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Implement extended slicing in bytes objects.
This commit is contained in:
Thomas Wouters
parent
5672904eff
commit
376446dd4e
2 changed files with 248 additions and 16 deletions
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@ -269,19 +269,62 @@ bytes_getitem(PyBytesObject *self, Py_ssize_t i)
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}
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static PyObject *
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bytes_getslice(PyBytesObject *self, Py_ssize_t lo, Py_ssize_t hi)
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bytes_subscript(PyBytesObject *self, PyObject *item)
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{
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if (lo < 0)
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lo = 0;
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if (hi > self->ob_size)
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hi = self->ob_size;
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if (lo >= hi)
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lo = hi = 0;
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return PyBytes_FromStringAndSize(self->ob_bytes + lo, hi - lo);
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}
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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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return NULL;
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if (i < 0)
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i += PyBytes_GET_SIZE(self);
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if (i < 0 || i >= self->ob_size) {
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PyErr_SetString(PyExc_IndexError, "bytes index out of range");
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return NULL;
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}
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return PyInt_FromLong((unsigned char)(self->ob_bytes[i]));
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}
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else if (PySlice_Check(item)) {
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Py_ssize_t start, stop, step, slicelength, cur, i;
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if (PySlice_GetIndicesEx((PySliceObject *)item,
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PyBytes_GET_SIZE(self),
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&start, &stop, &step, &slicelength) < 0) {
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return NULL;
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}
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if (slicelength <= 0)
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return PyBytes_FromStringAndSize("", 0);
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else if (step == 1) {
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return PyBytes_FromStringAndSize(self->ob_bytes + start,
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slicelength);
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}
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else {
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char *source_buf = PyBytes_AS_STRING(self);
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char *result_buf = (char *)PyMem_Malloc(slicelength);
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PyObject *result;
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if (result_buf == NULL)
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return PyErr_NoMemory();
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for (cur = start, i = 0; i < slicelength;
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cur += step, i++) {
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result_buf[i] = source_buf[cur];
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}
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result = PyBytes_FromStringAndSize(result_buf, slicelength);
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PyMem_Free(result_buf);
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return result;
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}
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}
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else {
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PyErr_SetString(PyExc_TypeError, "bytes indices must be integers");
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return NULL;
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}
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}
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static int
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bytes_setslice(PyBytesObject *self, Py_ssize_t lo, Py_ssize_t hi,
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bytes_setslice(PyBytesObject *self, Py_ssize_t lo, Py_ssize_t hi,
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PyObject *values)
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{
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int avail;
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@ -330,7 +373,7 @@ bytes_setslice(PyBytesObject *self, Py_ssize_t lo, Py_ssize_t hi,
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memmove(self->ob_bytes + lo + needed, self->ob_bytes + hi,
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self->ob_size - hi);
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}
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if (PyBytes_Resize((PyObject *)self,
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if (PyBytes_Resize((PyObject *)self,
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self->ob_size + needed - avail) < 0)
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return -1;
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if (avail < needed) {
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@ -380,6 +423,164 @@ bytes_setitem(PyBytesObject *self, Py_ssize_t i, PyObject *value)
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return 0;
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}
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static int
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bytes_ass_subscript(PyBytesObject *self, PyObject *item, PyObject *values)
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{
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Py_ssize_t start, stop, step, slicelen, needed;
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char *bytes;
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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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return -1;
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if (i < 0)
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i += PyBytes_GET_SIZE(self);
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if (i < 0 || i >= self->ob_size) {
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PyErr_SetString(PyExc_IndexError, "bytes index out of range");
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return -1;
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}
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if (values == NULL) {
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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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slicelen = 1;
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}
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else {
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Py_ssize_t ival = PyNumber_AsSsize_t(values, PyExc_ValueError);
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if (ival == -1 && PyErr_Occurred())
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return -1;
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if (ival < 0 || ival >= 256) {
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PyErr_SetString(PyExc_ValueError,
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"byte must be in range(0, 256)");
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return -1;
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}
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self->ob_bytes[i] = (char)ival;
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return 0;
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}
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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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PyBytes_GET_SIZE(self),
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&start, &stop, &step, &slicelen) < 0) {
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return -1;
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}
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}
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else {
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PyErr_SetString(PyExc_TypeError, "bytes indices must be integer");
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return -1;
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}
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if (values == NULL) {
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bytes = NULL;
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needed = 0;
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}
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else if (values == (PyObject *)self || !PyBytes_Check(values)) {
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/* Make a copy an call this function recursively */
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int err;
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values = PyBytes_FromObject(values);
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if (values == NULL)
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return -1;
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err = bytes_ass_subscript(self, item, values);
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Py_DECREF(values);
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return err;
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}
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else {
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assert(PyBytes_Check(values));
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bytes = ((PyBytesObject *)values)->ob_bytes;
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needed = ((PyBytesObject *)values)->ob_size;
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}
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/* Make sure b[5:2] = ... inserts before 5, not before 2. */
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if ((step < 0 && start < stop) ||
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(step > 0 && start > stop))
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stop = start;
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if (step == 1) {
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if (slicelen != needed) {
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if (slicelen > needed) {
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/*
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0 start stop old_size
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| |<---slicelen--->|<-----tomove------>|
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| |<-needed->|<-----tomove------>|
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0 lo new_hi new_size
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*/
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memmove(self->ob_bytes + start + needed, self->ob_bytes + stop,
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self->ob_size - stop);
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}
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if (PyBytes_Resize((PyObject *)self,
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self->ob_size + needed - slicelen) < 0)
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return -1;
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if (slicelen < needed) {
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/*
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0 lo hi old_size
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| |<-avail->|<-----tomove------>|
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| |<----needed---->|<-----tomove------>|
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0 lo new_hi new_size
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*/
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memmove(self->ob_bytes + start + needed, self->ob_bytes + stop,
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self->ob_size - start - needed);
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}
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}
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if (needed > 0)
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memcpy(self->ob_bytes + start, bytes, needed);
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return 0;
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}
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else {
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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 * (slicelen - 1) - 1;
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step = -step;
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}
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for (cur = start, i = 0;
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i < slicelen; cur += step, i++) {
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Py_ssize_t lim = step - 1;
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if (cur + step >= PyBytes_GET_SIZE(self))
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lim = PyBytes_GET_SIZE(self) - cur - 1;
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memmove(self->ob_bytes + cur - i,
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self->ob_bytes + cur + 1, lim);
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}
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/* Move the tail of the bytes, in one chunk */
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cur = start + slicelen*step;
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if (cur < PyBytes_GET_SIZE(self)) {
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memmove(self->ob_bytes + cur - slicelen,
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self->ob_bytes + cur,
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PyBytes_GET_SIZE(self) - cur);
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}
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if (PyBytes_Resize((PyObject *)self,
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PyBytes_GET_SIZE(self) - slicelen) < 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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/* Assign slice */
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Py_ssize_t cur, i;
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if (needed != slicelen) {
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PyErr_Format(PyExc_ValueError,
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"attempt to assign bytes of size %zd "
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"to extended slice of size %zd",
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needed, slicelen);
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return -1;
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}
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for (cur = start, i = 0; i < slicelen; cur += step, i++)
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self->ob_bytes[cur] = bytes[i];
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return 0;
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}
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}
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}
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static int
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bytes_init(PyBytesObject *self, PyObject *args, PyObject *kwds)
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{
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@ -776,9 +977,9 @@ static PySequenceMethods bytes_as_sequence = {
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(binaryfunc)bytes_concat, /*sq_concat*/
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(ssizeargfunc)bytes_repeat, /*sq_repeat*/
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(ssizeargfunc)bytes_getitem, /*sq_item*/
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(ssizessizeargfunc)bytes_getslice, /*sq_slice*/
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0, /*sq_slice*/
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(ssizeobjargproc)bytes_setitem, /*sq_ass_item*/
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(ssizessizeobjargproc)bytes_setslice, /* sq_ass_slice */
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0, /* sq_ass_slice */
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(objobjproc)bytes_contains, /* sq_contains */
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(binaryfunc)bytes_iconcat, /* sq_inplace_concat */
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(ssizeargfunc)bytes_irepeat, /* sq_inplace_repeat */
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@ -786,8 +987,8 @@ static PySequenceMethods bytes_as_sequence = {
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static PyMappingMethods bytes_as_mapping = {
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(lenfunc)bytes_length,
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(binaryfunc)0,
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0,
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(binaryfunc)bytes_subscript,
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(objobjargproc)bytes_ass_subscript,
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};
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static PyBufferProcs bytes_as_buffer = {
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@ -833,7 +1034,7 @@ PyTypeObject PyBytes_Type = {
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PyObject_GenericGetAttr, /* tp_getattro */
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0, /* tp_setattro */
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&bytes_as_buffer, /* tp_as_buffer */
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Py_TPFLAGS_DEFAULT, /* tp_flags */
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Py_TPFLAGS_DEFAULT, /* tp_flags */
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/* bytes is 'final' or 'sealed' */
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bytes_doc, /* tp_doc */
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0, /* tp_traverse */
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