#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);

}

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 */

};