cpython/Objects/sliceobject.c

/*
Written by Jim Hugunin and Chris Chase.

This includes both the singular ellipsis object and slice objects.

Guido, feel free to do whatever you want in the way of copyrights
for this file.
*/

/*
Py_Ellipsis encodes the '...' rubber index token. It is similar to
the Py_NoneStruct in that there is no way to create other objects of
this type and there is exactly one in existence.
*/

#include "Python.h"
#include "pycore_abstract.h"      // _PyIndex_Check()
#include "pycore_freelist.h"      // _Py_FREELIST_FREE(), _Py_FREELIST_POP()
#include "pycore_long.h"          // _PyLong_GetZero()
#include "pycore_modsupport.h"    // _PyArg_NoKeywords()
#include "pycore_object.h"        // _PyObject_GC_TRACK()


static PyObject *
ellipsis_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
{ … }

static void
ellipsis_dealloc(PyObject *ellipsis)
{ … }

static PyObject *
ellipsis_repr(PyObject *op)
{ … }

static PyObject *
ellipsis_reduce(PyObject *op, PyObject *Py_UNUSED(ignored))
{ … }

static PyMethodDef ellipsis_methods[] = …;

PyDoc_STRVAR(ellipsis_doc,
"ellipsis()\n"
"--\n\n"
"The type of the Ellipsis singleton.");

PyTypeObject PyEllipsis_Type = …;

PyObject _Py_EllipsisObject = …;


/* Slice object implementation */

/* start, stop, and step are python objects with None indicating no
   index is present.
*/

static PySliceObject *
_PyBuildSlice_Consume2(PyObject *start, PyObject *stop, PyObject *step)
{ … }

PyObject *
PySlice_New(PyObject *start, PyObject *stop, PyObject *step)
{ … }

PyObject *
_PyBuildSlice_ConsumeRefs(PyObject *start, PyObject *stop)
{ … }

PyObject *
_PySlice_FromIndices(Py_ssize_t istart, Py_ssize_t istop)
{ … }

int
PySlice_GetIndices(PyObject *_r, Py_ssize_t length,
                   Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step)
{ … }

int
PySlice_Unpack(PyObject *_r,
               Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step)
{ … }

Py_ssize_t
PySlice_AdjustIndices(Py_ssize_t length,
                      Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t step)
{ … }

#undef PySlice_GetIndicesEx

int
PySlice_GetIndicesEx(PyObject *_r, Py_ssize_t length,
                     Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step,
                     Py_ssize_t *slicelength)
{ … }

static PyObject *
slice_new(PyTypeObject *type, PyObject *args, PyObject *kw)
{ … }

PyDoc_STRVAR(slice_doc,
"slice(stop)\n\
slice(start, stop[, step])\n\
\n\
Create a slice object.  This is used for extended slicing (e.g. a[0:10:2]).");

static void
slice_dealloc(PySliceObject *r)
{ … }

static PyObject *
slice_repr(PySliceObject *r)
{ … }

static PyMemberDef slice_members[] = …;

/* Helper function to convert a slice argument to a PyLong, and raise TypeError
   with a suitable message on failure. */

static PyObject*
evaluate_slice_index(PyObject *v)
{ … }

/* Compute slice indices given a slice and length.  Return -1 on failure.  Used
   by slice.indices and rangeobject slicing.  Assumes that `len` is a
   nonnegative instance of PyLong. */

int
_PySlice_GetLongIndices(PySliceObject *self, PyObject *length,
                        PyObject **start_ptr, PyObject **stop_ptr,
                        PyObject **step_ptr)
{ … }

/* Implementation of slice.indices. */

static PyObject*
slice_indices(PySliceObject* self, PyObject* len)
{ … }

PyDoc_STRVAR(slice_indices_doc,
"S.indices(len) -> (start, stop, stride)\n\
\n\
Assuming a sequence of length len, calculate the start and stop\n\
indices, and the stride length of the extended slice described by\n\
S. Out of bounds indices are clipped in a manner consistent with the\n\
handling of normal slices.");

static PyObject *
slice_reduce(PySliceObject* self, PyObject *Py_UNUSED(ignored))
{ … }

PyDoc_STRVAR(reduce_doc, "Return state information for pickling.");

static PyMethodDef slice_methods[] = …;

static PyObject *
slice_richcompare(PyObject *v, PyObject *w, int op)
{ … }

static int
slice_traverse(PySliceObject *v, visitproc visit, void *arg)
{ … }

/* code based on tuplehash() of Objects/tupleobject.c */
#if SIZEOF_PY_UHASH_T > 4
#define _PyHASH_XXPRIME_1 …
#define _PyHASH_XXPRIME_2 …
#define _PyHASH_XXPRIME_5 …
#define _PyHASH_XXROTATE(x) …
#else
#define _PyHASH_XXPRIME_1 …
#define _PyHASH_XXPRIME_2 …
#define _PyHASH_XXPRIME_5 …
#define _PyHASH_XXROTATE …
#endif

static Py_hash_t
slicehash(PySliceObject *v)
{ … }

PyTypeObject PySlice_Type = …;