AppPkg/Applications/Python/Python-2.7.2/Lib/lib2to3/fixes/fix_filter.py

   1 # Copyright 2007 Google, Inc. All Rights Reserved.
   2 # Licensed to PSF under a Contributor Agreement.
   3
   4 """Fixer that changes filter(F, X) into list(filter(F, X)).
   5
   6 We avoid the transformation if the filter() call is directly contained
   7 in iter(<>), list(<>), tuple(<>), sorted(<>), ...join(<>), or
   8 for V in <>:.
   9
  10 NOTE: This is still not correct if the original code was depending on
  11 filter(F, X) to return a string if X is a string and a tuple if X is a
  12 tuple.  That would require type inference, which we don't do.  Let
  13 Python 2.6 figure it out.
  14 """
  15
  16 # Local imports
  17 from ..pgen2 import token
  18 from .. import fixer_base
  19 from ..fixer_util import Name, Call, ListComp, in_special_context
  20
  21 class FixFilter(fixer_base.ConditionalFix):
  22     BM_compatible = True
  23
  24     PATTERN = """
  25     filter_lambda=power<
  26         'filter'
  27         trailer<
  28             '('
  29             arglist<
  30                 lambdef< 'lambda'
  31                          (fp=NAME | vfpdef< '(' fp=NAME ')'> ) ':' xp=any
  32                 >
  33                 ','
  34                 it=any
  35             >
  36             ')'
  37         >
  38     >
  39     |
  40     power<
  41         'filter'
  42         trailer< '(' arglist< none='None' ',' seq=any > ')' >
  43     >
  44     |
  45     power<
  46         'filter'
  47         args=trailer< '(' [any] ')' >
  48     >
  49     """
  50
  51     skip_on = "future_builtins.filter"
  52
  53     def transform(self, node, results):
  54         if self.should_skip(node):
  55             return
  56
  57         if "filter_lambda" in results:
  58             new = ListComp(results.get("fp").clone(),
  59                            results.get("fp").clone(),
  60                            results.get("it").clone(),
  61                            results.get("xp").clone())
  62
  63         elif "none" in results:
  64             new = ListComp(Name(u"_f"),
  65                            Name(u"_f"),
  66                            results["seq"].clone(),
  67                            Name(u"_f"))
  68
  69         else:
  70             if in_special_context(node):
  71                 return None
  72             new = node.clone()
  73             new.prefix = u""
  74             new = Call(Name(u"list"), [new])
  75         new.prefix = node.prefix
  76         return new