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Python Source  |  2011-02-15  |  3.8 KB  |  135 lines
  1. """Adjust some old Python 2 idioms to their modern counterparts.
  2.  
  3. * Change some type comparisons to isinstance() calls:
  4.     type(x) == T -> isinstance(x, T)
  5.     type(x) is T -> isinstance(x, T)
  6.     type(x) != T -> not isinstance(x, T)
  7.     type(x) is not T -> not isinstance(x, T)
  8.  
  9. * Change "while 1:" into "while True:".
  10.  
  11. * Change both
  12.  
  13.     v = list(EXPR)
  14.     v.sort()
  15.     foo(v)
  16.  
  17. and the more general
  18.  
  19.     v = EXPR
  20.     v.sort()
  21.     foo(v)
  22.  
  23. into
  24.  
  25.     v = sorted(EXPR)
  26.     foo(v)
  27. """
  28. # Author: Jacques Frechet, Collin Winter
  29.  
  30. # Local imports
  31. from .. import fixer_base
  32. from ..fixer_util import Call, Comma, Name, Node, syms
  33.  
  34. CMP = "(n='!=' | '==' | 'is' | n=comp_op< 'is' 'not' >)"
  35. TYPE = "power< 'type' trailer< '(' x=any ')' > >"
  36.  
  37. class FixIdioms(fixer_base.BaseFix):
  38.  
  39.     explicit = True # The user must ask for this fixer
  40.  
  41.     PATTERN = r"""
  42.         isinstance=comparison< %s %s T=any >
  43.         |
  44.         isinstance=comparison< T=any %s %s >
  45.         |
  46.         while_stmt< 'while' while='1' ':' any+ >
  47.         |
  48.         sorted=any<
  49.             any*
  50.             simple_stmt<
  51.               expr_stmt< id1=any '='
  52.                          power< list='list' trailer< '(' (not arglist<any+>) any ')' > >
  53.               >
  54.               '\n'
  55.             >
  56.             sort=
  57.             simple_stmt<
  58.               power< id2=any
  59.                      trailer< '.' 'sort' > trailer< '(' ')' >
  60.               >
  61.               '\n'
  62.             >
  63.             next=any*
  64.         >
  65.         |
  66.         sorted=any<
  67.             any*
  68.             simple_stmt< expr_stmt< id1=any '=' expr=any > '\n' >
  69.             sort=
  70.             simple_stmt<
  71.               power< id2=any
  72.                      trailer< '.' 'sort' > trailer< '(' ')' >
  73.               >
  74.               '\n'
  75.             >
  76.             next=any*
  77.         >
  78.     """ % (TYPE, CMP, CMP, TYPE)
  79.  
  80.     def match(self, node):
  81.         r = super(FixIdioms, self).match(node)
  82.         # If we've matched one of the sort/sorted subpatterns above, we
  83.         # want to reject matches where the initial assignment and the
  84.         # subsequent .sort() call involve different identifiers.
  85.         if r and "sorted" in r:
  86.             if r["id1"] == r["id2"]:
  87.                 return r
  88.             return None
  89.         return r
  90.  
  91.     def transform(self, node, results):
  92.         if "isinstance" in results:
  93.             return self.transform_isinstance(node, results)
  94.         elif "while" in results:
  95.             return self.transform_while(node, results)
  96.         elif "sorted" in results:
  97.             return self.transform_sort(node, results)
  98.         else:
  99.             raise RuntimeError("Invalid match")
  100.  
  101.     def transform_isinstance(self, node, results):
  102.         x = results["x"].clone() # The thing inside of type()
  103.         T = results["T"].clone() # The type being compared against
  104.         x.set_prefix("")
  105.         T.set_prefix(" ")
  106.         test = Call(Name("isinstance"), [x, Comma(), T])
  107.         if "n" in results:
  108.             test.set_prefix(" ")
  109.             test = Node(syms.not_test, [Name("not"), test])
  110.         test.set_prefix(node.get_prefix())
  111.         return test
  112.  
  113.     def transform_while(self, node, results):
  114.         one = results["while"]
  115.         one.replace(Name("True", prefix=one.get_prefix()))
  116.  
  117.     def transform_sort(self, node, results):
  118.         sort_stmt = results["sort"]
  119.         next_stmt = results["next"]
  120.         list_call = results.get("list")
  121.         simple_expr = results.get("expr")
  122.  
  123.         if list_call:
  124.             list_call.replace(Name("sorted", prefix=list_call.get_prefix()))
  125.         elif simple_expr:
  126.             new = simple_expr.clone()
  127.             new.set_prefix("")
  128.             simple_expr.replace(Call(Name("sorted"), [new],
  129.                                      prefix=simple_expr.get_prefix()))
  130.         else:
  131.             raise RuntimeError("should not have reached here")
  132.         sort_stmt.remove()
  133.         if next_stmt:
  134.             next_stmt[0].set_prefix(sort_stmt.get_prefix())
  135.