"""Fixer that changes 'a ,b' into 'a, b'. This also changes '{a :b}' into '{a: b}', but does not touch other uses of colons. It does not touch other uses of whitespace. """ from .. import pytree from ..pgen2 import token from .. import fixer_base class FixWsComma(fixer_base.BaseFix): explicit = True # The user must ask for this fixers PATTERN = """ any<(not(',') any)+ ',' ((not(',') any)+ ',')* [not(',') any]> """ COMMA = pytree.Leaf(token.COMMA, ",") COLON = pytree.Leaf(token.COLON, ":") SEPS = (COMMA, COLON) def transform(self, node, results): new = node.clone() comma = False for child in new.children: if child in self.SEPS: prefix = child.prefix if prefix.isspace() and "\n" not in prefix: child.prefix = "" comma = True else: if comma: prefix = child.prefix if not prefix: child.prefix = " " comma = False return new