source: vendor/python/2.5/Objects/genobject.c

Last change on this file was 3225, checked in by bird, 18 years ago

Python 2.5
File size: 9.4 KB
Line 
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
10static int
11gen_traverse(PyGenObject *gen, visitproc visit, void *arg)
12{
13 Py_VISIT((PyObject *)gen->gi_frame);
14 return 0;
15}
16
17static void
18gen_dealloc(PyGenObject *gen)
19{
20 PyObject *self = (PyObject *) gen;
21
22 _PyObject_GC_UNTRACK(gen);
23
24 if (gen->gi_weakreflist != NULL)
25 PyObject_ClearWeakRefs(self);
26
27 _PyObject_GC_TRACK(self);
28
29 if (gen->gi_frame != NULL && gen->gi_frame->f_stacktop != NULL) {
30 /* Generator is paused, so we need to close */
31 gen->ob_type->tp_del(self);
32 if (self->ob_refcnt > 0)
33 return; /* resurrected. :( */
34 }
35
36 _PyObject_GC_UNTRACK(self);
37 Py_CLEAR(gen->gi_frame);
38 PyObject_GC_Del(gen);
39}
40
41
42static PyObject *
43gen_send_ex(PyGenObject *gen, PyObject *arg, int exc)
44{
45 PyThreadState *tstate = PyThreadState_GET();
46 PyFrameObject *f = gen->gi_frame;
47 PyObject *result;
48
49 if (gen->gi_running) {
50 PyErr_SetString(PyExc_ValueError,
51 "generator already executing");
52 return NULL;
53 }
54 if (f==NULL || f->f_stacktop == NULL) {
55 /* Only set exception if called from send() */
56 if (arg && !exc)
57 PyErr_SetNone(PyExc_StopIteration);
58 return NULL;
59 }
60
61 if (f->f_lasti == -1) {
62 if (arg && arg != Py_None) {
63 PyErr_SetString(PyExc_TypeError,
64 "can't send non-None value to a "
65 "just-started generator");
66 return NULL;
67 }
68 } else {
69 /* Push arg onto the frame's value stack */
70 result = arg ? arg : Py_None;
71 Py_INCREF(result);
72 *(f->f_stacktop++) = result;
73 }
74
75 /* Generators always return to their most recent caller, not
76 * necessarily their creator. */
77 Py_XINCREF(tstate->frame);
78 assert(f->f_back == NULL);
79 f->f_back = tstate->frame;
80
81 gen->gi_running = 1;
82 result = PyEval_EvalFrameEx(f, exc);
83 gen->gi_running = 0;
84
85 /* Don't keep the reference to f_back any longer than necessary. It
86 * may keep a chain of frames alive or it could create a reference
87 * cycle. */
88 assert(f->f_back == tstate->frame);
89 Py_CLEAR(f->f_back);
90
91 /* If the generator just returned (as opposed to yielding), signal
92 * that the generator is exhausted. */
93 if (result == Py_None && f->f_stacktop == NULL) {
94 Py_DECREF(result);
95 result = NULL;
96 /* Set exception if not called by gen_iternext() */
97 if (arg)
98 PyErr_SetNone(PyExc_StopIteration);
99 }
100
101 if (!result || f->f_stacktop == NULL) {
102 /* generator can't be rerun, so release the frame */
103 Py_DECREF(f);
104 gen->gi_frame = NULL;
105 }
106
107 return result;
108}
109
110PyDoc_STRVAR(send_doc,
111"send(arg) -> send 'arg' into generator,\n\
112return next yielded value or raise StopIteration.");
113
114static PyObject *
115gen_send(PyGenObject *gen, PyObject *arg)
116{
117 return gen_send_ex(gen, arg, 0);
118}
119
120PyDoc_STRVAR(close_doc,
121"close(arg) -> raise GeneratorExit inside generator.");
122
123static PyObject *
124gen_close(PyGenObject *gen, PyObject *args)
125{
126 PyObject *retval;
127 PyErr_SetNone(PyExc_GeneratorExit);
128 retval = gen_send_ex(gen, Py_None, 1);
129 if (retval) {
130 Py_DECREF(retval);
131 PyErr_SetString(PyExc_RuntimeError,
132 "generator ignored GeneratorExit");
133 return NULL;
134 }
135 if (PyErr_ExceptionMatches(PyExc_StopIteration)
136 || PyErr_ExceptionMatches(PyExc_GeneratorExit))
137 {
138 PyErr_Clear(); /* ignore these errors */
139 Py_INCREF(Py_None);
140 return Py_None;
141 }
142 return NULL;
143}
144
145static void
146gen_del(PyObject *self)
147{
148 PyObject *res;
149 PyObject *error_type, *error_value, *error_traceback;
150 PyGenObject *gen = (PyGenObject *)self;
151
152 if (gen->gi_frame == NULL || gen->gi_frame->f_stacktop == NULL)
153 /* Generator isn't paused, so no need to close */
154 return;
155
156 /* Temporarily resurrect the object. */
157 assert(self->ob_refcnt == 0);
158 self->ob_refcnt = 1;
159
160 /* Save the current exception, if any. */
161 PyErr_Fetch(&error_type, &error_value, &error_traceback);
162
163 res = gen_close(gen, NULL);
164
165 if (res == NULL)
166 PyErr_WriteUnraisable(self);
167 else
168 Py_DECREF(res);
169
170 /* Restore the saved exception. */
171 PyErr_Restore(error_type, error_value, error_traceback);
172
173 /* Undo the temporary resurrection; can't use DECREF here, it would
174 * cause a recursive call.
175 */
176 assert(self->ob_refcnt > 0);
177 if (--self->ob_refcnt == 0)
178 return; /* this is the normal path out */
179
180 /* close() resurrected it! Make it look like the original Py_DECREF
181 * never happened.
182 */
183 {
184 Py_ssize_t refcnt = self->ob_refcnt;
185 _Py_NewReference(self);
186 self->ob_refcnt = refcnt;
187 }
188 assert(PyType_IS_GC(self->ob_type) &&
189 _Py_AS_GC(self)->gc.gc_refs != _PyGC_REFS_UNTRACKED);
190
191 /* If Py_REF_DEBUG, _Py_NewReference bumped _Py_RefTotal, so
192 * we need to undo that. */
193 _Py_DEC_REFTOTAL;
194 /* If Py_TRACE_REFS, _Py_NewReference re-added self to the object
195 * chain, so no more to do there.
196 * If COUNT_ALLOCS, the original decref bumped tp_frees, and
197 * _Py_NewReference bumped tp_allocs: both of those need to be
198 * undone.
199 */
200#ifdef COUNT_ALLOCS
201 --self->ob_type->tp_frees;
202 --self->ob_type->tp_allocs;
203#endif
204}
205
206
207
208PyDoc_STRVAR(throw_doc,
209"throw(typ[,val[,tb]]) -> raise exception in generator,\n\
210return next yielded value or raise StopIteration.");
211
212static PyObject *
213gen_throw(PyGenObject *gen, PyObject *args)
214{
215 PyObject *typ;
216 PyObject *tb = NULL;
217 PyObject *val = NULL;
218
219 if (!PyArg_UnpackTuple(args, "throw", 1, 3, &typ, &val, &tb))
220 return NULL;
221
222 /* First, check the traceback argument, replacing None with
223 NULL. */
224 if (tb == Py_None)
225 tb = NULL;
226 else if (tb != NULL && !PyTraceBack_Check(tb)) {
227 PyErr_SetString(PyExc_TypeError,
228 "throw() third argument must be a traceback object");
229 return NULL;
230 }
231
232 Py_INCREF(typ);
233 Py_XINCREF(val);
234 Py_XINCREF(tb);
235
236 if (PyExceptionClass_Check(typ)) {
237 PyErr_NormalizeException(&typ, &val, &tb);
238 }
239
240 else if (PyExceptionInstance_Check(typ)) {
241 /* Raising an instance. The value should be a dummy. */
242 if (val && val != Py_None) {
243 PyErr_SetString(PyExc_TypeError,
244 "instance exception may not have a separate value");
245 goto failed_throw;
246 }
247 else {
248 /* Normalize to raise <class>, <instance> */
249 Py_XDECREF(val);
250 val = typ;
251 typ = PyExceptionInstance_Class(typ);
252 Py_INCREF(typ);
253 }
254 }
255
256 /* Allow raising builtin string exceptions */
257
258 else if (!PyString_CheckExact(typ)) {
259 /* Not something you can raise. throw() fails. */
260 PyErr_Format(PyExc_TypeError,
261 "exceptions must be classes, or instances, not %s",
262 typ->ob_type->tp_name);
263 goto failed_throw;
264 }
265
266 PyErr_Restore(typ, val, tb);
267 return gen_send_ex(gen, Py_None, 1);
268
269failed_throw:
270 /* Didn't use our arguments, so restore their original refcounts */
271 Py_DECREF(typ);
272 Py_XDECREF(val);
273 Py_XDECREF(tb);
274 return NULL;
275}
276
277
278static PyObject *
279gen_iternext(PyGenObject *gen)
280{
281 return gen_send_ex(gen, NULL, 0);
282}
283
284
285static PyMemberDef gen_memberlist[] = {
286 {"gi_frame", T_OBJECT, offsetof(PyGenObject, gi_frame), RO},
287 {"gi_running", T_INT, offsetof(PyGenObject, gi_running), RO},
288 {NULL} /* Sentinel */
289};
290
291static PyMethodDef gen_methods[] = {
292 {"send",(PyCFunction)gen_send, METH_O, send_doc},
293 {"throw",(PyCFunction)gen_throw, METH_VARARGS, throw_doc},
294 {"close",(PyCFunction)gen_close, METH_NOARGS, close_doc},
295 {NULL, NULL} /* Sentinel */
296};
297
298PyTypeObject PyGen_Type = {
299 PyObject_HEAD_INIT(&PyType_Type)
300 0, /* ob_size */
301 "generator", /* tp_name */
302 sizeof(PyGenObject), /* tp_basicsize */
303 0, /* tp_itemsize */
304 /* methods */
305 (destructor)gen_dealloc, /* tp_dealloc */
306 0, /* tp_print */
307 0, /* tp_getattr */
308 0, /* tp_setattr */
309 0, /* tp_compare */
310 0, /* tp_repr */
311 0, /* tp_as_number */
312 0, /* tp_as_sequence */
313 0, /* tp_as_mapping */
314 0, /* tp_hash */
315 0, /* tp_call */
316 0, /* tp_str */
317 PyObject_GenericGetAttr, /* tp_getattro */
318 0, /* tp_setattro */
319 0, /* tp_as_buffer */
320 Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */
321 0, /* tp_doc */
322 (traverseproc)gen_traverse, /* tp_traverse */
323 0, /* tp_clear */
324 0, /* tp_richcompare */
325 offsetof(PyGenObject, gi_weakreflist), /* tp_weaklistoffset */
326 PyObject_SelfIter, /* tp_iter */
327 (iternextfunc)gen_iternext, /* tp_iternext */
328 gen_methods, /* tp_methods */
329 gen_memberlist, /* tp_members */
330 0, /* tp_getset */
331 0, /* tp_base */
332 0, /* tp_dict */
333
334 0, /* tp_descr_get */
335 0, /* tp_descr_set */
336 0, /* tp_dictoffset */
337 0, /* tp_init */
338 0, /* tp_alloc */
339 0, /* tp_new */
340 0, /* tp_free */
341 0, /* tp_is_gc */
342 0, /* tp_bases */
343 0, /* tp_mro */
344 0, /* tp_cache */
345 0, /* tp_subclasses */
346 0, /* tp_weaklist */
347 gen_del, /* tp_del */
348};
349
350PyObject *
351PyGen_New(PyFrameObject *f)
352{
353 PyGenObject *gen = PyObject_GC_New(PyGenObject, &PyGen_Type);
354 if (gen == NULL) {
355 Py_DECREF(f);
356 return NULL;
357 }
358 gen->gi_frame = f;
359 gen->gi_running = 0;
360 gen->gi_weakreflist = NULL;
361 _PyObject_GC_TRACK(gen);
362 return (PyObject *)gen;
363}
364
365int
366PyGen_NeedsFinalizing(PyGenObject *gen)
367{
368 int i;
369 PyFrameObject *f = gen->gi_frame;
370
371 if (f == NULL || f->f_stacktop == NULL || f->f_iblock <= 0)
372 return 0; /* no frame or empty blockstack == no finalization */
373
374 /* Any block type besides a loop requires cleanup. */
375 i = f->f_iblock;
376 while (--i >= 0) {
377 if (f->f_blockstack[i].b_type != SETUP_LOOP)
378 return 1;
379 }
380
381 /* No blocks except loops, it's safe to skip finalization. */
382 return 0;
383}
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