This file is indexed.

/usr/lib/python3/dist-packages/jinja2/parser.py is in python3-jinja2 2.7.3-1.

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
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
# -*- coding: utf-8 -*-
"""
    jinja2.parser
    ~~~~~~~~~~~~~

    Implements the template parser.

    :copyright: (c) 2010 by the Jinja Team.
    :license: BSD, see LICENSE for more details.
"""
from jinja2 import nodes
from jinja2.exceptions import TemplateSyntaxError, TemplateAssertionError
from jinja2.lexer import describe_token, describe_token_expr
from jinja2._compat import next, imap


#: statements that callinto 
_statement_keywords = frozenset(['for', 'if', 'block', 'extends', 'print',
                                 'macro', 'include', 'from', 'import',
                                 'set'])
_compare_operators = frozenset(['eq', 'ne', 'lt', 'lteq', 'gt', 'gteq'])


class Parser(object):
    """This is the central parsing class Jinja2 uses.  It's passed to
    extensions and can be used to parse expressions or statements.
    """

    def __init__(self, environment, source, name=None, filename=None,
                 state=None):
        self.environment = environment
        self.stream = environment._tokenize(source, name, filename, state)
        self.name = name
        self.filename = filename
        self.closed = False
        self.extensions = {}
        for extension in environment.iter_extensions():
            for tag in extension.tags:
                self.extensions[tag] = extension.parse
        self._last_identifier = 0
        self._tag_stack = []
        self._end_token_stack = []

    def fail(self, msg, lineno=None, exc=TemplateSyntaxError):
        """Convenience method that raises `exc` with the message, passed
        line number or last line number as well as the current name and
        filename.
        """
        if lineno is None:
            lineno = self.stream.current.lineno
        raise exc(msg, lineno, self.name, self.filename)

    def _fail_ut_eof(self, name, end_token_stack, lineno):
        expected = []
        for exprs in end_token_stack:
            expected.extend(imap(describe_token_expr, exprs))
        if end_token_stack:
            currently_looking = ' or '.join(
                "'%s'" % describe_token_expr(expr)
                for expr in end_token_stack[-1])
        else:
            currently_looking = None

        if name is None:
            message = ['Unexpected end of template.']
        else:
            message = ['Encountered unknown tag \'%s\'.' % name]

        if currently_looking:
            if name is not None and name in expected:
                message.append('You probably made a nesting mistake. Jinja '
                               'is expecting this tag, but currently looking '
                               'for %s.' % currently_looking)
            else:
                message.append('Jinja was looking for the following tags: '
                               '%s.' % currently_looking)

        if self._tag_stack:
            message.append('The innermost block that needs to be '
                           'closed is \'%s\'.' % self._tag_stack[-1])

        self.fail(' '.join(message), lineno)

    def fail_unknown_tag(self, name, lineno=None):
        """Called if the parser encounters an unknown tag.  Tries to fail
        with a human readable error message that could help to identify
        the problem.
        """
        return self._fail_ut_eof(name, self._end_token_stack, lineno)

    def fail_eof(self, end_tokens=None, lineno=None):
        """Like fail_unknown_tag but for end of template situations."""
        stack = list(self._end_token_stack)
        if end_tokens is not None:
            stack.append(end_tokens)
        return self._fail_ut_eof(None, stack, lineno)

    def is_tuple_end(self, extra_end_rules=None):
        """Are we at the end of a tuple?"""
        if self.stream.current.type in ('variable_end', 'block_end', 'rparen'):
            return True
        elif extra_end_rules is not None:
            return self.stream.current.test_any(extra_end_rules)
        return False

    def free_identifier(self, lineno=None):
        """Return a new free identifier as :class:`~jinja2.nodes.InternalName`."""
        self._last_identifier += 1
        rv = object.__new__(nodes.InternalName)
        nodes.Node.__init__(rv, 'fi%d' % self._last_identifier, lineno=lineno)
        return rv

    def parse_statement(self):
        """Parse a single statement."""
        token = self.stream.current
        if token.type != 'name':
            self.fail('tag name expected', token.lineno)
        self._tag_stack.append(token.value)
        pop_tag = True
        try:
            if token.value in _statement_keywords:
                return getattr(self, 'parse_' + self.stream.current.value)()
            if token.value == 'call':
                return self.parse_call_block()
            if token.value == 'filter':
                return self.parse_filter_block()
            ext = self.extensions.get(token.value)
            if ext is not None:
                return ext(self)

            # did not work out, remove the token we pushed by accident
            # from the stack so that the unknown tag fail function can
            # produce a proper error message.
            self._tag_stack.pop()
            pop_tag = False
            self.fail_unknown_tag(token.value, token.lineno)
        finally:
            if pop_tag:
                self._tag_stack.pop()

    def parse_statements(self, end_tokens, drop_needle=False):
        """Parse multiple statements into a list until one of the end tokens
        is reached.  This is used to parse the body of statements as it also
        parses template data if appropriate.  The parser checks first if the
        current token is a colon and skips it if there is one.  Then it checks
        for the block end and parses until if one of the `end_tokens` is
        reached.  Per default the active token in the stream at the end of
        the call is the matched end token.  If this is not wanted `drop_needle`
        can be set to `True` and the end token is removed.
        """
        # the first token may be a colon for python compatibility
        self.stream.skip_if('colon')

        # in the future it would be possible to add whole code sections
        # by adding some sort of end of statement token and parsing those here.
        self.stream.expect('block_end')
        result = self.subparse(end_tokens)

        # we reached the end of the template too early, the subparser
        # does not check for this, so we do that now
        if self.stream.current.type == 'eof':
            self.fail_eof(end_tokens)

        if drop_needle:
            next(self.stream)
        return result

    def parse_set(self):
        """Parse an assign statement."""
        lineno = next(self.stream).lineno
        target = self.parse_assign_target()
        self.stream.expect('assign')
        expr = self.parse_tuple()
        return nodes.Assign(target, expr, lineno=lineno)

    def parse_for(self):
        """Parse a for loop."""
        lineno = self.stream.expect('name:for').lineno
        target = self.parse_assign_target(extra_end_rules=('name:in',))
        self.stream.expect('name:in')
        iter = self.parse_tuple(with_condexpr=False,
                                extra_end_rules=('name:recursive',))
        test = None
        if self.stream.skip_if('name:if'):
            test = self.parse_expression()
        recursive = self.stream.skip_if('name:recursive')
        body = self.parse_statements(('name:endfor', 'name:else'))
        if next(self.stream).value == 'endfor':
            else_ = []
        else:
            else_ = self.parse_statements(('name:endfor',), drop_needle=True)
        return nodes.For(target, iter, body, else_, test,
                         recursive, lineno=lineno)

    def parse_if(self):
        """Parse an if construct."""
        node = result = nodes.If(lineno=self.stream.expect('name:if').lineno)
        while 1:
            node.test = self.parse_tuple(with_condexpr=False)
            node.body = self.parse_statements(('name:elif', 'name:else',
                                               'name:endif'))
            token = next(self.stream)
            if token.test('name:elif'):
                new_node = nodes.If(lineno=self.stream.current.lineno)
                node.else_ = [new_node]
                node = new_node
                continue
            elif token.test('name:else'):
                node.else_ = self.parse_statements(('name:endif',),
                                                   drop_needle=True)
            else:
                node.else_ = []
            break
        return result

    def parse_block(self):
        node = nodes.Block(lineno=next(self.stream).lineno)
        node.name = self.stream.expect('name').value
        node.scoped = self.stream.skip_if('name:scoped')

        # common problem people encounter when switching from django
        # to jinja.  we do not support hyphens in block names, so let's
        # raise a nicer error message in that case.
        if self.stream.current.type == 'sub':
            self.fail('Block names in Jinja have to be valid Python '
                      'identifiers and may not contain hyphens, use an '
                      'underscore instead.')

        node.body = self.parse_statements(('name:endblock',), drop_needle=True)
        self.stream.skip_if('name:' + node.name)
        return node

    def parse_extends(self):
        node = nodes.Extends(lineno=next(self.stream).lineno)
        node.template = self.parse_expression()
        return node

    def parse_import_context(self, node, default):
        if self.stream.current.test_any('name:with', 'name:without') and \
           self.stream.look().test('name:context'):
            node.with_context = next(self.stream).value == 'with'
            self.stream.skip()
        else:
            node.with_context = default
        return node

    def parse_include(self):
        node = nodes.Include(lineno=next(self.stream).lineno)
        node.template = self.parse_expression()
        if self.stream.current.test('name:ignore') and \
           self.stream.look().test('name:missing'):
            node.ignore_missing = True
            self.stream.skip(2)
        else:
            node.ignore_missing = False
        return self.parse_import_context(node, True)

    def parse_import(self):
        node = nodes.Import(lineno=next(self.stream).lineno)
        node.template = self.parse_expression()
        self.stream.expect('name:as')
        node.target = self.parse_assign_target(name_only=True).name
        return self.parse_import_context(node, False)

    def parse_from(self):
        node = nodes.FromImport(lineno=next(self.stream).lineno)
        node.template = self.parse_expression()
        self.stream.expect('name:import')
        node.names = []

        def parse_context():
            if self.stream.current.value in ('with', 'without') and \
               self.stream.look().test('name:context'):
                node.with_context = next(self.stream).value == 'with'
                self.stream.skip()
                return True
            return False

        while 1:
            if node.names:
                self.stream.expect('comma')
            if self.stream.current.type == 'name':
                if parse_context():
                    break
                target = self.parse_assign_target(name_only=True)
                if target.name.startswith('_'):
                    self.fail('names starting with an underline can not '
                              'be imported', target.lineno,
                              exc=TemplateAssertionError)
                if self.stream.skip_if('name:as'):
                    alias = self.parse_assign_target(name_only=True)
                    node.names.append((target.name, alias.name))
                else:
                    node.names.append(target.name)
                if parse_context() or self.stream.current.type != 'comma':
                    break
            else:
                break
        if not hasattr(node, 'with_context'):
            node.with_context = False
            self.stream.skip_if('comma')
        return node

    def parse_signature(self, node):
        node.args = args = []
        node.defaults = defaults = []
        self.stream.expect('lparen')
        while self.stream.current.type != 'rparen':
            if args:
                self.stream.expect('comma')
            arg = self.parse_assign_target(name_only=True)
            arg.set_ctx('param')
            if self.stream.skip_if('assign'):
                defaults.append(self.parse_expression())
            args.append(arg)
        self.stream.expect('rparen')

    def parse_call_block(self):
        node = nodes.CallBlock(lineno=next(self.stream).lineno)
        if self.stream.current.type == 'lparen':
            self.parse_signature(node)
        else:
            node.args = []
            node.defaults = []

        node.call = self.parse_expression()
        if not isinstance(node.call, nodes.Call):
            self.fail('expected call', node.lineno)
        node.body = self.parse_statements(('name:endcall',), drop_needle=True)
        return node

    def parse_filter_block(self):
        node = nodes.FilterBlock(lineno=next(self.stream).lineno)
        node.filter = self.parse_filter(None, start_inline=True)
        node.body = self.parse_statements(('name:endfilter',),
                                          drop_needle=True)
        return node

    def parse_macro(self):
        node = nodes.Macro(lineno=next(self.stream).lineno)
        node.name = self.parse_assign_target(name_only=True).name
        self.parse_signature(node)
        node.body = self.parse_statements(('name:endmacro',),
                                          drop_needle=True)
        return node

    def parse_print(self):
        node = nodes.Output(lineno=next(self.stream).lineno)
        node.nodes = []
        while self.stream.current.type != 'block_end':
            if node.nodes:
                self.stream.expect('comma')
            node.nodes.append(self.parse_expression())
        return node

    def parse_assign_target(self, with_tuple=True, name_only=False,
                            extra_end_rules=None):
        """Parse an assignment target.  As Jinja2 allows assignments to
        tuples, this function can parse all allowed assignment targets.  Per
        default assignments to tuples are parsed, that can be disable however
        by setting `with_tuple` to `False`.  If only assignments to names are
        wanted `name_only` can be set to `True`.  The `extra_end_rules`
        parameter is forwarded to the tuple parsing function.
        """
        if name_only:
            token = self.stream.expect('name')
            target = nodes.Name(token.value, 'store', lineno=token.lineno)
        else:
            if with_tuple:
                target = self.parse_tuple(simplified=True,
                                          extra_end_rules=extra_end_rules)
            else:
                target = self.parse_primary()
            target.set_ctx('store')
        if not target.can_assign():
            self.fail('can\'t assign to %r' % target.__class__.
                      __name__.lower(), target.lineno)
        return target

    def parse_expression(self, with_condexpr=True):
        """Parse an expression.  Per default all expressions are parsed, if
        the optional `with_condexpr` parameter is set to `False` conditional
        expressions are not parsed.
        """
        if with_condexpr:
            return self.parse_condexpr()
        return self.parse_or()

    def parse_condexpr(self):
        lineno = self.stream.current.lineno
        expr1 = self.parse_or()
        while self.stream.skip_if('name:if'):
            expr2 = self.parse_or()
            if self.stream.skip_if('name:else'):
                expr3 = self.parse_condexpr()
            else:
                expr3 = None
            expr1 = nodes.CondExpr(expr2, expr1, expr3, lineno=lineno)
            lineno = self.stream.current.lineno
        return expr1

    def parse_or(self):
        lineno = self.stream.current.lineno
        left = self.parse_and()
        while self.stream.skip_if('name:or'):
            right = self.parse_and()
            left = nodes.Or(left, right, lineno=lineno)
            lineno = self.stream.current.lineno
        return left

    def parse_and(self):
        lineno = self.stream.current.lineno
        left = self.parse_not()
        while self.stream.skip_if('name:and'):
            right = self.parse_not()
            left = nodes.And(left, right, lineno=lineno)
            lineno = self.stream.current.lineno
        return left

    def parse_not(self):
        if self.stream.current.test('name:not'):
            lineno = next(self.stream).lineno
            return nodes.Not(self.parse_not(), lineno=lineno)
        return self.parse_compare()

    def parse_compare(self):
        lineno = self.stream.current.lineno
        expr = self.parse_add()
        ops = []
        while 1:
            token_type = self.stream.current.type
            if token_type in _compare_operators:
                next(self.stream)
                ops.append(nodes.Operand(token_type, self.parse_add()))
            elif self.stream.skip_if('name:in'):
                ops.append(nodes.Operand('in', self.parse_add()))
            elif self.stream.current.test('name:not') and \
                 self.stream.look().test('name:in'):
                self.stream.skip(2)
                ops.append(nodes.Operand('notin', self.parse_add()))
            else:
                break
            lineno = self.stream.current.lineno
        if not ops:
            return expr
        return nodes.Compare(expr, ops, lineno=lineno)

    def parse_add(self):
        lineno = self.stream.current.lineno
        left = self.parse_sub()
        while self.stream.current.type == 'add':
            next(self.stream)
            right = self.parse_sub()
            left = nodes.Add(left, right, lineno=lineno)
            lineno = self.stream.current.lineno
        return left

    def parse_sub(self):
        lineno = self.stream.current.lineno
        left = self.parse_concat()
        while self.stream.current.type == 'sub':
            next(self.stream)
            right = self.parse_concat()
            left = nodes.Sub(left, right, lineno=lineno)
            lineno = self.stream.current.lineno
        return left

    def parse_concat(self):
        lineno = self.stream.current.lineno
        args = [self.parse_mul()]
        while self.stream.current.type == 'tilde':
            next(self.stream)
            args.append(self.parse_mul())
        if len(args) == 1:
            return args[0]
        return nodes.Concat(args, lineno=lineno)

    def parse_mul(self):
        lineno = self.stream.current.lineno
        left = self.parse_div()
        while self.stream.current.type == 'mul':
            next(self.stream)
            right = self.parse_div()
            left = nodes.Mul(left, right, lineno=lineno)
            lineno = self.stream.current.lineno
        return left

    def parse_div(self):
        lineno = self.stream.current.lineno
        left = self.parse_floordiv()
        while self.stream.current.type == 'div':
            next(self.stream)
            right = self.parse_floordiv()
            left = nodes.Div(left, right, lineno=lineno)
            lineno = self.stream.current.lineno
        return left

    def parse_floordiv(self):
        lineno = self.stream.current.lineno
        left = self.parse_mod()
        while self.stream.current.type == 'floordiv':
            next(self.stream)
            right = self.parse_mod()
            left = nodes.FloorDiv(left, right, lineno=lineno)
            lineno = self.stream.current.lineno
        return left

    def parse_mod(self):
        lineno = self.stream.current.lineno
        left = self.parse_pow()
        while self.stream.current.type == 'mod':
            next(self.stream)
            right = self.parse_pow()
            left = nodes.Mod(left, right, lineno=lineno)
            lineno = self.stream.current.lineno
        return left

    def parse_pow(self):
        lineno = self.stream.current.lineno
        left = self.parse_unary()
        while self.stream.current.type == 'pow':
            next(self.stream)
            right = self.parse_unary()
            left = nodes.Pow(left, right, lineno=lineno)
            lineno = self.stream.current.lineno
        return left

    def parse_unary(self, with_filter=True):
        token_type = self.stream.current.type
        lineno = self.stream.current.lineno
        if token_type == 'sub':
            next(self.stream)
            node = nodes.Neg(self.parse_unary(False), lineno=lineno)
        elif token_type == 'add':
            next(self.stream)
            node = nodes.Pos(self.parse_unary(False), lineno=lineno)
        else:
            node = self.parse_primary()
        node = self.parse_postfix(node)
        if with_filter:
            node = self.parse_filter_expr(node)
        return node

    def parse_primary(self):
        token = self.stream.current
        if token.type == 'name':
            if token.value in ('true', 'false', 'True', 'False'):
                node = nodes.Const(token.value in ('true', 'True'),
                                   lineno=token.lineno)
            elif token.value in ('none', 'None'):
                node = nodes.Const(None, lineno=token.lineno)
            else:
                node = nodes.Name(token.value, 'load', lineno=token.lineno)
            next(self.stream)
        elif token.type == 'string':
            next(self.stream)
            buf = [token.value]
            lineno = token.lineno
            while self.stream.current.type == 'string':
                buf.append(self.stream.current.value)
                next(self.stream)
            node = nodes.Const(''.join(buf), lineno=lineno)
        elif token.type in ('integer', 'float'):
            next(self.stream)
            node = nodes.Const(token.value, lineno=token.lineno)
        elif token.type == 'lparen':
            next(self.stream)
            node = self.parse_tuple(explicit_parentheses=True)
            self.stream.expect('rparen')
        elif token.type == 'lbracket':
            node = self.parse_list()
        elif token.type == 'lbrace':
            node = self.parse_dict()
        else:
            self.fail("unexpected '%s'" % describe_token(token), token.lineno)
        return node

    def parse_tuple(self, simplified=False, with_condexpr=True,
                    extra_end_rules=None, explicit_parentheses=False):
        """Works like `parse_expression` but if multiple expressions are
        delimited by a comma a :class:`~jinja2.nodes.Tuple` node is created.
        This method could also return a regular expression instead of a tuple
        if no commas where found.

        The default parsing mode is a full tuple.  If `simplified` is `True`
        only names and literals are parsed.  The `no_condexpr` parameter is
        forwarded to :meth:`parse_expression`.

        Because tuples do not require delimiters and may end in a bogus comma
        an extra hint is needed that marks the end of a tuple.  For example
        for loops support tuples between `for` and `in`.  In that case the
        `extra_end_rules` is set to ``['name:in']``.

        `explicit_parentheses` is true if the parsing was triggered by an
        expression in parentheses.  This is used to figure out if an empty
        tuple is a valid expression or not.
        """
        lineno = self.stream.current.lineno
        if simplified:
            parse = self.parse_primary
        elif with_condexpr:
            parse = self.parse_expression
        else:
            parse = lambda: self.parse_expression(with_condexpr=False)
        args = []
        is_tuple = False
        while 1:
            if args:
                self.stream.expect('comma')
            if self.is_tuple_end(extra_end_rules):
                break
            args.append(parse())
            if self.stream.current.type == 'comma':
                is_tuple = True
            else:
                break
            lineno = self.stream.current.lineno

        if not is_tuple:
            if args:
                return args[0]

            # if we don't have explicit parentheses, an empty tuple is
            # not a valid expression.  This would mean nothing (literally
            # nothing) in the spot of an expression would be an empty
            # tuple.
            if not explicit_parentheses:
                self.fail('Expected an expression, got \'%s\'' %
                          describe_token(self.stream.current))

        return nodes.Tuple(args, 'load', lineno=lineno)

    def parse_list(self):
        token = self.stream.expect('lbracket')
        items = []
        while self.stream.current.type != 'rbracket':
            if items:
                self.stream.expect('comma')
            if self.stream.current.type == 'rbracket':
                break
            items.append(self.parse_expression())
        self.stream.expect('rbracket')
        return nodes.List(items, lineno=token.lineno)

    def parse_dict(self):
        token = self.stream.expect('lbrace')
        items = []
        while self.stream.current.type != 'rbrace':
            if items:
                self.stream.expect('comma')
            if self.stream.current.type == 'rbrace':
                break
            key = self.parse_expression()
            self.stream.expect('colon')
            value = self.parse_expression()
            items.append(nodes.Pair(key, value, lineno=key.lineno))
        self.stream.expect('rbrace')
        return nodes.Dict(items, lineno=token.lineno)

    def parse_postfix(self, node):
        while 1:
            token_type = self.stream.current.type
            if token_type == 'dot' or token_type == 'lbracket':
                node = self.parse_subscript(node)
            # calls are valid both after postfix expressions (getattr
            # and getitem) as well as filters and tests
            elif token_type == 'lparen':
                node = self.parse_call(node)
            else:
                break
        return node

    def parse_filter_expr(self, node):
        while 1:
            token_type = self.stream.current.type
            if token_type == 'pipe':
                node = self.parse_filter(node)
            elif token_type == 'name' and self.stream.current.value == 'is':
                node = self.parse_test(node)
            # calls are valid both after postfix expressions (getattr
            # and getitem) as well as filters and tests
            elif token_type == 'lparen':
                node = self.parse_call(node)
            else:
                break
        return node

    def parse_subscript(self, node):
        token = next(self.stream)
        if token.type == 'dot':
            attr_token = self.stream.current
            next(self.stream)
            if attr_token.type == 'name':
                return nodes.Getattr(node, attr_token.value, 'load',
                                     lineno=token.lineno)
            elif attr_token.type != 'integer':
                self.fail('expected name or number', attr_token.lineno)
            arg = nodes.Const(attr_token.value, lineno=attr_token.lineno)
            return nodes.Getitem(node, arg, 'load', lineno=token.lineno)
        if token.type == 'lbracket':
            args = []
            while self.stream.current.type != 'rbracket':
                if args:
                    self.stream.expect('comma')
                args.append(self.parse_subscribed())
            self.stream.expect('rbracket')
            if len(args) == 1:
                arg = args[0]
            else:
                arg = nodes.Tuple(args, 'load', lineno=token.lineno)
            return nodes.Getitem(node, arg, 'load', lineno=token.lineno)
        self.fail('expected subscript expression', self.lineno)

    def parse_subscribed(self):
        lineno = self.stream.current.lineno

        if self.stream.current.type == 'colon':
            next(self.stream)
            args = [None]
        else:
            node = self.parse_expression()
            if self.stream.current.type != 'colon':
                return node
            next(self.stream)
            args = [node]

        if self.stream.current.type == 'colon':
            args.append(None)
        elif self.stream.current.type not in ('rbracket', 'comma'):
            args.append(self.parse_expression())
        else:
            args.append(None)

        if self.stream.current.type == 'colon':
            next(self.stream)
            if self.stream.current.type not in ('rbracket', 'comma'):
                args.append(self.parse_expression())
            else:
                args.append(None)
        else:
            args.append(None)

        return nodes.Slice(lineno=lineno, *args)

    def parse_call(self, node):
        token = self.stream.expect('lparen')
        args = []
        kwargs = []
        dyn_args = dyn_kwargs = None
        require_comma = False

        def ensure(expr):
            if not expr:
                self.fail('invalid syntax for function call expression',
                          token.lineno)

        while self.stream.current.type != 'rparen':
            if require_comma:
                self.stream.expect('comma')
                # support for trailing comma
                if self.stream.current.type == 'rparen':
                    break
            if self.stream.current.type == 'mul':
                ensure(dyn_args is None and dyn_kwargs is None)
                next(self.stream)
                dyn_args = self.parse_expression()
            elif self.stream.current.type == 'pow':
                ensure(dyn_kwargs is None)
                next(self.stream)
                dyn_kwargs = self.parse_expression()
            else:
                ensure(dyn_args is None and dyn_kwargs is None)
                if self.stream.current.type == 'name' and \
                    self.stream.look().type == 'assign':
                    key = self.stream.current.value
                    self.stream.skip(2)
                    value = self.parse_expression()
                    kwargs.append(nodes.Keyword(key, value,
                                                lineno=value.lineno))
                else:
                    ensure(not kwargs)
                    args.append(self.parse_expression())

            require_comma = True
        self.stream.expect('rparen')

        if node is None:
            return args, kwargs, dyn_args, dyn_kwargs
        return nodes.Call(node, args, kwargs, dyn_args, dyn_kwargs,
                          lineno=token.lineno)

    def parse_filter(self, node, start_inline=False):
        while self.stream.current.type == 'pipe' or start_inline:
            if not start_inline:
                next(self.stream)
            token = self.stream.expect('name')
            name = token.value
            while self.stream.current.type == 'dot':
                next(self.stream)
                name += '.' + self.stream.expect('name').value
            if self.stream.current.type == 'lparen':
                args, kwargs, dyn_args, dyn_kwargs = self.parse_call(None)
            else:
                args = []
                kwargs = []
                dyn_args = dyn_kwargs = None
            node = nodes.Filter(node, name, args, kwargs, dyn_args,
                                dyn_kwargs, lineno=token.lineno)
            start_inline = False
        return node

    def parse_test(self, node):
        token = next(self.stream)
        if self.stream.current.test('name:not'):
            next(self.stream)
            negated = True
        else:
            negated = False
        name = self.stream.expect('name').value
        while self.stream.current.type == 'dot':
            next(self.stream)
            name += '.' + self.stream.expect('name').value
        dyn_args = dyn_kwargs = None
        kwargs = []
        if self.stream.current.type == 'lparen':
            args, kwargs, dyn_args, dyn_kwargs = self.parse_call(None)
        elif self.stream.current.type in ('name', 'string', 'integer',
                                          'float', 'lparen', 'lbracket',
                                          'lbrace') and not \
             self.stream.current.test_any('name:else', 'name:or',
                                          'name:and'):
            if self.stream.current.test('name:is'):
                self.fail('You cannot chain multiple tests with is')
            args = [self.parse_expression()]
        else:
            args = []
        node = nodes.Test(node, name, args, kwargs, dyn_args,
                          dyn_kwargs, lineno=token.lineno)
        if negated:
            node = nodes.Not(node, lineno=token.lineno)
        return node

    def subparse(self, end_tokens=None):
        body = []
        data_buffer = []
        add_data = data_buffer.append

        if end_tokens is not None:
            self._end_token_stack.append(end_tokens)

        def flush_data():
            if data_buffer:
                lineno = data_buffer[0].lineno
                body.append(nodes.Output(data_buffer[:], lineno=lineno))
                del data_buffer[:]

        try:
            while self.stream:
                token = self.stream.current
                if token.type == 'data':
                    if token.value:
                        add_data(nodes.TemplateData(token.value,
                                                    lineno=token.lineno))
                    next(self.stream)
                elif token.type == 'variable_begin':
                    next(self.stream)
                    add_data(self.parse_tuple(with_condexpr=True))
                    self.stream.expect('variable_end')
                elif token.type == 'block_begin':
                    flush_data()
                    next(self.stream)
                    if end_tokens is not None and \
                       self.stream.current.test_any(*end_tokens):
                        return body
                    rv = self.parse_statement()
                    if isinstance(rv, list):
                        body.extend(rv)
                    else:
                        body.append(rv)
                    self.stream.expect('block_end')
                else:
                    raise AssertionError('internal parsing error')

            flush_data()
        finally:
            if end_tokens is not None:
                self._end_token_stack.pop()

        return body

    def parse(self):
        """Parse the whole template into a `Template` node."""
        result = nodes.Template(self.subparse(), lineno=1)
        result.set_environment(self.environment)
        return result