File: i18n.py

package info (click to toggle)
genshi 0.7-5
  • links: PTS, VCS
  • area: main
  • in suites: stretch
  • size: 5,132 kB
  • ctags: 4,961
  • sloc: python: 16,522; ansic: 618; xml: 45; cs: 31; sh: 21; makefile: 6
file content (1260 lines) | stat: -rw-r--r-- 50,193 bytes parent folder | download
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
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
# -*- coding: utf-8 -*-
#
# Copyright (C) 2007-2010 Edgewall Software
# All rights reserved.
#
# This software is licensed as described in the file COPYING, which
# you should have received as part of this distribution. The terms
# are also available at http://genshi.edgewall.org/wiki/License.
#
# This software consists of voluntary contributions made by many
# individuals. For the exact contribution history, see the revision
# history and logs, available at http://genshi.edgewall.org/log/.

"""Directives and utilities for internationalization and localization of
templates.

:since: version 0.4
:note: Directives support added since version 0.6
"""

try:
    any
except NameError:
    from genshi.util import any
from gettext import NullTranslations
import os
import re
from types import FunctionType

from genshi.core import Attrs, Namespace, QName, START, END, TEXT, \
                        XML_NAMESPACE, _ensure, StreamEventKind
from genshi.template.eval import _ast
from genshi.template.base import DirectiveFactory, EXPR, SUB, _apply_directives
from genshi.template.directives import Directive, StripDirective
from genshi.template.markup import MarkupTemplate, EXEC
from genshi.compat import IS_PYTHON2

__all__ = ['Translator', 'extract']
__docformat__ = 'restructuredtext en'


I18N_NAMESPACE = Namespace('http://genshi.edgewall.org/i18n')

MSGBUF = StreamEventKind('MSGBUF')
SUB_START = StreamEventKind('SUB_START')
SUB_END = StreamEventKind('SUB_END')

GETTEXT_FUNCTIONS = ('_', 'gettext', 'ngettext', 'dgettext', 'dngettext',
                     'ugettext', 'ungettext')


class I18NDirective(Directive):
    """Simple interface for i18n directives to support messages extraction."""

    def __call__(self, stream, directives, ctxt, **vars):
        return _apply_directives(stream, directives, ctxt, vars)


class ExtractableI18NDirective(I18NDirective):
    """Simple interface for directives to support messages extraction."""

    def extract(self, translator, stream, gettext_functions=GETTEXT_FUNCTIONS,
                search_text=True, comment_stack=None):
        raise NotImplementedError


class CommentDirective(I18NDirective):
    """Implementation of the ``i18n:comment`` template directive which adds
    translation comments.
    
    >>> tmpl = MarkupTemplate('''<html xmlns:i18n="http://genshi.edgewall.org/i18n">
    ...   <p i18n:comment="As in Foo Bar">Foo</p>
    ... </html>''')
    >>> translator = Translator()
    >>> translator.setup(tmpl)
    >>> list(translator.extract(tmpl.stream))
    [(2, None, u'Foo', [u'As in Foo Bar'])]
    """
    __slots__ = ['comment']

    def __init__(self, value, template=None, namespaces=None, lineno=-1,
                 offset=-1):
        Directive.__init__(self, None, template, namespaces, lineno, offset)
        self.comment = value


class MsgDirective(ExtractableI18NDirective):
    r"""Implementation of the ``i18n:msg`` directive which marks inner content
    as translatable. Consider the following examples:
    
    >>> tmpl = MarkupTemplate('''<html xmlns:i18n="http://genshi.edgewall.org/i18n">
    ...   <div i18n:msg="">
    ...     <p>Foo</p>
    ...     <p>Bar</p>
    ...   </div>
    ...   <p i18n:msg="">Foo <em>bar</em>!</p>
    ... </html>''')
    
    >>> translator = Translator()
    >>> translator.setup(tmpl)
    >>> list(translator.extract(tmpl.stream))
    [(2, None, u'[1:Foo]\n    [2:Bar]', []), (6, None, u'Foo [1:bar]!', [])]
    >>> print(tmpl.generate().render())
    <html>
      <div><p>Foo</p>
        <p>Bar</p></div>
      <p>Foo <em>bar</em>!</p>
    </html>

    >>> tmpl = MarkupTemplate('''<html xmlns:i18n="http://genshi.edgewall.org/i18n">
    ...   <div i18n:msg="fname, lname">
    ...     <p>First Name: ${fname}</p>
    ...     <p>Last Name: ${lname}</p>
    ...   </div>
    ...   <p i18n:msg="">Foo <em>bar</em>!</p>
    ... </html>''')
    >>> translator.setup(tmpl)
    >>> list(translator.extract(tmpl.stream)) #doctest: +NORMALIZE_WHITESPACE
    [(2, None, u'[1:First Name: %(fname)s]\n    [2:Last Name: %(lname)s]', []),
    (6, None, u'Foo [1:bar]!', [])]

    >>> tmpl = MarkupTemplate('''<html xmlns:i18n="http://genshi.edgewall.org/i18n">
    ...   <div i18n:msg="fname, lname">
    ...     <p>First Name: ${fname}</p>
    ...     <p>Last Name: ${lname}</p>
    ...   </div>
    ...   <p i18n:msg="">Foo <em>bar</em>!</p>
    ... </html>''')
    >>> translator.setup(tmpl)
    >>> print(tmpl.generate(fname='John', lname='Doe').render())
    <html>
      <div><p>First Name: John</p>
        <p>Last Name: Doe</p></div>
      <p>Foo <em>bar</em>!</p>
    </html>

    Starting and ending white-space is stripped of to make it simpler for
    translators. Stripping it is not that important since it's on the html
    source, the rendered output will remain the same.
    """
    __slots__ = ['params', 'lineno']

    def __init__(self, value, template=None, namespaces=None, lineno=-1,
                 offset=-1):
        Directive.__init__(self, None, template, namespaces, lineno, offset)
        self.params = [param.strip() for param in value.split(',') if param]
        self.lineno = lineno

    @classmethod
    def attach(cls, template, stream, value, namespaces, pos):
        if type(value) is dict:
            value = value.get('params', '').strip()
        return super(MsgDirective, cls).attach(template, stream, value.strip(),
                                               namespaces, pos)

    def __call__(self, stream, directives, ctxt, **vars):
        gettext = ctxt.get('_i18n.gettext')
        if ctxt.get('_i18n.domain'):
            dgettext = ctxt.get('_i18n.dgettext')
            assert hasattr(dgettext, '__call__'), \
                'No domain gettext function passed'
            gettext = lambda msg: dgettext(ctxt.get('_i18n.domain'), msg)

        def _generate():
            msgbuf = MessageBuffer(self)
            previous = stream.next()
            if previous[0] is START:
                yield previous
            else:
                msgbuf.append(*previous)
            previous = stream.next()
            for kind, data, pos in stream:
                msgbuf.append(*previous)
                previous = kind, data, pos
            if previous[0] is not END:
                msgbuf.append(*previous)
                previous = None
            for event in msgbuf.translate(gettext(msgbuf.format())):
                yield event
            if previous:
                yield previous

        return _apply_directives(_generate(), directives, ctxt, vars)

    def extract(self, translator, stream, gettext_functions=GETTEXT_FUNCTIONS,
                search_text=True, comment_stack=None):
        msgbuf = MessageBuffer(self)
        strip = False

        stream = iter(stream)
        previous = stream.next()
        if previous[0] is START:
            for message in translator._extract_attrs(previous,
                                                     gettext_functions,
                                                     search_text=search_text):
                yield message
            previous = stream.next()
            strip = True
        for event in stream:
            if event[0] is START:
                for message in translator._extract_attrs(event,
                                                         gettext_functions,
                                                         search_text=search_text):
                    yield message
            msgbuf.append(*previous)
            previous = event
        if not strip:
            msgbuf.append(*previous)

        yield self.lineno, None, msgbuf.format(), comment_stack[-1:]


class ChooseBranchDirective(I18NDirective):
    __slots__ = ['params']

    def __call__(self, stream, directives, ctxt, **vars):
        self.params = ctxt.get('_i18n.choose.params', [])[:]
        msgbuf = MessageBuffer(self)
        stream = _apply_directives(stream, directives, ctxt, vars)

        previous = stream.next()
        if previous[0] is START:
            yield previous
        else:
            msgbuf.append(*previous)

        try:
            previous = stream.next()
        except StopIteration:
            # For example <i18n:singular> or <i18n:plural> directives
            yield MSGBUF, (), -1 # the place holder for msgbuf output
            ctxt['_i18n.choose.%s' % self.tagname] = msgbuf
            return

        for event in stream:
            msgbuf.append(*previous)
            previous = event
        yield MSGBUF, (), -1 # the place holder for msgbuf output

        if previous[0] is END:
            yield previous # the outer end tag
        else:
            msgbuf.append(*previous)
        ctxt['_i18n.choose.%s' % self.tagname] = msgbuf

    def extract(self, translator, stream, gettext_functions=GETTEXT_FUNCTIONS,
                search_text=True, comment_stack=None, msgbuf=None):
        stream = iter(stream)
        previous = stream.next()

        if previous[0] is START:
            # skip the enclosing element
            for message in translator._extract_attrs(previous,
                                                     gettext_functions,
                                                     search_text=search_text):
                yield message
            previous = stream.next()

        for event in stream:
            if previous[0] is START:
                for message in translator._extract_attrs(previous,
                                                         gettext_functions,
                                                         search_text=search_text):
                    yield message
            msgbuf.append(*previous)
            previous = event

        if previous[0] is not END:
            msgbuf.append(*previous)


class SingularDirective(ChooseBranchDirective):
    """Implementation of the ``i18n:singular`` directive to be used with the
    ``i18n:choose`` directive."""


class PluralDirective(ChooseBranchDirective):
    """Implementation of the ``i18n:plural`` directive to be used with the
    ``i18n:choose`` directive."""


class ChooseDirective(ExtractableI18NDirective):
    """Implementation of the ``i18n:choose`` directive which provides plural
    internationalisation of strings.
    
    This directive requires at least one parameter, the one which evaluates to
    an integer which will allow to choose the plural/singular form. If you also
    have expressions inside the singular and plural version of the string you
    also need to pass a name for those parameters. Consider the following
    examples:
    
    >>> tmpl = MarkupTemplate('''<html xmlns:i18n="http://genshi.edgewall.org/i18n">
    ...   <div i18n:choose="num; num">
    ...     <p i18n:singular="">There is $num coin</p>
    ...     <p i18n:plural="">There are $num coins</p>
    ...   </div>
    ... </html>''')
    >>> translator = Translator()
    >>> translator.setup(tmpl)
    >>> list(translator.extract(tmpl.stream)) #doctest: +NORMALIZE_WHITESPACE
    [(2, 'ngettext', (u'There is %(num)s coin',
                      u'There are %(num)s coins'), [])]

    >>> tmpl = MarkupTemplate('''<html xmlns:i18n="http://genshi.edgewall.org/i18n">
    ...   <div i18n:choose="num; num">
    ...     <p i18n:singular="">There is $num coin</p>
    ...     <p i18n:plural="">There are $num coins</p>
    ...   </div>
    ... </html>''')
    >>> translator.setup(tmpl)
    >>> print(tmpl.generate(num=1).render())
    <html>
      <div>
        <p>There is 1 coin</p>
      </div>
    </html>
    >>> print(tmpl.generate(num=2).render())
    <html>
      <div>
        <p>There are 2 coins</p>
      </div>
    </html>

    When used as a element and not as an attribute:

    >>> tmpl = MarkupTemplate('''<html xmlns:i18n="http://genshi.edgewall.org/i18n">
    ...   <i18n:choose numeral="num" params="num">
    ...     <p i18n:singular="">There is $num coin</p>
    ...     <p i18n:plural="">There are $num coins</p>
    ...   </i18n:choose>
    ... </html>''')
    >>> translator.setup(tmpl)
    >>> list(translator.extract(tmpl.stream)) #doctest: +NORMALIZE_WHITESPACE
    [(2, 'ngettext', (u'There is %(num)s coin',
                      u'There are %(num)s coins'), [])]
    """
    __slots__ = ['numeral', 'params', 'lineno']

    def __init__(self, value, template=None, namespaces=None, lineno=-1,
                 offset=-1):
        Directive.__init__(self, None, template, namespaces, lineno, offset)
        params = [v.strip() for v in value.split(';')]
        self.numeral = self._parse_expr(params.pop(0), template, lineno, offset)
        self.params = params and [name.strip() for name in
                                  params[0].split(',') if name] or []
        self.lineno = lineno

    @classmethod
    def attach(cls, template, stream, value, namespaces, pos):
        if type(value) is dict:
            numeral = value.get('numeral', '').strip()
            assert numeral is not '', "at least pass the numeral param"
            params = [v.strip() for v in value.get('params', '').split(',')]
            value = '%s; ' % numeral + ', '.join(params)
        return super(ChooseDirective, cls).attach(template, stream, value,
                                                  namespaces, pos)

    def __call__(self, stream, directives, ctxt, **vars):
        ctxt.push({'_i18n.choose.params': self.params,
                   '_i18n.choose.singular': None,
                   '_i18n.choose.plural': None})

        ngettext = ctxt.get('_i18n.ngettext')
        assert hasattr(ngettext, '__call__'), 'No ngettext function available'
        dngettext = ctxt.get('_i18n.dngettext')
        if not dngettext:
            dngettext = lambda d, s, p, n: ngettext(s, p, n)

        new_stream = []
        singular_stream = None
        singular_msgbuf = None
        plural_stream = None
        plural_msgbuf = None

        numeral = self.numeral.evaluate(ctxt)
        is_plural = self._is_plural(numeral, ngettext)

        for event in stream:
            if event[0] is SUB and any(isinstance(d, ChooseBranchDirective)
                                       for d in event[1][0]):
                subdirectives, substream = event[1]

                if isinstance(subdirectives[0], SingularDirective):
                    singular_stream = list(_apply_directives(substream,
                                                             subdirectives,
                                                             ctxt, vars))
                    new_stream.append((MSGBUF, None, (None, -1, -1)))

                elif isinstance(subdirectives[0], PluralDirective):
                    if is_plural:
                        plural_stream = list(_apply_directives(substream,
                                                               subdirectives,
                                                               ctxt, vars))

            else:
                new_stream.append(event)

        if ctxt.get('_i18n.domain'):
            ngettext = lambda s, p, n: dngettext(ctxt.get('_i18n.domain'),
                                                 s, p, n)

        singular_msgbuf = ctxt.get('_i18n.choose.singular')
        if is_plural:
            plural_msgbuf = ctxt.get('_i18n.choose.plural')
            msgbuf, choice = plural_msgbuf, plural_stream
        else:
            msgbuf, choice = singular_msgbuf, singular_stream
            plural_msgbuf = MessageBuffer(self)

        for kind, data, pos in new_stream:
            if kind is MSGBUF:
                for event in choice:
                    if event[0] is MSGBUF:
                        translation = ngettext(singular_msgbuf.format(),
                                               plural_msgbuf.format(),
                                               numeral)
                        for subevent in msgbuf.translate(translation):
                            yield subevent
                    else:
                        yield event
            else:
                yield kind, data, pos

        ctxt.pop()

    def extract(self, translator, stream, gettext_functions=GETTEXT_FUNCTIONS,
                search_text=True, comment_stack=None):
        strip = False
        stream = iter(stream)
        previous = stream.next()

        if previous[0] is START:
            # skip the enclosing element
            for message in translator._extract_attrs(previous,
                                                     gettext_functions,
                                                     search_text=search_text):
                yield message
            previous = stream.next()
            strip = True

        singular_msgbuf = MessageBuffer(self)
        plural_msgbuf = MessageBuffer(self)

        for event in stream:
            if previous[0] is SUB:
                directives, substream = previous[1]
                for directive in directives:
                    if isinstance(directive, SingularDirective):
                        for message in directive.extract(translator,
                                substream, gettext_functions, search_text,
                                comment_stack, msgbuf=singular_msgbuf):
                            yield message
                    elif isinstance(directive, PluralDirective):
                        for message in directive.extract(translator,
                                substream, gettext_functions, search_text,
                                comment_stack, msgbuf=plural_msgbuf):
                            yield message
                    elif not isinstance(directive, StripDirective):
                        singular_msgbuf.append(*previous)
                        plural_msgbuf.append(*previous)
            else:
                if previous[0] is START:
                    for message in translator._extract_attrs(previous,
                                                             gettext_functions,
                                                             search_text):
                        yield message
                singular_msgbuf.append(*previous)
                plural_msgbuf.append(*previous)
            previous = event

        if not strip:
            singular_msgbuf.append(*previous)
            plural_msgbuf.append(*previous)

        yield self.lineno, 'ngettext', \
            (singular_msgbuf.format(), plural_msgbuf.format()), \
            comment_stack[-1:]

    def _is_plural(self, numeral, ngettext):
        # XXX: should we test which form was chosen like this!?!?!?
        # There should be no match in any catalogue for these singular and
        # plural test strings
        singular = u'O\x85\xbe\xa9\xa8az\xc3?\xe6\xa1\x02n\x84\x93'
        plural = u'\xcc\xfb+\xd3Pn\x9d\tT\xec\x1d\xda\x1a\x88\x00'
        return ngettext(singular, plural, numeral) == plural


class DomainDirective(I18NDirective):
    """Implementation of the ``i18n:domain`` directive which allows choosing
    another i18n domain(catalog) to translate from.
    
    >>> from genshi.filters.tests.i18n import DummyTranslations
    >>> tmpl = MarkupTemplate('''<html xmlns:i18n="http://genshi.edgewall.org/i18n">
    ...   <p i18n:msg="">Bar</p>
    ...   <div i18n:domain="foo">
    ...     <p i18n:msg="">FooBar</p>
    ...     <p>Bar</p>
    ...     <p i18n:domain="bar" i18n:msg="">Bar</p>
    ...     <p i18n:domain="">Bar</p>
    ...   </div>
    ...   <p>Bar</p>
    ... </html>''')

    >>> translations = DummyTranslations({'Bar': 'Voh'})
    >>> translations.add_domain('foo', {'FooBar': 'BarFoo', 'Bar': 'foo_Bar'})
    >>> translations.add_domain('bar', {'Bar': 'bar_Bar'})
    >>> translator = Translator(translations)
    >>> translator.setup(tmpl)

    >>> print(tmpl.generate().render())
    <html>
      <p>Voh</p>
      <div>
        <p>BarFoo</p>
        <p>foo_Bar</p>
        <p>bar_Bar</p>
        <p>Voh</p>
      </div>
      <p>Voh</p>
    </html>
    """
    __slots__ = ['domain']

    def __init__(self, value, template=None, namespaces=None, lineno=-1,
                 offset=-1):
        Directive.__init__(self, None, template, namespaces, lineno, offset)
        self.domain = value and value.strip() or '__DEFAULT__'

    @classmethod
    def attach(cls, template, stream, value, namespaces, pos):
        if type(value) is dict:
            value = value.get('name')
        return super(DomainDirective, cls).attach(template, stream, value,
                                                  namespaces, pos)

    def __call__(self, stream, directives, ctxt, **vars):
        ctxt.push({'_i18n.domain': self.domain})
        for event in _apply_directives(stream, directives, ctxt, vars):
            yield event
        ctxt.pop()


class Translator(DirectiveFactory):
    """Can extract and translate localizable strings from markup streams and
    templates.
    
    For example, assume the following template:
    
    >>> tmpl = MarkupTemplate('''<html xmlns:py="http://genshi.edgewall.org/">
    ...   <head>
    ...     <title>Example</title>
    ...   </head>
    ...   <body>
    ...     <h1>Example</h1>
    ...     <p>${_("Hello, %(name)s") % dict(name=username)}</p>
    ...   </body>
    ... </html>''', filename='example.html')
    
    For demonstration, we define a dummy ``gettext``-style function with a
    hard-coded translation table, and pass that to the `Translator` initializer:
    
    >>> def pseudo_gettext(string):
    ...     return {
    ...         'Example': 'Beispiel',
    ...         'Hello, %(name)s': 'Hallo, %(name)s'
    ...     }[string]
    >>> translator = Translator(pseudo_gettext)
    
    Next, the translator needs to be prepended to any already defined filters
    on the template:
    
    >>> tmpl.filters.insert(0, translator)
    
    When generating the template output, our hard-coded translations should be
    applied as expected:
    
    >>> print(tmpl.generate(username='Hans', _=pseudo_gettext))
    <html>
      <head>
        <title>Beispiel</title>
      </head>
      <body>
        <h1>Beispiel</h1>
        <p>Hallo, Hans</p>
      </body>
    </html>
    
    Note that elements defining ``xml:lang`` attributes that do not contain
    variable expressions are ignored by this filter. That can be used to
    exclude specific parts of a template from being extracted and translated.
    """

    directives = [
        ('domain', DomainDirective),
        ('comment', CommentDirective),
        ('msg', MsgDirective),
        ('choose', ChooseDirective),
        ('singular', SingularDirective),
        ('plural', PluralDirective)
    ]

    IGNORE_TAGS = frozenset([
        QName('script'), QName('http://www.w3.org/1999/xhtml}script'),
        QName('style'), QName('http://www.w3.org/1999/xhtml}style')
    ])
    INCLUDE_ATTRS = frozenset([
        'abbr', 'alt', 'label', 'prompt', 'standby', 'summary', 'title'
    ])
    NAMESPACE = I18N_NAMESPACE

    def __init__(self, translate=NullTranslations(), ignore_tags=IGNORE_TAGS,
                 include_attrs=INCLUDE_ATTRS, extract_text=True):
        """Initialize the translator.
        
        :param translate: the translation function, for example ``gettext`` or
                          ``ugettext``.
        :param ignore_tags: a set of tag names that should not be localized
        :param include_attrs: a set of attribute names should be localized
        :param extract_text: whether the content of text nodes should be
                             extracted, or only text in explicit ``gettext``
                             function calls
        
        :note: Changed in 0.6: the `translate` parameter can now be either
               a ``gettext``-style function, or an object compatible with the
               ``NullTransalations`` or ``GNUTranslations`` interface
        """
        self.translate = translate
        self.ignore_tags = ignore_tags
        self.include_attrs = include_attrs
        self.extract_text = extract_text

    def __call__(self, stream, ctxt=None, translate_text=True,
                 translate_attrs=True):
        """Translate any localizable strings in the given stream.
        
        This function shouldn't be called directly. Instead, an instance of
        the `Translator` class should be registered as a filter with the
        `Template` or the `TemplateLoader`, or applied as a regular stream
        filter. If used as a template filter, it should be inserted in front of
        all the default filters.
        
        :param stream: the markup event stream
        :param ctxt: the template context (not used)
        :param translate_text: whether text nodes should be translated (used
                               internally)
        :param translate_attrs: whether attribute values should be translated
                                (used internally)
        :return: the localized stream
        """
        ignore_tags = self.ignore_tags
        include_attrs = self.include_attrs
        skip = 0
        xml_lang = XML_NAMESPACE['lang']
        if not self.extract_text:
            translate_text = False
            translate_attrs = False

        if type(self.translate) is FunctionType:
            gettext = self.translate
            if ctxt:
                ctxt['_i18n.gettext'] = gettext
        else:
            if IS_PYTHON2:
                gettext = self.translate.ugettext
                ngettext = self.translate.ungettext
            else:
                gettext = self.translate.gettext
                ngettext = self.translate.ngettext
            try:
                if IS_PYTHON2:
                    dgettext = self.translate.dugettext
                    dngettext = self.translate.dungettext
                else:
                    dgettext = self.translate.dgettext
                    dngettext = self.translate.dngettext
            except AttributeError:
                dgettext = lambda _, y: gettext(y)
                dngettext = lambda _, s, p, n: ngettext(s, p, n)
            if ctxt:
                ctxt['_i18n.gettext'] = gettext
                ctxt['_i18n.ngettext'] = ngettext
                ctxt['_i18n.dgettext'] = dgettext
                ctxt['_i18n.dngettext'] = dngettext

        if ctxt and ctxt.get('_i18n.domain'):
            # TODO: This can cause infinite recursion if dgettext is defined
            #       via the AttributeError case above!
            gettext = lambda msg: dgettext(ctxt.get('_i18n.domain'), msg)

        for kind, data, pos in stream:

            # skip chunks that should not be localized
            if skip:
                if kind is START:
                    skip += 1
                elif kind is END:
                    skip -= 1
                yield kind, data, pos
                continue

            # handle different events that can be localized
            if kind is START:
                tag, attrs = data
                if tag in self.ignore_tags or \
                        isinstance(attrs.get(xml_lang), basestring):
                    skip += 1
                    yield kind, data, pos
                    continue

                new_attrs = []
                changed = False

                for name, value in attrs:
                    newval = value
                    if isinstance(value, basestring):
                        if translate_attrs and name in include_attrs:
                            newval = gettext(value)
                    else:
                        newval = list(
                            self(_ensure(value), ctxt, translate_text=False)
                        )
                    if newval != value:
                        value = newval
                        changed = True
                    new_attrs.append((name, value))
                if changed:
                    attrs = Attrs(new_attrs)

                yield kind, (tag, attrs), pos

            elif translate_text and kind is TEXT:
                text = data.strip()
                if text:
                    data = data.replace(text, unicode(gettext(text)))
                yield kind, data, pos

            elif kind is SUB:
                directives, substream = data
                current_domain = None
                for idx, directive in enumerate(directives):
                    # Organize directives to make everything work
                    # FIXME: There's got to be a better way to do this!
                    if isinstance(directive, DomainDirective):
                        # Grab current domain and update context
                        current_domain = directive.domain
                        ctxt.push({'_i18n.domain': current_domain})
                        # Put domain directive as the first one in order to
                        # update context before any other directives evaluation
                        directives.insert(0, directives.pop(idx))

                # If this is an i18n directive, no need to translate text
                # nodes here
                is_i18n_directive = any([
                    isinstance(d, ExtractableI18NDirective)
                    for d in directives
                ])
                substream = list(self(substream, ctxt,
                                      translate_text=not is_i18n_directive,
                                      translate_attrs=translate_attrs))
                yield kind, (directives, substream), pos

                if current_domain:
                    ctxt.pop()
            else:
                yield kind, data, pos

    def extract(self, stream, gettext_functions=GETTEXT_FUNCTIONS,
                search_text=True, comment_stack=None):
        """Extract localizable strings from the given template stream.
        
        For every string found, this function yields a ``(lineno, function,
        message, comments)`` tuple, where:
        
        * ``lineno`` is the number of the line on which the string was found,
        * ``function`` is the name of the ``gettext`` function used (if the
          string was extracted from embedded Python code), and
        *  ``message`` is the string itself (a ``unicode`` object, or a tuple
           of ``unicode`` objects for functions with multiple string
           arguments).
        *  ``comments`` is a list of comments related to the message, extracted
           from ``i18n:comment`` attributes found in the markup
        
        >>> tmpl = MarkupTemplate('''<html xmlns:py="http://genshi.edgewall.org/">
        ...   <head>
        ...     <title>Example</title>
        ...   </head>
        ...   <body>
        ...     <h1>Example</h1>
        ...     <p>${_("Hello, %(name)s") % dict(name=username)}</p>
        ...     <p>${ngettext("You have %d item", "You have %d items", num)}</p>
        ...   </body>
        ... </html>''', filename='example.html')
        >>> for line, func, msg, comments in Translator().extract(tmpl.stream):
        ...    print('%d, %r, %r' % (line, func, msg))
        3, None, u'Example'
        6, None, u'Example'
        7, '_', u'Hello, %(name)s'
        8, 'ngettext', (u'You have %d item', u'You have %d items', None)
        
        :param stream: the event stream to extract strings from; can be a
                       regular stream or a template stream
        :param gettext_functions: a sequence of function names that should be
                                  treated as gettext-style localization
                                  functions
        :param search_text: whether the content of text nodes should be
                            extracted (used internally)
        
        :note: Changed in 0.4.1: For a function with multiple string arguments
               (such as ``ngettext``), a single item with a tuple of strings is
               yielded, instead an item for each string argument.
        :note: Changed in 0.6: The returned tuples now include a fourth
               element, which is a list of comments for the translator.
        """
        if not self.extract_text:
            search_text = False
        if comment_stack is None:
            comment_stack = []
        skip = 0

        xml_lang = XML_NAMESPACE['lang']

        for kind, data, pos in stream:
            if skip:
                if kind is START:
                    skip += 1
                if kind is END:
                    skip -= 1

            if kind is START and not skip:
                tag, attrs = data
                if tag in self.ignore_tags or \
                        isinstance(attrs.get(xml_lang), basestring):
                    skip += 1
                    continue

                for message in self._extract_attrs((kind, data, pos),
                                                   gettext_functions,
                                                   search_text=search_text):
                    yield message

            elif not skip and search_text and kind is TEXT:
                text = data.strip()
                if text and [ch for ch in text if ch.isalpha()]:
                    yield pos[1], None, text, comment_stack[-1:]

            elif kind is EXPR or kind is EXEC:
                for funcname, strings in extract_from_code(data,
                                                           gettext_functions):
                    # XXX: Do we need to grab i18n:comment from comment_stack ???
                    yield pos[1], funcname, strings, []

            elif kind is SUB:
                directives, substream = data
                in_comment = False

                for idx, directive in enumerate(directives):
                    # Do a first loop to see if there's a comment directive
                    # If there is update context and pop it from directives
                    if isinstance(directive, CommentDirective):
                        in_comment = True
                        comment_stack.append(directive.comment)
                        if len(directives) == 1:
                            # in case we're in the presence of something like:
                            # <p i18n:comment="foo">Foo</p>
                            for message in self.extract(
                                    substream, gettext_functions,
                                    search_text=search_text and not skip,
                                    comment_stack=comment_stack):
                                yield message
                        directives.pop(idx)
                    elif not isinstance(directive, I18NDirective):
                        # Remove all other non i18n directives from the process
                        directives.pop(idx)

                if not directives and not in_comment:
                    # Extract content if there's no directives because
                    # strip was pop'ed and not because comment was pop'ed.
                    # Extraction in this case has been taken care of.
                    for message in self.extract(
                            substream, gettext_functions,
                            search_text=search_text and not skip):
                        yield message

                for directive in directives:
                    if isinstance(directive, ExtractableI18NDirective):
                        for message in directive.extract(self,
                                substream, gettext_functions,
                                search_text=search_text and not skip,
                                comment_stack=comment_stack):
                            yield message
                    else:
                        for message in self.extract(
                                substream, gettext_functions,
                                search_text=search_text and not skip,
                                comment_stack=comment_stack):
                            yield message

                if in_comment:
                    comment_stack.pop()

    def get_directive_index(self, dir_cls):
        total = len(self._dir_order)
        if dir_cls in self._dir_order:
            return self._dir_order.index(dir_cls) - total
        return total

    def setup(self, template):
        """Convenience function to register the `Translator` filter and the
        related directives with the given template.
        
        :param template: a `Template` instance
        """
        template.filters.insert(0, self)
        if hasattr(template, 'add_directives'):
            template.add_directives(Translator.NAMESPACE, self)

    def _extract_attrs(self, event, gettext_functions, search_text):
        for name, value in event[1][1]:
            if search_text and isinstance(value, basestring):
                if name in self.include_attrs:
                    text = value.strip()
                    if text:
                        yield event[2][1], None, text, []
            else:
                for message in self.extract(_ensure(value), gettext_functions,
                                            search_text=False):
                    yield message


class MessageBuffer(object):
    """Helper class for managing internationalized mixed content.
    
    :since: version 0.5
    """

    def __init__(self, directive=None):
        """Initialize the message buffer.
        
        :param directive: the directive owning the buffer
        :type directive: I18NDirective
        """
        # params list needs to be copied so that directives can be evaluated
        # more than once
        self.orig_params = self.params = directive.params[:]
        self.directive = directive
        self.string = []
        self.events = {}
        self.values = {}
        self.depth = 1
        self.order = 1
        self._prev_order = None
        self.stack = [0]
        self.subdirectives = {}

    def _add_event(self, order, event):
        if order == self._prev_order:
            self.events[order][-1].append(event)
        else:
            self._prev_order = order
            self.events.setdefault(order, [])
            self.events[order].append([event])

    def append(self, kind, data, pos):
        """Append a stream event to the buffer.
        
        :param kind: the stream event kind
        :param data: the event data
        :param pos: the position of the event in the source
        """
        if kind is SUB:
            # The order needs to be +1 because a new START kind event will
            # happen and we we need to wrap those events into our custom kind(s)
            order = self.stack[-1] + 1
            subdirectives, substream = data
            # Store the directives that should be applied after translation
            self.subdirectives.setdefault(order, []).extend(subdirectives)
            self._add_event(order, (SUB_START, None, pos))
            for skind, sdata, spos in substream:
                self.append(skind, sdata, spos)
            self._add_event(order, (SUB_END, None, pos))
        elif kind is TEXT:
            if '[' in data or ']' in data:
                # Quote [ and ] if it ain't us adding it, ie, if the user is
                # using those chars in his templates, escape them
                data = data.replace('[', '\[').replace(']', '\]')
            self.string.append(data)
            self._add_event(self.stack[-1], (kind, data, pos))
        elif kind is EXPR:
            if self.params:
                param = self.params.pop(0)
            else:
                params = ', '.join(['"%s"' % p for p in self.orig_params if p])
                if params:
                    params = "(%s)" % params
                raise IndexError("%d parameters%s given to 'i18n:%s' but "
                                 "%d or more expressions used in '%s', line %s"
                                 % (len(self.orig_params), params, 
                                    self.directive.tagname,
                                    len(self.orig_params) + 1,
                                    os.path.basename(pos[0] or
                                                     'In-memory Template'),
                                    pos[1]))
            self.string.append('%%(%s)s' % param)
            self._add_event(self.stack[-1], (kind, data, pos))
            self.values[param] = (kind, data, pos)
        else:
            if kind is START: 
                self.string.append('[%d:' % self.order)
                self.stack.append(self.order)
                self._add_event(self.stack[-1], (kind, data, pos))
                self.depth += 1
                self.order += 1
            elif kind is END:
                self.depth -= 1
                if self.depth:
                    self._add_event(self.stack[-1], (kind, data, pos))
                    self.string.append(']')
                    self.stack.pop()

    def format(self):
        """Return a message identifier representing the content in the
        buffer.
        """
        return ''.join(self.string).strip()

    def translate(self, string, regex=re.compile(r'%\((\w+)\)s')):
        """Interpolate the given message translation with the events in the
        buffer and return the translated stream.
        
        :param string: the translated message string
        """
        substream = None

        def yield_parts(string):
            for idx, part in enumerate(regex.split(string)):
                if idx % 2:
                    yield self.values[part]
                elif part:
                    yield (TEXT,
                           part.replace('\[', '[').replace('\]', ']'),
                           (None, -1, -1)
                    )

        parts = parse_msg(string)
        parts_counter = {}
        for order, string in parts:
            parts_counter.setdefault(order, []).append(None)

        while parts:
            order, string = parts.pop(0)
            events = self.events[order]
            if events:
                events = events.pop(0)
            else:
                # create a dummy empty text event so any remaining
                # part of the translation can be processed.
                events = [(TEXT, "", (None, -1, -1))]
            parts_counter[order].pop()

            for event in events:
                if event[0] is SUB_START:
                    substream = []
                elif event[0] is SUB_END:
                    # Yield a substream which might have directives to be
                    # applied to it (after translation events)
                    yield SUB, (self.subdirectives[order], substream), event[2]
                    substream = None
                elif event[0] is TEXT:
                    if string:
                        for part in yield_parts(string):
                            if substream is not None:
                                substream.append(part)
                            else:
                                yield part
                        # String handled, reset it
                        string = None
                elif event[0] is START:
                    if substream is not None:
                        substream.append(event)
                    else:
                        yield event
                    if string:
                        for part in yield_parts(string):
                            if substream is not None:
                                substream.append(part)
                            else:
                                yield part
                        # String handled, reset it
                        string = None
                elif event[0] is END:
                    if string:
                        for part in yield_parts(string):
                            if substream is not None:
                                substream.append(part)
                            else:
                                yield part
                        # String handled, reset it
                        string = None
                    if substream is not None:
                        substream.append(event)
                    else:
                        yield event
                elif event[0] is EXPR:
                    # These are handled on the strings itself
                    continue
                else:
                    if string:
                        for part in yield_parts(string):
                            if substream is not None:
                                substream.append(part)
                            else:
                                yield part
                        # String handled, reset it
                        string = None
                    if substream is not None:
                        substream.append(event)
                    else:
                        yield event


def parse_msg(string, regex=re.compile(r'(?:\[(\d+)\:)|(?<!\\)\]')):
    """Parse a translated message using Genshi mixed content message
    formatting.
    
    >>> parse_msg("See [1:Help].")
    [(0, 'See '), (1, 'Help'), (0, '.')]
    
    >>> parse_msg("See [1:our [2:Help] page] for details.")
    [(0, 'See '), (1, 'our '), (2, 'Help'), (1, ' page'), (0, ' for details.')]
    
    >>> parse_msg("[2:Details] finden Sie in [1:Hilfe].")
    [(2, 'Details'), (0, ' finden Sie in '), (1, 'Hilfe'), (0, '.')]
    
    >>> parse_msg("[1:] Bilder pro Seite anzeigen.")
    [(1, ''), (0, ' Bilder pro Seite anzeigen.')]
    
    :param string: the translated message string
    :return: a list of ``(order, string)`` tuples
    :rtype: `list`
    """
    parts = []
    stack = [0]
    while True:
        mo = regex.search(string)
        if not mo:
            break

        if mo.start() or stack[-1]:
            parts.append((stack[-1], string[:mo.start()]))
        string = string[mo.end():]

        orderno = mo.group(1)
        if orderno is not None:
            stack.append(int(orderno))
        else:
            stack.pop()
        if not stack:
            break

    if string:
        parts.append((stack[-1], string))

    return parts


def extract_from_code(code, gettext_functions):
    """Extract strings from Python bytecode.
    
    >>> from genshi.template.eval import Expression
    >>> expr = Expression('_("Hello")')
    >>> list(extract_from_code(expr, GETTEXT_FUNCTIONS))
    [('_', u'Hello')]
    
    >>> expr = Expression('ngettext("You have %(num)s item", '
    ...                            '"You have %(num)s items", num)')
    >>> list(extract_from_code(expr, GETTEXT_FUNCTIONS))
    [('ngettext', (u'You have %(num)s item', u'You have %(num)s items', None))]
    
    :param code: the `Code` object
    :type code: `genshi.template.eval.Code`
    :param gettext_functions: a sequence of function names
    :since: version 0.5
    """
    def _walk(node):
        if isinstance(node, _ast.Call) and isinstance(node.func, _ast.Name) \
                and node.func.id in gettext_functions:
            strings = []
            def _add(arg):
                if isinstance(arg, _ast.Str) and isinstance(arg.s, unicode):
                    strings.append(arg.s)
                elif isinstance(arg, _ast.Str):
                    strings.append(unicode(arg.s, 'utf-8'))
                elif arg:
                    strings.append(None)
            [_add(arg) for arg in node.args]
            if hasattr(node, 'starargs'):
                _add(node.starargs)
            if hasattr(node, 'kwargs'):
                _add(node.kwargs)
            if len(strings) == 1:
                strings = strings[0]
            else:
                strings = tuple(strings)
            yield node.func.id, strings
        elif node._fields:
            children = []
            for field in node._fields:
                child = getattr(node, field, None)
                if isinstance(child, list):
                    for elem in child:
                        children.append(elem)
                elif isinstance(child, _ast.AST):
                    children.append(child)
            for child in children:
                for funcname, strings in _walk(child):
                    yield funcname, strings
    return _walk(code.ast)


def extract(fileobj, keywords, comment_tags, options):
    """Babel extraction method for Genshi templates.
    
    :param fileobj: the file-like object the messages should be extracted from
    :param keywords: a list of keywords (i.e. function names) that should be
                     recognized as translation functions
    :param comment_tags: a list of translator tags to search for and include
                         in the results
    :param options: a dictionary of additional options (optional)
    :return: an iterator over ``(lineno, funcname, message, comments)`` tuples
    :rtype: ``iterator``
    """
    template_class = options.get('template_class', MarkupTemplate)
    if isinstance(template_class, basestring):
        module, clsname = template_class.split(':', 1)
        template_class = getattr(__import__(module, {}, {}, [clsname]), clsname)
    encoding = options.get('encoding', None)

    extract_text = options.get('extract_text', True)
    if isinstance(extract_text, basestring):
        extract_text = extract_text.lower() in ('1', 'on', 'yes', 'true')

    ignore_tags = options.get('ignore_tags', Translator.IGNORE_TAGS)
    if isinstance(ignore_tags, basestring):
        ignore_tags = ignore_tags.split()
    ignore_tags = [QName(tag) for tag in ignore_tags]

    include_attrs = options.get('include_attrs', Translator.INCLUDE_ATTRS)
    if isinstance(include_attrs, basestring):
        include_attrs = include_attrs.split()
    include_attrs = [QName(attr) for attr in include_attrs]

    tmpl = template_class(fileobj, filename=getattr(fileobj, 'name', None),
                          encoding=encoding)
    tmpl.loader = None

    translator = Translator(None, ignore_tags, include_attrs, extract_text)
    if hasattr(tmpl, 'add_directives'):
        tmpl.add_directives(Translator.NAMESPACE, translator)
    for message in translator.extract(tmpl.stream, gettext_functions=keywords):
        yield message