mirror of https://github.com/python/cpython
127 lines
4.5 KiB
ReStructuredText
127 lines
4.5 KiB
ReStructuredText
.. highlight:: c
|
|
|
|
.. _slice-objects:
|
|
|
|
Slice Objects
|
|
-------------
|
|
|
|
|
|
.. c:var:: PyTypeObject PySlice_Type
|
|
|
|
The type object for slice objects. This is the same as :class:`slice` in the
|
|
Python layer.
|
|
|
|
|
|
.. c:function:: int PySlice_Check(PyObject *ob)
|
|
|
|
Return true if *ob* is a slice object; *ob* must not be ``NULL``. This
|
|
function always succeeds.
|
|
|
|
|
|
.. c:function:: PyObject* PySlice_New(PyObject *start, PyObject *stop, PyObject *step)
|
|
|
|
Return a new slice object with the given values. The *start*, *stop*, and
|
|
*step* parameters are used as the values of the slice object attributes of
|
|
the same names. Any of the values may be ``NULL``, in which case the
|
|
``None`` will be used for the corresponding attribute. Return ``NULL`` if
|
|
the new object could not be allocated.
|
|
|
|
|
|
.. c:function:: int PySlice_GetIndices(PyObject *slice, Py_ssize_t length, Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step)
|
|
|
|
Retrieve the start, stop and step indices from the slice object *slice*,
|
|
assuming a sequence of length *length*. Treats indices greater than
|
|
*length* as errors.
|
|
|
|
Returns ``0`` on success and ``-1`` on error with no exception set (unless one of
|
|
the indices was not :const:`None` and failed to be converted to an integer,
|
|
in which case ``-1`` is returned with an exception set).
|
|
|
|
You probably do not want to use this function.
|
|
|
|
.. versionchanged:: 3.2
|
|
The parameter type for the *slice* parameter was ``PySliceObject*``
|
|
before.
|
|
|
|
|
|
.. 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)
|
|
|
|
Usable replacement for :c:func:`PySlice_GetIndices`. Retrieve the start,
|
|
stop, and step indices from the slice object *slice* assuming a sequence of
|
|
length *length*, and store the length of the slice in *slicelength*. Out
|
|
of bounds indices are clipped in a manner consistent with the handling of
|
|
normal slices.
|
|
|
|
Returns ``0`` on success and ``-1`` on error with exception set.
|
|
|
|
.. note::
|
|
This function is considered not safe for resizable sequences.
|
|
Its invocation should be replaced by a combination of
|
|
:c:func:`PySlice_Unpack` and :c:func:`PySlice_AdjustIndices` where ::
|
|
|
|
if (PySlice_GetIndicesEx(slice, length, &start, &stop, &step, &slicelength) < 0) {
|
|
// return error
|
|
}
|
|
|
|
is replaced by ::
|
|
|
|
if (PySlice_Unpack(slice, &start, &stop, &step) < 0) {
|
|
// return error
|
|
}
|
|
slicelength = PySlice_AdjustIndices(length, &start, &stop, step);
|
|
|
|
.. versionchanged:: 3.2
|
|
The parameter type for the *slice* parameter was ``PySliceObject*``
|
|
before.
|
|
|
|
.. versionchanged:: 3.6.1
|
|
If ``Py_LIMITED_API`` is not set or set to the value between ``0x03050400``
|
|
and ``0x03060000`` (not including) or ``0x03060100`` or higher
|
|
:c:func:`!PySlice_GetIndicesEx` is implemented as a macro using
|
|
:c:func:`!PySlice_Unpack` and :c:func:`!PySlice_AdjustIndices`.
|
|
Arguments *start*, *stop* and *step* are evaluated more than once.
|
|
|
|
.. deprecated:: 3.6.1
|
|
If ``Py_LIMITED_API`` is set to the value less than ``0x03050400`` or
|
|
between ``0x03060000`` and ``0x03060100`` (not including)
|
|
:c:func:`!PySlice_GetIndicesEx` is a deprecated function.
|
|
|
|
|
|
.. c:function:: int PySlice_Unpack(PyObject *slice, Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step)
|
|
|
|
Extract the start, stop and step data members from a slice object as
|
|
C integers. Silently reduce values larger than ``PY_SSIZE_T_MAX`` to
|
|
``PY_SSIZE_T_MAX``, silently boost the start and stop values less than
|
|
``PY_SSIZE_T_MIN`` to ``PY_SSIZE_T_MIN``, and silently boost the step
|
|
values less than ``-PY_SSIZE_T_MAX`` to ``-PY_SSIZE_T_MAX``.
|
|
|
|
Return ``-1`` on error, ``0`` on success.
|
|
|
|
.. versionadded:: 3.6.1
|
|
|
|
|
|
.. c:function:: Py_ssize_t PySlice_AdjustIndices(Py_ssize_t length, Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t step)
|
|
|
|
Adjust start/end slice indices assuming a sequence of the specified length.
|
|
Out of bounds indices are clipped in a manner consistent with the handling
|
|
of normal slices.
|
|
|
|
Return the length of the slice. Always successful. Doesn't call Python
|
|
code.
|
|
|
|
.. versionadded:: 3.6.1
|
|
|
|
|
|
Ellipsis Object
|
|
^^^^^^^^^^^^^^^
|
|
|
|
|
|
.. c:var:: PyObject *Py_Ellipsis
|
|
|
|
The Python ``Ellipsis`` object. This object has no methods. Like
|
|
:c:data:`Py_None`, it is an `immortal <https://peps.python.org/pep-0683/>`_.
|
|
singleton object.
|
|
|
|
.. versionchanged:: 3.12
|
|
:c:data:`Py_Ellipsis` is immortal.
|