expression.py 文件源码

def _interpret_as_column_or_from(element):
    if isinstance(element, Visitable):
        return element
    elif hasattr(element, '__clause_element__'):
        return element.__clause_element__()

    insp = inspection.inspect(element, raiseerr=False)
    if insp is None:
        if isinstance(element, (util.NoneType, bool)):
            return _const_expr(element)
    elif hasattr(insp, "selectable"):
        return insp.selectable

    return literal_column(str(element))