/* Descriptors -- a new, flexible way to describe attributes */

#include "Python.h"

#include "structmember.h" /* Why is this not included in Python.h? */

static void

descr_dealloc(PyDescrObject *descr)

{

	_PyObject_GC_UNTRACK(descr);

	Py_XDECREF(descr->d_type);

	Py_XDECREF(descr->d_name);

	PyObject_GC_Del(descr);

}

static char *

descr_name(PyDescrObject *descr)

{

	if (descr->d_name != NULL && PyString_Check(descr->d_name))

		return PyString_AS_STRING(descr->d_name);

	else

		return "?";

}

static PyObject *

descr_repr(PyDescrObject *descr, char *format)

{

	return PyString_FromFormat(format, descr_name(descr),

				   descr->d_type->tp_name);

}

static PyObject *

method_repr(PyMethodDescrObject *descr)

{

	return descr_repr((PyDescrObject *)descr, 

			  "<method '%s' of '%s' objects>");

}

static PyObject *

member_repr(PyMemberDescrObject *descr)

{

	return descr_repr((PyDescrObject *)descr, 

			  "<member '%s' of '%s' objects>");

}

static PyObject *

getset_repr(PyGetSetDescrObject *descr)

{

	return descr_repr((PyDescrObject *)descr, 

			  "<attribute '%s' of '%s' objects>");

}

static PyObject *

wrapperdescr_repr(PyWrapperDescrObject *descr)

{

	return descr_repr((PyDescrObject *)descr, 

			  "<slot wrapper '%s' of '%s' objects>");

}

static int

descr_check(PyDescrObject *descr, PyObject *obj, PyObject **pres)

{

	if (obj == NULL) {

		Py_INCREF(descr);

		*pres = (PyObject *)descr;

		return 1;

	}

	if (!PyObject_TypeCheck(obj, descr->d_type)) {

		PyErr_Format(PyExc_TypeError,

			     "descriptor '%s' for '%s' objects "

			     "doesn't apply to '%s' object",

			     descr_name((PyDescrObject *)descr),

			     descr->d_type->tp_name,

			     obj->ob_type->tp_name);

		*pres = NULL;

		return 1;

	}

	return 0;

}

static PyObject *

classmethod_get(PyMethodDescrObject *descr, PyObject *obj, PyObject *type)

{

	/* Ensure a valid type.  Class methods ignore obj. */

	if (type == NULL) {

		if (obj != NULL)

			type = (PyObject *)obj->ob_type;

		else {

			/* Wot - no type?! */

			PyErr_Format(PyExc_TypeError,

				     "descriptor '%s' for type '%s' "

				     "needs either an object or a type",

				     descr_name((PyDescrObject *)descr),

				     descr->d_type->tp_name);

			return NULL;

		}

	}

	if (!PyType_Check(type)) {

		PyErr_Format(PyExc_TypeError,

			     "descriptor '%s' for type '%s' "

			     "needs a type, not a '%s' as arg 2",

			     descr_name((PyDescrObject *)descr),

			     descr->d_type->tp_name,

			     type->ob_type->tp_name);

		return NULL;

	}

	if (!PyType_IsSubtype((PyTypeObject *)type, descr->d_type)) {

		PyErr_Format(PyExc_TypeError,

			     "descriptor '%s' for type '%s' "

			     "doesn't apply to type '%s'",

			     descr_name((PyDescrObject *)descr),

			     descr->d_type->tp_name,

			     ((PyTypeObject *)type)->tp_name);

		return NULL;

	}

	return PyCFunction_New(descr->d_method, type);

}

static PyObject *

method_get(PyMethodDescrObject *descr, PyObject *obj, PyObject *type)

{

	PyObject *res;

	if (descr_check((PyDescrObject *)descr, obj, &res))

		return res;

	return PyCFunction_New(descr->d_method, obj);

}

static PyObject *

member_get(PyMemberDescrObject *descr, PyObject *obj, PyObject *type)

{

	PyObject *res;

	if (descr_check((PyDescrObject *)descr, obj, &res))

		return res;

	return PyMember_GetOne((char *)obj, descr->d_member);

}

static PyObject *

getset_get(PyGetSetDescrObject *descr, PyObject *obj, PyObject *type)

{

	PyObject *res;

	if (descr_check((PyDescrObject *)descr, obj, &res))

		return res;

	if (descr->d_getset->get != NULL)

		return descr->d_getset->get(obj, descr->d_getset->closure);

	PyErr_Format(PyExc_AttributeError,

		     "attribute '%.300s' of '%.100s' objects is not readable",

		     descr_name((PyDescrObject *)descr),

		     descr->d_type->tp_name);

	return NULL;

}

static PyObject *

wrapperdescr_get(PyWrapperDescrObject *descr, PyObject *obj, PyObject *type)

{

	PyObject *res;

	if (descr_check((PyDescrObject *)descr, obj, &res))

		return res;

	return PyWrapper_New((PyObject *)descr, obj);

}

static int

descr_setcheck(PyDescrObject *descr, PyObject *obj, PyObject *value,

	       int *pres)

{

	assert(obj != NULL);

	if (!PyObject_TypeCheck(obj, descr->d_type)) {

		PyErr_Format(PyExc_TypeError,

			     "descriptor '%.200s' for '%.100s' objects "

			     "doesn't apply to '%.100s' object",

			     descr_name(descr),

			     descr->d_type->tp_name,

			     obj->ob_type->tp_name);

		*pres = -1;

		return 1;

	}

	return 0;

}

static int

member_set(PyMemberDescrObject *descr, PyObject *obj, PyObject *value)

{

	int res;

	if (descr_setcheck((PyDescrObject *)descr, obj, value, &res))

		return res;

	return PyMember_SetOne((char *)obj, descr->d_member, value);

}

static int

getset_set(PyGetSetDescrObject *descr, PyObject *obj, PyObject *value)

{

	int res;

	if (descr_setcheck((PyDescrObject *)descr, obj, value, &res))

		return res;

	if (descr->d_getset->set != NULL)

		return descr->d_getset->set(obj, value,

					    descr->d_getset->closure);

	PyErr_Format(PyExc_AttributeError,

		     "attribute '%.300s' of '%.100s' objects is not writable",

		     descr_name((PyDescrObject *)descr),

		     descr->d_type->tp_name);

	return -1;

}

static PyObject *

methoddescr_call(PyMethodDescrObject *descr, PyObject *args, PyObject *kwds)

{

	Py_ssize_t argc;

	PyObject *self, *func, *result;

	/* Make sure that the first argument is acceptable as 'self' */

	assert(PyTuple_Check(args));

	argc = PyTuple_GET_SIZE(args);

	if (argc < 1) {

		PyErr_Format(PyExc_TypeError,

			     "descriptor '%.300s' of '%.100s' "

			     "object needs an argument",

			     descr_name((PyDescrObject *)descr),

			     descr->d_type->tp_name);

		return NULL;

	}

	self = PyTuple_GET_ITEM(args, 0);

	if (!PyObject_IsInstance(self, (PyObject *)(descr->d_type))) {

		PyErr_Format(PyExc_TypeError,

			     "descriptor '%.200s' "

			     "requires a '%.100s' object "

			     "but received a '%.100s'",

			     descr_name((PyDescrObject *)descr),

			     descr->d_type->tp_name,

			     self->ob_type->tp_name);

		return NULL;

	}

	func = PyCFunction_New(descr->d_method, self);

	if (func == NULL)

		return NULL;

	args = PyTuple_GetSlice(args, 1, argc);

	if (args == NULL) {

		Py_DECREF(func);

		return NULL;

	}

	result = PyEval_CallObjectWithKeywords(func, args, kwds);

	Py_DECREF(args);

	Py_DECREF(func);

	return result;

}

static PyObject *

classmethoddescr_call(PyMethodDescrObject *descr, PyObject *args,

		      PyObject *kwds)

{

	PyObject *func, *result;

	func = PyCFunction_New(descr->d_method, (PyObject *)descr->d_type);

	if (func == NULL)

		return NULL;

	result = PyEval_CallObjectWithKeywords(func, args, kwds);

	Py_DECREF(func);

	return result;

}

static PyObject *

wrapperdescr_call(PyWrapperDescrObject *descr, PyObject *args, PyObject *kwds)

{

	Py_ssize_t argc;

	PyObject *self, *func, *result;

	/* Make sure that the first argument is acceptable as 'self' */

	assert(PyTuple_Check(args));

	argc = PyTuple_GET_SIZE(args);

	if (argc < 1) {

		PyErr_Format(PyExc_TypeError,

			     "descriptor '%.300s' of '%.100s' "

			     "object needs an argument",

			     descr_name((PyDescrObject *)descr),

			     descr->d_type->tp_name);

		return NULL;

	}

	self = PyTuple_GET_ITEM(args, 0);

	if (!PyObject_IsInstance(self, (PyObject *)(descr->d_type))) {

		PyErr_Format(PyExc_TypeError,

			     "descriptor '%.200s' "

			     "requires a '%.100s' object "

			     "but received a '%.100s'",

			     descr_name((PyDescrObject *)descr),

			     descr->d_type->tp_name,

			     self->ob_type->tp_name);

		return NULL;

	}

	func = PyWrapper_New((PyObject *)descr, self);

	if (func == NULL)

		return NULL;

	args = PyTuple_GetSlice(args, 1, argc);

	if (args == NULL) {

		Py_DECREF(func);

		return NULL;

	}

	result = PyEval_CallObjectWithKeywords(func, args, kwds);

	Py_DECREF(args);

	Py_DECREF(func);

	return result;

}

static PyObject *

method_get_doc(PyMethodDescrObject *descr, void *closure)

{

	if (descr->d_method->ml_doc == NULL) {

		Py_INCREF(Py_None);

		return Py_None;

	}

	return PyString_FromString(descr->d_method->ml_doc);

}

static PyMemberDef descr_members[] = {

	{"__objclass__", T_OBJECT, offsetof(PyDescrObject, d_type), READONLY},

	{"__name__", T_OBJECT, offsetof(PyDescrObject, d_name), READONLY},

	{0}

};

static PyGetSetDef method_getset[] = {

	{"__doc__", (getter)method_get_doc},

	{0}

};

static PyObject *

member_get_doc(PyMemberDescrObject *descr, void *closure)

{

	if (descr->d_member->doc == NULL) {

		Py_INCREF(Py_None);

		return Py_None;

	}

	return PyString_FromString(descr->d_member->doc);

}

static PyGetSetDef member_getset[] = {

	{"__doc__", (getter)member_get_doc},

	{0}

};

static PyObject *

getset_get_doc(PyGetSetDescrObject *descr, void *closure)

{

	if (descr->d_getset->doc == NULL) {

		Py_INCREF(Py_None);

		return Py_None;

	}

	return PyString_FromString(descr->d_getset->doc);

}

static PyGetSetDef getset_getset[] = {

	{"__doc__", (getter)getset_get_doc},

	{0}

};

static PyObject *

wrapperdescr_get_doc(PyWrapperDescrObject *descr, void *closure)

{

	if (descr->d_base->doc == NULL) {

		Py_INCREF(Py_None);

		return Py_None;

	}

	return PyString_FromString(descr->d_base->doc);

}

static PyGetSetDef wrapperdescr_getset[] = {

	{"__doc__", (getter)wrapperdescr_get_doc},

	{0}

};

static int

descr_traverse(PyObject *self, visitproc visit, void *arg)

{

	PyDescrObject *descr = (PyDescrObject *)self;

	Py_VISIT(descr->d_type);

	return 0;

}

static PyTypeObject PyMethodDescr_Type = {

	PyVarObject_HEAD_INIT(&PyType_Type, 0)

	"method_descriptor",

	sizeof(PyMethodDescrObject),

	0,

	(destructor)descr_dealloc,		/* tp_dealloc */

	0,					/* tp_print */

	0,					/* tp_getattr */

	0,					/* tp_setattr */

	0,					/* tp_compare */

	(reprfunc)method_repr,			/* tp_repr */

	0,					/* tp_as_number */

	0,					/* tp_as_sequence */

	0,					/* tp_as_mapping */

	0,					/* tp_hash */

	(ternaryfunc)methoddescr_call,		/* tp_call */

	0,					/* tp_str */

	PyObject_GenericGetAttr,		/* tp_getattro */

	0,					/* tp_setattro */

	0,					/* tp_as_buffer */

	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */

	0,					/* tp_doc */

	descr_traverse,				/* tp_traverse */

	0,					/* tp_clear */

	0,					/* tp_richcompare */

	0,					/* tp_weaklistoffset */

	0,					/* tp_iter */

	0,					/* tp_iternext */

	0,					/* tp_methods */

	descr_members,				/* tp_members */

	method_getset,				/* tp_getset */

	0,					/* tp_base */

	0,					/* tp_dict */

	(descrgetfunc)method_get,		/* tp_descr_get */

	0,					/* tp_descr_set */

};

/* This is for METH_CLASS in C, not for "f = classmethod(f)" in Python! */

static PyTypeObject PyClassMethodDescr_Type = {

	PyVarObject_HEAD_INIT(&PyType_Type, 0)

	"classmethod_descriptor",

	sizeof(PyMethodDescrObject),

	0,

	(destructor)descr_dealloc,		/* tp_dealloc */

	0,					/* tp_print */

	0,					/* tp_getattr */

	0,					/* tp_setattr */

	0,					/* tp_compare */

	(reprfunc)method_repr,			/* tp_repr */

	0,					/* tp_as_number */

	0,					/* tp_as_sequence */

	0,					/* tp_as_mapping */

	0,					/* tp_hash */

	(ternaryfunc)classmethoddescr_call,	/* tp_call */

	0,					/* tp_str */

	PyObject_GenericGetAttr,		/* tp_getattro */

	0,					/* tp_setattro */

	0,					/* tp_as_buffer */

	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */

	0,					/* tp_doc */

	descr_traverse,				/* tp_traverse */

	0,					/* tp_clear */

	0,					/* tp_richcompare */

	0,					/* tp_weaklistoffset */

	0,					/* tp_iter */

	0,					/* tp_iternext */

	0,					/* tp_methods */

	descr_members,				/* tp_members */

	method_getset,				/* tp_getset */

	0,					/* tp_base */

	0,					/* tp_dict */

	(descrgetfunc)classmethod_get,		/* tp_descr_get */

	0,					/* tp_descr_set */

};

static PyTypeObject PyMemberDescr_Type = {

	PyVarObject_HEAD_INIT(&PyType_Type, 0)

	"member_descriptor",

	sizeof(PyMemberDescrObject),

	0,

	(destructor)descr_dealloc,		/* tp_dealloc */

	0,					/* tp_print */

	0,					/* tp_getattr */

	0,					/* tp_setattr */

	0,					/* tp_compare */

	(reprfunc)member_repr,			/* tp_repr */

	0,					/* tp_as_number */

	0,					/* tp_as_sequence */

	0,					/* tp_as_mapping */

	0,					/* tp_hash */

	0,					/* tp_call */

	0,					/* tp_str */

	PyObject_GenericGetAttr,		/* tp_getattro */

	0,					/* tp_setattro */

	0,					/* tp_as_buffer */

	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */

	0,					/* tp_doc */

	descr_traverse,				/* tp_traverse */

	0,					/* tp_clear */

	0,					/* tp_richcompare */

	0,					/* tp_weaklistoffset */

	0,					/* tp_iter */

	0,					/* tp_iternext */

	0,					/* tp_methods */

	descr_members,				/* tp_members */

	member_getset,				/* tp_getset */

	0,					/* tp_base */

	0,					/* tp_dict */

	(descrgetfunc)member_get,		/* tp_descr_get */

	(descrsetfunc)member_set,		/* tp_descr_set */

};

static PyTypeObject PyGetSetDescr_Type = {

	PyVarObject_HEAD_INIT(&PyType_Type, 0)

	"getset_descriptor",

	sizeof(PyGetSetDescrObject),

	0,

	(destructor)descr_dealloc,		/* tp_dealloc */

	0,					/* tp_print */

	0,					/* tp_getattr */

	0,					/* tp_setattr */

	0,					/* tp_compare */

	(reprfunc)getset_repr,			/* tp_repr */

	0,					/* tp_as_number */

	0,					/* tp_as_sequence */

	0,					/* tp_as_mapping */

	0,					/* tp_hash */

	0,					/* tp_call */

	0,					/* tp_str */

	PyObject_GenericGetAttr,		/* tp_getattro */

	0,					/* tp_setattro */

	0,					/* tp_as_buffer */

	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */

	0,					/* tp_doc */

	descr_traverse,				/* tp_traverse */

	0,					/* tp_clear */

	0,					/* tp_richcompare */

	0,					/* tp_weaklistoffset */

	0,					/* tp_iter */

	0,					/* tp_iternext */

	0,					/* tp_methods */

	descr_members,				/* tp_members */

	getset_getset,				/* tp_getset */

	0,					/* tp_base */

	0,					/* tp_dict */

	(descrgetfunc)getset_get,		/* tp_descr_get */