先把原始碼放在這裡

PyDoc_STRVAR(translate__doc__,
"S.translate(table [,deletechars]) -> string\n\
\n\
Return a copy of the string S, where all characters occurring\n\
in the optional argument deletechars are removed, and the\n\
remaining characters have been mapped through the given\n\
translation table, which must be a string of length 256 or None.\n\
If the table argument is None, no translation is applied and\n\
the operation simply removes the characters in deletechars."
 
);

static PyObject *
string_translate(PyStringObject *self, PyObject *args)
{
    register char *input, *output;
    const char *table;
    register Py_ssize_t i, c, changed = 0;
    PyObject *input_obj = (PyObject*)self;
    const char *output_start, *del_table=NULL;
    Py_ssize_t inlen, tablen, dellen = 0
 
;
    PyObject *result;
    int trans_table[256];
    PyObject *tableobj, *delobj = NULL;

    if (!PyArg_UnpackTuple(args, "translate", 1, 2,
                          &tableobj, &delobj))
        return NULL;

    if (PyString_Check(tableobj)) {
        table = PyString_AS_STRING(tableobj);
        tablen = PyString_GET_SIZE(tableobj);
    }
    else
 
 if (tableobj == Py_None) {
        table = NULL;
        tablen = 256;
    }
#ifdef Py_USING_UNICODE
    else if (PyUnicode_Check(tableobj)) {
        /* Unicode .translate() does not support the deletechars
           parameter; instead a mapping to None will cause characters
           to be deleted. */
        if (delobj != NULL) {
            PyErr_SetString(PyExc_TypeError,
            "deletions are implemented differently for unicode");
            return NULL;
        }
        return PyUnicode_Translate((PyObject *)self, tableobj, NULL);
    }
#endif
    else if (PyObject_AsCharBuffer(tableobj, &table, &tablen))
        return NULL;

    if (tablen != 256) {
        PyErr_SetString(PyExc_ValueError,
          "translation table must be 256 characters long");
        return NULL;
    }

    if (delobj != NULL) {
        if (PyString_Check(delobj)) {
            del_table = PyString_AS_STRING(delobj);
            dellen = PyString_GET_SIZE(delobj);
        }
#ifdef Py_USING_UNICODE
        else if (PyUnicode_Check(delobj)) {
            PyErr_SetString(PyExc_TypeError,
            "deletions are implemented differently for unicode");
            return NULL;
        }
#endif
        else if (PyObject_AsCharBuffer(delobj, &del_table, &dellen))
            return NULL;
    }
    else {
        del_table = NULL;
        dellen = 0;
    }

    inlen = PyString_GET_SIZE(input_obj);
    result = PyString_FromStringAndSize((char *)NULL, inlen);
    if (result == NULL)
        return NULL;
    output_start = output = PyString_AsString(result);
    input = PyString_AS_STRING(input_obj);

    if (dellen == 0 && table != NULL) {
        /* If no deletions are required, use faster code */
        for (i = inlen; --i >= 0; ) {
            c = Py_CHARMASK(*input++);
            if (Py_CHARMASK((*output++ = table[c])) != c)
                changed = 1;
        }
        if (changed || !PyString_CheckExact(input_obj))
            return result;
        Py_DECREF(result);
        Py_INCREF(input_obj);
        return input_obj;
    }

    if (table == NULL) {
        for (i = 0; i < 256; i++)
            trans_table[i] = Py_CHARMASK(i);
    } else {
        for (i = 0; i < 256; i++)
            trans_table[i] = Py_CHARMASK(table[i]);
    }

    for (i = 0; i < dellen; i++)
        trans_table[(int) Py_CHARMASK(del_table[i])] = -1;

    for (i = inlen; --i >= 0; ) {
        c = Py_CHARMASK(*input++);
        if (trans_table[c] != -1)
            if (Py_CHARMASK(*output++ = (char)trans_table[c]) == c)
                continue;
        changed = 1;
    }
    if (!changed && PyString_CheckExact(input_obj)) {
        Py_DECREF(result);
        Py_INCREF(input_obj);
        return input_obj;
    }
    /* Fix the size of the resulting string */
    if (inlen > 0 && _PyString_Resize(&result, output - output_start))
        return NULL;
    return result;
}