1 """Fixer that changes 'a ,b' into 'a, b'.

     2 

     3 This also changes '{a :b}' into '{a: b}', but does not touch other

     4 uses of colons.  It does not touch other uses of whitespace.

     5 

     6 """

     7 

     8 from .. import pytree

     9 from ..pgen2 import token

    10 from .. import fixer_base

    11 

    12 class FixWsComma(fixer_base.BaseFix):

    13 

    14     explicit = True # The user must ask for this fixers

    15 

    16     PATTERN = """

    17     any<(not(',') any)+ ',' ((not(',') any)+ ',')* [not(',') any]>

    18     """

    19 

    20     COMMA = pytree.Leaf(token.COMMA, ",")

    21     COLON = pytree.Leaf(token.COLON, ":")

    22     SEPS = (COMMA, COLON)

    23 

    24     def transform(self, node, results):

    25         new = node.clone()

    26         comma = False

    27         for child in new.children:

    28             if child in self.SEPS:

    29                 prefix = child.get_prefix()

    30                 if prefix.isspace() and "\n" not in prefix:

    31                     child.set_prefix("")

    32                 comma = True

    33             else:

    34                 if comma:

    35                     prefix = child.get_prefix()

    36                     if not prefix:

    37                         child.set_prefix(" ")

    38                 comma = False

    39         return new