slices.h

//     Copyright 2025, Kay Hayen, mailto:kay.hayen@gmail.com find license text at end of file
 
#ifndef __NUITKA_HELPER_SLICES_H__
#define __NUITKA_HELPER_SLICES_H__
 
/* This file is included from another C file, help IDEs to still parse it on its own. */
#ifdef __IDE_ONLY__
#include "nuitka/prelude.h"
#endif
 
#if PYTHON_VERSION >= 0x3a0
extern PyObject *Nuitka_Slice_New(PyThreadState *tstate, PyObject *start, PyObject *stop, PyObject *step);
#else
#define Nuitka_Slice_New(tstate, start, stop, step) PySlice_New(start, stop, step)
#endif
 
// Note: Cannot these cannot fail, PySlice_New does not return errors.
NUITKA_MAY_BE_UNUSED static PyObject *MAKE_SLICE_OBJECT3(PyThreadState *tstate, PyObject *start, PyObject *stop,
                                                         PyObject *step) {
    CHECK_OBJECT(start);
    CHECK_OBJECT(stop);
    CHECK_OBJECT(step);
 
    return Nuitka_Slice_New(tstate, start, stop, step);
}
NUITKA_MAY_BE_UNUSED static PyObject *MAKE_SLICE_OBJECT2(PyThreadState *tstate, PyObject *start, PyObject *stop) {
    CHECK_OBJECT(start);
    CHECK_OBJECT(stop);
 
    return Nuitka_Slice_New(tstate, start, stop, Py_None);
}
NUITKA_MAY_BE_UNUSED static PyObject *MAKE_SLICE_OBJECT1(PyThreadState *tstate, PyObject *stop) {
    CHECK_OBJECT(stop);
 
    return Nuitka_Slice_New(tstate, Py_None, stop, Py_None);
}
 
#if PYTHON_VERSION < 0x300
// Note: It appears that Python3 has no index slicing operations anymore, but
// uses slice objects all the time. That's fine and make sure we adhere to it by
// guarding the presence of the helpers.
 
static inline bool IS_INDEXABLE(PyObject *value) {
    return value == Py_None ||
#if PYTHON_VERSION < 0x300
           PyInt_Check(value) ||
#endif
           PyLong_Check(value) || Nuitka_Index_Check(value);
}
 
static Py_ssize_t CONVERT_TO_INDEX(PyThreadState *tstate, PyObject *value) {
    CHECK_OBJECT(value);
 
    if (PyInt_Check(value)) {
        return PyInt_AS_LONG(value);
    } else if (Nuitka_Index_Check(value)) {
        return PyNumber_AsSsize_t(value, NULL);
    } else {
        SET_CURRENT_EXCEPTION_TYPE0_STR(tstate, PyExc_TypeError,
                                        "slice indices must be integers or None or have an __index__ method");
        return -1;
    }
}
 
NUITKA_MAY_BE_UNUSED static PyObject *LOOKUP_SLICE(PyThreadState *tstate, PyObject *source, PyObject *lower,
                                                   PyObject *upper) {
    CHECK_OBJECT(source);
    CHECK_OBJECT(lower);
    CHECK_OBJECT(upper);
 
    PySequenceMethods *tp_as_sequence = Py_TYPE(source)->tp_as_sequence;
 
    if (tp_as_sequence && tp_as_sequence->sq_slice && IS_INDEXABLE(lower) && IS_INDEXABLE(upper)) {
        Py_ssize_t ilow = 0;
 
        if (lower != Py_None) {
            ilow = CONVERT_TO_INDEX(tstate, lower);
 
            if (ilow == -1 && HAS_ERROR_OCCURRED(tstate)) {
                return NULL;
            }
        }
 
        Py_ssize_t ihigh = PY_SSIZE_T_MAX;
 
        if (upper != Py_None) {
            ihigh = CONVERT_TO_INDEX(tstate, upper);
 
            if (ihigh == -1 && HAS_ERROR_OCCURRED(tstate)) {
                return NULL;
            }
        }
 
        PyObject *result = PySequence_GetSlice(source, ilow, ihigh);
 
        if (unlikely(result == NULL)) {
            return NULL;
        }
 
        return result;
    } else {
        PyObject *slice = PySlice_New(lower, upper, NULL);
 
        if (unlikely(slice == NULL)) {
            return NULL;
        }
 
        PyObject *result = PyObject_GetItem(source, slice);
        Py_DECREF(slice);
 
        if (unlikely(result == NULL)) {
            return NULL;
        }
 
        return result;
    }
}
 
NUITKA_MAY_BE_UNUSED static PyObject *LOOKUP_INDEX_SLICE(PyObject *source, Py_ssize_t lower, Py_ssize_t upper) {
    CHECK_OBJECT(source);
 
    PyObject *result = PySequence_GetSlice(source, lower, upper);
 
    if (unlikely(result == NULL)) {
        return NULL;
    }
 
    return result;
}
 
NUITKA_MAY_BE_UNUSED static bool SET_SLICE(PyThreadState *tstate, PyObject *target, PyObject *lower, PyObject *upper,
                                           PyObject *value) {
    CHECK_OBJECT(target);
    CHECK_OBJECT(lower);
    CHECK_OBJECT(upper);
    CHECK_OBJECT(value);
 
    PySequenceMethods *tp_as_sequence = Py_TYPE(target)->tp_as_sequence;
 
    if (tp_as_sequence && tp_as_sequence->sq_ass_slice && IS_INDEXABLE(lower) && IS_INDEXABLE(upper)) {
        Py_ssize_t lower_int = 0;
 
        if (lower != Py_None) {
            lower_int = CONVERT_TO_INDEX(tstate, lower);
 
            if (lower_int == -1 && HAS_ERROR_OCCURRED(tstate)) {
                return false;
            }
        }
 
        Py_ssize_t upper_int = PY_SSIZE_T_MAX;
 
        if (upper != Py_None) {
            upper_int = CONVERT_TO_INDEX(tstate, upper);
 
            if (upper_int == -1 && HAS_ERROR_OCCURRED(tstate)) {
                return false;
            }
        }
 
        int status = PySequence_SetSlice(target, lower_int, upper_int, value);
 
        if (unlikely(status == -1)) {
            return false;
        }
    } else {
        PyObject *slice = PySlice_New(lower, upper, NULL);
 
        if (unlikely(slice == NULL)) {
            return false;
        }
 
        int status = PyObject_SetItem(target, slice, value);
        Py_DECREF(slice);
 
        if (unlikely(status == -1)) {
            return false;
        }
    }
 
    return true;
}
 
NUITKA_MAY_BE_UNUSED static bool SET_INDEX_SLICE(PyObject *target, Py_ssize_t lower, Py_ssize_t upper,
                                                 PyObject *value) {
    CHECK_OBJECT(target);
    CHECK_OBJECT(value);
 
    PySequenceMethods *tp_as_sequence = Py_TYPE(target)->tp_as_sequence;
 
    if (tp_as_sequence && tp_as_sequence->sq_ass_slice) {
        int status = PySequence_SetSlice(target, lower, upper, value);
 
        if (unlikely(status == -1)) {
            return false;
        }
    } else {
        PyObject *slice = _PySlice_FromIndices(lower, upper);
 
        if (unlikely(slice == NULL)) {
            return false;
        }
 
        int status = PyObject_SetItem(target, slice, value);
 
        Py_DECREF(slice);
 
        if (unlikely(status == -1)) {
            return false;
        }
    }
 
    return true;
}
 
NUITKA_MAY_BE_UNUSED static bool DEL_SLICE(PyThreadState *tstate, PyObject *target, PyObject *lower, PyObject *upper) {
    CHECK_OBJECT(target);
    CHECK_OBJECT(lower);
    CHECK_OBJECT(upper);
 
    PySequenceMethods *tp_as_sequence = Py_TYPE(target)->tp_as_sequence;
 
    if (tp_as_sequence && tp_as_sequence->sq_ass_slice && IS_INDEXABLE(lower) && IS_INDEXABLE(upper)) {
        Py_ssize_t lower_int = 0;
 
        if (lower != Py_None) {
            lower_int = CONVERT_TO_INDEX(tstate, lower);
 
            if (lower_int == -1 && HAS_ERROR_OCCURRED(tstate)) {
                return false;
            }
        }
 
        Py_ssize_t upper_int = PY_SSIZE_T_MAX;
 
        if (upper != Py_None) {
            upper_int = CONVERT_TO_INDEX(tstate, upper);
 
            if (upper_int == -1 && HAS_ERROR_OCCURRED(tstate)) {
                return false;
            }
        }
 
        int status = PySequence_DelSlice(target, lower_int, upper_int);
 
        if (unlikely(status == -1)) {
            return false;
        }
    } else {
        PyObject *slice = PySlice_New(lower, upper, NULL);
 
        if (unlikely(slice == NULL)) {
            return false;
        }
 
        int status = PyObject_DelItem(target, slice);
        Py_DECREF(slice);
 
        if (unlikely(status == -1)) {
            return false;
        }
    }
 
    return true;
}
 
NUITKA_MAY_BE_UNUSED static bool DEL_INDEX_SLICE(PyObject *target, Py_ssize_t lower, Py_ssize_t upper) {
    CHECK_OBJECT(target);
 
    PySequenceMethods *tp_as_sequence = Py_TYPE(target)->tp_as_sequence;
 
    if (tp_as_sequence && tp_as_sequence->sq_ass_slice) {
        int status = PySequence_DelSlice(target, lower, upper);
 
        if (unlikely(status == -1)) {
            return false;
        }
    } else {
        PyObject *slice = _PySlice_FromIndices(lower, upper);
 
        if (unlikely(slice == NULL)) {
            return false;
        }
 
        int status = PyObject_DelItem(target, slice);
 
        Py_DECREF(slice);
 
        if (unlikely(status == -1)) {
            return false;
        }
    }
 
    return true;
}
 
#endif
 
#endif
 
//     Part of "Nuitka", an optimizing Python compiler that is compatible and
//     integrates with CPython, but also works on its own.
//
//     Licensed under the Apache License, Version 2.0 (the "License");
//     you may not use this file except in compliance with the License.
//     You may obtain a copy of the License at
//
//        http://www.apache.org/licenses/LICENSE-2.0
//
//     Unless required by applicable law or agreed to in writing, software
//     distributed under the License is distributed on an "AS IS" BASIS,
//     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//     See the License for the specific language governing permissions and
//     limitations under the License.