Improve extended slicing support in builtin types and classes. Specifically:
- Specialcase extended slices that amount to a shallow copy the same way as
is done for simple slices, in the tuple, string and unicode case.
- Specialcase step-1 extended slices to optimize the common case for all
involved types.
- For lists, allow extended slice assignment of differing lengths as long
as the step is 1. (Previously, 'l[:2:1] = []' failed even though
'l[:2] = []' and 'l[:2:None] = []' do not.)
- Implement extended slicing for buffer, array, structseq, mmap and
UserString.UserString.
- Implement slice-object support (but not non-step-1 slice assignment) for
UserString.MutableString.
- Add tests for all new functionality.
diff --git a/Modules/arraymodule.c b/Modules/arraymodule.c
index 21a5e5b..b2ee5b0 100644
--- a/Modules/arraymodule.c
+++ b/Modules/arraymodule.c
@@ -1605,6 +1605,16 @@
if (slicelength <= 0) {
return newarrayobject(&Arraytype, 0, self->ob_descr);
}
+ else if (step == 1) {
+ PyObject *result = newarrayobject(&Arraytype,
+ slicelength, self->ob_descr);
+ if (result == NULL)
+ return NULL;
+ memcpy(((arrayobject *)result)->ob_item,
+ self->ob_item + start * itemsize,
+ slicelength * itemsize);
+ return result;
+ }
else {
result = newarrayobject(&Arraytype, slicelength, self->ob_descr);
if (!result) return NULL;
@@ -1623,7 +1633,7 @@
}
else {
PyErr_SetString(PyExc_TypeError,
- "list indices must be integers");
+ "array indices must be integers");
return NULL;
}
}
@@ -1631,112 +1641,146 @@
static int
array_ass_subscr(arrayobject* self, PyObject* item, PyObject* value)
{
+ Py_ssize_t start, stop, step, slicelength, needed;
+ arrayobject* other;
+ int itemsize;
+
if (PyIndex_Check(item)) {
Py_ssize_t i = PyNumber_AsSsize_t(item, PyExc_IndexError);
- if (i==-1 && PyErr_Occurred())
+
+ if (i == -1 && PyErr_Occurred())
return -1;
if (i < 0)
i += Py_Size(self);
- return array_ass_item(self, i, value);
- }
- else if (PySlice_Check(item)) {
- Py_ssize_t start, stop, step, slicelength;
- int itemsize = self->ob_descr->itemsize;
-
- if (PySlice_GetIndicesEx((PySliceObject*)item, Py_Size(self),
- &start, &stop, &step, &slicelength) < 0) {
+ if (i < 0 || i >= Py_Size(self)) {
+ PyErr_SetString(PyExc_IndexError,
+ "array assignment index out of range");
return -1;
}
-
- /* treat A[slice(a,b)] = v _exactly_ like A[a:b] = v */
- if (step == 1 && ((PySliceObject*)item)->step == Py_None)
- return array_ass_slice(self, start, stop, value);
-
if (value == NULL) {
- /* delete slice */
- Py_ssize_t cur, i, extra;
-
- if (slicelength <= 0)
- return 0;
-
- if (step < 0) {
- stop = start + 1;
- start = stop + step*(slicelength - 1) - 1;
- step = -step;
- }
-
- for (cur = start, i = 0; i < slicelength - 1;
- cur += step, i++) {
- memmove(self->ob_item + (cur - i)*itemsize,
- self->ob_item + (cur + 1)*itemsize,
- (step - 1) * itemsize);
- }
- extra = Py_Size(self) - (cur + 1);
- if (extra > 0) {
- memmove(self->ob_item + (cur - i)*itemsize,
- self->ob_item + (cur + 1)*itemsize,
- extra*itemsize);
- }
-
- Py_Size(self) -= slicelength;
- self->ob_item = (char *)PyMem_REALLOC(self->ob_item,
- itemsize*Py_Size(self));
- self->allocated = Py_Size(self);
-
- return 0;
+ /* Fall through to slice assignment */
+ start = i;
+ stop = i + 1;
+ step = 1;
+ slicelength = 1;
}
- else {
- /* assign slice */
- Py_ssize_t cur, i;
- arrayobject* av;
-
- if (!array_Check(value)) {
- PyErr_Format(PyExc_TypeError,
- "must assign array (not \"%.200s\") to slice",
- Py_Type(value)->tp_name);
- return -1;
- }
-
- av = (arrayobject*)value;
-
- if (Py_Size(av) != slicelength) {
- PyErr_Format(PyExc_ValueError,
- "attempt to assign array of size %ld to extended slice of size %ld",
- /*XXX*/(long)Py_Size(av), /*XXX*/(long)slicelength);
- return -1;
- }
-
- if (!slicelength)
- return 0;
-
- /* protect against a[::-1] = a */
- if (self == av) {
- value = array_slice(av, 0, Py_Size(av));
- av = (arrayobject*)value;
- if (!av)
- return -1;
- }
- else {
- Py_INCREF(value);
- }
-
- for (cur = start, i = 0; i < slicelength;
- cur += step, i++) {
- memcpy(self->ob_item + cur*itemsize,
- av->ob_item + i*itemsize,
- itemsize);
- }
-
- Py_DECREF(value);
-
- return 0;
+ else
+ return (*self->ob_descr->setitem)(self, i, value);
+ }
+ else if (PySlice_Check(item)) {
+ if (PySlice_GetIndicesEx((PySliceObject *)item,
+ Py_Size(self), &start, &stop,
+ &step, &slicelength) < 0) {
+ return -1;
}
- }
+ }
else {
- PyErr_SetString(PyExc_TypeError,
- "list indices must be integers");
+ PyErr_SetString(PyExc_TypeError,
+ "array indices must be integer");
return -1;
}
+ if (value == NULL) {
+ other = NULL;
+ needed = 0;
+ }
+ else if (array_Check(value)) {
+ other = (arrayobject *)value;
+ needed = Py_Size(other);
+ if (self == other) {
+ /* Special case "self[i:j] = self" -- copy self first */
+ int ret;
+ value = array_slice(other, 0, needed);
+ if (value == NULL)
+ return -1;
+ ret = array_ass_subscr(self, item, value);
+ Py_DECREF(value);
+ return ret;
+ }
+ if (other->ob_descr != self->ob_descr) {
+ PyErr_BadArgument();
+ return -1;
+ }
+ }
+ else {
+ PyErr_Format(PyExc_TypeError,
+ "can only assign array (not \"%.200s\") to array slice",
+ Py_Type(value)->tp_name);
+ return -1;
+ }
+ itemsize = self->ob_descr->itemsize;
+ /* for 'a[2:1] = ...', the insertion point is 'start', not 'stop' */
+ if ((step > 0 && stop < start) ||
+ (step < 0 && stop > start))
+ stop = start;
+ if (step == 1) {
+ if (slicelength > needed) {
+ memmove(self->ob_item + (start + needed) * itemsize,
+ self->ob_item + stop * itemsize,
+ (Py_Size(self) - stop) * itemsize);
+ if (array_resize(self, Py_Size(self) +
+ needed - slicelength) < 0)
+ return -1;
+ }
+ else if (slicelength < needed) {
+ if (array_resize(self, Py_Size(self) +
+ needed - slicelength) < 0)
+ return -1;
+ memmove(self->ob_item + (start + needed) * itemsize,
+ self->ob_item + stop * itemsize,
+ (Py_Size(self) - start - needed) * itemsize);
+ }
+ if (needed > 0)
+ memcpy(self->ob_item + start * itemsize,
+ other->ob_item, needed * itemsize);
+ return 0;
+ }
+ else if (needed == 0) {
+ /* Delete slice */
+ Py_ssize_t cur, i;
+
+ if (step < 0) {
+ stop = start + 1;
+ start = stop + step * (slicelength - 1) - 1;
+ step = -step;
+ }
+ for (cur = start, i = 0; i < slicelength;
+ cur += step, i++) {
+ Py_ssize_t lim = step - 1;
+
+ if (cur + step >= Py_Size(self))
+ lim = Py_Size(self) - cur - 1;
+ memmove(self->ob_item + (cur - i) * itemsize,
+ self->ob_item + (cur + 1) * itemsize,
+ lim * itemsize);
+ }
+ cur = start + slicelength * step;
+ if (cur < Py_Size(self)) {
+ memmove(self->ob_item + (cur-slicelength) * itemsize,
+ self->ob_item + cur * itemsize,
+ (Py_Size(self) - cur) * itemsize);
+ }
+ if (array_resize(self, Py_Size(self) - slicelength) < 0)
+ return -1;
+ return 0;
+ }
+ else {
+ Py_ssize_t cur, i;
+
+ if (needed != slicelength) {
+ PyErr_Format(PyExc_ValueError,
+ "attempt to assign array of size %zd "
+ "to extended slice of size %zd",
+ needed, slicelength);
+ return -1;
+ }
+ for (cur = start, i = 0; i < slicelength;
+ cur += step, i++) {
+ memcpy(self->ob_item + cur * itemsize,
+ other->ob_item + i * itemsize,
+ itemsize);
+ }
+ return 0;
+ }
}
static PyMappingMethods array_as_mapping = {