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
7 static const char visible_length_key[] = "n_sequence_fields";
8 static const char real_length_key[] = "n_fields";
9 static const char unnamed_fields_key[] = "n_unnamed_fields";
10
11 /* Fields with this name have only a field index, not a field name.
12 They are only allowed for indices < n_visible_fields. */
13 char *PyStructSequence_UnnamedField = "unnamed field";
14 _Py_IDENTIFIER(n_sequence_fields);
15 _Py_IDENTIFIER(n_fields);
16 _Py_IDENTIFIER(n_unnamed_fields);
17
18 #define VISIBLE_SIZE(op) Py_SIZE(op)
19 #define VISIBLE_SIZE_TP(tp) PyLong_AsSsize_t( \
20 _PyDict_GetItemId((tp)->tp_dict, &PyId_n_sequence_fields))
21
22 #define REAL_SIZE_TP(tp) PyLong_AsSsize_t( \
23 _PyDict_GetItemId((tp)->tp_dict, &PyId_n_fields))
24 #define REAL_SIZE(op) REAL_SIZE_TP(Py_TYPE(op))
25
26 #define UNNAMED_FIELDS_TP(tp) PyLong_AsSsize_t( \
27 _PyDict_GetItemId((tp)->tp_dict, &PyId_n_unnamed_fields))
28 #define UNNAMED_FIELDS(op) UNNAMED_FIELDS_TP(Py_TYPE(op))
29
30
31 PyObject *
PyStructSequence_New(PyTypeObject * type)32 PyStructSequence_New(PyTypeObject *type)
33 {
34 PyStructSequence *obj;
35 Py_ssize_t size = REAL_SIZE_TP(type), i;
36
37 obj = PyObject_GC_NewVar(PyStructSequence, type, size);
38 if (obj == NULL)
39 return NULL;
40 /* Hack the size of the variable object, so invisible fields don't appear
41 to Python code. */
42 Py_SIZE(obj) = VISIBLE_SIZE_TP(type);
43 for (i = 0; i < size; i++)
44 obj->ob_item[i] = NULL;
45
46 return (PyObject*)obj;
47 }
48
49 void
PyStructSequence_SetItem(PyObject * op,Py_ssize_t i,PyObject * v)50 PyStructSequence_SetItem(PyObject* op, Py_ssize_t i, PyObject* v)
51 {
52 PyStructSequence_SET_ITEM(op, i, v);
53 }
54
55 PyObject*
PyStructSequence_GetItem(PyObject * op,Py_ssize_t i)56 PyStructSequence_GetItem(PyObject* op, Py_ssize_t i)
57 {
58 return PyStructSequence_GET_ITEM(op, i);
59 }
60
61 static void
structseq_dealloc(PyStructSequence * obj)62 structseq_dealloc(PyStructSequence *obj)
63 {
64 Py_ssize_t i, size;
65
66 size = REAL_SIZE(obj);
67 for (i = 0; i < size; ++i) {
68 Py_XDECREF(obj->ob_item[i]);
69 }
70 PyObject_GC_Del(obj);
71 }
72
73 static PyObject *
structseq_new(PyTypeObject * type,PyObject * args,PyObject * kwds)74 structseq_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
75 {
76 PyObject *arg = NULL;
77 PyObject *dict = NULL;
78 PyObject *ob;
79 PyStructSequence *res = NULL;
80 Py_ssize_t len, min_len, max_len, i, n_unnamed_fields;
81 static char *kwlist[] = {"sequence", "dict", 0};
82
83 if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|O:structseq",
84 kwlist, &arg, &dict))
85 return NULL;
86
87 arg = PySequence_Fast(arg, "constructor requires a sequence");
88
89 if (!arg) {
90 return NULL;
91 }
92
93 if (dict && !PyDict_Check(dict)) {
94 PyErr_Format(PyExc_TypeError,
95 "%.500s() takes a dict as second arg, if any",
96 type->tp_name);
97 Py_DECREF(arg);
98 return NULL;
99 }
100
101 len = PySequence_Fast_GET_SIZE(arg);
102 min_len = VISIBLE_SIZE_TP(type);
103 max_len = REAL_SIZE_TP(type);
104 n_unnamed_fields = UNNAMED_FIELDS_TP(type);
105
106 if (min_len != max_len) {
107 if (len < min_len) {
108 PyErr_Format(PyExc_TypeError,
109 "%.500s() takes an at least %zd-sequence (%zd-sequence given)",
110 type->tp_name, min_len, len);
111 Py_DECREF(arg);
112 return NULL;
113 }
114
115 if (len > max_len) {
116 PyErr_Format(PyExc_TypeError,
117 "%.500s() takes an at most %zd-sequence (%zd-sequence given)",
118 type->tp_name, max_len, len);
119 Py_DECREF(arg);
120 return NULL;
121 }
122 }
123 else {
124 if (len != min_len) {
125 PyErr_Format(PyExc_TypeError,
126 "%.500s() takes a %zd-sequence (%zd-sequence given)",
127 type->tp_name, min_len, len);
128 Py_DECREF(arg);
129 return NULL;
130 }
131 }
132
133 res = (PyStructSequence*) PyStructSequence_New(type);
134 if (res == NULL) {
135 Py_DECREF(arg);
136 return NULL;
137 }
138 for (i = 0; i < len; ++i) {
139 PyObject *v = PySequence_Fast_GET_ITEM(arg, i);
140 Py_INCREF(v);
141 res->ob_item[i] = v;
142 }
143 for (; i < max_len; ++i) {
144 if (dict && (ob = PyDict_GetItemString(
145 dict, type->tp_members[i-n_unnamed_fields].name))) {
146 }
147 else {
148 ob = Py_None;
149 }
150 Py_INCREF(ob);
151 res->ob_item[i] = ob;
152 }
153
154 Py_DECREF(arg);
155 return (PyObject*) res;
156 }
157
158
159 static PyObject *
structseq_repr(PyStructSequence * obj)160 structseq_repr(PyStructSequence *obj)
161 {
162 /* buffer and type size were chosen well considered. */
163 #define REPR_BUFFER_SIZE 512
164 #define TYPE_MAXSIZE 100
165
166 PyTypeObject *typ = Py_TYPE(obj);
167 Py_ssize_t i;
168 int removelast = 0;
169 Py_ssize_t len;
170 char buf[REPR_BUFFER_SIZE];
171 char *endofbuf, *pbuf = buf;
172
173 /* pointer to end of writeable buffer; safes space for "...)\0" */
174 endofbuf= &buf[REPR_BUFFER_SIZE-5];
175
176 /* "typename(", limited to TYPE_MAXSIZE */
177 len = strlen(typ->tp_name) > TYPE_MAXSIZE ? TYPE_MAXSIZE :
178 strlen(typ->tp_name);
179 strncpy(pbuf, typ->tp_name, len);
180 pbuf += len;
181 *pbuf++ = '(';
182
183 for (i=0; i < VISIBLE_SIZE(obj); i++) {
184 PyObject *val, *repr;
185 char *cname, *crepr;
186
187 cname = typ->tp_members[i].name;
188 if (cname == NULL) {
189 PyErr_Format(PyExc_SystemError, "In structseq_repr(), member %d name is NULL"
190 " for type %.500s", i, typ->tp_name);
191 return NULL;
192 }
193 val = PyStructSequence_GET_ITEM(obj, i);
194 repr = PyObject_Repr(val);
195 if (repr == NULL)
196 return NULL;
197 crepr = PyUnicode_AsUTF8(repr);
198 if (crepr == NULL) {
199 Py_DECREF(repr);
200 return NULL;
201 }
202
203 /* + 3: keep space for "=" and ", " */
204 len = strlen(cname) + strlen(crepr) + 3;
205 if ((pbuf+len) <= endofbuf) {
206 strcpy(pbuf, cname);
207 pbuf += strlen(cname);
208 *pbuf++ = '=';
209 strcpy(pbuf, crepr);
210 pbuf += strlen(crepr);
211 *pbuf++ = ',';
212 *pbuf++ = ' ';
213 removelast = 1;
214 Py_DECREF(repr);
215 }
216 else {
217 strcpy(pbuf, "...");
218 pbuf += 3;
219 removelast = 0;
220 Py_DECREF(repr);
221 break;
222 }
223 }
224 if (removelast) {
225 /* overwrite last ", " */
226 pbuf-=2;
227 }
228 *pbuf++ = ')';
229 *pbuf = '\0';
230
231 return PyUnicode_FromString(buf);
232 }
233
234 static PyObject *
structseq_reduce(PyStructSequence * self)235 structseq_reduce(PyStructSequence* self)
236 {
237 PyObject* tup = NULL;
238 PyObject* dict = NULL;
239 PyObject* result;
240 Py_ssize_t n_fields, n_visible_fields, n_unnamed_fields, i;
241
242 n_fields = REAL_SIZE(self);
243 n_visible_fields = VISIBLE_SIZE(self);
244 n_unnamed_fields = UNNAMED_FIELDS(self);
245 tup = PyTuple_New(n_visible_fields);
246 if (!tup)
247 goto error;
248
249 dict = PyDict_New();
250 if (!dict)
251 goto error;
252
253 for (i = 0; i < n_visible_fields; i++) {
254 Py_INCREF(self->ob_item[i]);
255 PyTuple_SET_ITEM(tup, i, self->ob_item[i]);
256 }
257
258 for (; i < n_fields; i++) {
259 char *n = Py_TYPE(self)->tp_members[i-n_unnamed_fields].name;
260 if (PyDict_SetItemString(dict, n, self->ob_item[i]) < 0)
261 goto error;
262 }
263
264 result = Py_BuildValue("(O(OO))", Py_TYPE(self), tup, dict);
265
266 Py_DECREF(tup);
267 Py_DECREF(dict);
268
269 return result;
270
271 error:
272 Py_XDECREF(tup);
273 Py_XDECREF(dict);
274 return NULL;
275 }
276
277 static PyMethodDef structseq_methods[] = {
278 {"__reduce__", (PyCFunction)structseq_reduce, METH_NOARGS, NULL},
279 {NULL, NULL}
280 };
281
282 static PyTypeObject _struct_sequence_template = {
283 PyVarObject_HEAD_INIT(&PyType_Type, 0)
284 NULL, /* tp_name */
285 sizeof(PyStructSequence) - sizeof(PyObject *), /* tp_basicsize */
286 sizeof(PyObject *), /* tp_itemsize */
287 (destructor)structseq_dealloc, /* tp_dealloc */
288 0, /* tp_print */
289 0, /* tp_getattr */
290 0, /* tp_setattr */
291 0, /* tp_reserved */
292 (reprfunc)structseq_repr, /* tp_repr */
293 0, /* tp_as_number */
294 0, /* tp_as_sequence */
295 0, /* tp_as_mapping */
296 0, /* tp_hash */
297 0, /* tp_call */
298 0, /* tp_str */
299 0, /* tp_getattro */
300 0, /* tp_setattro */
301 0, /* tp_as_buffer */
302 Py_TPFLAGS_DEFAULT, /* tp_flags */
303 NULL, /* tp_doc */
304 0, /* tp_traverse */
305 0, /* tp_clear */
306 0, /* tp_richcompare */
307 0, /* tp_weaklistoffset */
308 0, /* tp_iter */
309 0, /* tp_iternext */
310 structseq_methods, /* tp_methods */
311 NULL, /* tp_members */
312 0, /* tp_getset */
313 0, /* tp_base */
314 0, /* tp_dict */
315 0, /* tp_descr_get */
316 0, /* tp_descr_set */
317 0, /* tp_dictoffset */
318 0, /* tp_init */
319 0, /* tp_alloc */
320 structseq_new, /* tp_new */
321 };
322
323 int
PyStructSequence_InitType2(PyTypeObject * type,PyStructSequence_Desc * desc)324 PyStructSequence_InitType2(PyTypeObject *type, PyStructSequence_Desc *desc)
325 {
326 PyObject *dict;
327 PyMemberDef* members;
328 Py_ssize_t n_members, n_unnamed_members, i, k;
329 PyObject *v;
330
331 #ifdef Py_TRACE_REFS
332 /* if the type object was chained, unchain it first
333 before overwriting its storage */
334 if (type->ob_base.ob_base._ob_next) {
335 _Py_ForgetReference((PyObject*)type);
336 }
337 #endif
338
339 n_unnamed_members = 0;
340 for (i = 0; desc->fields[i].name != NULL; ++i)
341 if (desc->fields[i].name == PyStructSequence_UnnamedField)
342 n_unnamed_members++;
343 n_members = i;
344
345 memcpy(type, &_struct_sequence_template, sizeof(PyTypeObject));
346 type->tp_base = &PyTuple_Type;
347 type->tp_name = desc->name;
348 type->tp_doc = desc->doc;
349
350 members = PyMem_NEW(PyMemberDef, n_members-n_unnamed_members+1);
351 if (members == NULL) {
352 PyErr_NoMemory();
353 return -1;
354 }
355
356 for (i = k = 0; i < n_members; ++i) {
357 if (desc->fields[i].name == PyStructSequence_UnnamedField)
358 continue;
359 members[k].name = desc->fields[i].name;
360 members[k].type = T_OBJECT;
361 members[k].offset = offsetof(PyStructSequence, ob_item)
362 + i * sizeof(PyObject*);
363 members[k].flags = READONLY;
364 members[k].doc = desc->fields[i].doc;
365 k++;
366 }
367 members[k].name = NULL;
368
369 type->tp_members = members;
370
371 if (PyType_Ready(type) < 0)
372 return -1;
373 Py_INCREF(type);
374
375 dict = type->tp_dict;
376 #define SET_DICT_FROM_SIZE(key, value) \
377 do { \
378 v = PyLong_FromSsize_t(value); \
379 if (v == NULL) \
380 return -1; \
381 if (PyDict_SetItemString(dict, key, v) < 0) { \
382 Py_DECREF(v); \
383 return -1; \
384 } \
385 Py_DECREF(v); \
386 } while (0)
387
388 SET_DICT_FROM_SIZE(visible_length_key, desc->n_in_sequence);
389 SET_DICT_FROM_SIZE(real_length_key, n_members);
390 SET_DICT_FROM_SIZE(unnamed_fields_key, n_unnamed_members);
391
392 return 0;
393 }
394
395 void
PyStructSequence_InitType(PyTypeObject * type,PyStructSequence_Desc * desc)396 PyStructSequence_InitType(PyTypeObject *type, PyStructSequence_Desc *desc)
397 {
398 (void)PyStructSequence_InitType2(type, desc);
399 }
400
401 PyTypeObject*
PyStructSequence_NewType(PyStructSequence_Desc * desc)402 PyStructSequence_NewType(PyStructSequence_Desc *desc)
403 {
404 PyTypeObject *result;
405
406 result = (PyTypeObject*)PyType_GenericAlloc(&PyType_Type, 0);
407 if (result == NULL)
408 return NULL;
409 if (PyStructSequence_InitType2(result, desc) < 0) {
410 Py_DECREF(result);
411 return NULL;
412 }
413 return result;
414 }
415
_PyStructSequence_Init(void)416 int _PyStructSequence_Init(void)
417 {
418 if (_PyUnicode_FromId(&PyId_n_sequence_fields) == NULL
419 || _PyUnicode_FromId(&PyId_n_fields) == NULL
420 || _PyUnicode_FromId(&PyId_n_unnamed_fields) == NULL)
421 return -1;
422
423 return 0;
424 }
425