Looks like someone renamed (or something) md5c.c to md5.c.
[python.git] / Objects / sliceobject.c
blob271a9ad62d223823cc4b8508f98d5a84eddb5f8d
1 /*
2 Written by Jim Hugunin and Chris Chase.
4 This includes both the singular ellipsis object and slice objects.
6 Guido, feel free to do whatever you want in the way of copyrights
7 for this file.
8 */
10 /*
11 Py_Ellipsis encodes the '...' rubber index token. It is similar to
12 the Py_NoneStruct in that there is no way to create other objects of
13 this type and there is exactly one in existence.
16 #include "Python.h"
17 #include "structmember.h"
19 static PyObject *
20 ellipsis_repr(PyObject *op)
22 return PyString_FromString("Ellipsis");
25 static PyTypeObject PyEllipsis_Type = {
26 PyObject_HEAD_INIT(&PyType_Type)
27 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 */
49 PyObject _Py_EllipsisObject = {
50 PyObject_HEAD_INIT(&PyEllipsis_Type)
54 /* Slice object implementation
56 start, stop, and step are python objects with None indicating no
57 index is present.
60 PyObject *
61 PySlice_New(PyObject *start, PyObject *stop, PyObject *step)
63 PySliceObject *obj = PyObject_New(PySliceObject, &PySlice_Type);
65 if (obj == NULL)
66 return NULL;
68 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);
75 obj->step = step;
76 obj->start = start;
77 obj->stop = stop;
79 return (PyObject *) obj;
82 PyObject *
83 _PySlice_FromIndices(Py_ssize_t istart, Py_ssize_t istop)
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;
95 slice = PySlice_New(start, end, NULL);
96 Py_DECREF(start);
97 Py_DECREF(end);
98 return slice;
102 PySlice_GetIndices(PySliceObject *r, Py_ssize_t length,
103 Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step)
105 /* XXX support long ints */
106 if (r->step == Py_None) {
107 *step = 1;
108 } else {
109 if (!PyInt_Check(r->step) && !PyLong_Check(r->step)) return -1;
110 *step = PyInt_AsSsize_t(r->step);
112 if (r->start == Py_None) {
113 *start = *step < 0 ? length-1 : 0;
114 } else {
115 if (!PyInt_Check(r->start) && !PyLong_Check(r->step)) return -1;
116 *start = PyInt_AsSsize_t(r->start);
117 if (*start < 0) *start += length;
119 if (r->stop == Py_None) {
120 *stop = *step < 0 ? -1 : length;
121 } else {
122 if (!PyInt_Check(r->stop) && !PyLong_Check(r->step)) return -1;
123 *stop = PyInt_AsSsize_t(r->stop);
124 if (*stop < 0) *stop += length;
126 if (*stop > length) return -1;
127 if (*start >= length) return -1;
128 if (*step == 0) return -1;
129 return 0;
133 PySlice_GetIndicesEx(PySliceObject *r, Py_ssize_t length,
134 Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step, Py_ssize_t *slicelength)
136 /* this is harder to get right than you might think */
138 Py_ssize_t defstart, defstop;
140 if (r->step == Py_None) {
141 *step = 1;
143 else {
144 if (!_PyEval_SliceIndex(r->step, step)) return -1;
145 if (*step == 0) {
146 PyErr_SetString(PyExc_ValueError,
147 "slice step cannot be zero");
148 return -1;
152 defstart = *step < 0 ? length-1 : 0;
153 defstop = *step < 0 ? -1 : length;
155 if (r->start == Py_None) {
156 *start = defstart;
158 else {
159 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;
166 if (r->stop == Py_None) {
167 *stop = defstop;
169 else {
170 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;
176 if ((*step < 0 && *stop >= *start)
177 || (*step > 0 && *start >= *stop)) {
178 *slicelength = 0;
180 else if (*step < 0) {
181 *slicelength = (*stop-*start+1)/(*step)+1;
183 else {
184 *slicelength = (*stop-*start-1)/(*step)+1;
187 return 0;
190 static PyObject *
191 slice_new(PyTypeObject *type, PyObject *args, PyObject *kw)
193 PyObject *start, *stop, *step;
195 start = stop = step = NULL;
197 if (!_PyArg_NoKeywords("slice()", kw))
198 return NULL;
200 if (!PyArg_UnpackTuple(args, "slice", 1, 3, &start, &stop, &step))
201 return NULL;
203 /* This swapping of stop and start is to maintain similarity with
204 range(). */
205 if (stop == NULL) {
206 stop = start;
207 start = NULL;
209 return PySlice_New(start, stop, step);
212 PyDoc_STRVAR(slice_doc,
213 "slice([start,] stop[, step])\n\
215 Create a slice object. This is used for extended slicing (e.g. a[0:10:2]).");
217 static void
218 slice_dealloc(PySliceObject *r)
220 Py_DECREF(r->step);
221 Py_DECREF(r->start);
222 Py_DECREF(r->stop);
223 PyObject_Del(r);
226 static PyObject *
227 slice_repr(PySliceObject *r)
229 PyObject *s, *comma;
231 s = PyString_FromString("slice(");
232 comma = PyString_FromString(", ");
233 PyString_ConcatAndDel(&s, PyObject_Repr(r->start));
234 PyString_Concat(&s, comma);
235 PyString_ConcatAndDel(&s, PyObject_Repr(r->stop));
236 PyString_Concat(&s, comma);
237 PyString_ConcatAndDel(&s, PyObject_Repr(r->step));
238 PyString_ConcatAndDel(&s, PyString_FromString(")"));
239 Py_DECREF(comma);
240 return s;
243 static PyMemberDef slice_members[] = {
244 {"start", T_OBJECT, offsetof(PySliceObject, start), READONLY},
245 {"stop", T_OBJECT, offsetof(PySliceObject, stop), READONLY},
246 {"step", T_OBJECT, offsetof(PySliceObject, step), READONLY},
250 static PyObject*
251 slice_indices(PySliceObject* self, PyObject* len)
253 Py_ssize_t ilen, start, stop, step, slicelength;
255 ilen = PyInt_AsSsize_t(len);
257 if (ilen == -1 && PyErr_Occurred()) {
258 return NULL;
261 if (PySlice_GetIndicesEx(self, ilen, &start, &stop,
262 &step, &slicelength) < 0) {
263 return NULL;
266 return Py_BuildValue("(nnn)", start, stop, step);
269 PyDoc_STRVAR(slice_indices_doc,
270 "S.indices(len) -> (start, stop, stride)\n\
272 Assuming a sequence of length len, calculate the start and stop\n\
273 indices, and the stride length of the extended slice described by\n\
274 S. Out of bounds indices are clipped in a manner consistent with the\n\
275 handling of normal slices.");
277 static PyMethodDef slice_methods[] = {
278 {"indices", (PyCFunction)slice_indices,
279 METH_O, slice_indices_doc},
280 {NULL, NULL}
283 static int
284 slice_compare(PySliceObject *v, PySliceObject *w)
286 int result = 0;
288 if (v == w)
289 return 0;
291 if (PyObject_Cmp(v->start, w->start, &result) < 0)
292 return -2;
293 if (result != 0)
294 return result;
295 if (PyObject_Cmp(v->stop, w->stop, &result) < 0)
296 return -2;
297 if (result != 0)
298 return result;
299 if (PyObject_Cmp(v->step, w->step, &result) < 0)
300 return -2;
301 return result;
304 static long
305 slice_hash(PySliceObject *v)
307 PyErr_SetString(PyExc_TypeError, "unhashable type");
308 return -1L;
311 PyTypeObject PySlice_Type = {
312 PyObject_HEAD_INIT(&PyType_Type)
313 0, /* Number of items for varobject */
314 "slice", /* Name of this type */
315 sizeof(PySliceObject), /* Basic object size */
316 0, /* Item size for varobject */
317 (destructor)slice_dealloc, /* tp_dealloc */
318 0, /* tp_print */
319 0, /* tp_getattr */
320 0, /* tp_setattr */
321 (cmpfunc)slice_compare, /* tp_compare */
322 (reprfunc)slice_repr, /* tp_repr */
323 0, /* tp_as_number */
324 0, /* tp_as_sequence */
325 0, /* tp_as_mapping */
326 (hashfunc)slice_hash, /* tp_hash */
327 0, /* tp_call */
328 0, /* tp_str */
329 PyObject_GenericGetAttr, /* tp_getattro */
330 0, /* tp_setattro */
331 0, /* tp_as_buffer */
332 Py_TPFLAGS_DEFAULT, /* tp_flags */
333 slice_doc, /* tp_doc */
334 0, /* tp_traverse */
335 0, /* tp_clear */
336 0, /* tp_richcompare */
337 0, /* tp_weaklistoffset */
338 0, /* tp_iter */
339 0, /* tp_iternext */
340 slice_methods, /* tp_methods */
341 slice_members, /* tp_members */
342 0, /* tp_getset */
343 0, /* tp_base */
344 0, /* tp_dict */
345 0, /* tp_descr_get */
346 0, /* tp_descr_set */
347 0, /* tp_dictoffset */
348 0, /* tp_init */
349 0, /* tp_alloc */
350 slice_new, /* tp_new */