This file is indexed.

/usr/lib/python3.6/lib2to3/refactor.py is in python3-lib2to3 3.6.5-3.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
# Copyright 2006 Google, Inc. All Rights Reserved.
# Licensed to PSF under a Contributor Agreement.

"""Refactoring framework.

Used as a main program, this can refactor any number of files and/or
recursively descend down directories.  Imported as a module, this
provides infrastructure to write your own refactoring tool.
"""

__author__ = "Guido van Rossum <guido@python.org>"


# Python imports
import os
import sys
import logging
import operator
import collections
import io
from itertools import chain

# Local imports
from .pgen2 import driver, tokenize, token
from .fixer_util import find_root
from . import pytree, pygram
from . import btm_matcher as bm


def get_all_fix_names(fixer_pkg, remove_prefix=True):
    """Return a sorted list of all available fix names in the given package."""
    pkg = __import__(fixer_pkg, [], [], ["*"])
    fixer_dir = os.path.dirname(pkg.__file__)
    fix_names = []
    for name in sorted(os.listdir(fixer_dir)):
        if name.startswith("fix_") and name.endswith(".py"):
            if remove_prefix:
                name = name[4:]
            fix_names.append(name[:-3])
    return fix_names


class _EveryNode(Exception):
    pass


def _get_head_types(pat):
    """ Accepts a pytree Pattern Node and returns a set
        of the pattern types which will match first. """

    if isinstance(pat, (pytree.NodePattern, pytree.LeafPattern)):
        # NodePatters must either have no type and no content
        #   or a type and content -- so they don't get any farther
        # Always return leafs
        if pat.type is None:
            raise _EveryNode
        return {pat.type}

    if isinstance(pat, pytree.NegatedPattern):
        if pat.content:
            return _get_head_types(pat.content)
        raise _EveryNode # Negated Patterns don't have a type

    if isinstance(pat, pytree.WildcardPattern):
        # Recurse on each node in content
        r = set()
        for p in pat.content:
            for x in p:
                r.update(_get_head_types(x))
        return r

    raise Exception("Oh no! I don't understand pattern %s" %(pat))


def _get_headnode_dict(fixer_list):
    """ Accepts a list of fixers and returns a dictionary
        of head node type --> fixer list.  """
    head_nodes = collections.defaultdict(list)
    every = []
    for fixer in fixer_list:
        if fixer.pattern:
            try:
                heads = _get_head_types(fixer.pattern)
            except _EveryNode:
                every.append(fixer)
            else:
                for node_type in heads:
                    head_nodes[node_type].append(fixer)
        else:
            if fixer._accept_type is not None:
                head_nodes[fixer._accept_type].append(fixer)
            else:
                every.append(fixer)
    for node_type in chain(pygram.python_grammar.symbol2number.values(),
                           pygram.python_grammar.tokens):
        head_nodes[node_type].extend(every)
    return dict(head_nodes)


def get_fixers_from_package(pkg_name):
    """
    Return the fully qualified names for fixers in the package pkg_name.
    """
    return [pkg_name + "." + fix_name
            for fix_name in get_all_fix_names(pkg_name, False)]

def _identity(obj):
    return obj

if sys.version_info < (3, 0):
    import codecs
    _open_with_encoding = codecs.open
    # codecs.open doesn't translate newlines sadly.
    def _from_system_newlines(input):
        return input.replace("\r\n", "\n")
    def _to_system_newlines(input):
        if os.linesep != "\n":
            return input.replace("\n", os.linesep)
        else:
            return input
else:
    _open_with_encoding = open
    _from_system_newlines = _identity
    _to_system_newlines = _identity


def _detect_future_features(source):
    have_docstring = False
    gen = tokenize.generate_tokens(io.StringIO(source).readline)
    def advance():
        tok = next(gen)
        return tok[0], tok[1]
    ignore = frozenset({token.NEWLINE, tokenize.NL, token.COMMENT})
    features = set()
    try:
        while True:
            tp, value = advance()
            if tp in ignore:
                continue
            elif tp == token.STRING:
                if have_docstring:
                    break
                have_docstring = True
            elif tp == token.NAME and value == "from":
                tp, value = advance()
                if tp != token.NAME or value != "__future__":
                    break
                tp, value = advance()
                if tp != token.NAME or value != "import":
                    break
                tp, value = advance()
                if tp == token.OP and value == "(":
                    tp, value = advance()
                while tp == token.NAME:
                    features.add(value)
                    tp, value = advance()
                    if tp != token.OP or value != ",":
                        break
                    tp, value = advance()
            else:
                break
    except StopIteration:
        pass
    return frozenset(features)


class FixerError(Exception):
    """A fixer could not be loaded."""


class RefactoringTool(object):

    _default_options = {"print_function" : False,
                        "write_unchanged_files" : False}

    CLASS_PREFIX = "Fix" # The prefix for fixer classes
    FILE_PREFIX = "fix_" # The prefix for modules with a fixer within

    def __init__(self, fixer_names, options=None, explicit=None):
        """Initializer.

        Args:
            fixer_names: a list of fixers to import
            options: a dict with configuration.
            explicit: a list of fixers to run even if they are explicit.
        """
        self.fixers = fixer_names
        self.explicit = explicit or []
        self.options = self._default_options.copy()
        if options is not None:
            self.options.update(options)
        if self.options["print_function"]:
            self.grammar = pygram.python_grammar_no_print_statement
        else:
            self.grammar = pygram.python_grammar
        # When this is True, the refactor*() methods will call write_file() for
        # files processed even if they were not changed during refactoring. If
        # and only if the refactor method's write parameter was True.
        self.write_unchanged_files = self.options.get("write_unchanged_files")
        self.errors = []
        self.logger = logging.getLogger("RefactoringTool")
        self.fixer_log = []
        self.wrote = False
        self.driver = driver.Driver(self.grammar,
                                    convert=pytree.convert,
                                    logger=self.logger)
        self.pre_order, self.post_order = self.get_fixers()


        self.files = []  # List of files that were or should be modified

        self.BM = bm.BottomMatcher()
        self.bmi_pre_order = [] # Bottom Matcher incompatible fixers
        self.bmi_post_order = []

        for fixer in chain(self.post_order, self.pre_order):
            if fixer.BM_compatible:
                self.BM.add_fixer(fixer)
                # remove fixers that will be handled by the bottom-up
                # matcher
            elif fixer in self.pre_order:
                self.bmi_pre_order.append(fixer)
            elif fixer in self.post_order:
                self.bmi_post_order.append(fixer)

        self.bmi_pre_order_heads = _get_headnode_dict(self.bmi_pre_order)
        self.bmi_post_order_heads = _get_headnode_dict(self.bmi_post_order)



    def get_fixers(self):
        """Inspects the options to load the requested patterns and handlers.

        Returns:
          (pre_order, post_order), where pre_order is the list of fixers that
          want a pre-order AST traversal, and post_order is the list that want
          post-order traversal.
        """
        pre_order_fixers = []
        post_order_fixers = []
        for fix_mod_path in self.fixers:
            mod = __import__(fix_mod_path, {}, {}, ["*"])
            fix_name = fix_mod_path.rsplit(".", 1)[-1]
            if fix_name.startswith(self.FILE_PREFIX):
                fix_name = fix_name[len(self.FILE_PREFIX):]
            parts = fix_name.split("_")
            class_name = self.CLASS_PREFIX + "".join([p.title() for p in parts])
            try:
                fix_class = getattr(mod, class_name)
            except AttributeError:
                raise FixerError("Can't find %s.%s" % (fix_name, class_name))
            fixer = fix_class(self.options, self.fixer_log)
            if fixer.explicit and self.explicit is not True and \
                    fix_mod_path not in self.explicit:
                self.log_message("Skipping optional fixer: %s", fix_name)
                continue

            self.log_debug("Adding transformation: %s", fix_name)
            if fixer.order == "pre":
                pre_order_fixers.append(fixer)
            elif fixer.order == "post":
                post_order_fixers.append(fixer)
            else:
                raise FixerError("Illegal fixer order: %r" % fixer.order)

        key_func = operator.attrgetter("run_order")
        pre_order_fixers.sort(key=key_func)
        post_order_fixers.sort(key=key_func)
        return (pre_order_fixers, post_order_fixers)

    def log_error(self, msg, *args, **kwds):
        """Called when an error occurs."""
        raise

    def log_message(self, msg, *args):
        """Hook to log a message."""
        if args:
            msg = msg % args
        self.logger.info(msg)

    def log_debug(self, msg, *args):
        if args:
            msg = msg % args
        self.logger.debug(msg)

    def print_output(self, old_text, new_text, filename, equal):
        """Called with the old version, new version, and filename of a
        refactored file."""
        pass

    def refactor(self, items, write=False, doctests_only=False):
        """Refactor a list of files and directories."""

        for dir_or_file in items:
            if os.path.isdir(dir_or_file):
                self.refactor_dir(dir_or_file, write, doctests_only)
            else:
                self.refactor_file(dir_or_file, write, doctests_only)

    def refactor_dir(self, dir_name, write=False, doctests_only=False):
        """Descends down a directory and refactor every Python file found.

        Python files are assumed to have a .py extension.

        Files and subdirectories starting with '.' are skipped.
        """
        py_ext = os.extsep + "py"
        for dirpath, dirnames, filenames in os.walk(dir_name):
            self.log_debug("Descending into %s", dirpath)
            dirnames.sort()
            filenames.sort()
            for name in filenames:
                if (not name.startswith(".") and
                    os.path.splitext(name)[1] == py_ext):
                    fullname = os.path.join(dirpath, name)
                    self.refactor_file(fullname, write, doctests_only)
            # Modify dirnames in-place to remove subdirs with leading dots
            dirnames[:] = [dn for dn in dirnames if not dn.startswith(".")]

    def _read_python_source(self, filename):
        """
        Do our best to decode a Python source file correctly.
        """
        try:
            f = open(filename, "rb")
        except OSError as err:
            self.log_error("Can't open %s: %s", filename, err)
            return None, None
        try:
            encoding = tokenize.detect_encoding(f.readline)[0]
        finally:
            f.close()
        with _open_with_encoding(filename, "r", encoding=encoding) as f:
            return _from_system_newlines(f.read()), encoding

    def refactor_file(self, filename, write=False, doctests_only=False):
        """Refactors a file."""
        input, encoding = self._read_python_source(filename)
        if input is None:
            # Reading the file failed.
            return
        input += "\n" # Silence certain parse errors
        if doctests_only:
            self.log_debug("Refactoring doctests in %s", filename)
            output = self.refactor_docstring(input, filename)
            if self.write_unchanged_files or output != input:
                self.processed_file(output, filename, input, write, encoding)
            else:
                self.log_debug("No doctest changes in %s", filename)
        else:
            tree = self.refactor_string(input, filename)
            if self.write_unchanged_files or (tree and tree.was_changed):
                # The [:-1] is to take off the \n we added earlier
                self.processed_file(str(tree)[:-1], filename,
                                    write=write, encoding=encoding)
            else:
                self.log_debug("No changes in %s", filename)

    def refactor_string(self, data, name):
        """Refactor a given input string.

        Args:
            data: a string holding the code to be refactored.
            name: a human-readable name for use in error/log messages.

        Returns:
            An AST corresponding to the refactored input stream; None if
            there were errors during the parse.
        """
        features = _detect_future_features(data)
        if "print_function" in features:
            self.driver.grammar = pygram.python_grammar_no_print_statement
        try:
            tree = self.driver.parse_string(data)
        except Exception as err:
            self.log_error("Can't parse %s: %s: %s",
                           name, err.__class__.__name__, err)
            return
        finally:
            self.driver.grammar = self.grammar
        tree.future_features = features
        self.log_debug("Refactoring %s", name)
        self.refactor_tree(tree, name)
        return tree

    def refactor_stdin(self, doctests_only=False):
        input = sys.stdin.read()
        if doctests_only:
            self.log_debug("Refactoring doctests in stdin")
            output = self.refactor_docstring(input, "<stdin>")
            if self.write_unchanged_files or output != input:
                self.processed_file(output, "<stdin>", input)
            else:
                self.log_debug("No doctest changes in stdin")
        else:
            tree = self.refactor_string(input, "<stdin>")
            if self.write_unchanged_files or (tree and tree.was_changed):
                self.processed_file(str(tree), "<stdin>", input)
            else:
                self.log_debug("No changes in stdin")

    def refactor_tree(self, tree, name):
        """Refactors a parse tree (modifying the tree in place).

        For compatible patterns the bottom matcher module is
        used. Otherwise the tree is traversed node-to-node for
        matches.

        Args:
            tree: a pytree.Node instance representing the root of the tree
                  to be refactored.
            name: a human-readable name for this tree.

        Returns:
            True if the tree was modified, False otherwise.
        """

        for fixer in chain(self.pre_order, self.post_order):
            fixer.start_tree(tree, name)

        #use traditional matching for the incompatible fixers
        self.traverse_by(self.bmi_pre_order_heads, tree.pre_order())
        self.traverse_by(self.bmi_post_order_heads, tree.post_order())

        # obtain a set of candidate nodes
        match_set = self.BM.run(tree.leaves())

        while any(match_set.values()):
            for fixer in self.BM.fixers:
                if fixer in match_set and match_set[fixer]:
                    #sort by depth; apply fixers from bottom(of the AST) to top
                    match_set[fixer].sort(key=pytree.Base.depth, reverse=True)

                    if fixer.keep_line_order:
                        #some fixers(eg fix_imports) must be applied
                        #with the original file's line order
                        match_set[fixer].sort(key=pytree.Base.get_lineno)

                    for node in list(match_set[fixer]):
                        if node in match_set[fixer]:
                            match_set[fixer].remove(node)

                        try:
                            find_root(node)
                        except ValueError:
                            # this node has been cut off from a
                            # previous transformation ; skip
                            continue

                        if node.fixers_applied and fixer in node.fixers_applied:
                            # do not apply the same fixer again
                            continue

                        results = fixer.match(node)

                        if results:
                            new = fixer.transform(node, results)
                            if new is not None:
                                node.replace(new)
                                #new.fixers_applied.append(fixer)
                                for node in new.post_order():
                                    # do not apply the fixer again to
                                    # this or any subnode
                                    if not node.fixers_applied:
                                        node.fixers_applied = []
                                    node.fixers_applied.append(fixer)

                                # update the original match set for
                                # the added code
                                new_matches = self.BM.run(new.leaves())
                                for fxr in new_matches:
                                    if not fxr in match_set:
                                        match_set[fxr]=[]

                                    match_set[fxr].extend(new_matches[fxr])

        for fixer in chain(self.pre_order, self.post_order):
            fixer.finish_tree(tree, name)
        return tree.was_changed

    def traverse_by(self, fixers, traversal):
        """Traverse an AST, applying a set of fixers to each node.

        This is a helper method for refactor_tree().

        Args:
            fixers: a list of fixer instances.
            traversal: a generator that yields AST nodes.

        Returns:
            None
        """
        if not fixers:
            return
        for node in traversal:
            for fixer in fixers[node.type]:
                results = fixer.match(node)
                if results:
                    new = fixer.transform(node, results)
                    if new is not None:
                        node.replace(new)
                        node = new

    def processed_file(self, new_text, filename, old_text=None, write=False,
                       encoding=None):
        """
        Called when a file has been refactored and there may be changes.
        """
        self.files.append(filename)
        if old_text is None:
            old_text = self._read_python_source(filename)[0]
            if old_text is None:
                return
        equal = old_text == new_text
        self.print_output(old_text, new_text, filename, equal)
        if equal:
            self.log_debug("No changes to %s", filename)
            if not self.write_unchanged_files:
                return
        if write:
            self.write_file(new_text, filename, old_text, encoding)
        else:
            self.log_debug("Not writing changes to %s", filename)

    def write_file(self, new_text, filename, old_text, encoding=None):
        """Writes a string to a file.

        It first shows a unified diff between the old text and the new text, and
        then rewrites the file; the latter is only done if the write option is
        set.
        """
        try:
            f = _open_with_encoding(filename, "w", encoding=encoding)
        except OSError as err:
            self.log_error("Can't create %s: %s", filename, err)
            return
        try:
            f.write(_to_system_newlines(new_text))
        except OSError as err:
            self.log_error("Can't write %s: %s", filename, err)
        finally:
            f.close()
        self.log_debug("Wrote changes to %s", filename)
        self.wrote = True

    PS1 = ">>> "
    PS2 = "... "

    def refactor_docstring(self, input, filename):
        """Refactors a docstring, looking for doctests.

        This returns a modified version of the input string.  It looks
        for doctests, which start with a ">>>" prompt, and may be
        continued with "..." prompts, as long as the "..." is indented
        the same as the ">>>".

        (Unfortunately we can't use the doctest module's parser,
        since, like most parsers, it is not geared towards preserving
        the original source.)
        """
        result = []
        block = None
        block_lineno = None
        indent = None
        lineno = 0
        for line in input.splitlines(keepends=True):
            lineno += 1
            if line.lstrip().startswith(self.PS1):
                if block is not None:
                    result.extend(self.refactor_doctest(block, block_lineno,
                                                        indent, filename))
                block_lineno = lineno
                block = [line]
                i = line.find(self.PS1)
                indent = line[:i]
            elif (indent is not None and
                  (line.startswith(indent + self.PS2) or
                   line == indent + self.PS2.rstrip() + "\n")):
                block.append(line)
            else:
                if block is not None:
                    result.extend(self.refactor_doctest(block, block_lineno,
                                                        indent, filename))
                block = None
                indent = None
                result.append(line)
        if block is not None:
            result.extend(self.refactor_doctest(block, block_lineno,
                                                indent, filename))
        return "".join(result)

    def refactor_doctest(self, block, lineno, indent, filename):
        """Refactors one doctest.

        A doctest is given as a block of lines, the first of which starts
        with ">>>" (possibly indented), while the remaining lines start
        with "..." (identically indented).

        """
        try:
            tree = self.parse_block(block, lineno, indent)
        except Exception as err:
            if self.logger.isEnabledFor(logging.DEBUG):
                for line in block:
                    self.log_debug("Source: %s", line.rstrip("\n"))
            self.log_error("Can't parse docstring in %s line %s: %s: %s",
                           filename, lineno, err.__class__.__name__, err)
            return block
        if self.refactor_tree(tree, filename):
            new = str(tree).splitlines(keepends=True)
            # Undo the adjustment of the line numbers in wrap_toks() below.
            clipped, new = new[:lineno-1], new[lineno-1:]
            assert clipped == ["\n"] * (lineno-1), clipped
            if not new[-1].endswith("\n"):
                new[-1] += "\n"
            block = [indent + self.PS1 + new.pop(0)]
            if new:
                block += [indent + self.PS2 + line for line in new]
        return block

    def summarize(self):
        if self.wrote:
            were = "were"
        else:
            were = "need to be"
        if not self.files:
            self.log_message("No files %s modified.", were)
        else:
            self.log_message("Files that %s modified:", were)
            for file in self.files:
                self.log_message(file)
        if self.fixer_log:
            self.log_message("Warnings/messages while refactoring:")
            for message in self.fixer_log:
                self.log_message(message)
        if self.errors:
            if len(self.errors) == 1:
                self.log_message("There was 1 error:")
            else:
                self.log_message("There were %d errors:", len(self.errors))
            for msg, args, kwds in self.errors:
                self.log_message(msg, *args, **kwds)

    def parse_block(self, block, lineno, indent):
        """Parses a block into a tree.

        This is necessary to get correct line number / offset information
        in the parser diagnostics and embedded into the parse tree.
        """
        tree = self.driver.parse_tokens(self.wrap_toks(block, lineno, indent))
        tree.future_features = frozenset()
        return tree

    def wrap_toks(self, block, lineno, indent):
        """Wraps a tokenize stream to systematically modify start/end."""
        tokens = tokenize.generate_tokens(self.gen_lines(block, indent).__next__)
        for type, value, (line0, col0), (line1, col1), line_text in tokens:
            line0 += lineno - 1
            line1 += lineno - 1
            # Don't bother updating the columns; this is too complicated
            # since line_text would also have to be updated and it would
            # still break for tokens spanning lines.  Let the user guess
            # that the column numbers for doctests are relative to the
            # end of the prompt string (PS1 or PS2).
            yield type, value, (line0, col0), (line1, col1), line_text


    def gen_lines(self, block, indent):
        """Generates lines as expected by tokenize from a list of lines.

        This strips the first len(indent + self.PS1) characters off each line.
        """
        prefix1 = indent + self.PS1
        prefix2 = indent + self.PS2
        prefix = prefix1
        for line in block:
            if line.startswith(prefix):
                yield line[len(prefix):]
            elif line == prefix.rstrip() + "\n":
                yield "\n"
            else:
                raise AssertionError("line=%r, prefix=%r" % (line, prefix))
            prefix = prefix2
        while True:
            yield ""


class MultiprocessingUnsupported(Exception):
    pass


class MultiprocessRefactoringTool(RefactoringTool):

    def __init__(self, *args, **kwargs):
        super(MultiprocessRefactoringTool, self).__init__(*args, **kwargs)
        self.queue = None
        self.output_lock = None

    def refactor(self, items, write=False, doctests_only=False,
                 num_processes=1):
        if num_processes == 1:
            return super(MultiprocessRefactoringTool, self).refactor(
                items, write, doctests_only)
        try:
            import multiprocessing
        except ImportError:
            raise MultiprocessingUnsupported
        if self.queue is not None:
            raise RuntimeError("already doing multiple processes")
        self.queue = multiprocessing.JoinableQueue()
        self.output_lock = multiprocessing.Lock()
        processes = [multiprocessing.Process(target=self._child)
                     for i in range(num_processes)]
        try:
            for p in processes:
                p.start()
            super(MultiprocessRefactoringTool, self).refactor(items, write,
                                                              doctests_only)
        finally:
            self.queue.join()
            for i in range(num_processes):
                self.queue.put(None)
            for p in processes:
                if p.is_alive():
                    p.join()
            self.queue = None

    def _child(self):
        task = self.queue.get()
        while task is not None:
            args, kwargs = task
            try:
                super(MultiprocessRefactoringTool, self).refactor_file(
                    *args, **kwargs)
            finally:
                self.queue.task_done()
            task = self.queue.get()

    def refactor_file(self, *args, **kwargs):
        if self.queue is not None:
            self.queue.put((args, kwargs))
        else:
            return super(MultiprocessRefactoringTool, self).refactor_file(
                *args, **kwargs)