Use a more idiomatic check in check_truediv.
[python.git] / Objects / enumobject.c
blob2c1c3f8a50b4ec18614b0e11962cae6f42f32ebb
1 /* enumerate object */
3 #include "Python.h"
5 typedef struct {
6 PyObject_HEAD
7 Py_ssize_t en_index; /* current index of enumeration */
8 PyObject* en_sit; /* secondary iterator of enumeration */
9 PyObject* en_result; /* result tuple */
10 PyObject* en_longindex; /* index for sequences >= PY_SSIZE_T_MAX */
11 } enumobject;
13 static PyObject *
14 enum_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
16 enumobject *en;
17 PyObject *seq = NULL;
18 PyObject *start = NULL;
19 static char *kwlist[] = {"sequence", "start", 0};
21 if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|O:enumerate", kwlist,
22 &seq, &start))
23 return NULL;
25 en = (enumobject *)type->tp_alloc(type, 0);
26 if (en == NULL)
27 return NULL;
28 if (start != NULL) {
29 start = PyNumber_Index(start);
30 if (start == NULL) {
31 Py_DECREF(en);
32 return NULL;
34 assert(PyInt_Check(start) || PyLong_Check(start));
35 en->en_index = PyInt_AsSsize_t(start);
36 if (en->en_index == -1 && PyErr_Occurred()) {
37 PyErr_Clear();
38 en->en_index = PY_SSIZE_T_MAX;
39 en->en_longindex = start;
40 } else {
41 en->en_longindex = NULL;
42 Py_DECREF(start);
44 } else {
45 en->en_index = 0;
46 en->en_longindex = NULL;
48 en->en_sit = PyObject_GetIter(seq);
49 if (en->en_sit == NULL) {
50 Py_DECREF(en);
51 return NULL;
53 en->en_result = PyTuple_Pack(2, Py_None, Py_None);
54 if (en->en_result == NULL) {
55 Py_DECREF(en);
56 return NULL;
58 return (PyObject *)en;
61 static void
62 enum_dealloc(enumobject *en)
64 PyObject_GC_UnTrack(en);
65 Py_XDECREF(en->en_sit);
66 Py_XDECREF(en->en_result);
67 Py_XDECREF(en->en_longindex);
68 Py_TYPE(en)->tp_free(en);
71 static int
72 enum_traverse(enumobject *en, visitproc visit, void *arg)
74 Py_VISIT(en->en_sit);
75 Py_VISIT(en->en_result);
76 Py_VISIT(en->en_longindex);
77 return 0;
80 static PyObject *
81 enum_next_long(enumobject *en, PyObject* next_item)
83 static PyObject *one = NULL;
84 PyObject *result = en->en_result;
85 PyObject *next_index;
86 PyObject *stepped_up;
88 if (en->en_longindex == NULL) {
89 en->en_longindex = PyInt_FromSsize_t(PY_SSIZE_T_MAX);
90 if (en->en_longindex == NULL)
91 return NULL;
93 if (one == NULL) {
94 one = PyInt_FromLong(1);
95 if (one == NULL)
96 return NULL;
98 next_index = en->en_longindex;
99 assert(next_index != NULL);
100 stepped_up = PyNumber_Add(next_index, one);
101 if (stepped_up == NULL)
102 return NULL;
103 en->en_longindex = stepped_up;
105 if (result->ob_refcnt == 1) {
106 Py_INCREF(result);
107 Py_DECREF(PyTuple_GET_ITEM(result, 0));
108 Py_DECREF(PyTuple_GET_ITEM(result, 1));
109 } else {
110 result = PyTuple_New(2);
111 if (result == NULL) {
112 Py_DECREF(next_index);
113 Py_DECREF(next_item);
114 return NULL;
117 PyTuple_SET_ITEM(result, 0, next_index);
118 PyTuple_SET_ITEM(result, 1, next_item);
119 return result;
122 static PyObject *
123 enum_next(enumobject *en)
125 PyObject *next_index;
126 PyObject *next_item;
127 PyObject *result = en->en_result;
128 PyObject *it = en->en_sit;
130 next_item = (*Py_TYPE(it)->tp_iternext)(it);
131 if (next_item == NULL)
132 return NULL;
134 if (en->en_index == PY_SSIZE_T_MAX)
135 return enum_next_long(en, next_item);
137 next_index = PyInt_FromSsize_t(en->en_index);
138 if (next_index == NULL) {
139 Py_DECREF(next_item);
140 return NULL;
142 en->en_index++;
144 if (result->ob_refcnt == 1) {
145 Py_INCREF(result);
146 Py_DECREF(PyTuple_GET_ITEM(result, 0));
147 Py_DECREF(PyTuple_GET_ITEM(result, 1));
148 } else {
149 result = PyTuple_New(2);
150 if (result == NULL) {
151 Py_DECREF(next_index);
152 Py_DECREF(next_item);
153 return NULL;
156 PyTuple_SET_ITEM(result, 0, next_index);
157 PyTuple_SET_ITEM(result, 1, next_item);
158 return result;
161 PyDoc_STRVAR(enum_doc,
162 "enumerate(iterable) -> iterator for index, value of iterable\n"
163 "\n"
164 "Return an enumerate object. iterable must be another object that supports\n"
165 "iteration. The enumerate object yields pairs containing a count (from\n"
166 "zero) and a value yielded by the iterable argument. enumerate is useful\n"
167 "for obtaining an indexed list: (0, seq[0]), (1, seq[1]), (2, seq[2]), ...");
169 PyTypeObject PyEnum_Type = {
170 PyVarObject_HEAD_INIT(&PyType_Type, 0)
171 "enumerate", /* tp_name */
172 sizeof(enumobject), /* tp_basicsize */
173 0, /* tp_itemsize */
174 /* methods */
175 (destructor)enum_dealloc, /* tp_dealloc */
176 0, /* tp_print */
177 0, /* tp_getattr */
178 0, /* tp_setattr */
179 0, /* tp_compare */
180 0, /* tp_repr */
181 0, /* tp_as_number */
182 0, /* tp_as_sequence */
183 0, /* tp_as_mapping */
184 0, /* tp_hash */
185 0, /* tp_call */
186 0, /* tp_str */
187 PyObject_GenericGetAttr, /* tp_getattro */
188 0, /* tp_setattro */
189 0, /* tp_as_buffer */
190 Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
191 Py_TPFLAGS_BASETYPE, /* tp_flags */
192 enum_doc, /* tp_doc */
193 (traverseproc)enum_traverse, /* tp_traverse */
194 0, /* tp_clear */
195 0, /* tp_richcompare */
196 0, /* tp_weaklistoffset */
197 PyObject_SelfIter, /* tp_iter */
198 (iternextfunc)enum_next, /* tp_iternext */
199 0, /* tp_methods */
200 0, /* tp_members */
201 0, /* tp_getset */
202 0, /* tp_base */
203 0, /* tp_dict */
204 0, /* tp_descr_get */
205 0, /* tp_descr_set */
206 0, /* tp_dictoffset */
207 0, /* tp_init */
208 PyType_GenericAlloc, /* tp_alloc */
209 enum_new, /* tp_new */
210 PyObject_GC_Del, /* tp_free */
213 /* Reversed Object ***************************************************************/
215 typedef struct {
216 PyObject_HEAD
217 Py_ssize_t index;
218 PyObject* seq;
219 } reversedobject;
221 static PyObject *
222 reversed_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
224 Py_ssize_t n;
225 PyObject *seq, *reversed_meth;
226 static PyObject *reversed_cache = NULL;
227 reversedobject *ro;
229 if (type == &PyReversed_Type && !_PyArg_NoKeywords("reversed()", kwds))
230 return NULL;
232 if (!PyArg_UnpackTuple(args, "reversed", 1, 1, &seq) )
233 return NULL;
235 if (PyInstance_Check(seq)) {
236 reversed_meth = PyObject_GetAttrString(seq, "__reversed__");
237 if (reversed_meth == NULL) {
238 if (PyErr_ExceptionMatches(PyExc_AttributeError))
239 PyErr_Clear();
240 else
241 return NULL;
244 else {
245 reversed_meth = _PyObject_LookupSpecial(seq, "__reversed__",
246 &reversed_cache);
247 if (reversed_meth == NULL && PyErr_Occurred())
248 return NULL;
250 if (reversed_meth != NULL) {
251 PyObject *res = PyObject_CallFunctionObjArgs(reversed_meth, NULL);
252 Py_DECREF(reversed_meth);
253 return res;
256 if (!PySequence_Check(seq)) {
257 PyErr_SetString(PyExc_TypeError,
258 "argument to reversed() must be a sequence");
259 return NULL;
262 n = PySequence_Size(seq);
263 if (n == -1)
264 return NULL;
266 ro = (reversedobject *)type->tp_alloc(type, 0);
267 if (ro == NULL)
268 return NULL;
270 ro->index = n-1;
271 Py_INCREF(seq);
272 ro->seq = seq;
273 return (PyObject *)ro;
276 static void
277 reversed_dealloc(reversedobject *ro)
279 PyObject_GC_UnTrack(ro);
280 Py_XDECREF(ro->seq);
281 Py_TYPE(ro)->tp_free(ro);
284 static int
285 reversed_traverse(reversedobject *ro, visitproc visit, void *arg)
287 Py_VISIT(ro->seq);
288 return 0;
291 static PyObject *
292 reversed_next(reversedobject *ro)
294 PyObject *item;
295 Py_ssize_t index = ro->index;
297 if (index >= 0) {
298 item = PySequence_GetItem(ro->seq, index);
299 if (item != NULL) {
300 ro->index--;
301 return item;
303 if (PyErr_ExceptionMatches(PyExc_IndexError) ||
304 PyErr_ExceptionMatches(PyExc_StopIteration))
305 PyErr_Clear();
307 ro->index = -1;
308 Py_CLEAR(ro->seq);
309 return NULL;
312 PyDoc_STRVAR(reversed_doc,
313 "reversed(sequence) -> reverse iterator over values of the sequence\n"
314 "\n"
315 "Return a reverse iterator");
317 static PyObject *
318 reversed_len(reversedobject *ro)
320 Py_ssize_t position, seqsize;
322 if (ro->seq == NULL)
323 return PyInt_FromLong(0);
324 seqsize = PySequence_Size(ro->seq);
325 if (seqsize == -1)
326 return NULL;
327 position = ro->index + 1;
328 return PyInt_FromSsize_t((seqsize < position) ? 0 : position);
331 PyDoc_STRVAR(length_hint_doc, "Private method returning an estimate of len(list(it)).");
333 static PyMethodDef reversediter_methods[] = {
334 {"__length_hint__", (PyCFunction)reversed_len, METH_NOARGS, length_hint_doc},
335 {NULL, NULL} /* sentinel */
338 PyTypeObject PyReversed_Type = {
339 PyVarObject_HEAD_INIT(&PyType_Type, 0)
340 "reversed", /* tp_name */
341 sizeof(reversedobject), /* tp_basicsize */
342 0, /* tp_itemsize */
343 /* methods */
344 (destructor)reversed_dealloc, /* tp_dealloc */
345 0, /* tp_print */
346 0, /* tp_getattr */
347 0, /* tp_setattr */
348 0, /* tp_compare */
349 0, /* tp_repr */
350 0, /* tp_as_number */
351 0, /* tp_as_sequence */
352 0, /* tp_as_mapping */
353 0, /* tp_hash */
354 0, /* tp_call */
355 0, /* tp_str */
356 PyObject_GenericGetAttr, /* tp_getattro */
357 0, /* tp_setattro */
358 0, /* tp_as_buffer */
359 Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
360 Py_TPFLAGS_BASETYPE, /* tp_flags */
361 reversed_doc, /* tp_doc */
362 (traverseproc)reversed_traverse,/* tp_traverse */
363 0, /* tp_clear */
364 0, /* tp_richcompare */
365 0, /* tp_weaklistoffset */
366 PyObject_SelfIter, /* tp_iter */
367 (iternextfunc)reversed_next, /* tp_iternext */
368 reversediter_methods, /* tp_methods */
369 0, /* tp_members */
370 0, /* tp_getset */
371 0, /* tp_base */
372 0, /* tp_dict */
373 0, /* tp_descr_get */
374 0, /* tp_descr_set */
375 0, /* tp_dictoffset */
376 0, /* tp_init */
377 PyType_GenericAlloc, /* tp_alloc */
378 reversed_new, /* tp_new */
379 PyObject_GC_Del, /* tp_free */