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bpo-38530: Refactor AttributeError suggestions #25776

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Merged
pablogsal merged 8 commits into from
May 3, 2021
Merged

bpo-38530: Refactor AttributeError suggestions #25776

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d04b5f4
Refactor suggestions
sweeneyde May 1, 2021
e680014
Apply changes from review
sweeneyde May 1, 2021
8e120f3
Add tests using _testinternalcapi
sweeneyde May 2, 2021
d716094
Remove unused buffer
sweeneyde May 2, 2021
eff17fb
Allow for suggestions on larger dir()s and names
sweeneyde May 2, 2021
e99baf1
Correct a comment
sweeneyde May 2, 2021
3af514a
Remove one more unneeded computation
sweeneyde May 2, 2021
ce87e15
Fix refleaks
pablogsal May 3, 2021
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@sweeneyde
sweeneyde committed May 1, 2021
commit e680014e99e96420b218d55f0bea6be6b1ff3f72
91 changes: 28 additions & 63 deletions Python/suggestions.c
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Original file line number Diff line number Diff line change
Expand Up @@ -10,10 +10,12 @@
#define MOVE_COST 2
#define CASE_COST 1

#define LEAST_FIVE_BITS(n) ((n) * 31)

static inline int
substitution_cost(char a, char b)
{
if ((a & 31) != (b & 31)) {
if (LEAST_FIVE_BITS(a) != LEAST_FIVE_BITS(b)) {
// Not the same, not a case flip.
return MOVE_COST;
}
Expand All @@ -36,8 +38,9 @@ substitution_cost(char a, char b)
static Py_ssize_t
levenshtein_distance(const char *a, size_t a_size,
const char *b, size_t b_size,
size_t *buffer, size_t max_cost)
size_t max_cost)
{
static size_t buffer[MAX_STRING_SIZE];
if (a_size > MAX_STRING_SIZE || b_size > MAX_STRING_SIZE) {
return max_cost + 1;
}
Expand Down Expand Up @@ -120,68 +123,10 @@ levenshtein_distance(const char *a, size_t a_size,
return result;
}

#define TEST_LEVENSHTEIN 0
#if TEST_LEVENSHTEIN

static void
do_test(const char *a, const char *b, size_t d)
{
static size_t buffer[500];
size_t a_len = strlen(a);
size_t b_len = strlen(b);
size_t d2 = levenshtein_distance(a, a_len, b, b_len, buffer, 9999);
printf("'%s' -> '%s':", a, b);
if (d != d2) {
printf("\n FAILURE: Expected %d, got %d.\n", (int)d, (int)d2);
}
else {
printf(" passed.\n");
}
size_t d3 = levenshtein_distance(a, a_len, b, b_len, buffer, d2);
assert(d2 == d3);
size_t d4 = levenshtein_distance(b, b_len, a, a_len, buffer, d2);
assert(d2 == d4);
}

static void
test_levenshtein_distances()
{
printf("\n\n--- Testing Levenshtein Distances ---\n\n");
do_test("", "", 0);
do_test("", "a", 2);
do_test("a", "A", 1);
do_test("Apple", "Aple", 2);
do_test("Banana", "B@n@n@", 6);
do_test("Cherry", "Cherry!", 2);
do_test("abc", "y", 6);
do_test("aa", "bb", 4);
do_test("aaaaa", "AAAAA", 5);
do_test("wxyz", "wXyZ", 2);
do_test("wxyz", "wXyZ123", 8);
do_test("Python", "Java", 12);
do_test("Java", "C#", 8);
do_test("AbstractFoobarManager", "abstract_foobar_manager", 3+2*2);
do_test("CPython", "PyPy", 10);
do_test("CPython", "pypy", 11);
do_test("AttributeError", "AttributeErrop", 2);
do_test("AttributeError", "AttributeErrorTests", 10);
printf("\n\n-------------------------------------\n\n");
}

#endif

static inline PyObject *
calculate_suggestions(PyObject *dir,
PyObject *name)
{

@pablogsal pablogsal May 1, 2021

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Ditto here: please remove the tests or move them to the test suite

#if TEST_LEVENSHTEIN
static int did_it;
if (!did_it) {
did_it = 1;
test_levenshtein_distances();
}
#endif

assert(!PyErr_Occurred());
assert(PyList_CheckExact(dir));

Expand Down Expand Up @@ -213,8 +158,7 @@ calculate_suggestions(PyObject *dir,
Py_ssize_t max_distance = (name_size + item_size + 3) * MOVE_COST / 6;
Py_ssize_t current_distance =
levenshtein_distance(name_str, name_size,
item_str, item_size,
work_buffer, max_distance);
item_str, item_size, max_distance);
if (current_distance > max_distance) {
continue;
}
Expand Down Expand Up @@ -303,7 +247,9 @@ offer_suggestions_for_name_error(PyNameErrorObject *exc)
// Offer suggestions for a given exception. Returns a python string object containing the
// suggestions. This function returns NULL if no suggestion was found or if an exception happened,
// users must call PyErr_Occurred() to disambiguate.
PyObject *_Py_Offer_Suggestions(PyObject *exception) {
PyObject *
_Py_Offer_Suggestions(PyObject *exception)
{
PyObject *result = NULL;
assert(!PyErr_Occurred());
if (Py_IS_TYPE(exception, (PyTypeObject*)PyExc_AttributeError)) {
Expand All @@ -314,3 +260,22 @@ PyObject *_Py_Offer_Suggestions(PyObject *exception) {
return result;
}

Py_ssize_t *
_Py_UTF8_Edit_Cost(PyObject *a, PyObject *b, Py_ssize_t max_cost)
{
assert(PyUnicode_Check(a) && PyUnicode_Check(b));
Py_ssize_t size_a, size_b;
const char *utf8_a = PyUnicode_AsUTF8AndSize(a, &size_a);
if (utf8_a == NULL) {
return -1;
}
const char *utf8_b = PyUnicode_AsUTF8AndSize(b, &size_b);
if (utf8_b == NULL) {
return -1;
}
if (max_cost == -1) {
max_cost = MOVE_COST * Py_MAX(size_a, size_b);
}
return levenshtein_distance(utf8_a, size_a, utf8_b, size_b, max_cost);
}