Function Str_like_lstrip

python/stringzilla.c:5002–5076

    "  Str: A new string with leading characters removed.";

static PyObject *Str_like_lstrip(PyObject *self, PyObject *const *args, Py_ssize_t positional_args_count,
                                 PyObject *args_names_tuple) {
    // Check arguments
    int is_member = self != NULL && PyObject_TypeCheck(self, &StrType);
    Py_ssize_t expected_min_args = !is_member;
    Py_ssize_t expected_max_args = !is_member + 1;
    if (positional_args_count < expected_min_args || positional_args_count > expected_max_args) {
        PyErr_SetString(PyExc_TypeError, "lstrip() takes at most 1 argument");
        return NULL;
    }

    PyObject *text_obj = is_member ? self : args[0];
    PyObject *chars_obj = positional_args_count > !is_member ? args[!is_member] : NULL;

    if (args_names_tuple) {
        Py_ssize_t args_names_count = PyTuple_GET_SIZE(args_names_tuple);
        for (Py_ssize_t i = 0; i < args_names_count; ++i) {
            PyObject *key = PyTuple_GET_ITEM(args_names_tuple, i);
            PyObject *value = args[positional_args_count + i];
            if (PyUnicode_CompareWithASCIIString(key, "chars") == 0 && !chars_obj) { chars_obj = value; }
            else if (PyErr_Format(PyExc_TypeError, "Got an unexpected keyword argument '%U'", key))
                return NULL;
        }
    }

    sz_string_view_t text;
    sz_string_view_t chars;

    // Validate and convert text
    if (!sz_py_export_string_like(text_obj, &text.start, &text.length)) {
        wrap_current_exception("The text argument must be string-like");
        return NULL;
    }

    // Default to whitespace if chars is not provided
    char const *default_chars = " \t\n\r\f\v";
    if (chars_obj) {
        if (!sz_py_export_string_like(chars_obj, &chars.start, &chars.length)) {
            wrap_current_exception("The chars argument must be string-like");
            return NULL;
        }
    }
    else {
        chars.start = default_chars;
        chars.length = 6;
    }

    // Create byteset from chars
    sz_byteset_t set;
    sz_byteset_init(&set);
    for (sz_size_t i = 0; i < chars.length; ++i) sz_byteset_add(&set, chars.start[i]);
    sz_byteset_invert(&set);

    // Find first character NOT in the set (i.e., not to be stripped)
    sz_cptr_t new_start = sz_find_byteset(text.start, text.length, &set);
    if (!new_start) {
        // Return empty string
        Str *result = (Str *)StrType.tp_alloc(&StrType, 0);