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