1.. highlight:: c 2 3.. _slice-objects: 4 5Slice Objects 6------------- 7 8 9.. c:var:: PyTypeObject PySlice_Type 10 11 The type object for slice objects. This is the same as :class:`slice` in the 12 Python layer. 13 14 15.. c:function:: int PySlice_Check(PyObject *ob) 16 17 Return true if *ob* is a slice object; *ob* must not be ``NULL``. This 18 function always succeeds. 19 20 21.. c:function:: PyObject* PySlice_New(PyObject *start, PyObject *stop, PyObject *step) 22 23 Return a new slice object with the given values. The *start*, *stop*, and 24 *step* parameters are used as the values of the slice object attributes of 25 the same names. Any of the values may be ``NULL``, in which case the 26 ``None`` will be used for the corresponding attribute. Return ``NULL`` if 27 the new object could not be allocated. 28 29 30.. c:function:: int PySlice_GetIndices(PyObject *slice, Py_ssize_t length, Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step) 31 32 Retrieve the start, stop and step indices from the slice object *slice*, 33 assuming a sequence of length *length*. Treats indices greater than 34 *length* as errors. 35 36 Returns ``0`` on success and ``-1`` on error with no exception set (unless one of 37 the indices was not :const:`None` and failed to be converted to an integer, 38 in which case ``-1`` is returned with an exception set). 39 40 You probably do not want to use this function. 41 42 .. versionchanged:: 3.2 43 The parameter type for the *slice* parameter was ``PySliceObject*`` 44 before. 45 46 47.. c:function:: int PySlice_GetIndicesEx(PyObject *slice, Py_ssize_t length, Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step, Py_ssize_t *slicelength) 48 49 Usable replacement for :c:func:`PySlice_GetIndices`. Retrieve the start, 50 stop, and step indices from the slice object *slice* assuming a sequence of 51 length *length*, and store the length of the slice in *slicelength*. Out 52 of bounds indices are clipped in a manner consistent with the handling of 53 normal slices. 54 55 Returns ``0`` on success and ``-1`` on error with exception set. 56 57 .. note:: 58 This function is considered not safe for resizable sequences. 59 Its invocation should be replaced by a combination of 60 :c:func:`PySlice_Unpack` and :c:func:`PySlice_AdjustIndices` where :: 61 62 if (PySlice_GetIndicesEx(slice, length, &start, &stop, &step, &slicelength) < 0) { 63 // return error 64 } 65 66 is replaced by :: 67 68 if (PySlice_Unpack(slice, &start, &stop, &step) < 0) { 69 // return error 70 } 71 slicelength = PySlice_AdjustIndices(length, &start, &stop, step); 72 73 .. versionchanged:: 3.2 74 The parameter type for the *slice* parameter was ``PySliceObject*`` 75 before. 76 77 .. versionchanged:: 3.6.1 78 If ``Py_LIMITED_API`` is not set or set to the value between ``0x03050400`` 79 and ``0x03060000`` (not including) or ``0x03060100`` or higher 80 :c:func:`!PySlice_GetIndicesEx` is implemented as a macro using 81 :c:func:`!PySlice_Unpack` and :c:func:`!PySlice_AdjustIndices`. 82 Arguments *start*, *stop* and *step* are evaluated more than once. 83 84 .. deprecated:: 3.6.1 85 If ``Py_LIMITED_API`` is set to the value less than ``0x03050400`` or 86 between ``0x03060000`` and ``0x03060100`` (not including) 87 :c:func:`!PySlice_GetIndicesEx` is a deprecated function. 88 89 90.. c:function:: int PySlice_Unpack(PyObject *slice, Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step) 91 92 Extract the start, stop and step data members from a slice object as 93 C integers. Silently reduce values larger than ``PY_SSIZE_T_MAX`` to 94 ``PY_SSIZE_T_MAX``, silently boost the start and stop values less than 95 ``PY_SSIZE_T_MIN`` to ``PY_SSIZE_T_MIN``, and silently boost the step 96 values less than ``-PY_SSIZE_T_MAX`` to ``-PY_SSIZE_T_MAX``. 97 98 Return ``-1`` on error, ``0`` on success. 99 100 .. versionadded:: 3.6.1 101 102 103.. c:function:: Py_ssize_t PySlice_AdjustIndices(Py_ssize_t length, Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t step) 104 105 Adjust start/end slice indices assuming a sequence of the specified length. 106 Out of bounds indices are clipped in a manner consistent with the handling 107 of normal slices. 108 109 Return the length of the slice. Always successful. Doesn't call Python 110 code. 111 112 .. versionadded:: 3.6.1 113 114 115Ellipsis Object 116--------------- 117 118 119.. c:var:: PyObject *Py_Ellipsis 120 121 The Python ``Ellipsis`` object. This object has no methods. It needs to be 122 treated just like any other object with respect to reference counts. Like 123 :c:data:`Py_None` it is a singleton object. 124