/Lib/lib2to3/fixes/fix_dict.py

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