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

   1 # Copyright 2006 Google, Inc. All Rights Reserved.
   2 # Licensed to PSF under a Contributor Agreement.
   3
   4 """Fixer for has_key().
   5
   6 Calls to .has_key() methods are expressed in terms of the 'in'
   7 operator:
   8
   9     d.has_key(k) -> k in d
  10
  11 CAVEATS:
  12 1) While the primary target of this fixer is dict.has_key(), the
  13    fixer will change any has_key() method call, regardless of its
  14    class.
  15
  16 2) Cases like this will not be converted:
  17
  18     m = d.has_key
  19     if m(k):
  20         ...
  21
  22    Only *calls* to has_key() are converted. While it is possible to
  23    convert the above to something like
  24
  25     m = d.__contains__
  26     if m(k):
  27         ...
  28
  29    this is currently not done.
  30 """
  31
  32 # Local imports
  33 from .. import pytree
  34 from ..pgen2 import token
  35 from .. import fixer_base
  36 from ..fixer_util import Name, parenthesize
  37
  38
  39 class FixHasKey(fixer_base.BaseFix):
  40     BM_compatible = True
  41
  42     PATTERN = """
  43     anchor=power<
  44         before=any+
  45         trailer< '.' 'has_key' >
  46         trailer<
  47             '('
  48             ( not(arglist | argument<any '=' any>) arg=any
  49             | arglist<(not argument<any '=' any>) arg=any ','>
  50             )
  51             ')'
  52         >
  53         after=any*
  54     >
  55     |
  56     negation=not_test<
  57         'not'
  58         anchor=power<
  59             before=any+
  60             trailer< '.' 'has_key' >
  61             trailer<
  62                 '('
  63                 ( not(arglist | argument<any '=' any>) arg=any
  64                 | arglist<(not argument<any '=' any>) arg=any ','>
  65                 )
  66                 ')'
  67             >
  68         >
  69     >
  70     """
  71
  72     def transform(self, node, results):
  73         assert results
  74         syms = self.syms
  75         if (node.parent.type == syms.not_test and
  76             self.pattern.match(node.parent)):
  77             # Don't transform a node matching the first alternative of the
  78             # pattern when its parent matches the second alternative
  79             return None
  80         negation = results.get("negation")
  81         anchor = results["anchor"]
  82         prefix = node.prefix
  83         before = [n.clone() for n in results["before"]]
  84         arg = results["arg"].clone()
  85         after = results.get("after")
  86         if after:
  87             after = [n.clone() for n in after]
  88         if arg.type in (syms.comparison, syms.not_test, syms.and_test,
  89                         syms.or_test, syms.test, syms.lambdef, syms.argument):
  90             arg = parenthesize(arg)
  91         if len(before) == 1:
  92             before = before[0]
  93         else:
  94             before = pytree.Node(syms.power, before)
  95         before.prefix = u" "
  96         n_op = Name(u"in", prefix=u" ")
  97         if negation:
  98             n_not = Name(u"not", prefix=u" ")
  99             n_op = pytree.Node(syms.comp_op, (n_not, n_op))
 100         new = pytree.Node(syms.comparison, (arg, n_op, before))
 101         if after:
 102             new = parenthesize(new)
 103             new = pytree.Node(syms.power, (new,) + tuple(after))
 104         if node.parent.type in (syms.comparison, syms.expr, syms.xor_expr,
 105                                 syms.and_expr, syms.shift_expr,
 106                                 syms.arith_expr, syms.term,
 107                                 syms.factor, syms.power):
 108             new = parenthesize(new)
 109         new.prefix = prefix
 110         return new