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1# Copyright 2007 Google, Inc. All Rights Reserved.
2# Licensed to PSF under a Contributor Agreement.
3
4"""Fixer for dict methods.
5
6d.keys() -> list(d.keys())
7d.items() -> list(d.items())
8d.values() -> list(d.values())
9
10d.iterkeys() -> iter(d.keys())
11d.iteritems() -> iter(d.items())
12d.itervalues() -> iter(d.values())
13
14d.viewkeys() -> d.keys()
15d.viewitems() -> d.items()
16d.viewvalues() -> d.values()
17
18Except in certain very specific contexts: the iter() can be dropped
19when the context is list(), sorted(), iter() or for...in; the list()
20can be dropped when the context is list() or sorted() (but not iter()
21or for...in!). Special contexts that apply to both: list(), sorted(), tuple()
22set(), any(), all(), sum().
23
24Note: iter(d.keys()) could be written as iter(d) but since the
25original d.iterkeys() was also redundant we don't fix this.  And there
26are (rare) contexts where it makes a difference (e.g. when passing it
27as an argument to a function that introspects the argument).
28"""
29
30# Local imports
31from .. import pytree
32from .. import patcomp
33from ..pgen2 import token
34from .. import fixer_base
35from ..fixer_util import Name, Call, LParen, RParen, ArgList, Dot
36from .. import fixer_util
37
38
39iter_exempt = fixer_util.consuming_calls | set(["iter"])
40
41
42class FixDict(fixer_base.BaseFix):
43    BM_compatible = True
44
45    PATTERN = """
46    power< head=any+
47         trailer< '.' method=('keys'|'items'|'values'|
48                              'iterkeys'|'iteritems'|'itervalues'|
49                              'viewkeys'|'viewitems'|'viewvalues') >
50         parens=trailer< '(' ')' >
51         tail=any*
52    >
53    """
54
55    def transform(self, node, results):
56        head = results["head"]
57        method = results["method"][0] # Extract node for method name
58        tail = results["tail"]
59        syms = self.syms
60        method_name = method.value
61        isiter = method_name.startswith(u"iter")
62        isview = method_name.startswith(u"view")
63        if isiter or isview:
64            method_name = method_name[4:]
65        assert method_name in (u"keys", u"items", u"values"), repr(method)
66        head = [n.clone() for n in head]
67        tail = [n.clone() for n in tail]
68        special = not tail and self.in_special_context(node, isiter)
69        args = head + [pytree.Node(syms.trailer,
70                                   [Dot(),
71                                    Name(method_name,
72                                         prefix=method.prefix)]),
73                       results["parens"].clone()]
74        new = pytree.Node(syms.power, args)
75        if not (special or isview):
76            new.prefix = u""
77            new = Call(Name(u"iter" if isiter else u"list"), [new])
78        if tail:
79            new = pytree.Node(syms.power, [new] + tail)
80        new.prefix = node.prefix
81        return new
82
83    P1 = "power< func=NAME trailer< '(' node=any ')' > any* >"
84    p1 = patcomp.compile_pattern(P1)
85
86    P2 = """for_stmt< 'for' any 'in' node=any ':' any* >
87            | comp_for< 'for' any 'in' node=any any* >
88         """
89    p2 = patcomp.compile_pattern(P2)
90
91    def in_special_context(self, node, isiter):
92        if node.parent is None:
93            return False
94        results = {}
95        if (node.parent.parent is not None and
96               self.p1.match(node.parent.parent, results) and
97               results["node"] is node):
98            if isiter:
99                # iter(d.iterkeys()) -> iter(d.keys()), etc.
100                return results["func"].value in iter_exempt
101            else:
102                # list(d.keys()) -> list(d.keys()), etc.
103                return results["func"].value in fixer_util.consuming_calls
104        if not isiter:
105            return False
106        # for ... in d.iterkeys() -> for ... in d.keys(), etc.
107        return self.p2.match(node.parent, results) and results["node"] is node
108