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| 1 | /* | ||
| 2 | Written by Jim Hugunin and Chris Chase. | ||
| 3 | |||
| 4 | This includes both the singular ellipsis object and slice objects. | ||
| 5 | |||
| 6 | Guido, feel free to do whatever you want in the way of copyrights | ||
| 7 | for this file. | ||
| 8 | */ | ||
| 9 | |||
| 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. | ||
| 14 | */ | ||
| 15 | |||
| 16 | #include "Python.h" | ||
| 17 | #include "structmember.h" | ||
| 18 | |||
| 19 | static PyObject * | ||
| 20 | ellipsis_repr(PyObject *op) | ||
| 21 | { | ||
| 22 | return PyString_FromString("Ellipsis"); | ||
| 23 | } | ||
| 24 | |||
| 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 */ | ||
| 47 | }; | ||
| 48 | |||
| 49 | PyObject _Py_EllipsisObject = { | ||
| 50 | PyObject_HEAD_INIT(&PyEllipsis_Type) | ||
| 51 | }; | ||
| 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 | |||
| 60 | PyObject * | ||
| 61 | PySlice_New(PyObject *start, PyObject *stop, PyObject *step) | ||
| 62 | { | ||
| 63 | PySliceObject *obj = PyObject_New(PySliceObject, &PySlice_Type); | ||
| 64 | |||
| 65 | if (obj == NULL) | ||
| 66 | return NULL; | ||
| 67 | |||
| 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); | ||
| 74 | |||
| 75 | obj->step = step; | ||
| 76 | obj->start = start; | ||
| 77 | obj->stop = stop; | ||
| 78 | |||
| 79 | return (PyObject *) obj; | ||
| 80 | } | ||
| 81 | |||
| 82 | PyObject * | ||
| 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 | |||
| 101 | int | ||
| 102 | PySlice_GetIndices(PySliceObject *r, Py_ssize_t length, | ||
| 103 | Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step) | ||
| 104 | { | ||
| 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); | ||
| 111 | } | ||
| 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; | ||
| 118 | } | ||
| 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; | ||
| 125 | } | ||
| 126 | if (*stop > length) return -1; | ||
| 127 | if (*start >= length) return -1; | ||
| 128 | if (*step == 0) return -1; | ||
| 129 | return 0; | ||
| 130 | } | ||
| 131 | |||
| 132 | int | ||
| 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) | ||
| 135 | { | ||
| 136 | /* this is harder to get right than you might think */ | ||
| 137 | |||
| 138 | Py_ssize_t defstart, defstop; | ||
| 139 | |||
| 140 | if (r->step == Py_None) { | ||
| 141 | *step = 1; | ||
| 142 | } | ||
| 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; | ||
| 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; | ||
| 157 | } | ||
| 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; | ||
| 164 | } | ||
| 165 | |||
| 166 | if (r->stop == Py_None) { | ||
| 167 | *stop = defstop; | ||
| 168 | } | ||
| 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; | ||
| 174 | } | ||
| 175 | |||
| 176 | if ((*step < 0 && *stop >= *start) | ||
| 177 | || (*step > 0 && *start >= *stop)) { | ||
| 178 | *slicelength = 0; | ||
| 179 | } | ||
| 180 | else if (*step < 0) { | ||
| 181 | *slicelength = (*stop-*start+1)/(*step)+1; | ||
| 182 | } | ||
| 183 | else { | ||
| 184 | *slicelength = (*stop-*start-1)/(*step)+1; | ||
| 185 | } | ||
| 186 | |||
| 187 | return 0; | ||
| 188 | } | ||
| 189 | |||
| 190 | static PyObject * | ||
| 191 | slice_new(PyTypeObject *type, PyObject *args, PyObject *kw) | ||
| 192 | { | ||
| 193 | PyObject *start, *stop, *step; | ||
| 194 | |||
| 195 | start = stop = step = NULL; | ||
| 196 | |||
| 197 | if (!_PyArg_NoKeywords("slice()", kw)) | ||
| 198 | return NULL; | ||
| 199 | |||
| 200 | if (!PyArg_UnpackTuple(args, "slice", 1, 3, &start, &stop, &step)) | ||
| 201 | 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 | |||
| 212 | PyDoc_STRVAR(slice_doc, | ||
| 213 | "slice([start,] stop[, step])\n\ | ||
| 214 | \n\ | ||
| 215 | Create a slice object. This is used for extended slicing (e.g. a[0:10:2])."); | ||
| 216 | |||
| 217 | static void | ||
| 218 | slice_dealloc(PySliceObject *r) | ||
| 219 | { | ||
| 220 | Py_DECREF(r->step); | ||
| 221 | Py_DECREF(r->start); | ||
| 222 | Py_DECREF(r->stop); | ||
| 223 | PyObject_Del(r); | ||
| 224 | } | ||
| 225 | |||
| 226 | static PyObject * | ||
| 227 | slice_repr(PySliceObject *r) | ||
| 228 | { | ||
| 229 | PyObject *s, *comma; | ||
| 230 | |||
| 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; | ||
| 241 | } | ||
| 242 | |||
| 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}, | ||
| 247 | {0} | ||
| 248 | }; | ||
| 249 | |||
| 250 | static PyObject* | ||
| 251 | slice_indices(PySliceObject* self, PyObject* len) | ||
| 252 | { | ||
| 253 | Py_ssize_t ilen, start, stop, step, slicelength; | ||
| 254 | |||
| 255 | ilen = PyNumber_AsSsize_t(len, PyExc_OverflowError); | ||
| 256 | |||
| 257 | if (ilen == -1 && PyErr_Occurred()) { | ||
| 258 | return NULL; | ||
| 259 | } | ||
| 260 | |||
| 261 | if (PySlice_GetIndicesEx(self, ilen, &start, &stop, | ||
| 262 | &step, &slicelength) < 0) { | ||
| 263 | return NULL; | ||
| 264 | } | ||
| 265 | |||
| 266 | return Py_BuildValue("(nnn)", start, stop, step); | ||
| 267 | } | ||
| 268 | |||
| 269 | PyDoc_STRVAR(slice_indices_doc, | ||
| 270 | "S.indices(len) -> (start, stop, stride)\n\ | ||
| 271 | \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."); | ||
| 276 | |||
| 277 | static PyMethodDef slice_methods[] = { | ||
| 278 | {"indices", (PyCFunction)slice_indices, | ||
| 279 | METH_O, slice_indices_doc}, | ||
| 280 | {NULL, NULL} | ||
| 281 | }; | ||
| 282 | |||
| 283 | static int | ||
| 284 | slice_compare(PySliceObject *v, PySliceObject *w) | ||
| 285 | { | ||
| 286 | int result = 0; | ||
| 287 | |||
| 288 | if (v == w) | ||
| 289 | return 0; | ||
| 290 | |||
| 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; | ||
| 302 | } | ||
| 303 | |||
| 304 | static long | ||
| 305 | slice_hash(PySliceObject *v) | ||
| 306 | { | ||
| 307 | PyErr_SetString(PyExc_TypeError, "unhashable type"); | ||
| 308 | return -1L; | ||
| 309 | } | ||
| 310 | |||
| 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 */ | ||
| 351 | }; | ||