AppPkg/Applications/Python/Python-2.7.10/Objects/genobject.c

   1 /* Generator object implementation */
   2
   3 #include "Python.h"
   4 #include "frameobject.h"
   5 #include "genobject.h"
   6 #include "ceval.h"
   7 #include "structmember.h"
   8 #include "opcode.h"
   9
  10 static int
  11 gen_traverse(PyGenObject *gen, visitproc visit, void *arg)
  12 {
  13     Py_VISIT((PyObject *)gen->gi_frame);
  14     Py_VISIT(gen->gi_code);
  15     return 0;
  16 }
  17
  18 static void
  19 gen_dealloc(PyGenObject *gen)
  20 {
  21     PyObject *self = (PyObject *) gen;
  22
  23     _PyObject_GC_UNTRACK(gen);
  24
  25     if (gen->gi_weakreflist != NULL)
  26         PyObject_ClearWeakRefs(self);
  27
  28     _PyObject_GC_TRACK(self);
  29
  30     if (gen->gi_frame != NULL && gen->gi_frame->f_stacktop != NULL) {
  31         /* Generator is paused, so we need to close */
  32         Py_TYPE(gen)->tp_del(self);
  33         if (self->ob_refcnt > 0)
  34             return;                     /* resurrected.  :( */
  35     }
  36
  37     _PyObject_GC_UNTRACK(self);
  38     Py_CLEAR(gen->gi_frame);
  39     Py_CLEAR(gen->gi_code);
  40     PyObject_GC_Del(gen);
  41 }
  42
  43
  44 static PyObject *
  45 gen_send_ex(PyGenObject *gen, PyObject *arg, int exc)
  46 {
  47     PyThreadState *tstate = PyThreadState_GET();
  48     PyFrameObject *f = gen->gi_frame;
  49     PyObject *result;
  50
  51     if (gen->gi_running) {
  52         PyErr_SetString(PyExc_ValueError,
  53                         "generator already executing");
  54         return NULL;
  55     }
  56     if (f==NULL || f->f_stacktop == NULL) {
  57         /* Only set exception if called from send() */
  58         if (arg && !exc)
  59             PyErr_SetNone(PyExc_StopIteration);
  60         return NULL;
  61     }
  62
  63     if (f->f_lasti == -1) {
  64         if (arg && arg != Py_None) {
  65             PyErr_SetString(PyExc_TypeError,
  66                             "can't send non-None value to a "
  67                             "just-started generator");
  68             return NULL;
  69         }
  70     } else {
  71         /* Push arg onto the frame's value stack */
  72         result = arg ? arg : Py_None;
  73         Py_INCREF(result);
  74         *(f->f_stacktop++) = result;
  75     }
  76
  77     /* Generators always return to their most recent caller, not
  78      * necessarily their creator. */
  79     f->f_tstate = tstate;
  80     Py_XINCREF(tstate->frame);
  81     assert(f->f_back == NULL);
  82     f->f_back = tstate->frame;
  83
  84     gen->gi_running = 1;
  85     result = PyEval_EvalFrameEx(f, exc);
  86     gen->gi_running = 0;
  87
  88     /* Don't keep the reference to f_back any longer than necessary.  It
  89      * may keep a chain of frames alive or it could create a reference
  90      * cycle. */
  91     assert(f->f_back == tstate->frame);
  92     Py_CLEAR(f->f_back);
  93     /* Clear the borrowed reference to the thread state */
  94     f->f_tstate = NULL;
  95
  96     /* If the generator just returned (as opposed to yielding), signal
  97      * that the generator is exhausted. */
  98     if (result == Py_None && f->f_stacktop == NULL) {
  99         Py_DECREF(result);
 100         result = NULL;
 101         /* Set exception if not called by gen_iternext() */
 102         if (arg)
 103             PyErr_SetNone(PyExc_StopIteration);
 104     }
 105
 106     if (!result || f->f_stacktop == NULL) {
 107         /* generator can't be rerun, so release the frame */
 108         Py_DECREF(f);
 109         gen->gi_frame = NULL;
 110     }
 111
 112     return result;
 113 }
 114
 115 PyDoc_STRVAR(send_doc,
 116 "send(arg) -> send 'arg' into generator,\n\
 117 return next yielded value or raise StopIteration.");
 118
 119 static PyObject *
 120 gen_send(PyGenObject *gen, PyObject *arg)
 121 {
 122     return gen_send_ex(gen, arg, 0);
 123 }
 124
 125 PyDoc_STRVAR(close_doc,
 126 "close() -> raise GeneratorExit inside generator.");
 127
 128 static PyObject *
 129 gen_close(PyGenObject *gen, PyObject *args)
 130 {
 131     PyObject *retval;
 132     PyErr_SetNone(PyExc_GeneratorExit);
 133     retval = gen_send_ex(gen, Py_None, 1);
 134     if (retval) {
 135         Py_DECREF(retval);
 136         PyErr_SetString(PyExc_RuntimeError,
 137                         "generator ignored GeneratorExit");
 138         return NULL;
 139     }
 140     if (PyErr_ExceptionMatches(PyExc_StopIteration)
 141         || PyErr_ExceptionMatches(PyExc_GeneratorExit))
 142     {
 143         PyErr_Clear();          /* ignore these errors */
 144         Py_INCREF(Py_None);
 145         return Py_None;
 146     }
 147     return NULL;
 148 }
 149
 150 static void
 151 gen_del(PyObject *self)
 152 {
 153     PyObject *res;
 154     PyObject *error_type, *error_value, *error_traceback;
 155     PyGenObject *gen = (PyGenObject *)self;
 156
 157     if (gen->gi_frame == NULL || gen->gi_frame->f_stacktop == NULL)
 158         /* Generator isn't paused, so no need to close */
 159         return;
 160
 161     /* Temporarily resurrect the object. */
 162     assert(self->ob_refcnt == 0);
 163     self->ob_refcnt = 1;
 164
 165     /* Save the current exception, if any. */
 166     PyErr_Fetch(&error_type, &error_value, &error_traceback);
 167
 168     res = gen_close(gen, NULL);
 169
 170     if (res == NULL)
 171         PyErr_WriteUnraisable(self);
 172     else
 173         Py_DECREF(res);
 174
 175     /* Restore the saved exception. */
 176     PyErr_Restore(error_type, error_value, error_traceback);
 177
 178     /* Undo the temporary resurrection; can't use DECREF here, it would
 179      * cause a recursive call.
 180      */
 181     assert(self->ob_refcnt > 0);
 182     if (--self->ob_refcnt == 0)
 183         return; /* this is the normal path out */
 184
 185     /* close() resurrected it!  Make it look like the original Py_DECREF
 186      * never happened.
 187      */
 188     {
 189         Py_ssize_t refcnt = self->ob_refcnt;
 190         _Py_NewReference(self);
 191         self->ob_refcnt = refcnt;
 192     }
 193     assert(PyType_IS_GC(self->ob_type) &&
 194            _Py_AS_GC(self)->gc.gc_refs != _PyGC_REFS_UNTRACKED);
 195
 196     /* If Py_REF_DEBUG, _Py_NewReference bumped _Py_RefTotal, so
 197      * we need to undo that. */
 198     _Py_DEC_REFTOTAL;
 199     /* If Py_TRACE_REFS, _Py_NewReference re-added self to the object
 200      * chain, so no more to do there.
 201      * If COUNT_ALLOCS, the original decref bumped tp_frees, and
 202      * _Py_NewReference bumped tp_allocs:  both of those need to be
 203      * undone.
 204      */
 205 #ifdef COUNT_ALLOCS
 206     --self->ob_type->tp_frees;
 207     --self->ob_type->tp_allocs;
 208 #endif
 209 }
 210
 211
 212
 213 PyDoc_STRVAR(throw_doc,
 214 "throw(typ[,val[,tb]]) -> raise exception in generator,\n\
 215 return next yielded value or raise StopIteration.");
 216
 217 static PyObject *
 218 gen_throw(PyGenObject *gen, PyObject *args)
 219 {
 220     PyObject *typ;
 221     PyObject *tb = NULL;
 222     PyObject *val = NULL;
 223
 224     if (!PyArg_UnpackTuple(args, "throw", 1, 3, &typ, &val, &tb))
 225         return NULL;
 226
 227     /* First, check the traceback argument, replacing None with
 228        NULL. */
 229     if (tb == Py_None)
 230         tb = NULL;
 231     else if (tb != NULL && !PyTraceBack_Check(tb)) {
 232         PyErr_SetString(PyExc_TypeError,
 233             "throw() third argument must be a traceback object");
 234         return NULL;
 235     }
 236
 237     Py_INCREF(typ);
 238     Py_XINCREF(val);
 239     Py_XINCREF(tb);
 240
 241     if (PyExceptionClass_Check(typ)) {
 242         PyErr_NormalizeException(&typ, &val, &tb);
 243     }
 244
 245     else if (PyExceptionInstance_Check(typ)) {
 246         /* Raising an instance.  The value should be a dummy. */
 247         if (val && val != Py_None) {
 248             PyErr_SetString(PyExc_TypeError,
 249               "instance exception may not have a separate value");
 250             goto failed_throw;
 251         }
 252         else {
 253             /* Normalize to raise <class>, <instance> */
 254             Py_XDECREF(val);
 255             val = typ;
 256             typ = PyExceptionInstance_Class(typ);
 257             Py_INCREF(typ);
 258         }
 259     }
 260     else {
 261         /* Not something you can raise.  throw() fails. */
 262         PyErr_Format(PyExc_TypeError,
 263                      "exceptions must be classes, or instances, not %s",
 264                      typ->ob_type->tp_name);
 265             goto failed_throw;
 266     }
 267
 268     PyErr_Restore(typ, val, tb);
 269     return gen_send_ex(gen, Py_None, 1);
 270
 271 failed_throw:
 272     /* Didn't use our arguments, so restore their original refcounts */
 273     Py_DECREF(typ);
 274     Py_XDECREF(val);
 275     Py_XDECREF(tb);
 276     return NULL;
 277 }
 278
 279
 280 static PyObject *
 281 gen_iternext(PyGenObject *gen)
 282 {
 283     return gen_send_ex(gen, NULL, 0);
 284 }
 285
 286
 287 static PyObject *
 288 gen_repr(PyGenObject *gen)
 289 {
 290     char *code_name;
 291     code_name = PyString_AsString(((PyCodeObject *)gen->gi_code)->co_name);
 292     if (code_name == NULL)
 293         return NULL;
 294     return PyString_FromFormat("<generator object %.200s at %p>",
 295                                code_name, gen);
 296 }
 297
 298
 299 static PyObject *
 300 gen_get_name(PyGenObject *gen)
 301 {
 302     PyObject *name = ((PyCodeObject *)gen->gi_code)->co_name;
 303     Py_INCREF(name);
 304     return name;
 305 }
 306
 307
 308 PyDoc_STRVAR(gen__name__doc__,
 309 "Return the name of the generator's associated code object.");
 310
 311 static PyGetSetDef gen_getsetlist[] = {
 312     {"__name__", (getter)gen_get_name, NULL, gen__name__doc__},
 313     {NULL}
 314 };
 315
 316
 317 static PyMemberDef gen_memberlist[] = {
 318     {"gi_frame",        T_OBJECT, offsetof(PyGenObject, gi_frame),      RO},
 319     {"gi_running",      T_INT,    offsetof(PyGenObject, gi_running),    RO},
 320     {"gi_code",     T_OBJECT, offsetof(PyGenObject, gi_code),  RO},
 321     {NULL}      /* Sentinel */
 322 };
 323
 324 static PyMethodDef gen_methods[] = {
 325     {"send",(PyCFunction)gen_send, METH_O, send_doc},
 326     {"throw",(PyCFunction)gen_throw, METH_VARARGS, throw_doc},
 327     {"close",(PyCFunction)gen_close, METH_NOARGS, close_doc},
 328     {NULL, NULL}        /* Sentinel */
 329 };
 330
 331 PyTypeObject PyGen_Type = {
 332     PyVarObject_HEAD_INIT(&PyType_Type, 0)
 333     "generator",                                /* tp_name */
 334     sizeof(PyGenObject),                        /* tp_basicsize */
 335     0,                                          /* tp_itemsize */
 336     /* methods */
 337     (destructor)gen_dealloc,                    /* tp_dealloc */
 338     0,                                          /* tp_print */
 339     0,                                          /* tp_getattr */
 340     0,                                          /* tp_setattr */
 341     0,                                          /* tp_compare */
 342     (reprfunc)gen_repr,                         /* tp_repr */
 343     0,                                          /* tp_as_number */
 344     0,                                          /* tp_as_sequence */
 345     0,                                          /* tp_as_mapping */
 346     0,                                          /* tp_hash */
 347     0,                                          /* tp_call */
 348     0,                                          /* tp_str */
 349     PyObject_GenericGetAttr,                    /* tp_getattro */
 350     0,                                          /* tp_setattro */
 351     0,                                          /* tp_as_buffer */
 352     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */
 353     0,                                          /* tp_doc */
 354     (traverseproc)gen_traverse,                 /* tp_traverse */
 355     0,                                          /* tp_clear */
 356     0,                                          /* tp_richcompare */
 357     offsetof(PyGenObject, gi_weakreflist),      /* tp_weaklistoffset */
 358     PyObject_SelfIter,                          /* tp_iter */
 359     (iternextfunc)gen_iternext,                 /* tp_iternext */
 360     gen_methods,                                /* tp_methods */
 361     gen_memberlist,                             /* tp_members */
 362     gen_getsetlist,                             /* tp_getset */
 363     0,                                          /* tp_base */
 364     0,                                          /* tp_dict */
 365
 366     0,                                          /* tp_descr_get */
 367     0,                                          /* tp_descr_set */
 368     0,                                          /* tp_dictoffset */
 369     0,                                          /* tp_init */
 370     0,                                          /* tp_alloc */
 371     0,                                          /* tp_new */
 372     0,                                          /* tp_free */
 373     0,                                          /* tp_is_gc */
 374     0,                                          /* tp_bases */
 375     0,                                          /* tp_mro */
 376     0,                                          /* tp_cache */
 377     0,                                          /* tp_subclasses */
 378     0,                                          /* tp_weaklist */
 379     gen_del,                                    /* tp_del */
 380 };
 381
 382 PyObject *
 383 PyGen_New(PyFrameObject *f)
 384 {
 385     PyGenObject *gen = PyObject_GC_New(PyGenObject, &PyGen_Type);
 386     if (gen == NULL) {
 387         Py_DECREF(f);
 388         return NULL;
 389     }
 390     gen->gi_frame = f;
 391     Py_INCREF(f->f_code);
 392     gen->gi_code = (PyObject *)(f->f_code);
 393     gen->gi_running = 0;
 394     gen->gi_weakreflist = NULL;
 395     _PyObject_GC_TRACK(gen);
 396     return (PyObject *)gen;
 397 }
 398
 399 int
 400 PyGen_NeedsFinalizing(PyGenObject *gen)
 401 {
 402     int i;
 403     PyFrameObject *f = gen->gi_frame;
 404
 405     if (f == NULL || f->f_stacktop == NULL || f->f_iblock <= 0)
 406         return 0; /* no frame or empty blockstack == no finalization */
 407
 408     /* Any block type besides a loop requires cleanup. */
 409     i = f->f_iblock;
 410     while (--i >= 0) {
 411         if (f->f_blockstack[i].b_type != SETUP_LOOP)
 412             return 1;
 413     }
 414
 415     /* No blocks except loops, it's safe to skip finalization. */
 416     return 0;
 417 }