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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, BlankLine, syms
33
34CMP = "(n='!=' | '==' | 'is' | n=comp_op< 'is' 'not' >)"
35TYPE = "power< 'type' trailer< '(' x=any ')' > >"
36
37class FixIdioms(fixer_base.BaseFix):
38    explicit = True # The user must ask for this fixer
39
40    PATTERN = r"""
41        isinstance=comparison< %s %s T=any >
42        |
43        isinstance=comparison< T=any %s %s >
44        |
45        while_stmt< 'while' while='1' ':' any+ >
46        |
47        sorted=any<
48            any*
49            simple_stmt<
50              expr_stmt< id1=any '='
51                         power< list='list' trailer< '(' (not arglist<any+>) any ')' > >
52              >
53              '\n'
54            >
55            sort=
56            simple_stmt<
57              power< id2=any
58                     trailer< '.' 'sort' > trailer< '(' ')' >
59              >
60              '\n'
61            >
62            next=any*
63        >
64        |
65        sorted=any<
66            any*
67            simple_stmt< expr_stmt< id1=any '=' expr=any > '\n' >
68            sort=
69            simple_stmt<
70              power< id2=any
71                     trailer< '.' 'sort' > trailer< '(' ')' >
72              >
73              '\n'
74            >
75            next=any*
76        >
77    """ % (TYPE, CMP, CMP, TYPE)
78
79    def match(self, node):
80        r = super(FixIdioms, self).match(node)
81        # If we've matched one of the sort/sorted subpatterns above, we
82        # want to reject matches where the initial assignment and the
83        # subsequent .sort() call involve different identifiers.
84        if r and "sorted" in r:
85            if r["id1"] == r["id2"]:
86                return r
87            return None
88        return r
89
90    def transform(self, node, results):
91        if "isinstance" in results:
92            return self.transform_isinstance(node, results)
93        elif "while" in results:
94            return self.transform_while(node, results)
95        elif "sorted" in results:
96            return self.transform_sort(node, results)
97        else:
98            raise RuntimeError("Invalid match")
99
100    def transform_isinstance(self, node, results):
101        x = results["x"].clone() # The thing inside of type()
102        T = results["T"].clone() # The type being compared against
103        x.prefix = ""
104        T.prefix = " "
105        test = Call(Name("isinstance"), [x, Comma(), T])
106        if "n" in results:
107            test.prefix = " "
108            test = Node(syms.not_test, [Name("not"), test])
109        test.prefix = node.prefix
110        return test
111
112    def transform_while(self, node, results):
113        one = results["while"]
114        one.replace(Name("True", prefix=one.prefix))
115
116    def transform_sort(self, node, results):
117        sort_stmt = results["sort"]
118        next_stmt = results["next"]
119        list_call = results.get("list")
120        simple_expr = results.get("expr")
121
122        if list_call:
123            list_call.replace(Name("sorted", prefix=list_call.prefix))
124        elif simple_expr:
125            new = simple_expr.clone()
126            new.prefix = ""
127            simple_expr.replace(Call(Name("sorted"), [new],
128                                     prefix=simple_expr.prefix))
129        else:
130            raise RuntimeError("should not have reached here")
131        sort_stmt.remove()
132
133        btwn = sort_stmt.prefix
134        # Keep any prefix lines between the sort_stmt and the list_call and
135        # shove them right after the sorted() call.
136        if "\n" in btwn:
137            if next_stmt:
138                # The new prefix should be everything from the sort_stmt's
139                # prefix up to the last newline, then the old prefix after a new
140                # line.
141                prefix_lines = (btwn.rpartition("\n")[0], next_stmt[0].prefix)
142                next_stmt[0].prefix = "\n".join(prefix_lines)
143            else:
144                assert list_call.parent
145                assert list_call.next_sibling is None
146                # Put a blank line after list_call and set its prefix.
147                end_line = BlankLine()
148                list_call.parent.append_child(end_line)
149                assert list_call.next_sibling is end_line
150                # The new prefix should be everything up to the first new line
151                # of sort_stmt's prefix.
152                end_line.prefix = btwn.rpartition("\n")[0]
153