBaseObject_Type);
		if (bases == NULL)
			return NULL;
		nbases = 1;
	}
	else
		Py_INCREF(bases);

	/* XXX From here until type is allocated, "return NULL" leaks bases! */

	/* Calculate best base, and check that all bases are type objects */
	base = best_base(bases);
	if (base == NULL)
		return NULL;
	if (!PyType_HasFeature(base, Py_TPFLAGS_BASETYPE)) {
		PyErr_Format(PyExc_TypeError,
			     "type '%.100s' is not an acceptable base type",
			     base->tp_name);
		return NULL;
	}

	/* Check for a __slots__ sequence variable in dict, and count it */
	slots = PyDict_GetItemString(dict, "__slots__");
	nslots = 0;
	add_dict = 0;
	add_weak = 0;
	if (slots != NULL) {
		/* Make it into a tuple */
		if (PyString_Check(slots))
			slots = Py_BuildValue("(O)", slots);
		else
			slots = PySequence_Tuple(slots);
		if (slots == NULL)
			return NULL;
		nslots = PyTuple_GET_SIZE(slots);
		if (nslots > 0 && base->tp_itemsize != 0) {
			PyErr_Format(PyExc_TypeError,
				     "nonempty __slots__ "
				     "not supported for subtype of '%s'",
				     base->tp_name);
			return NULL;
		}
		for (i = 0; i < nslots; i++) {
			if (!PyString_Check(PyTuple_GET_ITEM(slots, i))) {
				PyErr_SetString(PyExc_TypeError,
				"__slots__ must be a sequence of strings");
				Py_DECREF(slots);
				return NULL;
			}
			/* XXX Check against null bytes in name */
		}
	}
	if (slots != NULL) {
		/* See if *this* class defines __getstate__ */
		PyObject *getstate = PyDict_GetItemString(dict,
							  "__getstate__");
		if (getstate == NULL) {
			/* If not, provide a bozo that raises TypeError */
			if (bozo_obj == NULL) {
				bozo_obj = PyCFunction_New(&bozo_ml, NULL);
				if (bozo_obj == NULL) {
					/* XXX decref various things */
					return NULL;
				}
			}
			if (PyDict_SetItemString(dict,
						 "__getstate__",
						 bozo_obj) < 0) {
				/* XXX decref various things */
				return NULL;
			}
		}
	}
	if (slots == NULL && base->tp_dictoffset == 0 &&
	    (base->tp_setattro == PyObject_GenericSetAttr ||
	     base->tp_setattro == NULL)) {
		add_dict++;
	}
	if (slots == NULL && base->tp_weaklistoffset == 0 &&
	    base->tp_itemsize == 0) {
		nslots++;
		add_weak++;
	}

	/* XXX From here until type is safely allocated,
	   "return NULL" may leak slots! */

	/* Allocate the type object */
	type = (PyTypeObject *)metatype->tp_alloc(metatype, nslots);
	if (type == NULL)
		return NULL;

	/* Keep name and slots alive in the extended type object */
	et = (etype *)type;
	Py_INCREF(name);
	et->name = name;
	et->slots = slots;

	/* Initialize tp_flags */
	type->tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HEAPTYPE |
		Py_TPFLAGS_BASETYPE;
	if (base->tp_flags & Py_TPFLAGS_HAVE_GC)
		type->tp_flags |= Py_TPFLAGS_HAVE_GC;

	/* It's a new-style number unless it specifically inherits any
	   old-style numeric behavior */
	if ((base->tp_flags & Py_TPFLAGS_CHECKTYPES) ||
	    (base->tp_as_number == NULL))
		type->tp_flags |= Py_TPFLAGS_CHECKTYPES;

	/* Initialize essential fields */
	type->tp_as_number = &et->as_number;
	type->tp_as_sequence = &et->as_sequence;
	type->tp_as_mapping = &et->as_mapping;
	type->tp_as_buffer = &et->as_buffer;
	type->tp_name = PyString_AS_STRING(name);

	/* Set tp_base and tp_bases */
	type->tp_bases = bases;
	Py_INCREF(base);
	type->tp_base = base;

	/* Initialize tp_dict from passed-in dict */
	type->tp_dict = dict = PyDict_Copy(dict);
	if (dict == NULL) {
		Py_DECREF(type);
		return NULL;
	}

	/* Set __module__ in the dict */
	if (PyDict_GetItemString(dict, "__module__") == NULL) {
		tmp = PyEval_GetGlobals();
		if (tmp != NULL) {
			tmp = PyDict_GetItemString(tmp, "__name__");
			if (tmp != NULL) {
				if (PyDict_SetItemString(dict, "__module__",
							 tmp) < 0)
					return NULL;
			}
		}
	}

	/* Set tp_doc to a copy of dict['__doc__'], if the latter is there
	   and is a string.  The __doc__ accessor will first look for tp_doc;
	   if that fails, it will still look into __dict__.
	*/
	{
		PyObject *doc = PyDict_GetItemString(dict, "__doc__");
		if (doc != NULL && PyString_Check(doc)) {
			const size_t n = (size_t)PyString_GET_SIZE(doc);
			type->tp_doc = (char *)PyObject_MALLOC(n+1);
			if (type->tp_doc == NULL) {
				Py_DECREF(type);
				return NULL;
			}
			// XXX:CW32
			memcpy((void *)type->tp_doc, PyString_AS_STRING(doc), n+1);
		}
	}

	/* Special-case __new__: if it's a plain function,
	   make it a static function */
	tmp = PyDict_GetItemString(dict, "__new__");
	if (tmp != NULL && PyFunction_Check(tmp)) {
		tmp = PyStaticMethod_New(tmp);
		if (tmp == NULL) {
			Py_DECREF(type);
			return NULL;
		}
		PyDict_SetItemString(dict, "__new__", tmp);
		Py_DECREF(tmp);
	}

	/* Add descriptors for custom slots from __slots__, or for __dict__ */
	mp = et->members;
	slotoffset = base->tp_basicsize;
	if (slots != NULL) {
		for (i = 0; i < nslots; i++, mp++) {
			mp->name = PyString_AS_STRING(
				PyTuple_GET_ITEM(slots, i));
			mp->type = T_OBJECT_EX;
			mp->offset = slotoffset;
			if (base->tp_weaklistoffset == 0 &&
			    strcmp(mp->name, "__weakref__") == 0) {
				mp->type = T_OBJECT;
				mp->flags = READONLY;
				type->tp_weaklistoffset = slotoffset;
			}
			slotoffset += sizeof(PyObject *);
		}
	}
	else {
		if (add_dict) {
			if (base->tp_itemsize)
				type->tp_dictoffset =
					-(long)sizeof(PyObject *);
			else
				type->tp_dictoffset = slotoffset;
			slotoffset += sizeof(PyObject *);
			type->tp_getset = subtype_getsets;
		}
		if (add_weak) {
			assert(!base->tp_itemsize);
			type->tp_weaklistoffset = slotoffset;
			mp->name = "__weakref__";
			mp->type = T_OBJECT;
			mp->offset = slotoffset;
			mp->flags = READONLY;
			mp++;
			slotoffset += sizeof(PyObject *);
		}
	}
	type->tp_basicsize = slotoffset;
	type->tp_itemsize = base->tp_itemsize;
	type->tp_members = et->members;

	/* Special case some slots */
	if (type->tp_dictoffset != 0 || nslots > 0) {
		if (base->tp_getattr == NULL && base->tp_getattro == NULL)
			type->tp_getattro = PyObject_GenericGetAttr;
		if (base->tp_setattr == NULL && base->tp_setattro == NULL)
			type->tp_setattro = PyObject_GenericSetAttr;
	}
	type->tp_dealloc = subtype_dealloc;

	/* Enable GC unless there are really no instance variables possible */
	if (!(type->tp_basicsize == sizeof(PyObject) &&
	      type->tp_itemsize == 0))
		type->tp_flags |= Py_TPFLAGS_HAVE_GC;

	/* Always override allocation strategy to use regular heap */
	type->tp_alloc = PyType_GenericAlloc;
	if (type->tp_flags & Py_TPFLAGS_HAVE_GC) {
		type->tp_free = _PyObject_GC_Del;
		type->tp_traverse = subtype_traverse;
		type->tp_clear = subtype_clear;
	}
	else
		type->tp_free = _PyObject_Del;

	/* Initialize the rest */
	if (PyType_Ready(type) < 0) {
		Py_DECREF(type);
		return NULL;
	}

	/* Put the proper slots in place */
	fixup_slot_dispatchers(type);

	return (PyObject *)type;
}

/* Internal API to look for a name through the MRO.
   This returns a borrowed reference, and doesn't set an exception! */
DL_EXPORT(PyObject *)
_PyType_Lookup(PyTypeObject *type, PyObject *name)
{
	int i, n;
	PyObject *mro, *res, *base, *dict;

	/* Look in tp_dict of types in MRO */
	mro = type->tp_mro;

	/* If mro is NULL, the type is either not yet initialized
	   by PyType_Ready(), or already cleared by type_clear().
	   Either way the safest thing to do is to return NULL. */
	if (mro == NULL)
		return NULL;

	assert(PyTuple_Check(mro));
	n = PyTuple_GET_SIZE(mro);
	for (i = 0; i < n; i++) {
		base = PyTuple_GET_ITEM(mro, i);
		if (PyClass_Check(base))
			dict = ((PyClassObject *)base)->cl_dict;
		else {
			assert(PyType_Check(base));
			dict = ((PyTypeObject *)base)->tp_dict;
		}
		assert(dict && PyDict_Check(dict));
		res = PyDict_GetItem(dict, name);
		if (res != NULL)
			return res;
	}
	return NULL;
}

/* This is similar to PyObject_GenericGetAttr(),
   but uses _PyType_Lookup() instead of just looking in type->tp_dict. */
static PyObject *
type_getattro(PyTypeObject *type, PyObject *name)
{
	PyTypeObject *metatype = type->ob_type;
	PyObject *descr, *res;
	descrgetfunc f;

	/* Initialize this type (we'll assume the metatype is initialized) */
	if (type->tp_dict == NULL) {
		if (PyType_Ready(type) < 0)
			return NULL;
	}

	/* Get a descriptor from the metatype */
	descr = _PyType_Lookup(metatype, name);
	f = NULL;
	if (descr != NULL) {
		f = descr->ob_type->tp_descr_get;
		if (f != NULL && PyDescr_IsData(descr))
			return f(descr,
				 (PyObject *)type, (PyObject *)metatype);
	}

	/* Look in tp_dict of this type and its bases */
	res = _PyType_Lookup(type, name);
	if (res != NULL) {
		f = res->ob_type->tp_descr_get;
		if (f != NULL)
			return f(res, (PyObject *)NULL, (PyObject *)type);
		Py_INCREF(res);
		return res;
	}

	/* Use the descriptor from the metatype */
	if (f != NULL) {
		res = f(descr, (PyObject *)type, (PyObject *)metatype);
		return res;
	}
	if (descr != NULL) {
		Py_INCREF(descr);
		return descr;
	}

	/* Give up */
	PyErr_Format(PyExc_AttributeError,
		     "type object '%.50s' has no attribute '%.400s'",
		     type->tp_name, PyString_AS_STRING(name));
	return NULL;
}

static int
type_setattro(PyTypeObject *type, PyObject *name, PyObject *value)
{
	if (!(type->tp_flags & Py_TPFLAGS_HEAPTYPE)) {
		PyErr_Format(
			PyExc_TypeError,
			"can't set attributes of built-in/extension type '%s'",
			type->tp_name);
		return -1;
	}
	if (PyObject_GenericSetAttr((PyObject *)type, name, value) < 0)
		return -1;
	return update_slot(type, name);
}

static void
type_dealloc(PyTypeObject *type)
{
	etype *et;

	/* Assert this is a heap-allocated type object */
	assert(type->tp_flags & Py_TPFLAGS_HEAPTYPE);
	_PyObject_GC_UNTRACK(type);
	PyObject_ClearWeakRefs((PyObject *)type);
	et = (etype *)type;
	Py_XDECREF(type->tp_base);
	Py_XDECREF(type->tp_dict);
	Py_XDECREF(type->tp_bases);
	Py_XDECREF(type->tp_mro);
	Py_XDECREF(type->tp_cache);
	Py_XDECREF(type->tp_subclasses);
	// XXX:CW32
	PyObject_Free((void *)type->tp_doc);
	Py_XDECREF(et->name);
	Py_XDECREF(et->slots);
	type->ob_type->tp_free((PyObject *)type);
}

static PyObject *
type_subclasses(PyTypeObject *type, PyObject *args_ignored)
{
	PyObject *list, *raw, *ref;
	int i, n;

	list = PyList_New(0);
	if (list == NULL)
		return NULL;
	raw = type->tp_subclasses;
	if (raw == NULL)
		return list;
	assert(PyList_Check(raw));
	n = PyList_GET_SIZE(raw);
	for (i = 0; i < n; i++) {
		ref = PyList_GET_ITEM(raw, i);
		assert(PyWeakref_CheckRef(ref));
		ref = PyWeakref_GET_OBJECT(ref);
		if (ref != Py_None) {
			if (PyList_Append(list, ref) < 0) {
				Py_DECREF(list);
				return NULL;
			}
		}
	}
	return list;
}

const static PyMethodDef type_methods[] = {
	{"mro", (PyCFunction)mro_external, METH_NOARGS,
	 "mro() -> list\nreturn a type's method resolution order"},
	{"__subclasses__", (PyCFunction)type_subclasses, METH_NOARGS,
	 "__subclasses__() -> list of immediate subclasses"},
	{0}
};

const static char type_doc[] =
#ifdef SYMBIAN
"";
#else
"type(object) -> the object's type\n"
"type(name, bases, dict) -> a new type";
#endif

static int
type_traverse(PyTypeObject *type, visitproc visit, void *arg)
{
	int err;

	/* Because of type_is_gc(), the collector only calls this
	   for heaptypes. */
	assert(type->tp_flags & Py_TPFLAGS_HEAPTYPE);

#define VISIT(SLOT) \
	if (SLOT) { \
		err = visit((PyObject *)(SLOT), arg); \
		if (err) \
			return err; \
	}

	VISIT(type->tp_dict);
	VISIT(type->tp_cache);
	VISIT(type->tp_mro);
	VISIT(type->tp_bases);
	VISIT(type->tp_base);

	/* There's no need to visit type->tp_subclasses or
	   ((etype *)type)->slots, because they can't be involved
	   in cycles; tp_subclasses is a list of weak references,
	   and slots is a tuple of strings. */

#undef VISIT

	return 0;
}

static int
type_clear(PyTypeObject *type)
{
	PyObject *tmp;

	/* Because of type_is_gc(), the collector only calls this
	   for heaptypes. */
	assert(type->tp_flags & Py_TPFLAGS_HEAPTYPE);

#define CLEAR(SLOT) \
	if (SLOT) { \
		tmp = (PyObject *)(SLOT); \
		SLOT = NULL; \
		Py_DECREF(tmp); \
	}

	/* The only field we need to clear is tp_mro, which is part of a
	   hard cycle (its first element is the class itself) that won't
	   be broken otherwise (it's a tuple and tuples don't have a
	   tp_clear handler).  None of the other fields need to be
	   cleared, and here's why:

	   tp_dict:
	       It is a dict, so the collector will call its tp_clear.

	   tp_cache:
	       Not used; if it were, it would be a dict.

	   tp_bases, tp_base:
	       If these are involved in a cycle, there must be at least
	       one other, mutable object in the cycle, e.g. a base
	       class's dict; the cycle will be broken that way.

	   tp_subclasses:
	       A list of weak references can't be part of a cycle; and
	       lists have their own tp_clear.