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299 lines
8.0 KiB
C
299 lines
8.0 KiB
C
/* Bisection algorithms. Drop in replacement for bisect.py
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Converted to C by Dmitry Vasiliev (dima at hlabs.spb.ru).
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*/
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#define PY_SSIZE_T_CLEAN
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#include "Python.h"
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/*[clinic input]
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module _bisect
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[clinic start generated code]*/
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/*[clinic end generated code: output=da39a3ee5e6b4b0d input=4d56a2b2033b462b]*/
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#include "clinic/_bisectmodule.c.h"
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_Py_IDENTIFIER(insert);
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static inline Py_ssize_t
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internal_bisect_right(PyObject *list, PyObject *item, Py_ssize_t lo, Py_ssize_t hi,
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PyObject* key)
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{
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PyObject *litem;
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Py_ssize_t mid;
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int res;
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if (lo < 0) {
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PyErr_SetString(PyExc_ValueError, "lo must be non-negative");
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return -1;
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}
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if (hi == -1) {
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hi = PySequence_Size(list);
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if (hi < 0)
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return -1;
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}
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while (lo < hi) {
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/* The (size_t)cast ensures that the addition and subsequent division
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are performed as unsigned operations, avoiding difficulties from
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signed overflow. (See issue 13496.) */
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mid = ((size_t)lo + hi) / 2;
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litem = PySequence_GetItem(list, mid);
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if (litem == NULL)
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return -1;
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if (key != Py_None) {
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PyObject *newitem = PyObject_CallOneArg(key, litem);
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if (newitem == NULL) {
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Py_DECREF(litem);
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return -1;
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}
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Py_SETREF(litem, newitem);
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}
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res = PyObject_RichCompareBool(item, litem, Py_LT);
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Py_DECREF(litem);
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if (res < 0)
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return -1;
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if (res)
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hi = mid;
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else
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lo = mid + 1;
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}
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return lo;
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}
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/*[clinic input]
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_bisect.bisect_right -> Py_ssize_t
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a: object
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x: object
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lo: Py_ssize_t = 0
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hi: Py_ssize_t(c_default='-1', accept={int, NoneType}) = None
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*
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key: object = None
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Return the index where to insert item x in list a, assuming a is sorted.
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The return value i is such that all e in a[:i] have e <= x, and all e in
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a[i:] have e > x. So if x already appears in the list, i points just
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beyond the rightmost x already there
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Optional args lo (default 0) and hi (default len(a)) bound the
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slice of a to be searched.
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[clinic start generated code]*/
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static Py_ssize_t
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_bisect_bisect_right_impl(PyObject *module, PyObject *a, PyObject *x,
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Py_ssize_t lo, Py_ssize_t hi, PyObject *key)
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/*[clinic end generated code: output=3a4bc09cc7c8a73d input=1313e9ca20c8bc3c]*/
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{
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return internal_bisect_right(a, x, lo, hi, key);
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}
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/*[clinic input]
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_bisect.insort_right
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a: object
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x: object
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lo: Py_ssize_t = 0
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hi: Py_ssize_t(c_default='-1', accept={int, NoneType}) = None
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*
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key: object = None
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Insert item x in list a, and keep it sorted assuming a is sorted.
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If x is already in a, insert it to the right of the rightmost x.
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Optional args lo (default 0) and hi (default len(a)) bound the
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slice of a to be searched.
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[clinic start generated code]*/
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static PyObject *
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_bisect_insort_right_impl(PyObject *module, PyObject *a, PyObject *x,
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Py_ssize_t lo, Py_ssize_t hi, PyObject *key)
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/*[clinic end generated code: output=ac3bf26d07aedda2 input=44e1708e26b7b802]*/
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{
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PyObject *result, *key_x;
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Py_ssize_t index;
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if (key == Py_None) {
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index = internal_bisect_right(a, x, lo, hi, key);
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} else {
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key_x = PyObject_CallOneArg(key, x);
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if (x == NULL) {
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return NULL;
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}
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index = internal_bisect_right(a, key_x, lo, hi, key);
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Py_DECREF(key_x);
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}
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if (index < 0)
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return NULL;
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if (PyList_CheckExact(a)) {
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if (PyList_Insert(a, index, x) < 0)
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return NULL;
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}
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else {
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result = _PyObject_CallMethodId(a, &PyId_insert, "nO", index, x);
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if (result == NULL)
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return NULL;
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Py_DECREF(result);
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}
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Py_RETURN_NONE;
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}
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static inline Py_ssize_t
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internal_bisect_left(PyObject *list, PyObject *item, Py_ssize_t lo, Py_ssize_t hi,
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PyObject *key)
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{
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PyObject *litem;
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Py_ssize_t mid;
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int res;
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if (lo < 0) {
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PyErr_SetString(PyExc_ValueError, "lo must be non-negative");
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return -1;
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}
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if (hi == -1) {
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hi = PySequence_Size(list);
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if (hi < 0)
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return -1;
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}
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while (lo < hi) {
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/* The (size_t)cast ensures that the addition and subsequent division
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are performed as unsigned operations, avoiding difficulties from
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signed overflow. (See issue 13496.) */
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mid = ((size_t)lo + hi) / 2;
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litem = PySequence_GetItem(list, mid);
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if (litem == NULL)
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return -1;
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if (key != Py_None) {
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PyObject *newitem = PyObject_CallOneArg(key, litem);
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if (newitem == NULL) {
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Py_DECREF(litem);
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return -1;
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}
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Py_SETREF(litem, newitem);
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}
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res = PyObject_RichCompareBool(litem, item, Py_LT);
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Py_DECREF(litem);
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if (res < 0)
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return -1;
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if (res)
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lo = mid + 1;
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else
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hi = mid;
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}
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return lo;
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}
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/*[clinic input]
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_bisect.bisect_left -> Py_ssize_t
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a: object
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x: object
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lo: Py_ssize_t = 0
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hi: Py_ssize_t(c_default='-1', accept={int, NoneType}) = None
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*
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key: object = None
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Return the index where to insert item x in list a, assuming a is sorted.
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The return value i is such that all e in a[:i] have e < x, and all e in
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a[i:] have e >= x. So if x already appears in the list, i points just
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before the leftmost x already there.
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Optional args lo (default 0) and hi (default len(a)) bound the
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slice of a to be searched.
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[clinic start generated code]*/
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static Py_ssize_t
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_bisect_bisect_left_impl(PyObject *module, PyObject *a, PyObject *x,
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Py_ssize_t lo, Py_ssize_t hi, PyObject *key)
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/*[clinic end generated code: output=70749d6e5cae9284 input=3cbeec690f2f6c6e]*/
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{
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return internal_bisect_left(a, x, lo, hi, key);
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}
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/*[clinic input]
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_bisect.insort_left
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a: object
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x: object
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lo: Py_ssize_t = 0
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hi: Py_ssize_t(c_default='-1', accept={int, NoneType}) = None
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*
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key: object = None
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Insert item x in list a, and keep it sorted assuming a is sorted.
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If x is already in a, insert it to the left of the leftmost x.
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Optional args lo (default 0) and hi (default len(a)) bound the
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slice of a to be searched.
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[clinic start generated code]*/
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static PyObject *
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_bisect_insort_left_impl(PyObject *module, PyObject *a, PyObject *x,
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Py_ssize_t lo, Py_ssize_t hi, PyObject *key)
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/*[clinic end generated code: output=b1d33e5e7ffff11e input=3ab65d8784f585b1]*/
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{
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PyObject *result, *key_x;
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Py_ssize_t index;
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if (key == Py_None) {
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index = internal_bisect_left(a, x, lo, hi, key);
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} else {
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key_x = PyObject_CallOneArg(key, x);
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if (x == NULL) {
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return NULL;
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}
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index = internal_bisect_left(a, key_x, lo, hi, key);
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Py_DECREF(key_x);
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}
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if (index < 0)
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return NULL;
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if (PyList_CheckExact(a)) {
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if (PyList_Insert(a, index, x) < 0)
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return NULL;
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} else {
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result = _PyObject_CallMethodId(a, &PyId_insert, "nO", index, x);
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if (result == NULL)
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return NULL;
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Py_DECREF(result);
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}
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Py_RETURN_NONE;
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}
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static PyMethodDef bisect_methods[] = {
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_BISECT_BISECT_RIGHT_METHODDEF
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_BISECT_INSORT_RIGHT_METHODDEF
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_BISECT_BISECT_LEFT_METHODDEF
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_BISECT_INSORT_LEFT_METHODDEF
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{NULL, NULL} /* sentinel */
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};
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PyDoc_STRVAR(module_doc,
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"Bisection algorithms.\n\
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\n\
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This module provides support for maintaining a list in sorted order without\n\
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having to sort the list after each insertion. For long lists of items with\n\
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expensive comparison operations, this can be an improvement over the more\n\
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common approach.\n");
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static struct PyModuleDef _bisectmodule = {
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PyModuleDef_HEAD_INIT,
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.m_name = "_bisect",
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.m_doc = module_doc,
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.m_methods = bisect_methods,
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.m_size = 0
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};
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PyMODINIT_FUNC
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PyInit__bisect(void)
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{
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return PyModuleDef_Init(&_bisectmodule);
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}
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