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
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.
17 #include "structmember.h"
20 ellipsis_repr(PyObject
*op
)
22 return PyString_FromString("Ellipsis");
25 static PyTypeObject PyEllipsis_Type
= {
26 PyObject_HEAD_INIT(&PyType_Type
)
28 "ellipsis", /* tp_name */
31 0, /*never called*/ /* tp_dealloc */
36 ellipsis_repr
, /* tp_repr */
38 0, /* tp_as_sequence */
39 0, /* tp_as_mapping */
43 PyObject_GenericGetAttr
, /* tp_getattro */
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
61 PySlice_New(PyObject
*start
, PyObject
*stop
, PyObject
*step
)
63 PySliceObject
*obj
= PyObject_New(PySliceObject
, &PySlice_Type
);
68 if (step
== NULL
) step
= Py_None
;
70 if (start
== NULL
) start
= Py_None
;
72 if (stop
== NULL
) stop
= Py_None
;
79 return (PyObject
*) obj
;
83 _PySlice_FromIndices(Py_ssize_t istart
, Py_ssize_t istop
)
85 PyObject
*start
, *end
, *slice
;
86 start
= PyInt_FromSsize_t(istart
);
89 end
= PyInt_FromSsize_t(istop
);
95 slice
= PySlice_New(start
, end
, NULL
);
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
) {
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;
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
;
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;
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
) {
144 if (!_PyEval_SliceIndex(r
->step
, step
)) return -1;
146 PyErr_SetString(PyExc_ValueError
,
147 "slice step cannot be zero");
152 defstart
= *step
< 0 ? length
-1 : 0;
153 defstop
= *step
< 0 ? -1 : length
;
155 if (r
->start
== Py_None
) {
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
) {
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
)) {
180 else if (*step
< 0) {
181 *slicelength
= (*stop
-*start
+1)/(*step
)+1;
184 *slicelength
= (*stop
-*start
-1)/(*step
)+1;
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
))
200 if (!PyArg_UnpackTuple(args
, "slice", 1, 3, &start
, &stop
, &step
))
203 /* This swapping of stop and start is to maintain similarity with
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]).");
218 slice_dealloc(PySliceObject
*r
)
227 slice_repr(PySliceObject
*r
)
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(")"));
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
},
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()) {
261 if (PySlice_GetIndicesEx(self
, ilen
, &start
, &stop
,
262 &step
, &slicelength
) < 0) {
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
},
284 slice_compare(PySliceObject
*v
, PySliceObject
*w
)
291 if (PyObject_Cmp(v
->start
, w
->start
, &result
) < 0)
295 if (PyObject_Cmp(v
->stop
, w
->stop
, &result
) < 0)
299 if (PyObject_Cmp(v
->step
, w
->step
, &result
) < 0)
305 slice_hash(PySliceObject
*v
)
307 PyErr_SetString(PyExc_TypeError
, "unhashable type");
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 */
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 */
329 PyObject_GenericGetAttr
, /* tp_getattro */
331 0, /* tp_as_buffer */
332 Py_TPFLAGS_DEFAULT
, /* tp_flags */
333 slice_doc
, /* tp_doc */
336 0, /* tp_richcompare */
337 0, /* tp_weaklistoffset */
340 slice_methods
, /* tp_methods */
341 slice_members
, /* tp_members */
345 0, /* tp_descr_get */
346 0, /* tp_descr_set */
347 0, /* tp_dictoffset */
350 slice_new
, /* tp_new */