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Guido van Rossumf2d125b1996-07-30 16:45:48 +00001/*
2Written by Jim Hugunin and Chris Chase.
3
Guido van Rossume449af71996-10-11 16:25:41 +00004This includes both the singular ellipsis object and slice objects.
Guido van Rossumf2d125b1996-07-30 16:45:48 +00005
6Guido, feel free to do whatever you want in the way of copyrights
7for this file.
8*/
9
10/*
Guido van Rossume449af71996-10-11 16:25:41 +000011Py_Ellipsis encodes the '...' rubber index token. It is similar to
Guido van Rossumf2d125b1996-07-30 16:45:48 +000012the Py_NoneStruct in that there is no way to create other objects of
13this type and there is exactly one in existence.
14*/
15
16#include "Python.h"
Tim Peters6d6c1a32001-08-02 04:15:00 +000017#include "structmember.h"
Guido van Rossumf2d125b1996-07-30 16:45:48 +000018
19static PyObject *
Fred Drake45cfbcc2000-07-09 06:21:27 +000020ellipsis_repr(PyObject *op)
Guido van Rossumf2d125b1996-07-30 16:45:48 +000021{
Walter Dörwald1ab83302007-05-18 17:15:44 +000022 return PyUnicode_FromString("Ellipsis");
Guido van Rossumf2d125b1996-07-30 16:45:48 +000023}
24
Guido van Rossume449af71996-10-11 16:25:41 +000025static PyTypeObject PyEllipsis_Type = {
Guido van Rossumf2d125b1996-07-30 16:45:48 +000026 PyObject_HEAD_INIT(&PyType_Type)
Thomas Wouters49fd7fa2006-04-21 10:40:58 +000027 0, /* ob_size */
28 "ellipsis", /* tp_name */
29 0, /* tp_basicsize */
30 0, /* tp_itemsize */
31 0, /*never called*/ /* tp_dealloc */
32 0, /* tp_print */
33 0, /* tp_getattr */
34 0, /* tp_setattr */
35 0, /* tp_compare */
36 ellipsis_repr, /* tp_repr */
37 0, /* tp_as_number */
38 0, /* tp_as_sequence */
39 0, /* tp_as_mapping */
40 0, /* tp_hash */
41 0, /* tp_call */
42 0, /* tp_str */
43 PyObject_GenericGetAttr, /* tp_getattro */
44 0, /* tp_setattro */
45 0, /* tp_as_buffer */
46 Py_TPFLAGS_DEFAULT, /* tp_flags */
Guido van Rossumf2d125b1996-07-30 16:45:48 +000047};
48
Guido van Rossume449af71996-10-11 16:25:41 +000049PyObject _Py_EllipsisObject = {
50 PyObject_HEAD_INIT(&PyEllipsis_Type)
Guido van Rossumf2d125b1996-07-30 16:45:48 +000051};
52
53
54/* Slice object implementation
55
56 start, stop, and step are python objects with None indicating no
57 index is present.
58*/
59
60PyObject *
Fred Drake45cfbcc2000-07-09 06:21:27 +000061PySlice_New(PyObject *start, PyObject *stop, PyObject *step)
Guido van Rossumf2d125b1996-07-30 16:45:48 +000062{
Neil Schemenauer7465ad22002-04-12 03:05:37 +000063 PySliceObject *obj = PyObject_New(PySliceObject, &PySlice_Type);
Guido van Rossumf2d125b1996-07-30 16:45:48 +000064
Guido van Rossumadf54102000-12-14 15:09:46 +000065 if (obj == NULL)
66 return NULL;
67
Guido van Rossumf2d125b1996-07-30 16:45:48 +000068 if (step == NULL) step = Py_None;
69 Py_INCREF(step);
70 if (start == NULL) start = Py_None;
71 Py_INCREF(start);
72 if (stop == NULL) stop = Py_None;
73 Py_INCREF(stop);
74
75 obj->step = step;
76 obj->start = start;
77 obj->stop = stop;
78
79 return (PyObject *) obj;
80}
81
Thomas Wouters49fd7fa2006-04-21 10:40:58 +000082PyObject *
83_PySlice_FromIndices(Py_ssize_t istart, Py_ssize_t istop)
84{
85 PyObject *start, *end, *slice;
86 start = PyInt_FromSsize_t(istart);
87 if (!start)
88 return NULL;
89 end = PyInt_FromSsize_t(istop);
90 if (!end) {
91 Py_DECREF(start);
92 return NULL;
93 }
94
95 slice = PySlice_New(start, end, NULL);
96 Py_DECREF(start);
97 Py_DECREF(end);
98 return slice;
99}
100
Guido van Rossumf2d125b1996-07-30 16:45:48 +0000101int
Martin v. Löwis18e16552006-02-15 17:27:45 +0000102PySlice_GetIndices(PySliceObject *r, Py_ssize_t length,
103 Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step)
Guido van Rossumf2d125b1996-07-30 16:45:48 +0000104{
Martin v. Löwis18e16552006-02-15 17:27:45 +0000105 /* XXX support long ints */
Guido van Rossumf2d125b1996-07-30 16:45:48 +0000106 if (r->step == Py_None) {
107 *step = 1;
108 } else {
Thomas Wouters49fd7fa2006-04-21 10:40:58 +0000109 if (!PyInt_Check(r->step) && !PyLong_Check(r->step)) return -1;
110 *step = PyInt_AsSsize_t(r->step);
Guido van Rossumf2d125b1996-07-30 16:45:48 +0000111 }
112 if (r->start == Py_None) {
113 *start = *step < 0 ? length-1 : 0;
114 } else {
Thomas Wouters49fd7fa2006-04-21 10:40:58 +0000115 if (!PyInt_Check(r->start) && !PyLong_Check(r->step)) return -1;
116 *start = PyInt_AsSsize_t(r->start);
Guido van Rossumf2d125b1996-07-30 16:45:48 +0000117 if (*start < 0) *start += length;
118 }
119 if (r->stop == Py_None) {
120 *stop = *step < 0 ? -1 : length;
121 } else {
Thomas Wouters49fd7fa2006-04-21 10:40:58 +0000122 if (!PyInt_Check(r->stop) && !PyLong_Check(r->step)) return -1;
123 *stop = PyInt_AsSsize_t(r->stop);
Guido van Rossumf2d125b1996-07-30 16:45:48 +0000124 if (*stop < 0) *stop += length;
125 }
126 if (*stop > length) return -1;
127 if (*start >= length) return -1;
128 if (*step == 0) return -1;
129 return 0;
130}
131
Michael W. Hudson5efaf7e2002-06-11 10:55:12 +0000132int
Martin v. Löwis18e16552006-02-15 17:27:45 +0000133PySlice_GetIndicesEx(PySliceObject *r, Py_ssize_t length,
134 Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step, Py_ssize_t *slicelength)
Michael W. Hudson5efaf7e2002-06-11 10:55:12 +0000135{
136 /* this is harder to get right than you might think */
Michael W. Hudson173f11d2002-11-05 15:28:51 +0000137
Martin v. Löwis18e16552006-02-15 17:27:45 +0000138 Py_ssize_t defstart, defstop;
Michael W. Hudson5efaf7e2002-06-11 10:55:12 +0000139
140 if (r->step == Py_None) {
141 *step = 1;
Michael W. Hudson173f11d2002-11-05 15:28:51 +0000142 }
143 else {
Michael W. Hudsoncbd6fb92002-11-06 15:17:32 +0000144 if (!_PyEval_SliceIndex(r->step, step)) return -1;
145 if (*step == 0) {
Michael W. Hudson5efaf7e2002-06-11 10:55:12 +0000146 PyErr_SetString(PyExc_ValueError,
147 "slice step cannot be zero");
148 return -1;
149 }
150 }
151
152 defstart = *step < 0 ? length-1 : 0;
153 defstop = *step < 0 ? -1 : length;
154
155 if (r->start == Py_None) {
156 *start = defstart;
Michael W. Hudson173f11d2002-11-05 15:28:51 +0000157 }
158 else {
Michael W. Hudson5efaf7e2002-06-11 10:55:12 +0000159 if (!_PyEval_SliceIndex(r->start, start)) return -1;
160 if (*start < 0) *start += length;
161 if (*start < 0) *start = (*step < 0) ? -1 : 0;
162 if (*start >= length)
163 *start = (*step < 0) ? length - 1 : length;
164 }
165
166 if (r->stop == Py_None) {
167 *stop = defstop;
Michael W. Hudson173f11d2002-11-05 15:28:51 +0000168 }
169 else {
Michael W. Hudson5efaf7e2002-06-11 10:55:12 +0000170 if (!_PyEval_SliceIndex(r->stop, stop)) return -1;
171 if (*stop < 0) *stop += length;
172 if (*stop < 0) *stop = -1;
173 if (*stop > length) *stop = length;
174 }
Michael W. Hudson173f11d2002-11-05 15:28:51 +0000175
176 if ((*step < 0 && *stop >= *start)
177 || (*step > 0 && *start >= *stop)) {
Michael W. Hudson589dc932002-06-11 13:38:42 +0000178 *slicelength = 0;
179 }
180 else if (*step < 0) {
Michael W. Hudson5efaf7e2002-06-11 10:55:12 +0000181 *slicelength = (*stop-*start+1)/(*step)+1;
Michael W. Hudson173f11d2002-11-05 15:28:51 +0000182 }
183 else {
Michael W. Hudson5efaf7e2002-06-11 10:55:12 +0000184 *slicelength = (*stop-*start-1)/(*step)+1;
185 }
Michael W. Hudson5efaf7e2002-06-11 10:55:12 +0000186
187 return 0;
188}
189
Guido van Rossumbea18cc2002-06-14 20:41:17 +0000190static PyObject *
191slice_new(PyTypeObject *type, PyObject *args, PyObject *kw)
192{
193 PyObject *start, *stop, *step;
194
195 start = stop = step = NULL;
196
Georg Brandl02c42872005-08-26 06:42:30 +0000197 if (!_PyArg_NoKeywords("slice()", kw))
198 return NULL;
199
Raymond Hettingerea3fdf42002-12-29 16:33:45 +0000200 if (!PyArg_UnpackTuple(args, "slice", 1, 3, &start, &stop, &step))
Guido van Rossumbea18cc2002-06-14 20:41:17 +0000201 return NULL;
202
203 /* This swapping of stop and start is to maintain similarity with
204 range(). */
205 if (stop == NULL) {
206 stop = start;
207 start = NULL;
208 }
209 return PySlice_New(start, stop, step);
210}
211
212PyDoc_STRVAR(slice_doc,
213"slice([start,] stop[, step])\n\
214\n\
215Create a slice object. This is used for extended slicing (e.g. a[0:10:2]).");
216
Guido van Rossumf2d125b1996-07-30 16:45:48 +0000217static void
Fred Drake45cfbcc2000-07-09 06:21:27 +0000218slice_dealloc(PySliceObject *r)
Guido van Rossumf2d125b1996-07-30 16:45:48 +0000219{
220 Py_DECREF(r->step);
221 Py_DECREF(r->start);
222 Py_DECREF(r->stop);
Neil Schemenauer7465ad22002-04-12 03:05:37 +0000223 PyObject_Del(r);
Guido van Rossumf2d125b1996-07-30 16:45:48 +0000224}
225
226static PyObject *
Fred Drake45cfbcc2000-07-09 06:21:27 +0000227slice_repr(PySliceObject *r)
Guido van Rossumf2d125b1996-07-30 16:45:48 +0000228{
Walter Dörwald7569dfe2007-05-19 21:49:49 +0000229 return PyUnicode_FromFormat("slice(%R, %R, %R)", r->start, r->stop, r->step);
Guido van Rossumf2d125b1996-07-30 16:45:48 +0000230}
231
Guido van Rossum6f799372001-09-20 20:46:19 +0000232static PyMemberDef slice_members[] = {
Tim Peters6d6c1a32001-08-02 04:15:00 +0000233 {"start", T_OBJECT, offsetof(PySliceObject, start), READONLY},
234 {"stop", T_OBJECT, offsetof(PySliceObject, stop), READONLY},
235 {"step", T_OBJECT, offsetof(PySliceObject, step), READONLY},
236 {0}
237};
Guido van Rossumf2d125b1996-07-30 16:45:48 +0000238
Michael W. Hudsonf0d777c2002-07-19 15:47:06 +0000239static PyObject*
240slice_indices(PySliceObject* self, PyObject* len)
241{
Martin v. Löwis18e16552006-02-15 17:27:45 +0000242 Py_ssize_t ilen, start, stop, step, slicelength;
Michael W. Hudsonf0d777c2002-07-19 15:47:06 +0000243
Thomas Wouters00ee7ba2006-08-21 19:07:27 +0000244 ilen = PyNumber_AsSsize_t(len, PyExc_OverflowError);
Michael W. Hudsonf0d777c2002-07-19 15:47:06 +0000245
246 if (ilen == -1 && PyErr_Occurred()) {
247 return NULL;
248 }
249
250 if (PySlice_GetIndicesEx(self, ilen, &start, &stop,
251 &step, &slicelength) < 0) {
252 return NULL;
253 }
254
Thomas Wouters49fd7fa2006-04-21 10:40:58 +0000255 return Py_BuildValue("(nnn)", start, stop, step);
Michael W. Hudsonf0d777c2002-07-19 15:47:06 +0000256}
257
258PyDoc_STRVAR(slice_indices_doc,
259"S.indices(len) -> (start, stop, stride)\n\
260\n\
261Assuming a sequence of length len, calculate the start and stop\n\
262indices, and the stride length of the extended slice described by\n\
263S. Out of bounds indices are clipped in a manner consistent with the\n\
264handling of normal slices.");
265
Guido van Rossumd8faa362007-04-27 19:54:29 +0000266static PyObject *
267slice_reduce(PySliceObject* self)
268{
269 return Py_BuildValue("O(OOO)", self->ob_type, self->start, self->stop, self->step);
270}
271
272PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");
273
Michael W. Hudsonf0d777c2002-07-19 15:47:06 +0000274static PyMethodDef slice_methods[] = {
Michael W. Hudson206d8f82002-07-19 15:52:38 +0000275 {"indices", (PyCFunction)slice_indices,
Michael W. Hudsonf0d777c2002-07-19 15:47:06 +0000276 METH_O, slice_indices_doc},
Guido van Rossumd8faa362007-04-27 19:54:29 +0000277 {"__reduce__", (PyCFunction)slice_reduce,
278 METH_NOARGS, reduce_doc},
Michael W. Hudsonf0d777c2002-07-19 15:47:06 +0000279 {NULL, NULL}
280};
281
Guido van Rossum47b9ff62006-08-24 00:41:19 +0000282static PyObject *
283slice_richcompare(PyObject *v, PyObject *w, int op)
Guido van Rossuma1351fb2001-03-20 12:41:34 +0000284{
Guido van Rossum47b9ff62006-08-24 00:41:19 +0000285 PyObject *t1;
286 PyObject *t2;
287 PyObject *res;
Guido van Rossuma1351fb2001-03-20 12:41:34 +0000288
Guido van Rossum47b9ff62006-08-24 00:41:19 +0000289 if (v == w) {
290 /* XXX Do we really need this shortcut?
291 There's a unit test for it, but is that fair? */
292 switch (op) {
293 case Py_EQ:
294 case Py_LE:
295 case Py_GE:
296 res = Py_True;
297 break;
298 default:
299 res = Py_False;
300 break;
301 }
302 Py_INCREF(res);
303 return res;
304 }
Guido van Rossuma1351fb2001-03-20 12:41:34 +0000305
Guido van Rossum47b9ff62006-08-24 00:41:19 +0000306 t1 = PyTuple_New(3);
307 t2 = PyTuple_New(3);
308 if (t1 == NULL || t2 == NULL)
309 return NULL;
310
311 PyTuple_SET_ITEM(t1, 0, ((PySliceObject *)v)->start);
312 PyTuple_SET_ITEM(t1, 1, ((PySliceObject *)v)->stop);
313 PyTuple_SET_ITEM(t1, 2, ((PySliceObject *)v)->step);
314 PyTuple_SET_ITEM(t2, 0, ((PySliceObject *)w)->start);
315 PyTuple_SET_ITEM(t2, 1, ((PySliceObject *)w)->stop);
316 PyTuple_SET_ITEM(t2, 2, ((PySliceObject *)w)->step);
317
318 res = PyObject_RichCompare(t1, t2, op);
319
320 PyTuple_SET_ITEM(t1, 0, NULL);
321 PyTuple_SET_ITEM(t1, 1, NULL);
322 PyTuple_SET_ITEM(t1, 2, NULL);
323 PyTuple_SET_ITEM(t2, 0, NULL);
324 PyTuple_SET_ITEM(t2, 1, NULL);
325 PyTuple_SET_ITEM(t2, 2, NULL);
326
327 Py_DECREF(t1);
328 Py_DECREF(t2);
329
330 return res;
Guido van Rossuma1351fb2001-03-20 12:41:34 +0000331}
Guido van Rossumf2d125b1996-07-30 16:45:48 +0000332
Raymond Hettingerb859c072003-09-05 14:27:30 +0000333static long
334slice_hash(PySliceObject *v)
335{
336 PyErr_SetString(PyExc_TypeError, "unhashable type");
337 return -1L;
338}
339
Guido van Rossumf2d125b1996-07-30 16:45:48 +0000340PyTypeObject PySlice_Type = {
341 PyObject_HEAD_INIT(&PyType_Type)
342 0, /* Number of items for varobject */
343 "slice", /* Name of this type */
344 sizeof(PySliceObject), /* Basic object size */
345 0, /* Item size for varobject */
Tim Peters6d6c1a32001-08-02 04:15:00 +0000346 (destructor)slice_dealloc, /* tp_dealloc */
347 0, /* tp_print */
348 0, /* tp_getattr */
349 0, /* tp_setattr */
Guido van Rossum47b9ff62006-08-24 00:41:19 +0000350 0, /* tp_compare */
Tim Peters6d6c1a32001-08-02 04:15:00 +0000351 (reprfunc)slice_repr, /* tp_repr */
352 0, /* tp_as_number */
353 0, /* tp_as_sequence */
354 0, /* tp_as_mapping */
Raymond Hettingerb859c072003-09-05 14:27:30 +0000355 (hashfunc)slice_hash, /* tp_hash */
Tim Peters6d6c1a32001-08-02 04:15:00 +0000356 0, /* tp_call */
357 0, /* tp_str */
358 PyObject_GenericGetAttr, /* tp_getattro */
359 0, /* tp_setattro */
360 0, /* tp_as_buffer */
361 Py_TPFLAGS_DEFAULT, /* tp_flags */
Guido van Rossumbea18cc2002-06-14 20:41:17 +0000362 slice_doc, /* tp_doc */
Tim Peters6d6c1a32001-08-02 04:15:00 +0000363 0, /* tp_traverse */
364 0, /* tp_clear */
Guido van Rossum47b9ff62006-08-24 00:41:19 +0000365 slice_richcompare, /* tp_richcompare */
Tim Peters6d6c1a32001-08-02 04:15:00 +0000366 0, /* tp_weaklistoffset */
367 0, /* tp_iter */
368 0, /* tp_iternext */
Michael W. Hudsonf0d777c2002-07-19 15:47:06 +0000369 slice_methods, /* tp_methods */
Tim Peters6d6c1a32001-08-02 04:15:00 +0000370 slice_members, /* tp_members */
371 0, /* tp_getset */
372 0, /* tp_base */
373 0, /* tp_dict */
Guido van Rossumbea18cc2002-06-14 20:41:17 +0000374 0, /* tp_descr_get */
375 0, /* tp_descr_set */
376 0, /* tp_dictoffset */
377 0, /* tp_init */
378 0, /* tp_alloc */
379 slice_new, /* tp_new */
Guido van Rossumf2d125b1996-07-30 16:45:48 +0000380};