#pragma once
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#include <torch/csrc/python_headers.h>
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// PyPy 3.6 does not yet have PySlice_Unpack
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#if PY_VERSION_HEX < 0x03060100 || defined(PYPY_VERSION)
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// PySlice_Unpack not introduced till python 3.6.1
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// included here for backwards compatibility
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// https://docs.python.org/3/c-api/slice.html#c.PySlice_Unpack
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// https://github.com/python/cpython/blob/master/Objects/sliceobject.c#L196
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inline int
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__PySlice_Unpack(PyObject *_r,
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Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step)
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{
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PySliceObject *r = (PySliceObject*)_r;
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/* this is harder to get right than you might think */
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// Py_BUILD_ASSERT replaced because it is not available in all versions
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static_assert(PY_SSIZE_T_MIN + 1 <= -PY_SSIZE_T_MAX, "Build failed");
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if (r->step == Py_None) {
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*step = 1;
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}
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else {
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if (!_PyEval_SliceIndex(r->step, step)) return -1;
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if (*step == 0) {
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PyErr_SetString(PyExc_ValueError,
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"slice step cannot be zero");
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return -1;
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}
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/* Here *step might be -PY_SSIZE_T_MAX-1; in this case we replace it
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* with -PY_SSIZE_T_MAX. This doesn't affect the semantics, and it
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* guards against later undefined behaviour resulting from code that
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* does "step = -step" as part of a slice reversal.
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*/
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if (*step < -PY_SSIZE_T_MAX)
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*step = -PY_SSIZE_T_MAX;
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}
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if (r->start == Py_None) {
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*start = *step < 0 ? PY_SSIZE_T_MAX : 0;
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}
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else {
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if (!_PyEval_SliceIndex(r->start, start)) return -1;
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}
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if (r->stop == Py_None) {
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*stop = *step < 0 ? PY_SSIZE_T_MIN : PY_SSIZE_T_MAX;
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}
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else {
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if (!_PyEval_SliceIndex(r->stop, stop)) return -1;
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}
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return 0;
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}
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#define THPUtils_unpackSlice(SLICE, START, STOP, STEP) \
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(__PySlice_Unpack(SLICE, START, STOP, STEP) == 0)
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#else
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#define THPUtils_unpackSlice(SLICE, START, STOP, STEP) \
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(PySlice_Unpack(SLICE, START, STOP, STEP) == 0)
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#endif
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// https://bugsfiles.kde.org/attachment.cgi?id=61186
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#if PY_VERSION_HEX >= 0x03020000
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#define THPUtils_parseSlice(SLICE, LEN, START, STOP, LENGTH, STEP) \
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(PySlice_GetIndicesEx(SLICE, LEN, START, STOP, LENGTH, STEP) == 0)
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#else
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#define THPUtils_parseSlice(SLICE, LEN, START, STOP, LENGTH, STEP) \
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(PySlice_GetIndicesEx((PySliceObject*)SLICE, LEN, START, STOP, LENGTH, STEP) == 0)
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#endif
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