where_expr.py 文件源码

def whereeval(str_, get=None):
    """Evaluate a set operation string, where each Name is fetched"""
    if get is None:
        import redbiom
        config = redbiom.get_config()
        get = redbiom._requests.make_get(config)

    # Load is subject to indirection to simplify testing
    globals()['Load'] = make_Load(get)

    formed = ast.parse(str_, mode='eval')

    node_types = (ast.Compare, ast.In, ast.NotIn, ast.BoolOp, ast.And,
                  ast.Name, ast.Or, ast.Eq, ast.Lt, ast.LtE, ast.Gt, ast.GtE,
                  ast.NotEq, ast.Str, ast.Num, ast.Load, ast.Expression,
                  ast.Tuple, ast.Is, ast.IsNot)

    for node in ast.walk(formed):
        if not isinstance(node, node_types):
            raise TypeError("Unsupported node type: %s" % ast.dump(node))

    result = eval(ast.dump(formed))

    # clean up
    global Load
    del Load

    return result