1 /* Implementation helper: a struct that looks like a tuple. See timemodule
2 and posixmodule for example uses. */
3
4 #include "Python.h"
5 #include "structmember.h"
6 #include "structseq.h"
7
8 static char visible_length_key[] = "n_sequence_fields";
9 static char real_length_key[] = "n_fields";
10 static char unnamed_fields_key[] = "n_unnamed_fields";
11
12 /* Fields with this name have only a field index, not a field name.
13 They are only allowed for indices < n_visible_fields. */
14 char *PyStructSequence_UnnamedField = "unnamed field";
15
16 #define VISIBLE_SIZE(op) Py_SIZE(op)
17 #define VISIBLE_SIZE_TP(tp) PyInt_AsLong( \
18 PyDict_GetItemString((tp)->tp_dict, visible_length_key))
19
20 #define REAL_SIZE_TP(tp) PyInt_AsLong( \
21 PyDict_GetItemString((tp)->tp_dict, real_length_key))
22 #define REAL_SIZE(op) REAL_SIZE_TP(Py_TYPE(op))
23
24 #define UNNAMED_FIELDS_TP(tp) PyInt_AsLong( \
25 PyDict_GetItemString((tp)->tp_dict, unnamed_fields_key))
26 #define UNNAMED_FIELDS(op) UNNAMED_FIELDS_TP(Py_TYPE(op))
27
28
29 PyObject *
PyStructSequence_New(PyTypeObject * type)30 PyStructSequence_New(PyTypeObject *type)
31 {
32 PyStructSequence *obj;
33
34 obj = PyObject_New(PyStructSequence, type);
35 if (obj == NULL)
36 return NULL;
37 Py_SIZE(obj) = VISIBLE_SIZE_TP(type);
38
39 return (PyObject*) obj;
40 }
41
42 static void
structseq_dealloc(PyStructSequence * obj)43 structseq_dealloc(PyStructSequence *obj)
44 {
45 Py_ssize_t i, size;
46
47 size = REAL_SIZE(obj);
48 for (i = 0; i < size; ++i) {
49 Py_XDECREF(obj->ob_item[i]);
50 }
51 PyObject_Del(obj);
52 }
53
54 static Py_ssize_t
structseq_length(PyStructSequence * obj)55 structseq_length(PyStructSequence *obj)
56 {
57 return VISIBLE_SIZE(obj);
58 }
59
60 static PyObject*
structseq_item(PyStructSequence * obj,Py_ssize_t i)61 structseq_item(PyStructSequence *obj, Py_ssize_t i)
62 {
63 if (i < 0 || i >= VISIBLE_SIZE(obj)) {
64 PyErr_SetString(PyExc_IndexError, "tuple index out of range");
65 return NULL;
66 }
67 Py_INCREF(obj->ob_item[i]);
68 return obj->ob_item[i];
69 }
70
71 static PyObject*
structseq_slice(PyStructSequence * obj,Py_ssize_t low,Py_ssize_t high)72 structseq_slice(PyStructSequence *obj, Py_ssize_t low, Py_ssize_t high)
73 {
74 PyTupleObject *np;
75 Py_ssize_t i;
76
77 if (low < 0)
78 low = 0;
79 if (high > VISIBLE_SIZE(obj))
80 high = VISIBLE_SIZE(obj);
81 if (high < low)
82 high = low;
83 np = (PyTupleObject *)PyTuple_New(high-low);
84 if (np == NULL)
85 return NULL;
86 for(i = low; i < high; ++i) {
87 PyObject *v = obj->ob_item[i];
88 Py_INCREF(v);
89 PyTuple_SET_ITEM(np, i-low, v);
90 }
91 return (PyObject *) np;
92 }
93
94 static PyObject *
structseq_subscript(PyStructSequence * self,PyObject * item)95 structseq_subscript(PyStructSequence *self, PyObject *item)
96 {
97 if (PyIndex_Check(item)) {
98 Py_ssize_t i = PyNumber_AsSsize_t(item, PyExc_IndexError);
99 if (i == -1 && PyErr_Occurred())
100 return NULL;
101
102 if (i < 0)
103 i += VISIBLE_SIZE(self);
104
105 if (i < 0 || i >= VISIBLE_SIZE(self)) {
106 PyErr_SetString(PyExc_IndexError,
107 "tuple index out of range");
108 return NULL;
109 }
110 Py_INCREF(self->ob_item[i]);
111 return self->ob_item[i];
112 }
113 else if (PySlice_Check(item)) {
114 Py_ssize_t start, stop, step, slicelen, cur, i;
115 PyObject *result;
116
117 if (PySlice_GetIndicesEx((PySliceObject *)item,
118 VISIBLE_SIZE(self), &start, &stop,
119 &step, &slicelen) < 0) {
120 return NULL;
121 }
122 if (slicelen <= 0)
123 return PyTuple_New(0);
124 result = PyTuple_New(slicelen);
125 if (result == NULL)
126 return NULL;
127 for (cur = start, i = 0; i < slicelen;
128 cur += step, i++) {
129 PyObject *v = self->ob_item[cur];
130 Py_INCREF(v);
131 PyTuple_SET_ITEM(result, i, v);
132 }
133 return result;
134 }
135 else {
136 PyErr_SetString(PyExc_TypeError,
137 "structseq index must be integer");
138 return NULL;
139 }
140 }
141
142 static PyObject *
structseq_new(PyTypeObject * type,PyObject * args,PyObject * kwds)143 structseq_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
144 {
145 PyObject *arg = NULL;
146 PyObject *dict = NULL;
147 PyObject *ob;
148 PyStructSequence *res = NULL;
149 Py_ssize_t len, min_len, max_len, i, n_unnamed_fields;
150 static char *kwlist[] = {"sequence", "dict", 0};
151
152 if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|O:structseq",
153 kwlist, &arg, &dict))
154 return NULL;
155
156 arg = PySequence_Fast(arg, "constructor requires a sequence");
157
158 if (!arg) {
159 return NULL;
160 }
161
162 if (dict && !PyDict_Check(dict)) {
163 PyErr_Format(PyExc_TypeError,
164 "%.500s() takes a dict as second arg, if any",
165 type->tp_name);
166 Py_DECREF(arg);
167 return NULL;
168 }
169
170 len = PySequence_Fast_GET_SIZE(arg);
171 min_len = VISIBLE_SIZE_TP(type);
172 max_len = REAL_SIZE_TP(type);
173 n_unnamed_fields = UNNAMED_FIELDS_TP(type);
174
175 if (min_len != max_len) {
176 if (len < min_len) {
177 PyErr_Format(PyExc_TypeError,
178 "%.500s() takes an at least %zd-sequence (%zd-sequence given)",
179 type->tp_name, min_len, len);
180 Py_DECREF(arg);
181 return NULL;
182 }
183
184 if (len > max_len) {
185 PyErr_Format(PyExc_TypeError,
186 "%.500s() takes an at most %zd-sequence (%zd-sequence given)",
187 type->tp_name, max_len, len);
188 Py_DECREF(arg);
189 return NULL;
190 }
191 }
192 else {
193 if (len != min_len) {
194 PyErr_Format(PyExc_TypeError,
195 "%.500s() takes a %zd-sequence (%zd-sequence given)",
196 type->tp_name, min_len, len);
197 Py_DECREF(arg);
198 return NULL;
199 }
200 }
201
202 res = (PyStructSequence*) PyStructSequence_New(type);
203 if (res == NULL) {
204 return NULL;
205 }
206 for (i = 0; i < len; ++i) {
207 PyObject *v = PySequence_Fast_GET_ITEM(arg, i);
208 Py_INCREF(v);
209 res->ob_item[i] = v;
210 }
211 for (; i < max_len; ++i) {
212 if (dict && (ob = PyDict_GetItemString(
213 dict, type->tp_members[i-n_unnamed_fields].name))) {
214 }
215 else {
216 ob = Py_None;
217 }
218 Py_INCREF(ob);
219 res->ob_item[i] = ob;
220 }
221
222 Py_DECREF(arg);
223 return (PyObject*) res;
224 }
225
226 static PyObject *
make_tuple(PyStructSequence * obj)227 make_tuple(PyStructSequence *obj)
228 {
229 return structseq_slice(obj, 0, VISIBLE_SIZE(obj));
230 }
231
232 static PyObject *
structseq_repr(PyStructSequence * obj)233 structseq_repr(PyStructSequence *obj)
234 {
235 /* buffer and type size were chosen well considered. */
236 #define REPR_BUFFER_SIZE 512
237 #define TYPE_MAXSIZE 100
238
239 PyObject *tup;
240 PyTypeObject *typ = Py_TYPE(obj);
241 int i, removelast = 0;
242 Py_ssize_t len;
243 char buf[REPR_BUFFER_SIZE];
244 char *endofbuf, *pbuf = buf;
245
246 /* pointer to end of writeable buffer; safes space for "...)\0" */
247 endofbuf= &buf[REPR_BUFFER_SIZE-5];
248
249 if ((tup = make_tuple(obj)) == NULL) {
250 return NULL;
251 }
252
253 /* "typename(", limited to TYPE_MAXSIZE */
254 len = strlen(typ->tp_name) > TYPE_MAXSIZE ? TYPE_MAXSIZE :
255 strlen(typ->tp_name);
256 strncpy(pbuf, typ->tp_name, len);
257 pbuf += len;
258 *pbuf++ = '(';
259
260 for (i=0; i < VISIBLE_SIZE(obj); i++) {
261 PyObject *val, *repr;
262 char *cname, *crepr;
263
264 cname = typ->tp_members[i].name;
265
266 val = PyTuple_GetItem(tup, i);
267 if (cname == NULL || val == NULL) {
268 return NULL;
269 }
270 repr = PyObject_Repr(val);
271 if (repr == NULL) {
272 Py_DECREF(tup);
273 return NULL;
274 }
275 crepr = PyString_AsString(repr);
276 if (crepr == NULL) {
277 Py_DECREF(tup);
278 Py_DECREF(repr);
279 return NULL;
280 }
281
282 /* + 3: keep space for "=" and ", " */
283 len = strlen(cname) + strlen(crepr) + 3;
284 if ((pbuf+len) <= endofbuf) {
285 strcpy(pbuf, cname);
286 pbuf += strlen(cname);
287 *pbuf++ = '=';
288 strcpy(pbuf, crepr);
289 pbuf += strlen(crepr);
290 *pbuf++ = ',';
291 *pbuf++ = ' ';
292 removelast = 1;
293 Py_DECREF(repr);
294 }
295 else {
296 strcpy(pbuf, "...");
297 pbuf += 3;
298 removelast = 0;
299 Py_DECREF(repr);
300 break;
301 }
302 }
303 Py_DECREF(tup);
304 if (removelast) {
305 /* overwrite last ", " */
306 pbuf-=2;
307 }
308 *pbuf++ = ')';
309 *pbuf = '\0';
310
311 return PyString_FromString(buf);
312 }
313
314 static PyObject *
structseq_concat(PyStructSequence * obj,PyObject * b)315 structseq_concat(PyStructSequence *obj, PyObject *b)
316 {
317 PyObject *tup, *result;
318 tup = make_tuple(obj);
319 result = PySequence_Concat(tup, b);
320 Py_DECREF(tup);
321 return result;
322 }
323
324 static PyObject *
structseq_repeat(PyStructSequence * obj,Py_ssize_t n)325 structseq_repeat(PyStructSequence *obj, Py_ssize_t n)
326 {
327 PyObject *tup, *result;
328 tup = make_tuple(obj);
329 result = PySequence_Repeat(tup, n);
330 Py_DECREF(tup);
331 return result;
332 }
333
334 static int
structseq_contains(PyStructSequence * obj,PyObject * o)335 structseq_contains(PyStructSequence *obj, PyObject *o)
336 {
337 PyObject *tup;
338 int result;
339 tup = make_tuple(obj);
340 if (!tup)
341 return -1;
342 result = PySequence_Contains(tup, o);
343 Py_DECREF(tup);
344 return result;
345 }
346
347 static long
structseq_hash(PyObject * obj)348 structseq_hash(PyObject *obj)
349 {
350 PyObject *tup;
351 long result;
352 tup = make_tuple((PyStructSequence*) obj);
353 if (!tup)
354 return -1;
355 result = PyObject_Hash(tup);
356 Py_DECREF(tup);
357 return result;
358 }
359
360 static PyObject *
structseq_richcompare(PyObject * obj,PyObject * o2,int op)361 structseq_richcompare(PyObject *obj, PyObject *o2, int op)
362 {
363 PyObject *tup, *result;
364 tup = make_tuple((PyStructSequence*) obj);
365 result = PyObject_RichCompare(tup, o2, op);
366 Py_DECREF(tup);
367 return result;
368 }
369
370 static PyObject *
structseq_reduce(PyStructSequence * self)371 structseq_reduce(PyStructSequence* self)
372 {
373 PyObject* tup;
374 PyObject* dict;
375 PyObject* result;
376 Py_ssize_t n_fields, n_visible_fields, n_unnamed_fields;
377 int i;
378
379 n_fields = REAL_SIZE(self);
380 n_visible_fields = VISIBLE_SIZE(self);
381 n_unnamed_fields = UNNAMED_FIELDS(self);
382 tup = PyTuple_New(n_visible_fields);
383 if (!tup) {
384 return NULL;
385 }
386
387 dict = PyDict_New();
388 if (!dict) {
389 Py_DECREF(tup);
390 return NULL;
391 }
392
393 for (i = 0; i < n_visible_fields; i++) {
394 Py_INCREF(self->ob_item[i]);
395 PyTuple_SET_ITEM(tup, i, self->ob_item[i]);
396 }
397
398 for (; i < n_fields; i++) {
399 char *n = Py_TYPE(self)->tp_members[i-n_unnamed_fields].name;
400 PyDict_SetItemString(dict, n,
401 self->ob_item[i]);
402 }
403
404 result = Py_BuildValue("(O(OO))", Py_TYPE(self), tup, dict);
405
406 Py_DECREF(tup);
407 Py_DECREF(dict);
408
409 return result;
410 }
411
412 static PySequenceMethods structseq_as_sequence = {
413 (lenfunc)structseq_length,
414 (binaryfunc)structseq_concat, /* sq_concat */
415 (ssizeargfunc)structseq_repeat, /* sq_repeat */
416 (ssizeargfunc)structseq_item, /* sq_item */
417 (ssizessizeargfunc)structseq_slice, /* sq_slice */
418 0, /* sq_ass_item */
419 0, /* sq_ass_slice */
420 (objobjproc)structseq_contains, /* sq_contains */
421 };
422
423 static PyMappingMethods structseq_as_mapping = {
424 (lenfunc)structseq_length,
425 (binaryfunc)structseq_subscript,
426 };
427
428 static PyMethodDef structseq_methods[] = {
429 {"__reduce__", (PyCFunction)structseq_reduce,
430 METH_NOARGS, NULL},
431 {NULL, NULL}
432 };
433
434 static PyTypeObject _struct_sequence_template = {
435 PyVarObject_HEAD_INIT(&PyType_Type, 0)
436 NULL, /* tp_name */
437 0, /* tp_basicsize */
438 0, /* tp_itemsize */
439 (destructor)structseq_dealloc, /* tp_dealloc */
440 0, /* tp_print */
441 0, /* tp_getattr */
442 0, /* tp_setattr */
443 0, /* tp_compare */
444 (reprfunc)structseq_repr, /* tp_repr */
445 0, /* tp_as_number */
446 &structseq_as_sequence, /* tp_as_sequence */
447 &structseq_as_mapping, /* tp_as_mapping */
448 structseq_hash, /* tp_hash */
449 0, /* tp_call */
450 0, /* tp_str */
451 0, /* tp_getattro */
452 0, /* tp_setattro */
453 0, /* tp_as_buffer */
454 Py_TPFLAGS_DEFAULT, /* tp_flags */
455 NULL, /* tp_doc */
456 0, /* tp_traverse */
457 0, /* tp_clear */
458 structseq_richcompare, /* tp_richcompare */
459 0, /* tp_weaklistoffset */
460 0, /* tp_iter */
461 0, /* tp_iternext */
462 structseq_methods, /* tp_methods */
463 NULL, /* tp_members */
464 0, /* tp_getset */
465 0, /* tp_base */
466 0, /* tp_dict */
467 0, /* tp_descr_get */
468 0, /* tp_descr_set */
469 0, /* tp_dictoffset */
470 0, /* tp_init */
471 0, /* tp_alloc */
472 structseq_new, /* tp_new */
473 };
474
475 void
PyStructSequence_InitType(PyTypeObject * type,PyStructSequence_Desc * desc)476 PyStructSequence_InitType(PyTypeObject *type, PyStructSequence_Desc *desc)
477 {
478 PyObject *dict;
479 PyMemberDef* members;
480 int n_members, n_unnamed_members, i, k;
481
482 #ifdef Py_TRACE_REFS
483 /* if the type object was chained, unchain it first
484 before overwriting its storage */
485 if (type->_ob_next) {
486 _Py_ForgetReference((PyObject*)type);
487 }
488 #endif
489
490 n_unnamed_members = 0;
491 for (i = 0; desc->fields[i].name != NULL; ++i)
492 if (desc->fields[i].name == PyStructSequence_UnnamedField)
493 n_unnamed_members++;
494 n_members = i;
495
496 memcpy(type, &_struct_sequence_template, sizeof(PyTypeObject));
497 type->tp_name = desc->name;
498 type->tp_doc = desc->doc;
499 type->tp_basicsize = sizeof(PyStructSequence)+
500 sizeof(PyObject*)*(n_members-1);
501 type->tp_itemsize = 0;
502
503 members = PyMem_NEW(PyMemberDef, n_members-n_unnamed_members+1);
504 if (members == NULL)
505 return;
506
507 for (i = k = 0; i < n_members; ++i) {
508 if (desc->fields[i].name == PyStructSequence_UnnamedField)
509 continue;
510 members[k].name = desc->fields[i].name;
511 members[k].type = T_OBJECT;
512 members[k].offset = offsetof(PyStructSequence, ob_item)
513 + i * sizeof(PyObject*);
514 members[k].flags = READONLY;
515 members[k].doc = desc->fields[i].doc;
516 k++;
517 }
518 members[k].name = NULL;
519
520 type->tp_members = members;
521
522 if (PyType_Ready(type) < 0)
523 return;
524 Py_INCREF(type);
525
526 dict = type->tp_dict;
527 #define SET_DICT_FROM_INT(key, value) \
528 do { \
529 PyObject *v = PyInt_FromLong((long) value); \
530 if (v != NULL) { \
531 PyDict_SetItemString(dict, key, v); \
532 Py_DECREF(v); \
533 } \
534 } while (0)
535
536 SET_DICT_FROM_INT(visible_length_key, desc->n_in_sequence);
537 SET_DICT_FROM_INT(real_length_key, n_members);
538 SET_DICT_FROM_INT(unnamed_fields_key, n_unnamed_members);
539 }
540