Sync contrib/tools/python3 layout with upstream

* Move src/ subdir contents to the top of the layout
* Rename self-written lib -> lib2 to avoid CaseFolding warning from the VCS
* Regenerate contrib/libs/python proxy-headers accordingly
4ccc62ac1511abcf0fed14ccade38e984e088f1e

1 files changed, 429 insertions, 0 deletions

diff --git a/contrib/tools/python3/Python/suggestions.c b/contrib/tools/python3/Python/suggestions.c
new file mode 100644
index 0000000000..ad58393490
--- /dev/null
+++ b/contrib/tools/python3/Python/suggestions.c
@@ -0,0 +1,429 @@
+#include "Python.h"
+#include "pycore_frame.h"
+#include "pycore_runtime.h"         // _PyRuntime
+#include "pycore_global_objects.h"  // _Py_ID()
+
+#include "pycore_pyerrors.h"
+#include "pycore_code.h"        // _PyCode_GetVarnames()
+#include "stdlib_module_names.h"  // _Py_stdlib_module_names
+
+#define MAX_CANDIDATE_ITEMS 750
+#define MAX_STRING_SIZE 40
+
+#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 (LEAST_FIVE_BITS(a) != LEAST_FIVE_BITS(b)) {
+        // Not the same, not a case flip.
+        return MOVE_COST;
+    }
+    if (a == b) {
+        return 0;
+    }
+    if ('A' <= a && a <= 'Z') {
+        a += ('a' - 'A');
+    }
+    if ('A' <= b && b <= 'Z') {
+        b += ('a' - 'A');
+    }
+    if (a == b) {
+        return CASE_COST;
+    }
+    return MOVE_COST;
+}
+
+/* Calculate the Levenshtein distance between string1 and string2 */
+static Py_ssize_t
+levenshtein_distance(const char *a, size_t a_size,
+                     const char *b, size_t b_size,
+                     size_t max_cost, size_t *buffer)
+{
+    // Both strings are the same (by identity)
+    if (a == b) {
+        return 0;
+    }
+
+    // Trim away common affixes.
+    while (a_size && b_size && a[0] == b[0]) {
+        a++; a_size--;
+        b++; b_size--;
+    }
+    while (a_size && b_size && a[a_size-1] == b[b_size-1]) {
+        a_size--;
+        b_size--;
+    }
+    if (a_size == 0 || b_size == 0) {
+        return (a_size + b_size) * MOVE_COST;
+    }
+    if (a_size > MAX_STRING_SIZE || b_size > MAX_STRING_SIZE) {
+        return max_cost + 1;
+    }
+
+    // Prefer shorter buffer
+    if (b_size < a_size) {
+        const char *t = a; a = b; b = t;
+        size_t t_size = a_size; a_size = b_size; b_size = t_size;
+    }
+
+    // quick fail when a match is impossible.
+    if ((b_size - a_size) * MOVE_COST > max_cost) {
+        return max_cost + 1;
+    }
+
+    // Instead of producing the whole traditional len(a)-by-len(b)
+    // matrix, we can update just one row in place.
+    // Initialize the buffer row
+    size_t tmp = MOVE_COST;
+    for (size_t i = 0; i < a_size; i++) {
+        // cost from b[:0] to a[:i+1]
+        buffer[i] = tmp;
+        tmp += MOVE_COST;
+    }
+
+    size_t result = 0;
+    for (size_t b_index = 0; b_index < b_size; b_index++) {
+        char code = b[b_index];
+        // cost(b[:b_index], a[:0]) == b_index * MOVE_COST
+        size_t distance = result = b_index * MOVE_COST;
+        size_t minimum = SIZE_MAX;
+        for (size_t index = 0; index < a_size; index++) {
+
+            // cost(b[:b_index+1], a[:index+1]) = min(
+            //     // 1) substitute
+            //     cost(b[:b_index], a[:index])
+            //         + substitution_cost(b[b_index], a[index]),
+            //     // 2) delete from b
+            //     cost(b[:b_index], a[:index+1]) + MOVE_COST,
+            //     // 3) delete from a
+            //     cost(b[:b_index+1], a[index]) + MOVE_COST
+            // )
+
+            // 1) Previous distance in this row is cost(b[:b_index], a[:index])
+            size_t substitute = distance + substitution_cost(code, a[index]);
+            // 2) cost(b[:b_index], a[:index+1]) from previous row
+            distance = buffer[index];
+            // 3) existing result is cost(b[:b_index+1], a[index])
+
+            size_t insert_delete = Py_MIN(result, distance) + MOVE_COST;
+            result = Py_MIN(insert_delete, substitute);
+
+            // cost(b[:b_index+1], a[:index+1])
+            buffer[index] = result;
+            if (result < minimum) {
+                minimum = result;
+            }
+        }
+        if (minimum > max_cost) {
+            // Everything in this row is too big, so bail early.
+            return max_cost + 1;
+        }
+    }
+    return result;
+}
+
+static inline PyObject *
+calculate_suggestions(PyObject *dir,
+                      PyObject *name)
+{
+    assert(!PyErr_Occurred());
+    assert(PyList_CheckExact(dir));
+
+    Py_ssize_t dir_size = PyList_GET_SIZE(dir);
+    if (dir_size >= MAX_CANDIDATE_ITEMS) {
+        return NULL;
+    }
+
+    Py_ssize_t suggestion_distance = PY_SSIZE_T_MAX;
+    PyObject *suggestion = NULL;
+    Py_ssize_t name_size;
+    const char *name_str = PyUnicode_AsUTF8AndSize(name, &name_size);
+    if (name_str == NULL) {
+        return NULL;
+    }
+    size_t *buffer = PyMem_New(size_t, MAX_STRING_SIZE);
+    if (buffer == NULL) {
+        return PyErr_NoMemory();
+    }
+    for (int i = 0; i < dir_size; ++i) {
+        PyObject *item = PyList_GET_ITEM(dir, i);
+        if (_PyUnicode_Equal(name, item)) {
+            continue;
+        }
+        Py_ssize_t item_size;
+        const char *item_str = PyUnicode_AsUTF8AndSize(item, &item_size);
+        if (item_str == NULL) {
+            PyMem_Free(buffer);
+            return NULL;
+        }
+        // No more than 1/3 of the involved characters should need changed.
+        Py_ssize_t max_distance = (name_size + item_size + 3) * MOVE_COST / 6;
+        // Don't take matches we've already beaten.
+        max_distance = Py_MIN(max_distance, suggestion_distance - 1);
+        Py_ssize_t current_distance =
+            levenshtein_distance(name_str, name_size, item_str,
+                                 item_size, max_distance, buffer);
+        if (current_distance > max_distance) {
+            continue;
+        }
+        if (!suggestion || current_distance < suggestion_distance) {
+            suggestion = item;
+            suggestion_distance = current_distance;
+        }
+    }
+    PyMem_Free(buffer);
+    return Py_XNewRef(suggestion);
+}
+
+static PyObject *
+get_suggestions_for_attribute_error(PyAttributeErrorObject *exc)
+{
+    PyObject *name = exc->name; // borrowed reference
+    PyObject *obj = exc->obj; // borrowed reference
+
+    // Abort if we don't have an attribute name or we have an invalid one
+    if (name == NULL || obj == NULL || !PyUnicode_CheckExact(name)) {
+        return NULL;
+    }
+
+    PyObject *dir = PyObject_Dir(obj);
+    if (dir == NULL) {
+        return NULL;
+    }
+
+    PyObject *suggestions = calculate_suggestions(dir, name);
+    Py_DECREF(dir);
+    return suggestions;
+}
+
+static PyObject *
+offer_suggestions_for_attribute_error(PyAttributeErrorObject *exc)
+{
+    PyObject* suggestion = get_suggestions_for_attribute_error(exc);
+    if (suggestion == NULL) {
+        return NULL;
+    }
+    // Add a trailer ". Did you mean: (...)?"
+    PyObject* result = PyUnicode_FromFormat(". Did you mean: %R?", suggestion);
+    Py_DECREF(suggestion);
+    return result;
+}
+
+static PyObject *
+get_suggestions_for_name_error(PyObject* name, PyFrameObject* frame)
+{
+    PyCodeObject *code = PyFrame_GetCode(frame);
+    assert(code != NULL && code->co_localsplusnames != NULL);
+
+    PyObject *varnames = _PyCode_GetVarnames(code);
+    Py_DECREF(code);
+    if (varnames == NULL) {
+        return NULL;
+    }
+    PyObject *dir = PySequence_List(varnames);
+    Py_DECREF(varnames);
+    if (dir == NULL) {
+        return NULL;
+    }
+
+    // Are we inside a method and the instance has an attribute called 'name'?
+    int res = PySequence_Contains(dir, &_Py_ID(self));
+    if (res < 0) {
+        goto error;
+    }
+    if (res > 0) {
+        PyObject* locals = PyFrame_GetLocals(frame);
+        if (!locals) {
+            goto error;
+        }
+        PyObject* self = PyDict_GetItemWithError(locals, &_Py_ID(self)); /* borrowed */
+        if (!self) {
+            Py_DECREF(locals);
+            goto error;
+        }
+
+        PyObject *value;
+        res = _PyObject_LookupAttr(self, name, &value);
+        Py_DECREF(locals);
+        if (res < 0) {
+            goto error;
+        }
+        if (value) {
+            Py_DECREF(value);
+            Py_DECREF(dir);
+            return PyUnicode_FromFormat("self.%U", name);
+        }
+    }
+
+    PyObject *suggestions = calculate_suggestions(dir, name);
+    Py_DECREF(dir);
+    if (suggestions != NULL || PyErr_Occurred()) {
+        return suggestions;
+    }
+
+    dir = PySequence_List(frame->f_frame->f_globals);
+    if (dir == NULL) {
+        return NULL;
+    }
+    suggestions = calculate_suggestions(dir, name);
+    Py_DECREF(dir);
+    if (suggestions != NULL || PyErr_Occurred()) {
+        return suggestions;
+    }
+
+    dir = PySequence_List(frame->f_frame->f_builtins);
+    if (dir == NULL) {
+        return NULL;
+    }
+    suggestions = calculate_suggestions(dir, name);
+    Py_DECREF(dir);
+
+    return suggestions;
+
+error:
+    Py_DECREF(dir);
+    return NULL;
+}
+
+static bool
+is_name_stdlib_module(PyObject* name)
+{
+    const char* the_name = PyUnicode_AsUTF8(name);
+    Py_ssize_t len = Py_ARRAY_LENGTH(_Py_stdlib_module_names);
+    for (Py_ssize_t i = 0; i < len; i++) {
+        if (strcmp(the_name, _Py_stdlib_module_names[i]) == 0) {
+            return 1;
+        }
+    }
+    return 0;
+}
+
+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 a variable name or we have an invalid one
+    // or if we don't have a traceback to work with
+    if (name == NULL || !PyUnicode_CheckExact(name) ||
+        traceback == NULL || !Py_IS_TYPE(traceback, &PyTraceBack_Type)
+    ) {
+        return NULL;
+    }
+
+    // Move to the traceback of the exception
+    while (1) {
+        PyTracebackObject *next = traceback->tb_next;
+        if (next == NULL || !Py_IS_TYPE(next, &PyTraceBack_Type)) {
+            break;
+        }
+        else {
+            traceback = next;
+        }
+    }
+
+    PyFrameObject *frame = traceback->tb_frame;
+    assert(frame != NULL);
+
+    PyObject* suggestion = get_suggestions_for_name_error(name, frame);
+    if (suggestion == NULL && PyErr_Occurred()) {
+        return NULL;
+    }
+
+    // Add a trailer ". Did you mean: (...)?"
+    PyObject* result = NULL;
+    if (!is_name_stdlib_module(name)) {
+        if (suggestion == NULL) {
+            return NULL;
+        }
+        result = PyUnicode_FromFormat(". Did you mean: %R?", suggestion);
+    } else if (suggestion == NULL) {
+        result = PyUnicode_FromFormat(". Did you forget to import %R?", name);
+    } else {
+        result = PyUnicode_FromFormat(". Did you mean: %R? Or did you forget to import %R?", suggestion, name);
+    }
+    Py_XDECREF(suggestion);
+    return result;
+}
+
+static PyObject *
+offer_suggestions_for_import_error(PyImportErrorObject *exc)
+{
+    PyObject *mod_name = exc->name; // borrowed reference
+    PyObject *name = exc->name_from; // borrowed reference
+    if (name == NULL || mod_name == NULL || name == Py_None ||
+        !PyUnicode_CheckExact(name) || !PyUnicode_CheckExact(mod_name)) {
+        return NULL;
+    }
+
+    PyObject* mod = PyImport_GetModule(mod_name);
+    if (mod == NULL) {
+        return NULL;
+    }
+
+    PyObject *dir = PyObject_Dir(mod);
+    Py_DECREF(mod);
+    if (dir == NULL) {
+        return NULL;
+    }
+
+    PyObject *suggestion = calculate_suggestions(dir, name);
+    Py_DECREF(dir);
+    if (!suggestion) {
+        return NULL;
+    }
+
+    PyObject* result = PyUnicode_FromFormat(". Did you mean: %R?", suggestion);
+    Py_DECREF(suggestion);
+    return result;
+}
+
+// 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 *result = NULL;
+    assert(!PyErr_Occurred());
+    if (Py_IS_TYPE(exception, (PyTypeObject*)PyExc_AttributeError)) {
+        result = offer_suggestions_for_attribute_error((PyAttributeErrorObject *) exception);
+    } else if (Py_IS_TYPE(exception, (PyTypeObject*)PyExc_NameError)) {
+        result = offer_suggestions_for_name_error((PyNameErrorObject *) exception);
+    } else if (Py_IS_TYPE(exception, (PyTypeObject*)PyExc_ImportError)) {
+        result = offer_suggestions_for_import_error((PyImportErrorObject *) 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);
+    }
+    size_t *buffer = PyMem_New(size_t, MAX_STRING_SIZE);
+    if (buffer == NULL) {
+        PyErr_NoMemory();
+        return -1;
+    }
+    Py_ssize_t res = levenshtein_distance(utf8_a, size_a,
+                                    utf8_b, size_b, max_cost, buffer);
+    PyMem_Free(buffer);
+    return res;
+}
+