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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.
This commit is contained in:
Thomas Wouters
parent
0f4a14b56f
commit
3ccec68a05
16 changed files with 730 additions and 120 deletions
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@ -1605,6 +1605,16 @@ array_subscr(arrayobject* self, PyObject* item)
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if (slicelength <= 0) {
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return newarrayobject(&Arraytype, 0, self->ob_descr);
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}
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else if (step == 1) {
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PyObject *result = newarrayobject(&Arraytype,
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slicelength, self->ob_descr);
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if (result == NULL)
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return NULL;
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memcpy(((arrayobject *)result)->ob_item,
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self->ob_item + start * itemsize,
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slicelength * itemsize);
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return result;
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}
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else {
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result = newarrayobject(&Arraytype, slicelength, self->ob_descr);
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if (!result) return NULL;
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@ -1623,7 +1633,7 @@ array_subscr(arrayobject* self, PyObject* item)
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}
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else {
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PyErr_SetString(PyExc_TypeError,
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"list indices must be integers");
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"array indices must be integers");
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return NULL;
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}
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}
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@ -1631,112 +1641,146 @@ array_subscr(arrayobject* self, PyObject* item)
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static int
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array_ass_subscr(arrayobject* self, PyObject* item, PyObject* value)
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{
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Py_ssize_t start, stop, step, slicelength, needed;
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arrayobject* other;
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int itemsize;
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if (PyIndex_Check(item)) {
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Py_ssize_t i = PyNumber_AsSsize_t(item, PyExc_IndexError);
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if (i==-1 && PyErr_Occurred())
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if (i == -1 && PyErr_Occurred())
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return -1;
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if (i < 0)
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i += Py_Size(self);
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return array_ass_item(self, i, value);
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}
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else if (PySlice_Check(item)) {
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Py_ssize_t start, stop, step, slicelength;
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int itemsize = self->ob_descr->itemsize;
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if (PySlice_GetIndicesEx((PySliceObject*)item, Py_Size(self),
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&start, &stop, &step, &slicelength) < 0) {
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if (i < 0 || i >= Py_Size(self)) {
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PyErr_SetString(PyExc_IndexError,
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"array assignment index out of range");
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return -1;
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}
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/* treat A[slice(a,b)] = v _exactly_ like A[a:b] = v */
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if (step == 1 && ((PySliceObject*)item)->step == Py_None)
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return array_ass_slice(self, start, stop, value);
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if (value == NULL) {
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/* delete slice */
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Py_ssize_t cur, i, extra;
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if (slicelength <= 0)
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return 0;
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if (step < 0) {
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stop = start + 1;
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start = stop + step*(slicelength - 1) - 1;
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step = -step;
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}
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for (cur = start, i = 0; i < slicelength - 1;
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cur += step, i++) {
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memmove(self->ob_item + (cur - i)*itemsize,
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self->ob_item + (cur + 1)*itemsize,
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(step - 1) * itemsize);
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}
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extra = Py_Size(self) - (cur + 1);
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if (extra > 0) {
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memmove(self->ob_item + (cur - i)*itemsize,
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self->ob_item + (cur + 1)*itemsize,
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extra*itemsize);
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}
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Py_Size(self) -= slicelength;
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self->ob_item = (char *)PyMem_REALLOC(self->ob_item,
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itemsize*Py_Size(self));
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self->allocated = Py_Size(self);
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return 0;
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/* Fall through to slice assignment */
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start = i;
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stop = i + 1;
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step = 1;
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slicelength = 1;
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}
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else {
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/* assign slice */
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Py_ssize_t cur, i;
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arrayobject* av;
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if (!array_Check(value)) {
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PyErr_Format(PyExc_TypeError,
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"must assign array (not \"%.200s\") to slice",
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Py_Type(value)->tp_name);
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return -1;
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}
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av = (arrayobject*)value;
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if (Py_Size(av) != slicelength) {
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PyErr_Format(PyExc_ValueError,
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"attempt to assign array of size %ld to extended slice of size %ld",
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/*XXX*/(long)Py_Size(av), /*XXX*/(long)slicelength);
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return -1;
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}
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if (!slicelength)
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return 0;
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/* protect against a[::-1] = a */
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if (self == av) {
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value = array_slice(av, 0, Py_Size(av));
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av = (arrayobject*)value;
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if (!av)
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return -1;
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}
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else {
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Py_INCREF(value);
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}
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for (cur = start, i = 0; i < slicelength;
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cur += step, i++) {
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memcpy(self->ob_item + cur*itemsize,
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av->ob_item + i*itemsize,
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itemsize);
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}
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Py_DECREF(value);
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return 0;
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else
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return (*self->ob_descr->setitem)(self, i, value);
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}
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else if (PySlice_Check(item)) {
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if (PySlice_GetIndicesEx((PySliceObject *)item,
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Py_Size(self), &start, &stop,
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&step, &slicelength) < 0) {
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return -1;
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}
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}
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}
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else {
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PyErr_SetString(PyExc_TypeError,
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"list indices must be integers");
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PyErr_SetString(PyExc_TypeError,
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"array indices must be integer");
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return -1;
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}
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if (value == NULL) {
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other = NULL;
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needed = 0;
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}
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else if (array_Check(value)) {
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other = (arrayobject *)value;
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needed = Py_Size(other);
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if (self == other) {
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/* Special case "self[i:j] = self" -- copy self first */
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int ret;
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value = array_slice(other, 0, needed);
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if (value == NULL)
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return -1;
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ret = array_ass_subscr(self, item, value);
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Py_DECREF(value);
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return ret;
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}
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if (other->ob_descr != self->ob_descr) {
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PyErr_BadArgument();
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return -1;
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}
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}
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else {
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PyErr_Format(PyExc_TypeError,
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"can only assign array (not \"%.200s\") to array slice",
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Py_Type(value)->tp_name);
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return -1;
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}
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itemsize = self->ob_descr->itemsize;
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/* for 'a[2:1] = ...', the insertion point is 'start', not 'stop' */
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if ((step > 0 && stop < start) ||
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(step < 0 && stop > start))
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stop = start;
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if (step == 1) {
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if (slicelength > needed) {
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memmove(self->ob_item + (start + needed) * itemsize,
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self->ob_item + stop * itemsize,
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(Py_Size(self) - stop) * itemsize);
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if (array_resize(self, Py_Size(self) +
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needed - slicelength) < 0)
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return -1;
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}
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else if (slicelength < needed) {
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if (array_resize(self, Py_Size(self) +
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needed - slicelength) < 0)
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return -1;
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memmove(self->ob_item + (start + needed) * itemsize,
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self->ob_item + stop * itemsize,
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(Py_Size(self) - start - needed) * itemsize);
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}
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if (needed > 0)
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memcpy(self->ob_item + start * itemsize,
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other->ob_item, needed * itemsize);
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return 0;
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}
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else if (needed == 0) {
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/* Delete slice */
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Py_ssize_t cur, i;
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if (step < 0) {
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stop = start + 1;
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start = stop + step * (slicelength - 1) - 1;
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step = -step;
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}
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for (cur = start, i = 0; i < slicelength;
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cur += step, i++) {
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Py_ssize_t lim = step - 1;
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if (cur + step >= Py_Size(self))
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lim = Py_Size(self) - cur - 1;
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memmove(self->ob_item + (cur - i) * itemsize,
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self->ob_item + (cur + 1) * itemsize,
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lim * itemsize);
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}
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cur = start + slicelength * step;
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if (cur < Py_Size(self)) {
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memmove(self->ob_item + (cur-slicelength) * itemsize,
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self->ob_item + cur * itemsize,
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(Py_Size(self) - cur) * itemsize);
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}
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if (array_resize(self, Py_Size(self) - slicelength) < 0)
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return -1;
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return 0;
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}
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else {
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Py_ssize_t cur, i;
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if (needed != slicelength) {
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PyErr_Format(PyExc_ValueError,
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"attempt to assign array of size %zd "
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"to extended slice of size %zd",
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needed, slicelength);
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return -1;
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}
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for (cur = start, i = 0; i < slicelength;
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cur += step, i++) {
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memcpy(self->ob_item + cur * itemsize,
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other->ob_item + i * itemsize,
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itemsize);
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}
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return 0;
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}
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}
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static PyMappingMethods array_as_mapping = {
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