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pythongh-106307: Add _PyMapping_LookupItem()
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Replacement of PyObject_GetItem() which doesn't raise KeyError.

  int _PyMapping_LookupItem(PyObject *obj, PyObject *key, PyObject **result)

Return 1 and set *result != NULL if a key is found.
Return 0 and set *result == NULL if a key is not found;
a KeyError is silenced.
Return -1 and set *result == NULL if an error other than KeyError
is raised.
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@serhiy-storchaka
serhiy-storchaka committed Jul 1, 2023
1 parent 04dfc6f commit cfc5851
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Showing 8 changed files with 639 additions and 846 deletions.
11 changes: 11 additions & 0 deletions Include/cpython/object.h
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Original file line number Diff line number Diff line change
Expand Up @@ -320,6 +320,17 @@ PyAPI_FUNC(int)
_PyObject_GenericSetAttrWithDict(PyObject *, PyObject *,
PyObject *, PyObject *);

/* Replacements of PyObject_GetItem() which don't raise KeyError.
Return 1 and set *result != NULL if a key is found.
Return 0 and set *result == NULL if a key is not found;
a KeyError is silenced.
Return -1 and set *result == NULL if an error other than KeyError
is raised.
*/
PyAPI_FUNC(int) _PyMapping_LookupItem(PyObject *, PyObject *, PyObject **);
PyAPI_FUNC(int) _PyMapping_LookupItemString(PyObject *, const char *, PyObject **);

PyAPI_FUNC(PyObject *) _PyObject_FunctionStr(PyObject *);

/* Safely decref `dst` and set `dst` to `src`.
Expand Down
22 changes: 9 additions & 13 deletions Modules/_lzmamodule.c
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Original file line number Diff line number Diff line change
Expand Up @@ -242,15 +242,10 @@ parse_filter_spec_lzma(_lzma_state *state, PyObject *spec)
/* First, fill in default values for all the options using a preset.
Then, override the defaults with any values given by the caller. */

preset_obj = PyMapping_GetItemString(spec, "preset");
if (preset_obj == NULL) {
if (PyErr_ExceptionMatches(PyExc_KeyError)) {
PyErr_Clear();
}
else {
return NULL;
}
} else {
if (_PyMapping_LookupItemString(spec, "preset", &preset_obj) < 0) {
return NULL;
}
if (preset_obj != NULL) {
int ok = uint32_converter(preset_obj, &preset);
Py_DECREF(preset_obj);
if (!ok) {
Expand Down Expand Up @@ -347,11 +342,12 @@ lzma_filter_converter(_lzma_state *state, PyObject *spec, void *ptr)
"Filter specifier must be a dict or dict-like object");
return 0;
}
id_obj = PyMapping_GetItemString(spec, "id");
if (_PyMapping_LookupItemString(spec, "id", &id_obj) < 0) {
return 0;
}
if (id_obj == NULL) {
if (PyErr_ExceptionMatches(PyExc_KeyError))
PyErr_SetString(PyExc_ValueError,
"Filter specifier must have an \"id\" entry");
PyErr_SetString(PyExc_ValueError,
"Filter specifier must have an \"id\" entry");
return 0;
}
f->id = PyLong_AsUnsignedLongLong(id_obj);
Expand Down
10 changes: 3 additions & 7 deletions Modules/_pickle.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4438,13 +4438,9 @@ save(PickleState *st, PicklerObject *self, PyObject *obj, int pers_save)
Py_INCREF(reduce_func);
}
} else {
reduce_func = PyObject_GetItem(self->dispatch_table,
(PyObject *)type);
if (reduce_func == NULL) {
if (PyErr_ExceptionMatches(PyExc_KeyError))
PyErr_Clear();
else
goto error;
if (_PyMapping_LookupItem(self->dispatch_table, (PyObject *)type,
&reduce_func) < 0) {
goto error;
}
}
if (reduce_func != NULL) {
Expand Down
39 changes: 39 additions & 0 deletions Objects/abstract.c
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Original file line number Diff line number Diff line change
Expand Up @@ -199,6 +199,30 @@ PyObject_GetItem(PyObject *o, PyObject *key)
return type_error("'%.200s' object is not subscriptable", o);
}

int
_PyMapping_LookupItem(PyObject *o, PyObject *key, PyObject **pvalue)
{
if (PyDict_CheckExact(o)) {
*pvalue = PyDict_GetItemWithError(o, key); /* borrowed */
if (*pvalue) {
Py_INCREF(*pvalue);
return 1;
}
return PyErr_Occurred() ? -1 : 0;
}

*pvalue = PyObject_GetItem(o, key);
if (*pvalue) {
return 1;
}
assert(PyErr_Occurred());
if (!PyErr_ExceptionMatches(PyExc_KeyError)) {
return -1;
}
PyErr_Clear();
return 0;
}

int
PyObject_SetItem(PyObject *o, PyObject *key, PyObject *value)
{
Expand Down Expand Up @@ -2366,6 +2390,21 @@ PyMapping_GetItemString(PyObject *o, const char *key)
return r;
}

int
_PyMapping_LookupItemString(PyObject *o, const char *key, PyObject **pvalue)
{
if (key == NULL) {
return null_error();
}
PyObject *okey = PyUnicode_FromString(key);
if (okey == NULL) {
return NULL;
}
int r = _PyMapping_LookupItem(o, okey, pvalue);
Py_DECREF(okey);
return r;
}

int
PyMapping_SetItemString(PyObject *o, const char *key, PyObject *value)
{
Expand Down
116 changes: 24 additions & 92 deletions Python/bytecodes.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1086,26 +1086,11 @@ dummy_func(
}

inst(LOAD_BUILD_CLASS, ( -- bc)) {
if (PyDict_CheckExact(BUILTINS())) {
bc = _PyDict_GetItemWithError(BUILTINS(),
&_Py_ID(__build_class__));
if (bc == NULL) {
if (!_PyErr_Occurred(tstate)) {
_PyErr_SetString(tstate, PyExc_NameError,
"__build_class__ not found");
}
ERROR_IF(true, error);
}
Py_INCREF(bc);
}
else {
bc = PyObject_GetItem(BUILTINS(), &_Py_ID(__build_class__));
if (bc == NULL) {
if (_PyErr_ExceptionMatches(tstate, PyExc_KeyError))
_PyErr_SetString(tstate, PyExc_NameError,
"__build_class__ not found");
ERROR_IF(true, error);
}
ERROR_IF(_PyMapping_LookupItem(BUILTINS(), &_Py_ID(__build_class__), &bc) < 0, error);
if (bc == NULL) {
_PyErr_SetString(tstate, PyExc_NameError,
"__build_class__ not found");
ERROR_IF(true, error);
}
}

Expand Down Expand Up @@ -1280,25 +1265,9 @@ dummy_func(

op(_LOAD_FROM_DICT_OR_GLOBALS, (mod_or_class_dict -- v)) {
PyObject *name = GETITEM(FRAME_CO_NAMES, oparg);
if (PyDict_CheckExact(mod_or_class_dict)) {
v = PyDict_GetItemWithError(mod_or_class_dict, name);
if (v != NULL) {
Py_INCREF(v);
}
else if (_PyErr_Occurred(tstate)) {
Py_DECREF(mod_or_class_dict);
goto error;
}
}
else {
v = PyObject_GetItem(mod_or_class_dict, name);
if (v == NULL) {
if (!_PyErr_ExceptionMatches(tstate, PyExc_KeyError)) {
Py_DECREF(mod_or_class_dict);
goto error;
}
_PyErr_Clear(tstate);
}
if (_PyMapping_LookupItem(mod_or_class_dict, name, &v) < 0) {
Py_DECREF(mod_or_class_dict);
goto error;
}
Py_DECREF(mod_or_class_dict);
if (v == NULL) {
Expand All @@ -1310,28 +1279,14 @@ dummy_func(
goto error;
}
else {
if (PyDict_CheckExact(BUILTINS())) {
v = PyDict_GetItemWithError(BUILTINS(), name);
if (v == NULL) {
if (!_PyErr_Occurred(tstate)) {
format_exc_check_arg(
tstate, PyExc_NameError,
NAME_ERROR_MSG, name);
}
goto error;
}
Py_INCREF(v);
if (_PyMapping_LookupItem(BUILTINS(), name, &v) < 0) {
goto error;
}
else {
v = PyObject_GetItem(BUILTINS(), name);
if (v == NULL) {
if (_PyErr_ExceptionMatches(tstate, PyExc_KeyError)) {
format_exc_check_arg(
tstate, PyExc_NameError,
NAME_ERROR_MSG, name);
}
goto error;
}
if (v == NULL) {
format_exc_check_arg(
tstate, PyExc_NameError,
NAME_ERROR_MSG, name);
goto error;
}
}
}
Expand Down Expand Up @@ -1381,19 +1336,14 @@ dummy_func(
/* Slow-path if globals or builtins is not a dict */

/* namespace 1: globals */
v = PyObject_GetItem(GLOBALS(), name);
ERROR_IF(_PyMapping_LookupItem(GLOBALS(), name, &v) < 0, error);
if (v == NULL) {
ERROR_IF(!_PyErr_ExceptionMatches(tstate, PyExc_KeyError), error);
_PyErr_Clear(tstate);

/* namespace 2: builtins */
v = PyObject_GetItem(BUILTINS(), name);
ERROR_IF(_PyMapping_LookupItem(BUILTINS(), name, &v) < 0, error);
if (v == NULL) {
if (_PyErr_ExceptionMatches(tstate, PyExc_KeyError)) {
format_exc_check_arg(
tstate, PyExc_NameError,
NAME_ERROR_MSG, name);
}
format_exc_check_arg(
tstate, PyExc_NameError,
NAME_ERROR_MSG, name);
ERROR_IF(true, error);
}
}
Expand Down Expand Up @@ -1466,25 +1416,9 @@ dummy_func(
assert(class_dict);
assert(oparg >= 0 && oparg < _PyFrame_GetCode(frame)->co_nlocalsplus);
name = PyTuple_GET_ITEM(_PyFrame_GetCode(frame)->co_localsplusnames, oparg);
if (PyDict_CheckExact(class_dict)) {
value = PyDict_GetItemWithError(class_dict, name);
if (value != NULL) {
Py_INCREF(value);
}
else if (_PyErr_Occurred(tstate)) {
Py_DECREF(class_dict);
goto error;
}
}
else {
value = PyObject_GetItem(class_dict, name);
if (value == NULL) {
if (!_PyErr_ExceptionMatches(tstate, PyExc_KeyError)) {
Py_DECREF(class_dict);
goto error;
}
_PyErr_Clear(tstate);
}
if (_PyMapping_LookupItem(class_dict, name, &value) < 0) {
Py_DECREF(class_dict);
goto error;
}
Py_DECREF(class_dict);
if (!value) {
Expand Down Expand Up @@ -1622,10 +1556,8 @@ dummy_func(
}
else {
/* do the same if locals() is not a dict */
ann_dict = PyObject_GetItem(LOCALS(), &_Py_ID(__annotations__));
ERROR_IF(_PyMapping_LookupItem(LOCALS(), &_Py_ID(__annotations__), &ann_dict) < 0, error);
if (ann_dict == NULL) {
ERROR_IF(!_PyErr_ExceptionMatches(tstate, PyExc_KeyError), error);
_PyErr_Clear(tstate);
ann_dict = PyDict_New();
ERROR_IF(ann_dict == NULL, error);
err = PyObject_SetItem(LOCALS(), &_Py_ID(__annotations__),
Expand Down
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