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/Lib/lib2to3/fixes/fix_idioms.py

http://unladen-swallow.googlecode.com/
Python | 134 lines | 126 code | 0 blank | 8 comment | 1 complexity | 0281b19c721594c6eb341c83270d37bd MD5 | raw file
  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
 17and the more general
 18
 19    v = EXPR
 20    v.sort()
 21    foo(v)
 22
 23into
 24
 25    v = sorted(EXPR)
 26    foo(v)
 27"""
 28# Author: Jacques Frechet, Collin Winter
 29
 30# Local imports
 31from .. import fixer_base
 32from ..fixer_util import Call, Comma, Name, Node, syms
 33
 34CMP = "(n='!=' | '==' | 'is' | n=comp_op< 'is' 'not' >)"
 35TYPE = "power< 'type' trailer< '(' x=any ')' > >"
 36
 37class 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())