"""Fixer that addes parentheses where they are required This converts ``[x for x in 1, 2]`` to ``[x for x in (1, 2)]``.""" # By Taek Joo Kim and Benjamin Peterson # Local imports from .. import fixer_base from ..fixer_util import LParen, RParen # XXX This doesn't support nested for loops like [x for x in 1, 2 for x in 1, 2] class FixParen(fixer_base.BaseFix): BM_compatible = True PATTERN = """ atom< ('[' | '(') (listmaker< any comp_for< 'for' NAME 'in' target=testlist_safe< any (',' any)+ [','] > [any] > > | testlist_gexp< any comp_for< 'for' NAME 'in' target=testlist_safe< any (',' any)+ [','] > [any] > >) (']' | ')') > """ def transform(self, node, results): target = results["target"] lparen = LParen() lparen.prefix = target.prefix target.prefix = "" # Make it hug the parentheses target.insert_child(0, lparen) target.append_child(RParen())