mirror of
https://github.com/python/cpython
synced 2024-09-05 16:38:56 +00:00
430 lines
12 KiB
C
430 lines
12 KiB
C
#include "Python.h"
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#include "pycore_frame.h"
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#include "pycore_runtime.h" // _PyRuntime
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#include "pycore_global_objects.h" // _Py_ID()
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#include "pycore_pyerrors.h"
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#include "pycore_code.h" // _PyCode_GetVarnames()
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#include "stdlib_module_names.h" // _Py_stdlib_module_names
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#define MAX_CANDIDATE_ITEMS 750
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#define MAX_STRING_SIZE 40
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#define MOVE_COST 2
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#define CASE_COST 1
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#define LEAST_FIVE_BITS(n) ((n) & 31)
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static inline int
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substitution_cost(char a, char b)
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{
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if (LEAST_FIVE_BITS(a) != LEAST_FIVE_BITS(b)) {
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// Not the same, not a case flip.
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return MOVE_COST;
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}
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if (a == b) {
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return 0;
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}
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if ('A' <= a && a <= 'Z') {
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a += ('a' - 'A');
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}
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if ('A' <= b && b <= 'Z') {
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b += ('a' - 'A');
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}
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if (a == b) {
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return CASE_COST;
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}
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return MOVE_COST;
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}
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/* Calculate the Levenshtein distance between string1 and string2 */
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static Py_ssize_t
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levenshtein_distance(const char *a, size_t a_size,
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const char *b, size_t b_size,
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size_t max_cost, size_t *buffer)
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{
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// Both strings are the same (by identity)
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if (a == b) {
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return 0;
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}
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// Trim away common affixes.
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while (a_size && b_size && a[0] == b[0]) {
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a++; a_size--;
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b++; b_size--;
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}
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while (a_size && b_size && a[a_size-1] == b[b_size-1]) {
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a_size--;
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b_size--;
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}
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if (a_size == 0 || b_size == 0) {
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return (a_size + b_size) * MOVE_COST;
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}
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if (a_size > MAX_STRING_SIZE || b_size > MAX_STRING_SIZE) {
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return max_cost + 1;
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}
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// Prefer shorter buffer
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if (b_size < a_size) {
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const char *t = a; a = b; b = t;
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size_t t_size = a_size; a_size = b_size; b_size = t_size;
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}
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// quick fail when a match is impossible.
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if ((b_size - a_size) * MOVE_COST > max_cost) {
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return max_cost + 1;
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}
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// Instead of producing the whole traditional len(a)-by-len(b)
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// matrix, we can update just one row in place.
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// Initialize the buffer row
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size_t tmp = MOVE_COST;
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for (size_t i = 0; i < a_size; i++) {
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// cost from b[:0] to a[:i+1]
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buffer[i] = tmp;
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tmp += MOVE_COST;
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}
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size_t result = 0;
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for (size_t b_index = 0; b_index < b_size; b_index++) {
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char code = b[b_index];
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// cost(b[:b_index], a[:0]) == b_index * MOVE_COST
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size_t distance = result = b_index * MOVE_COST;
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size_t minimum = SIZE_MAX;
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for (size_t index = 0; index < a_size; index++) {
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// cost(b[:b_index+1], a[:index+1]) = min(
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// // 1) substitute
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// cost(b[:b_index], a[:index])
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// + substitution_cost(b[b_index], a[index]),
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// // 2) delete from b
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// cost(b[:b_index], a[:index+1]) + MOVE_COST,
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// // 3) delete from a
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// cost(b[:b_index+1], a[index]) + MOVE_COST
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// )
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// 1) Previous distance in this row is cost(b[:b_index], a[:index])
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size_t substitute = distance + substitution_cost(code, a[index]);
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// 2) cost(b[:b_index], a[:index+1]) from previous row
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distance = buffer[index];
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// 3) existing result is cost(b[:b_index+1], a[index])
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size_t insert_delete = Py_MIN(result, distance) + MOVE_COST;
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result = Py_MIN(insert_delete, substitute);
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// cost(b[:b_index+1], a[:index+1])
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buffer[index] = result;
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if (result < minimum) {
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minimum = result;
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}
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}
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if (minimum > max_cost) {
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// Everything in this row is too big, so bail early.
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return max_cost + 1;
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}
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}
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return result;
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}
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static inline PyObject *
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calculate_suggestions(PyObject *dir,
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PyObject *name)
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{
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assert(!PyErr_Occurred());
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assert(PyList_CheckExact(dir));
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Py_ssize_t dir_size = PyList_GET_SIZE(dir);
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if (dir_size >= MAX_CANDIDATE_ITEMS) {
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return NULL;
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}
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Py_ssize_t suggestion_distance = PY_SSIZE_T_MAX;
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PyObject *suggestion = NULL;
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Py_ssize_t name_size;
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const char *name_str = PyUnicode_AsUTF8AndSize(name, &name_size);
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if (name_str == NULL) {
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return NULL;
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}
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size_t *buffer = PyMem_New(size_t, MAX_STRING_SIZE);
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if (buffer == NULL) {
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return PyErr_NoMemory();
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}
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for (int i = 0; i < dir_size; ++i) {
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PyObject *item = PyList_GET_ITEM(dir, i);
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if (_PyUnicode_Equal(name, item)) {
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continue;
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}
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Py_ssize_t item_size;
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const char *item_str = PyUnicode_AsUTF8AndSize(item, &item_size);
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if (item_str == NULL) {
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PyMem_Free(buffer);
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return NULL;
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}
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// No more than 1/3 of the involved characters should need changed.
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Py_ssize_t max_distance = (name_size + item_size + 3) * MOVE_COST / 6;
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// Don't take matches we've already beaten.
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max_distance = Py_MIN(max_distance, suggestion_distance - 1);
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Py_ssize_t current_distance =
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levenshtein_distance(name_str, name_size, item_str,
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item_size, max_distance, buffer);
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if (current_distance > max_distance) {
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continue;
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}
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if (!suggestion || current_distance < suggestion_distance) {
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suggestion = item;
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suggestion_distance = current_distance;
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}
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}
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PyMem_Free(buffer);
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return Py_XNewRef(suggestion);
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}
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static PyObject *
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get_suggestions_for_attribute_error(PyAttributeErrorObject *exc)
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{
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PyObject *name = exc->name; // borrowed reference
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PyObject *obj = exc->obj; // borrowed reference
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// Abort if we don't have an attribute name or we have an invalid one
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if (name == NULL || obj == NULL || !PyUnicode_CheckExact(name)) {
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return NULL;
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}
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PyObject *dir = PyObject_Dir(obj);
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if (dir == NULL) {
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return NULL;
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}
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PyObject *suggestions = calculate_suggestions(dir, name);
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Py_DECREF(dir);
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return suggestions;
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}
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static PyObject *
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offer_suggestions_for_attribute_error(PyAttributeErrorObject *exc)
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{
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PyObject* suggestion = get_suggestions_for_attribute_error(exc);
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if (suggestion == NULL) {
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return NULL;
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}
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// Add a trailer ". Did you mean: (...)?"
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PyObject* result = PyUnicode_FromFormat(". Did you mean: %R?", suggestion);
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Py_DECREF(suggestion);
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return result;
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}
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static PyObject *
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get_suggestions_for_name_error(PyObject* name, PyFrameObject* frame)
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{
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PyCodeObject *code = PyFrame_GetCode(frame);
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assert(code != NULL && code->co_localsplusnames != NULL);
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PyObject *varnames = _PyCode_GetVarnames(code);
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Py_DECREF(code);
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if (varnames == NULL) {
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return NULL;
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}
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PyObject *dir = PySequence_List(varnames);
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Py_DECREF(varnames);
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if (dir == NULL) {
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return NULL;
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}
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// Are we inside a method and the instance has an attribute called 'name'?
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int res = PySequence_Contains(dir, &_Py_ID(self));
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if (res < 0) {
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goto error;
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}
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if (res > 0) {
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PyObject* locals = PyFrame_GetLocals(frame);
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if (!locals) {
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goto error;
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}
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PyObject* self = PyDict_GetItemWithError(locals, &_Py_ID(self)); /* borrowed */
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if (!self) {
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Py_DECREF(locals);
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goto error;
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}
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PyObject *value;
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res = PyObject_GetOptionalAttr(self, name, &value);
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Py_DECREF(locals);
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if (res < 0) {
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goto error;
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}
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if (value) {
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Py_DECREF(value);
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Py_DECREF(dir);
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return PyUnicode_FromFormat("self.%U", name);
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}
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}
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PyObject *suggestions = calculate_suggestions(dir, name);
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Py_DECREF(dir);
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if (suggestions != NULL || PyErr_Occurred()) {
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return suggestions;
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}
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dir = PySequence_List(frame->f_frame->f_globals);
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if (dir == NULL) {
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return NULL;
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}
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suggestions = calculate_suggestions(dir, name);
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Py_DECREF(dir);
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if (suggestions != NULL || PyErr_Occurred()) {
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return suggestions;
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}
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dir = PySequence_List(frame->f_frame->f_builtins);
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if (dir == NULL) {
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return NULL;
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}
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suggestions = calculate_suggestions(dir, name);
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Py_DECREF(dir);
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return suggestions;
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error:
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Py_DECREF(dir);
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return NULL;
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}
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static bool
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is_name_stdlib_module(PyObject* name)
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{
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const char* the_name = PyUnicode_AsUTF8(name);
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Py_ssize_t len = Py_ARRAY_LENGTH(_Py_stdlib_module_names);
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for (Py_ssize_t i = 0; i < len; i++) {
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if (strcmp(the_name, _Py_stdlib_module_names[i]) == 0) {
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return 1;
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}
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}
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return 0;
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}
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static PyObject *
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offer_suggestions_for_name_error(PyNameErrorObject *exc)
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{
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PyObject *name = exc->name; // borrowed reference
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PyTracebackObject *traceback = (PyTracebackObject *) exc->traceback; // borrowed reference
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// Abort if we don't have a variable name or we have an invalid one
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// or if we don't have a traceback to work with
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if (name == NULL || !PyUnicode_CheckExact(name) ||
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traceback == NULL || !Py_IS_TYPE(traceback, &PyTraceBack_Type)
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) {
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return NULL;
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}
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// Move to the traceback of the exception
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while (1) {
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PyTracebackObject *next = traceback->tb_next;
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if (next == NULL || !Py_IS_TYPE(next, &PyTraceBack_Type)) {
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break;
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}
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else {
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traceback = next;
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}
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}
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PyFrameObject *frame = traceback->tb_frame;
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assert(frame != NULL);
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PyObject* suggestion = get_suggestions_for_name_error(name, frame);
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if (suggestion == NULL && PyErr_Occurred()) {
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return NULL;
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}
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// Add a trailer ". Did you mean: (...)?"
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PyObject* result = NULL;
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if (!is_name_stdlib_module(name)) {
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if (suggestion == NULL) {
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return NULL;
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}
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result = PyUnicode_FromFormat(". Did you mean: %R?", suggestion);
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} else if (suggestion == NULL) {
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result = PyUnicode_FromFormat(". Did you forget to import %R?", name);
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} else {
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result = PyUnicode_FromFormat(". Did you mean: %R? Or did you forget to import %R?", suggestion, name);
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}
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Py_XDECREF(suggestion);
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return result;
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}
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static PyObject *
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offer_suggestions_for_import_error(PyImportErrorObject *exc)
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{
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PyObject *mod_name = exc->name; // borrowed reference
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PyObject *name = exc->name_from; // borrowed reference
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if (name == NULL || mod_name == NULL || name == Py_None ||
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!PyUnicode_CheckExact(name) || !PyUnicode_CheckExact(mod_name)) {
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return NULL;
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}
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PyObject* mod = PyImport_GetModule(mod_name);
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if (mod == NULL) {
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return NULL;
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}
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PyObject *dir = PyObject_Dir(mod);
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Py_DECREF(mod);
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if (dir == NULL) {
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return NULL;
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}
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PyObject *suggestion = calculate_suggestions(dir, name);
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Py_DECREF(dir);
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if (!suggestion) {
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return NULL;
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}
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PyObject* result = PyUnicode_FromFormat(". Did you mean: %R?", suggestion);
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Py_DECREF(suggestion);
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return result;
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}
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// Offer suggestions for a given exception. Returns a python string object containing the
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// suggestions. This function returns NULL if no suggestion was found or if an exception happened,
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// users must call PyErr_Occurred() to disambiguate.
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PyObject *
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_Py_Offer_Suggestions(PyObject *exception)
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{
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PyObject *result = NULL;
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assert(!PyErr_Occurred());
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if (Py_IS_TYPE(exception, (PyTypeObject*)PyExc_AttributeError)) {
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result = offer_suggestions_for_attribute_error((PyAttributeErrorObject *) exception);
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} else if (Py_IS_TYPE(exception, (PyTypeObject*)PyExc_NameError)) {
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result = offer_suggestions_for_name_error((PyNameErrorObject *) exception);
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} else if (Py_IS_TYPE(exception, (PyTypeObject*)PyExc_ImportError)) {
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result = offer_suggestions_for_import_error((PyImportErrorObject *) exception);
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}
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return result;
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}
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Py_ssize_t
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_Py_UTF8_Edit_Cost(PyObject *a, PyObject *b, Py_ssize_t max_cost)
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{
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assert(PyUnicode_Check(a) && PyUnicode_Check(b));
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Py_ssize_t size_a, size_b;
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const char *utf8_a = PyUnicode_AsUTF8AndSize(a, &size_a);
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if (utf8_a == NULL) {
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return -1;
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}
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const char *utf8_b = PyUnicode_AsUTF8AndSize(b, &size_b);
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if (utf8_b == NULL) {
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return -1;
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}
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if (max_cost == -1) {
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max_cost = MOVE_COST * Py_MAX(size_a, size_b);
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}
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size_t *buffer = PyMem_New(size_t, MAX_STRING_SIZE);
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if (buffer == NULL) {
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PyErr_NoMemory();
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return -1;
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}
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Py_ssize_t res = levenshtein_distance(utf8_a, size_a,
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utf8_b, size_b, max_cost, buffer);
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PyMem_Free(buffer);
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return res;
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}
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