/* Cell object implementation */

#include "Python.h"

PyObject *

PyCell_New(PyObject *obj)

{

	PyCellObject *op;

	op = (PyCellObject *)PyObject_GC_New(PyCellObject, &PyCell_Type);

	if (op == NULL)

		return NULL;

	op->ob_ref = obj;

	Py_XINCREF(obj);

	_PyObject_GC_TRACK(op);

	return (PyObject *)op;

}

PyObject *

PyCell_Get(PyObject *op)

{

	if (!PyCell_Check(op)) {

		PyErr_BadInternalCall();

		return NULL;

	}

	Py_XINCREF(((PyCellObject*)op)->ob_ref);

	return PyCell_GET(op);

}

int

PyCell_Set(PyObject *op, PyObject *obj)

{

	PyObject* oldobj;

	if (!PyCell_Check(op)) {

		PyErr_BadInternalCall();

		return -1;

	}

	oldobj = PyCell_GET(op);

	Py_XINCREF(obj);

	PyCell_SET(op, obj);

	Py_XDECREF(oldobj);

	return 0;

}

static void

cell_dealloc(PyCellObject *op)

{

	_PyObject_GC_UNTRACK(op);

	Py_XDECREF(op->ob_ref);

	PyObject_GC_Del(op);

}

static int

cell_compare(PyCellObject *a, PyCellObject *b)

{

	/* Py3K warning for comparisons  */

	if (PyErr_WarnPy3k("cell comparisons not supported in 3.x",

			   1) < 0) {

		return -2;

	}

	if (a->ob_ref == NULL) {

		if (b->ob_ref == NULL)

			return 0;

		return -1;

	} else if (b->ob_ref == NULL)

		return 1;

	return PyObject_Compare(a->ob_ref, b->ob_ref);

}

static PyObject *

cell_repr(PyCellObject *op)

{

	if (op->ob_ref == NULL)

		return PyString_FromFormat("<cell at %p: empty>", op);

	return PyString_FromFormat("<cell at %p: %.80s object at %p>",

				   op, op->ob_ref->ob_type->tp_name,

				   op->ob_ref);

}

static int

cell_traverse(PyCellObject *op, visitproc visit, void *arg)

{

	Py_VISIT(op->ob_ref);

	return 0;

}

static int

cell_clear(PyCellObject *op)

{

	Py_CLEAR(op->ob_ref);

	return 0;

}

static PyObject *

cell_get_contents(PyCellObject *op, void *closure)

{

	if (op->ob_ref == NULL)

	{

		PyErr_SetString(PyExc_ValueError, "Cell is empty");

		return NULL;

	}

	Py_INCREF(op->ob_ref);

	return op->ob_ref;

}

static PyGetSetDef cell_getsetlist[] = {

	{"cell_contents", (getter)cell_get_contents, NULL},

	{NULL} /* sentinel */

};

PyTypeObject PyCell_Type = {

	PyVarObject_HEAD_INIT(&PyType_Type, 0)

	"cell",

	sizeof(PyCellObject),

	0,

	(destructor)cell_dealloc,               /* tp_dealloc */

	0,                                      /* tp_print */

	0,	                                /* tp_getattr */

	0,					/* tp_setattr */

	(cmpfunc)cell_compare,			/* tp_compare */

	(reprfunc)cell_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 */

 	(traverseproc)cell_traverse,		/* tp_traverse */

 	(inquiry)cell_clear,			/* tp_clear */

	0,					/* tp_richcompare */

	0,					/* tp_weaklistoffset */

	0, 					/* tp_iter */

	0,					/* tp_iternext */

	0,					/* tp_methods */

	0,					/* tp_members */

	cell_getsetlist,			/* tp_getset */

};