[Python-checkins] bpo-38530: Optimize the calculation of string sizes when offering suggestions (GH-25412)

Wed Apr 14 19:03:51 EDT 2021

https://github.com/python/cpython/commit/3fc65b97d09fd29272fdf60d2e567bfb070da824
commit: 3fc65b97d09fd29272fdf60d2e567bfb070da824
branch: master
author: Pablo Galindo <Pablogsal at gmail.com>
committer: pablogsal <Pablogsal at gmail.com>
date: 2021年04月15日T00:03:43+01:00
summary:
bpo-38530: Optimize the calculation of string sizes when offering suggestions (GH-25412)
files:
M Python/suggestions.c

diff --git a/Python/suggestions.c b/Python/suggestions.c
index bdc8e2fd1bb08..258e3f1833e6b 100644
--- a/Python/suggestions.c
+++ b/Python/suggestions.c
@@ -9,10 +9,8 @@
 
 /* Calculate the Levenshtein distance between string1 and string2 */
 static size_t
-levenshtein_distance(const char *a, const char *b) {
-
- const size_t a_size = strlen(a);
- const size_t b_size = strlen(b);
+levenshtein_distance(const char *a, size_t a_size,
+ const char *b, size_t b_size) {
 
 if (a_size > MAX_STRING_SIZE || b_size > MAX_STRING_SIZE) {
 return 0;
@@ -87,17 +85,20 @@ calculate_suggestions(PyObject *dir,
 
 Py_ssize_t suggestion_distance = PyUnicode_GetLength(name);
 PyObject *suggestion = NULL;
- const char *name_str = PyUnicode_AsUTF8(name);
+ Py_ssize_t name_size;
+ const char *name_str = PyUnicode_AsUTF8AndSize(name, &name_size);
 if (name_str == NULL) {
 return NULL;
 }
 for (int i = 0; i < dir_size; ++i) {
 PyObject *item = PyList_GET_ITEM(dir, i);
- const char *item_str = PyUnicode_AsUTF8(item);
+ Py_ssize_t item_size;
+ const char *item_str = PyUnicode_AsUTF8AndSize(item, &item_size);
 if (item_str == NULL) {
 return NULL;
 }
- Py_ssize_t current_distance = levenshtein_distance(name_str, item_str);
+ Py_ssize_t current_distance = levenshtein_distance(
+ name_str, name_size, item_str, item_size);
 if (current_distance == 0 || current_distance > MAX_DISTANCE) {
 continue;
 }
@@ -138,7 +139,8 @@ static PyObject *
 offer_suggestions_for_name_error(PyNameErrorObject *exc) {
 PyObject *name = exc->name; // borrowed reference
 PyTracebackObject *traceback = (PyTracebackObject *) exc->traceback; // borrowed reference
- // Abort if we don't have an attribute name or we have an invalid one
+ // Abort if we don't have a variable name or we have an invalid one
+ // or if we don't have a traceback to work with
 if (name == NULL || traceback == NULL || !PyUnicode_CheckExact(name)) {
 return NULL;
 }
