Objects/cellobject.c

   1 /* Cell object implementation */
   2
   3 #include "Python.h"
   4
   5 PyObject *
   6 PyCell_New(PyObject *obj)
   7 {
   8     PyCellObject *op;
   9
  10     op = (PyCellObject *)PyObject_GC_New(PyCellObject, &PyCell_Type);
  11     if (op == NULL)
  12         return NULL;
  13     op->ob_ref = obj;
  14     Py_XINCREF(obj);
  15
  16     _PyObject_GC_TRACK(op);
  17     return (PyObject *)op;
  18 }
  19
  20 PyObject *
  21 PyCell_Get(PyObject *op)
  22 {
  23     if (!PyCell_Check(op)) {
  24         PyErr_BadInternalCall();
  25         return NULL;
  26     }
  27     Py_XINCREF(((PyCellObject*)op)->ob_ref);
  28     return PyCell_GET(op);
  29 }
  30
  31 int
  32 PyCell_Set(PyObject *op, PyObject *obj)
  33 {
  34     PyObject* oldobj;
  35     if (!PyCell_Check(op)) {
  36         PyErr_BadInternalCall();
  37         return -1;
  38     }
  39     oldobj = PyCell_GET(op);
  40     Py_XINCREF(obj);
  41     PyCell_SET(op, obj);
  42     Py_XDECREF(oldobj);
  43     return 0;
  44 }
  45
  46 static void
  47 cell_dealloc(PyCellObject *op)
  48 {
  49     _PyObject_GC_UNTRACK(op);
  50     Py_XDECREF(op->ob_ref);
  51     PyObject_GC_Del(op);
  52 }
  53
  54 #define TEST_COND(cond) ((cond) ? Py_True : Py_False)
  55
  56 static PyObject *
  57 cell_richcompare(PyObject *a, PyObject *b, int op)
  58 {
  59     int result;
  60     PyObject *v;
  61
  62     /* neither argument should be NULL, unless something's gone wrong */
  63     assert(a != NULL && b != NULL);
  64
  65     /* both arguments should be instances of PyCellObject */
  66     if (!PyCell_Check(a) || !PyCell_Check(b)) {
  67         v = Py_NotImplemented;
  68         Py_INCREF(v);
  69         return v;
  70     }
  71
  72     /* compare cells by contents; empty cells come before anything else */
  73     a = ((PyCellObject *)a)->ob_ref;
  74     b = ((PyCellObject *)b)->ob_ref;
  75     if (a != NULL && b != NULL)
  76         return PyObject_RichCompare(a, b, op);
  77
  78     result = (b == NULL) - (a == NULL);
  79     switch (op) {
  80     case Py_EQ:
  81         v = TEST_COND(result == 0);
  82         break;
  83     case Py_NE:
  84         v = TEST_COND(result != 0);
  85         break;
  86     case Py_LE:
  87         v = TEST_COND(result <= 0);
  88         break;
  89     case Py_GE:
  90         v = TEST_COND(result >= 0);
  91         break;
  92     case Py_LT:
  93         v = TEST_COND(result < 0);
  94         break;
  95     case Py_GT:
  96         v = TEST_COND(result > 0);
  97         break;
  98     default:
  99         PyErr_BadArgument();
 100         return NULL;
 101     }
 102     Py_INCREF(v);
 103     return v;
 104 }
 105
 106 static PyObject *
 107 cell_repr(PyCellObject *op)
 108 {
 109     if (op->ob_ref == NULL)
 110         return PyUnicode_FromFormat("<cell at %p: empty>", op);
 111
 112     return PyUnicode_FromFormat("<cell at %p: %.80s object at %p>",
 113                                op, op->ob_ref->ob_type->tp_name,
 114                                op->ob_ref);
 115 }
 116
 117 static int
 118 cell_traverse(PyCellObject *op, visitproc visit, void *arg)
 119 {
 120     Py_VISIT(op->ob_ref);
 121     return 0;
 122 }
 123
 124 static int
 125 cell_clear(PyCellObject *op)
 126 {
 127     Py_CLEAR(op->ob_ref);
 128     return 0;
 129 }
 130
 131 static PyObject *
 132 cell_get_contents(PyCellObject *op, void *closure)
 133 {
 134     if (op->ob_ref == NULL)
 135     {
 136         PyErr_SetString(PyExc_ValueError, "Cell is empty");
 137         return NULL;
 138     }
 139     Py_INCREF(op->ob_ref);
 140     return op->ob_ref;
 141 }
 142
 143 static PyGetSetDef cell_getsetlist[] = {
 144     {"cell_contents", (getter)cell_get_contents, NULL},
 145     {NULL} /* sentinel */
 146 };
 147
 148 PyTypeObject PyCell_Type = {
 149     PyVarObject_HEAD_INIT(&PyType_Type, 0)
 150     "cell",
 151     sizeof(PyCellObject),
 152     0,
 153     (destructor)cell_dealloc,               /* tp_dealloc */
 154     0,                                      /* tp_print */
 155     0,                                          /* tp_getattr */
 156     0,                                          /* tp_setattr */
 157     0,                                          /* tp_reserved */
 158     (reprfunc)cell_repr,                        /* tp_repr */
 159     0,                                          /* tp_as_number */
 160     0,                                          /* tp_as_sequence */
 161     0,                                          /* tp_as_mapping */
 162     0,                                          /* tp_hash */
 163     0,                                          /* tp_call */
 164     0,                                          /* tp_str */
 165     PyObject_GenericGetAttr,                    /* tp_getattro */
 166     0,                                          /* tp_setattro */
 167     0,                                          /* tp_as_buffer */
 168     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */
 169     0,                                          /* tp_doc */
 170     (traverseproc)cell_traverse,                /* tp_traverse */
 171     (inquiry)cell_clear,                        /* tp_clear */
 172     cell_richcompare,                           /* tp_richcompare */
 173     0,                                          /* tp_weaklistoffset */
 174     0,                                          /* tp_iter */
 175     0,                                          /* tp_iternext */
 176     0,                                          /* tp_methods */
 177     0,                                          /* tp_members */
 178     cell_getsetlist,                            /* tp_getset */
 179 };