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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
6We avoid the transformation if the filter() call is directly contained
7in iter(<>), list(<>), tuple(<>), sorted(<>), ...join(<>), or
8for V in <>:.
9
10NOTE: This is still not correct if the original code was depending on
11filter(F, X) to return a string if X is a string and a tuple if X is a
12tuple.  That would require type inference, which we don't do.  Let
13Python 2.6 figure it out.
14"""
15
16# Local imports
17from .. import fixer_base
18from ..pytree import Node
19from ..pygram import python_symbols as syms
20from ..fixer_util import Name, ArgList, ListComp, in_special_context, parenthesize
21
22
23class FixFilter(fixer_base.ConditionalFix):
24    BM_compatible = True
25
26    PATTERN = """
27    filter_lambda=power<
28        'filter'
29        trailer<
30            '('
31            arglist<
32                lambdef< 'lambda'
33                         (fp=NAME | vfpdef< '(' fp=NAME ')'> ) ':' xp=any
34                >
35                ','
36                it=any
37            >
38            ')'
39        >
40        [extra_trailers=trailer*]
41    >
42    |
43    power<
44        'filter'
45        trailer< '(' arglist< none='None' ',' seq=any > ')' >
46        [extra_trailers=trailer*]
47    >
48    |
49    power<
50        'filter'
51        args=trailer< '(' [any] ')' >
52        [extra_trailers=trailer*]
53    >
54    """
55
56    skip_on = "future_builtins.filter"
57
58    def transform(self, node, results):
59        if self.should_skip(node):
60            return
61
62        trailers = []
63        if 'extra_trailers' in results:
64            for t in results['extra_trailers']:
65                trailers.append(t.clone())
66
67        if "filter_lambda" in results:
68            xp = results.get("xp").clone()
69            if xp.type == syms.test:
70                xp.prefix = ""
71                xp = parenthesize(xp)
72
73            new = ListComp(results.get("fp").clone(),
74                           results.get("fp").clone(),
75                           results.get("it").clone(), xp)
76            new = Node(syms.power, [new] + trailers, prefix="")
77
78        elif "none" in results:
79            new = ListComp(Name("_f"),
80                           Name("_f"),
81                           results["seq"].clone(),
82                           Name("_f"))
83            new = Node(syms.power, [new] + trailers, prefix="")
84
85        else:
86            if in_special_context(node):
87                return None
88
89            args = results['args'].clone()
90            new = Node(syms.power, [Name("filter"), args], prefix="")
91            new = Node(syms.power, [Name("list"), ArgList([new])] + trailers)
92            new.prefix = ""
93        new.prefix = node.prefix
94        return new
95