summaryrefslogtreecommitdiffhomepage
path: root/scripts/jinja2/compiler.py
blob: 96b32f7d6b4af673371c1a8dbd5298a6151cd6f3 (plain)
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
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
# -*- coding: utf-8 -*-
"""
    jinja2.compiler
    ~~~~~~~~~~~~~~~

    Compiles nodes into python code.

    :copyright: (c) 2010 by the Jinja Team.
    :license: BSD, see LICENSE for more details.
"""
from itertools import chain
from copy import deepcopy
from keyword import iskeyword as is_python_keyword
from jinja2 import nodes
from jinja2.nodes import EvalContext
from jinja2.visitor import NodeVisitor
from jinja2.exceptions import TemplateAssertionError
from jinja2.utils import Markup, concat, escape
from jinja2._compat import range_type, text_type, string_types, \
     iteritems, NativeStringIO, imap


operators = {
    'eq':       '==',
    'ne':       '!=',
    'gt':       '>',
    'gteq':     '>=',
    'lt':       '<',
    'lteq':     '<=',
    'in':       'in',
    'notin':    'not in'
}

# what method to iterate over items do we want to use for dict iteration
# in generated code?  on 2.x let's go with iteritems, on 3.x with items
if hasattr(dict, 'iteritems'):
    dict_item_iter = 'iteritems'
else:
    dict_item_iter = 'items'


# does if 0: dummy(x) get us x into the scope?
def unoptimize_before_dead_code():
    x = 42
    def f():
        if 0: dummy(x)
    return f

# The getattr is necessary for pypy which does not set this attribute if
# no closure is on the function
unoptimize_before_dead_code = bool(
    getattr(unoptimize_before_dead_code(), '__closure__', None))


def generate(node, environment, name, filename, stream=None,
             defer_init=False):
    """Generate the python source for a node tree."""
    if not isinstance(node, nodes.Template):
        raise TypeError('Can\'t compile non template nodes')
    generator = CodeGenerator(environment, name, filename, stream, defer_init)
    generator.visit(node)
    if stream is None:
        return generator.stream.getvalue()


def has_safe_repr(value):
    """Does the node have a safe representation?"""
    if value is None or value is NotImplemented or value is Ellipsis:
        return True
    if isinstance(value, (bool, int, float, complex, range_type,
            Markup) + string_types):
        return True
    if isinstance(value, (tuple, list, set, frozenset)):
        for item in value:
            if not has_safe_repr(item):
                return False
        return True
    elif isinstance(value, dict):
        for key, value in iteritems(value):
            if not has_safe_repr(key):
                return False
            if not has_safe_repr(value):
                return False
        return True
    return False


def find_undeclared(nodes, names):
    """Check if the names passed are accessed undeclared.  The return value
    is a set of all the undeclared names from the sequence of names found.
    """
    visitor = UndeclaredNameVisitor(names)
    try:
        for node in nodes:
            visitor.visit(node)
    except VisitorExit:
        pass
    return visitor.undeclared


class Identifiers(object):
    """Tracks the status of identifiers in frames."""

    def __init__(self):
        # variables that are known to be declared (probably from outer
        # frames or because they are special for the frame)
        self.declared = set()

        # undeclared variables from outer scopes
        self.outer_undeclared = set()

        # names that are accessed without being explicitly declared by
        # this one or any of the outer scopes.  Names can appear both in
        # declared and undeclared.
        self.undeclared = set()

        # names that are declared locally
        self.declared_locally = set()

        # names that are declared by parameters
        self.declared_parameter = set()

    def add_special(self, name):
        """Register a special name like `loop`."""
        self.undeclared.discard(name)
        self.declared.add(name)

    def is_declared(self, name):
        """Check if a name is declared in this or an outer scope."""
        if name in self.declared_locally or name in self.declared_parameter:
            return True
        return name in self.declared

    def copy(self):
        return deepcopy(self)


class Frame(object):
    """Holds compile time information for us."""

    def __init__(self, eval_ctx, parent=None):
        self.eval_ctx = eval_ctx
        self.identifiers = Identifiers()

        # a toplevel frame is the root + soft frames such as if conditions.
        self.toplevel = False

        # the root frame is basically just the outermost frame, so no if
        # conditions.  This information is used to optimize inheritance
        # situations.
        self.rootlevel = False

        # in some dynamic inheritance situations the compiler needs to add
        # write tests around output statements.
        self.require_output_check = parent and parent.require_output_check

        # inside some tags we are using a buffer rather than yield statements.
        # this for example affects {% filter %} or {% macro %}.  If a frame
        # is buffered this variable points to the name of the list used as
        # buffer.
        self.buffer = None

        # the name of the block we're in, otherwise None.
        self.block = parent and parent.block or None

        # a set of actually assigned names
        self.assigned_names = set()

        # the parent of this frame
        self.parent = parent

        if parent is not None:
            self.identifiers.declared.update(
                parent.identifiers.declared |
                parent.identifiers.declared_parameter |
                parent.assigned_names
            )
            self.identifiers.outer_undeclared.update(
                parent.identifiers.undeclared -
                self.identifiers.declared
            )
            self.buffer = parent.buffer

    def copy(self):
        """Create a copy of the current one."""
        rv = object.__new__(self.__class__)
        rv.__dict__.update(self.__dict__)
        rv.identifiers = object.__new__(self.identifiers.__class__)
        rv.identifiers.__dict__.update(self.identifiers.__dict__)
        return rv

    def inspect(self, nodes):
        """Walk the node and check for identifiers.  If the scope is hard (eg:
        enforce on a python level) overrides from outer scopes are tracked
        differently.
        """
        visitor = FrameIdentifierVisitor(self.identifiers)
        for node in nodes:
            visitor.visit(node)

    def find_shadowed(self, extra=()):
        """Find all the shadowed names.  extra is an iterable of variables
        that may be defined with `add_special` which may occour scoped.
        """
        i = self.identifiers
        return (i.declared | i.outer_undeclared) & \
               (i.declared_locally | i.declared_parameter) | \
               set(x for x in extra if i.is_declared(x))

    def inner(self):
        """Return an inner frame."""
        return Frame(self.eval_ctx, self)

    def soft(self):
        """Return a soft frame.  A soft frame may not be modified as
        standalone thing as it shares the resources with the frame it
        was created of, but it's not a rootlevel frame any longer.
        """
        rv = self.copy()
        rv.rootlevel = False
        return rv

    __copy__ = copy


class VisitorExit(RuntimeError):
    """Exception used by the `UndeclaredNameVisitor` to signal a stop."""


class DependencyFinderVisitor(NodeVisitor):
    """A visitor that collects filter and test calls."""

    def __init__(self):
        self.filters = set()
        self.tests = set()

    def visit_Filter(self, node):
        self.generic_visit(node)
        self.filters.add(node.name)

    def visit_Test(self, node):
        self.generic_visit(node)
        self.tests.add(node.name)

    def visit_Block(self, node):
        """Stop visiting at blocks."""


class UndeclaredNameVisitor(NodeVisitor):
    """A visitor that checks if a name is accessed without being
    declared.  This is different from the frame visitor as it will
    not stop at closure frames.
    """

    def __init__(self, names):
        self.names = set(names)
        self.undeclared = set()

    def visit_Name(self, node):
        if node.ctx == 'load' and node.name in self.names:
            self.undeclared.add(node.name)
            if self.undeclared == self.names:
                raise VisitorExit()
        else:
            self.names.discard(node.name)

    def visit_Block(self, node):
        """Stop visiting a blocks."""


class FrameIdentifierVisitor(NodeVisitor):
    """A visitor for `Frame.inspect`."""

    def __init__(self, identifiers):
        self.identifiers = identifiers

    def visit_Name(self, node):
        """All assignments to names go through this function."""
        if node.ctx == 'store':
            self.identifiers.declared_locally.add(node.name)
        elif node.ctx == 'param':
            self.identifiers.declared_parameter.add(node.name)
        elif node.ctx == 'load' and not \
             self.identifiers.is_declared(node.name):
            self.identifiers.undeclared.add(node.name)

    def visit_If(self, node):
        self.visit(node.test)
        real_identifiers = self.identifiers

        old_names = real_identifiers.declared_locally | \
                    real_identifiers.declared_parameter

        def inner_visit(nodes):
            if not nodes:
                return set()
            self.identifiers = real_identifiers.copy()
            for subnode in nodes:
                self.visit(subnode)
            rv = self.identifiers.declared_locally - old_names
            # we have to remember the undeclared variables of this branch
            # because we will have to pull them.
            real_identifiers.undeclared.update(self.identifiers.undeclared)
            self.identifiers = real_identifiers
            return rv

        body = inner_visit(node.body)
        else_ = inner_visit(node.else_ or ())

        # the differences between the two branches are also pulled as
        # undeclared variables
        real_identifiers.undeclared.update(body.symmetric_difference(else_) -
                                           real_identifiers.declared)

        # remember those that are declared.
        real_identifiers.declared_locally.update(body | else_)

    def visit_Macro(self, node):
        self.identifiers.declared_locally.add(node.name)

    def visit_Import(self, node):
        self.generic_visit(node)
        self.identifiers.declared_locally.add(node.target)

    def visit_FromImport(self, node):
        self.generic_visit(node)
        for name in node.names:
            if isinstance(name, tuple):
                self.identifiers.declared_locally.add(name[1])
            else:
                self.identifiers.declared_locally.add(name)

    def visit_Assign(self, node):
        """Visit assignments in the correct order."""
        self.visit(node.node)
        self.visit(node.target)

    def visit_For(self, node):
        """Visiting stops at for blocks.  However the block sequence
        is visited as part of the outer scope.
        """
        self.visit(node.iter)

    def visit_CallBlock(self, node):
        self.visit(node.call)

    def visit_FilterBlock(self, node):
        self.visit(node.filter)

    def visit_AssignBlock(self, node):
        """Stop visiting at block assigns."""

    def visit_Scope(self, node):
        """Stop visiting at scopes."""

    def visit_Block(self, node):
        """Stop visiting at blocks."""


class CompilerExit(Exception):
    """Raised if the compiler encountered a situation where it just
    doesn't make sense to further process the code.  Any block that
    raises such an exception is not further processed.
    """


class CodeGenerator(NodeVisitor):

    def __init__(self, environment, name, filename, stream=None,
                 defer_init=False):
        if stream is None:
            stream = NativeStringIO()
        self.environment = environment
        self.name = name
        self.filename = filename
        self.stream = stream
        self.created_block_context = False
        self.defer_init = defer_init

        # aliases for imports
        self.import_aliases = {}

        # a registry for all blocks.  Because blocks are moved out
        # into the global python scope they are registered here
        self.blocks = {}

        # the number of extends statements so far
        self.extends_so_far = 0

        # some templates have a rootlevel extends.  In this case we
        # can safely assume that we're a child template and do some
        # more optimizations.
        self.has_known_extends = False

        # the current line number
        self.code_lineno = 1

        # registry of all filters and tests (global, not block local)
        self.tests = {}
        self.filters = {}

        # the debug information
        self.debug_info = []
        self._write_debug_info = None

        # the number of new lines before the next write()
        self._new_lines = 0

        # the line number of the last written statement
        self._last_line = 0

        # true if nothing was written so far.
        self._first_write = True

        # used by the `temporary_identifier` method to get new
        # unique, temporary identifier
        self._last_identifier = 0

        # the current indentation
        self._indentation = 0

    # -- Various compilation helpers

    def fail(self, msg, lineno):
        """Fail with a :exc:`TemplateAssertionError`."""
        raise TemplateAssertionError(msg, lineno, self.name, self.filename)

    def temporary_identifier(self):
        """Get a new unique identifier."""
        self._last_identifier += 1
        return 't_%d' % self._last_identifier

    def buffer(self, frame):
        """Enable buffering for the frame from that point onwards."""
        frame.buffer = self.temporary_identifier()
        self.writeline('%s = []' % frame.buffer)

    def return_buffer_contents(self, frame):
        """Return the buffer contents of the frame."""
        if frame.eval_ctx.volatile:
            self.writeline('if context.eval_ctx.autoescape:')
            self.indent()
            self.writeline('return Markup(concat(%s))' % frame.buffer)
            self.outdent()
            self.writeline('else:')
            self.indent()
            self.writeline('return concat(%s)' % frame.buffer)
            self.outdent()
        elif frame.eval_ctx.autoescape:
            self.writeline('return Markup(concat(%s))' % frame.buffer)
        else:
            self.writeline('return concat(%s)' % frame.buffer)

    def indent(self):
        """Indent by one."""
        self._indentation += 1

    def outdent(self, step=1):
        """Outdent by step."""
        self._indentation -= step

    def start_write(self, frame, node=None):
        """Yield or write into the frame buffer."""
        if frame.buffer is None:
            self.writeline('yield ', node)
        else:
            self.writeline('%s.append(' % frame.buffer, node)

    def end_write(self, frame):
        """End the writing process started by `start_write`."""
        if frame.buffer is not None:
            self.write(')')

    def simple_write(self, s, frame, node=None):
        """Simple shortcut for start_write + write + end_write."""
        self.start_write(frame, node)
        self.write(s)
        self.end_write(frame)

    def blockvisit(self, nodes, frame):
        """Visit a list of nodes as block in a frame.  If the current frame
        is no buffer a dummy ``if 0: yield None`` is written automatically
        unless the force_generator parameter is set to False.
        """
        if frame.buffer is None:
            self.writeline('if 0: yield None')
        else:
            self.writeline('pass')
        try:
            for node in nodes:
                self.visit(node, frame)
        except CompilerExit:
            pass

    def write(self, x):
        """Write a string into the output stream."""
        if self._new_lines:
            if not self._first_write:
                self.stream.write('\n' * self._new_lines)
                self.code_lineno += self._new_lines
                if self._write_debug_info is not None:
                    self.debug_info.append((self._write_debug_info,
                                            self.code_lineno))
                    self._write_debug_info = None
            self._first_write = False
            self.stream.write('    ' * self._indentation)
            self._new_lines = 0
        self.stream.write(x)

    def writeline(self, x, node=None, extra=0):
        """Combination of newline and write."""
        self.newline(node, extra)
        self.write(x)

    def newline(self, node=None, extra=0):
        """Add one or more newlines before the next write."""
        self._new_lines = max(self._new_lines, 1 + extra)
        if node is not None and node.lineno != self._last_line:
            self._write_debug_info = node.lineno
            self._last_line = node.lineno

    def signature(self, node, frame, extra_kwargs=None):
        """Writes a function call to the stream for the current node.
        A leading comma is added automatically.  The extra keyword
        arguments may not include python keywords otherwise a syntax
        error could occour.  The extra keyword arguments should be given
        as python dict.
        """
        # if any of the given keyword arguments is a python keyword
        # we have to make sure that no invalid call is created.
        kwarg_workaround = False
        for kwarg in chain((x.key for x in node.kwargs), extra_kwargs or ()):
            if is_python_keyword(kwarg):
                kwarg_workaround = True
                break

        for arg in node.args:
            self.write(', ')
            self.visit(arg, frame)

        if not kwarg_workaround:
            for kwarg in node.kwargs:
                self.write(', ')
                self.visit(kwarg, frame)
            if extra_kwargs is not None:
                for key, value in iteritems(extra_kwargs):
                    self.write(', %s=%s' % (key, value))
        if node.dyn_args:
            self.write(', *')
            self.visit(node.dyn_args, frame)

        if kwarg_workaround:
            if node.dyn_kwargs is not None:
                self.write(', **dict({')
            else:
                self.write(', **{')
            for kwarg in node.kwargs:
                self.write('%r: ' % kwarg.key)
                self.visit(kwarg.value, frame)
                self.write(', ')
            if extra_kwargs is not None:
                for key, value in iteritems(extra_kwargs):
                    self.write('%r: %s, ' % (key, value))
            if node.dyn_kwargs is not None:
                self.write('}, **')
                self.visit(node.dyn_kwargs, frame)
                self.write(')')
            else:
                self.write('}')

        elif node.dyn_kwargs is not None:
            self.write(', **')
            self.visit(node.dyn_kwargs, frame)

    def pull_locals(self, frame):
        """Pull all the references identifiers into the local scope."""
        for name in frame.identifiers.undeclared:
            self.writeline('l_%s = context.resolve(%r)' % (name, name))

    def pull_dependencies(self, nodes):
        """Pull all the dependencies."""
        visitor = DependencyFinderVisitor()
        for node in nodes:
            visitor.visit(node)
        for dependency in 'filters', 'tests':
            mapping = getattr(self, dependency)
            for name in getattr(visitor, dependency):
                if name not in mapping:
                    mapping[name] = self.temporary_identifier()
                self.writeline('%s = environment.%s[%r]' %
                               (mapping[name], dependency, name))

    def unoptimize_scope(self, frame):
        """Disable Python optimizations for the frame."""
        # XXX: this is not that nice but it has no real overhead.  It
        # mainly works because python finds the locals before dead code
        # is removed.  If that breaks we have to add a dummy function
        # that just accepts the arguments and does nothing.
        if frame.identifiers.declared:
            self.writeline('%sdummy(%s)' % (
                unoptimize_before_dead_code and 'if 0: ' or '',
                ', '.join('l_' + name for name in frame.identifiers.declared)
            ))

    def push_scope(self, frame, extra_vars=()):
        """This function returns all the shadowed variables in a dict
        in the form name: alias and will write the required assignments
        into the current scope.  No indentation takes place.

        This also predefines locally declared variables from the loop
        body because under some circumstances it may be the case that

        `extra_vars` is passed to `Frame.find_shadowed`.
        """
        aliases = {}
        for name in frame.find_shadowed(extra_vars):
            aliases[name] = ident = self.temporary_identifier()
            self.writeline('%s = l_%s' % (ident, name))
        to_declare = set()
        for name in frame.identifiers.declared_locally:
            if name not in aliases:
                to_declare.add('l_' + name)
        if to_declare:
            self.writeline(' = '.join(to_declare) + ' = missing')
        return aliases

    def pop_scope(self, aliases, frame):
        """Restore all aliases and delete unused variables."""
        for name, alias in iteritems(aliases):
            self.writeline('l_%s = %s' % (name, alias))
        to_delete = set()
        for name in frame.identifiers.declared_locally:
            if name not in aliases:
                to_delete.add('l_' + name)
        if to_delete:
            # we cannot use the del statement here because enclosed
            # scopes can trigger a SyntaxError:
            #   a = 42; b = lambda: a; del a
            self.writeline(' = '.join(to_delete) + ' = missing')

    def function_scoping(self, node, frame, children=None,
                         find_special=True):
        """In Jinja a few statements require the help of anonymous
        functions.  Those are currently macros and call blocks and in
        the future also recursive loops.  As there is currently
        technical limitation that doesn't allow reading and writing a
        variable in a scope where the initial value is coming from an
        outer scope, this function tries to fall back with a common
        error message.  Additionally the frame passed is modified so
        that the argumetns are collected and callers are looked up.

        This will return the modified frame.
        """
        # we have to iterate twice over it, make sure that works
        if children is None:
            children = node.iter_child_nodes()
        children = list(children)
        func_frame = frame.inner()
        func_frame.inspect(children)

        # variables that are undeclared (accessed before declaration) and
        # declared locally *and* part of an outside scope raise a template
        # assertion error. Reason: we can't generate reasonable code from
        # it without aliasing all the variables.
        # this could be fixed in Python 3 where we have the nonlocal
        # keyword or if we switch to bytecode generation
        overridden_closure_vars = (
            func_frame.identifiers.undeclared &
            func_frame.identifiers.declared &
            (func_frame.identifiers.declared_locally |
             func_frame.identifiers.declared_parameter)
        )
        if overridden_closure_vars:
            self.fail('It\'s not possible to set and access variables '
                      'derived from an outer scope! (affects: %s)' %
                      ', '.join(sorted(overridden_closure_vars)), node.lineno)

        # remove variables from a closure from the frame's undeclared
        # identifiers.
        func_frame.identifiers.undeclared -= (
            func_frame.identifiers.undeclared &
            func_frame.identifiers.declared
        )

        # no special variables for this scope, abort early
        if not find_special:
            return func_frame

        func_frame.accesses_kwargs = False
        func_frame.accesses_varargs = False
        func_frame.accesses_caller = False
        func_frame.arguments = args = ['l_' + x.name for x in node.args]

        undeclared = find_undeclared(children, ('caller', 'kwargs', 'varargs'))

        if 'caller' in undeclared:
            func_frame.accesses_caller = True
            func_frame.identifiers.add_special('caller')
            args.append('l_caller')
        if 'kwargs' in undeclared:
            func_frame.accesses_kwargs = True
            func_frame.identifiers.add_special('kwargs')
            args.append('l_kwargs')
        if 'varargs' in undeclared:
            func_frame.accesses_varargs = True
            func_frame.identifiers.add_special('varargs')
            args.append('l_varargs')
        return func_frame

    def macro_body(self, node, frame, children=None):
        """Dump the function def of a macro or call block."""
        frame = self.function_scoping(node, frame, children)
        # macros are delayed, they never require output checks
        frame.require_output_check = False
        args = frame.arguments
        # XXX: this is an ugly fix for the loop nesting bug
        # (tests.test_old_bugs.test_loop_call_bug).  This works around
        # a identifier nesting problem we have in general.  It's just more
        # likely to happen in loops which is why we work around it.  The
        # real solution would be "nonlocal" all the identifiers that are
        # leaking into a new python frame and might be used both unassigned
        # and assigned.
        if 'loop' in frame.identifiers.declared:
            args = args + ['l_loop=l_loop']
        self.writeline('def macro(%s):' % ', '.join(args), node)
        self.indent()
        self.buffer(frame)
        self.pull_locals(frame)
        self.blockvisit(node.body, frame)
        self.return_buffer_contents(frame)
        self.outdent()
        return frame

    def macro_def(self, node, frame):
        """Dump the macro definition for the def created by macro_body."""
        arg_tuple = ', '.join(repr(x.name) for x in node.args)
        name = getattr(node, 'name', None)
        if len(node.args) == 1:
            arg_tuple += ','
        self.write('Macro(environment, macro, %r, (%s), (' %
                   (name, arg_tuple))
        for arg in node.defaults:
            self.visit(arg, frame)
            self.write(', ')
        self.write('), %r, %r, %r)' % (
            bool(frame.accesses_kwargs),
            bool(frame.accesses_varargs),
            bool(frame.accesses_caller)
        ))

    def position(self, node):
        """Return a human readable position for the node."""
        rv = 'line %d' % node.lineno
        if self.name is not None:
            rv += ' in ' + repr(self.name)
        return rv

    # -- Statement Visitors

    def visit_Template(self, node, frame=None):
        assert frame is None, 'no root frame allowed'
        eval_ctx = EvalContext(self.environment, self.name)

        from jinja2.runtime import __all__ as exported
        self.writeline('from __future__ import division')
        self.writeline('from jinja2.runtime import ' + ', '.join(exported))
        if not unoptimize_before_dead_code:
            self.writeline('dummy = lambda *x: None')

        # if we want a deferred initialization we cannot move the
        # environment into a local name
        envenv = not self.defer_init and ', environment=environment' or ''

        # do we have an extends tag at all?  If not, we can save some
        # overhead by just not processing any inheritance code.
        have_extends = node.find(nodes.Extends) is not None

        # find all blocks
        for block in node.find_all(nodes.Block):
            if block.name in self.blocks:
                self.fail('block %r defined twice' % block.name, block.lineno)
            self.blocks[block.name] = block

        # find all imports and import them
        for import_ in node.find_all(nodes.ImportedName):
            if import_.importname not in self.import_aliases:
                imp = import_.importname
                self.import_aliases[imp] = alias = self.temporary_identifier()
                if '.' in imp:
                    module, obj = imp.rsplit('.', 1)
                    self.writeline('from %s import %s as %s' %
                                   (module, obj, alias))
                else:
                    self.writeline('import %s as %s' % (imp, alias))

        # add the load name
        self.writeline('name = %r' % self.name)

        # generate the root render function.
        self.writeline('def root(context%s):' % envenv, extra=1)

        # process the root
        frame = Frame(eval_ctx)
        frame.inspect(node.body)
        frame.toplevel = frame.rootlevel = True
        frame.require_output_check = have_extends and not self.has_known_extends
        self.indent()
        if have_extends:
            self.writeline('parent_template = None')
        if 'self' in find_undeclared(node.body, ('self',)):
            frame.identifiers.add_special('self')
            self.writeline('l_self = TemplateReference(context)')
        self.pull_locals(frame)
        self.pull_dependencies(node.body)
        self.blockvisit(node.body, frame)
        self.outdent()

        # make sure that the parent root is called.
        if have_extends:
            if not self.has_known_extends:
                self.indent()
                self.writeline('if parent_template is not None:')
            self.indent()
            self.writeline('for event in parent_template.'
                           'root_render_func(context):')
            self.indent()
            self.writeline('yield event')
            self.outdent(2 + (not self.has_known_extends))

        # at this point we now have the blocks collected and can visit them too.
        for name, block in iteritems(self.blocks):
            block_frame = Frame(eval_ctx)
            block_frame.inspect(block.body)
            block_frame.block = name
            self.writeline('def block_%s(context%s):' % (name, envenv),
                           block, 1)
            self.indent()
            undeclared = find_undeclared(block.body, ('self', 'super'))
            if 'self' in undeclared:
                block_frame.identifiers.add_special('self')
                self.writeline('l_self = TemplateReference(context)')
            if 'super' in undeclared:
                block_frame.identifiers.add_special('super')
                self.writeline('l_super = context.super(%r, '
                               'block_%s)' % (name, name))
            self.pull_locals(block_frame)
            self.pull_dependencies(block.body)
            self.blockvisit(block.body, block_frame)
            self.outdent()

        self.writeline('blocks = {%s}' % ', '.join('%r: block_%s' % (x, x)
                                                   for x in self.blocks),
                       extra=1)

        # add a function that returns the debug info
        self.writeline('debug_info = %r' % '&'.join('%s=%s' % x for x
                                                    in self.debug_info))

    def visit_Block(self, node, frame):
        """Call a block and register it for the template."""
        level = 1
        if frame.toplevel:
            # if we know that we are a child template, there is no need to
            # check if we are one
            if self.has_known_extends:
                return
            if self.extends_so_far > 0:
                self.writeline('if parent_template is None:')
                self.indent()
                level += 1
        context = node.scoped and 'context.derived(locals())' or 'context'
        self.writeline('for event in context.blocks[%r][0](%s):' % (
                       node.name, context), node)
        self.indent()
        self.simple_write('event', frame)
        self.outdent(level)

    def visit_Extends(self, node, frame):
        """Calls the extender."""
        if not frame.toplevel:
            self.fail('cannot use extend from a non top-level scope',
                      node.lineno)

        # if the number of extends statements in general is zero so
        # far, we don't have to add a check if something extended
        # the template before this one.
        if self.extends_so_far > 0:

            # if we have a known extends we just add a template runtime
            # error into the generated code.  We could catch that at compile
            # time too, but i welcome it not to confuse users by throwing the
            # same error at different times just "because we can".
            if not self.has_known_extends:
                self.writeline('if parent_template is not None:')
                self.indent()
            self.writeline('raise TemplateRuntimeError(%r)' %
                           'extended multiple times')

            # if we have a known extends already we don't need that code here
            # as we know that the template execution will end here.
            if self.has_known_extends:
                raise CompilerExit()
            else:
                self.outdent()

        self.writeline('parent_template = environment.get_template(', node)
        self.visit(node.template, frame)
        self.write(', %r)' % self.name)
        self.writeline('for name, parent_block in parent_template.'
                       'blocks.%s():' % dict_item_iter)
        self.indent()
        self.writeline('context.blocks.setdefault(name, []).'
                       'append(parent_block)')
        self.outdent()

        # if this extends statement was in the root level we can take
        # advantage of that information and simplify the generated code
        # in the top level from this point onwards
        if frame.rootlevel:
            self.has_known_extends = True

        # and now we have one more
        self.extends_so_far += 1

    def visit_Include(self, node, frame):
        """Handles includes."""
        if node.with_context:
            self.unoptimize_scope(frame)
        if node.ignore_missing:
            self.writeline('try:')
            self.indent()

        func_name = 'get_or_select_template'
        if isinstance(node.template, nodes.Const):
            if isinstance(node.template.value, string_types):
                func_name = 'get_template'
            elif isinstance(node.template.value, (tuple, list)):
                func_name = 'select_template'
        elif isinstance(node.template, (nodes.Tuple, nodes.List)):
            func_name = 'select_template'

        self.writeline('template = environment.%s(' % func_name, node)
        self.visit(node.template, frame)
        self.write(', %r)' % self.name)
        if node.ignore_missing:
            self.outdent()
            self.writeline('except TemplateNotFound:')
            self.indent()
            self.writeline('pass')
            self.outdent()
            self.writeline('else:')
            self.indent()

        if node.with_context:
            self.writeline('for event in template.root_render_func('
                           'template.new_context(context.parent, True, '
                           'locals())):')
        else:
            self.writeline('for event in template.module._body_stream:')

        self.indent()
        self.simple_write('event', frame)
        self.outdent()

        if node.ignore_missing:
            self.outdent()

    def visit_Import(self, node, frame):
        """Visit regular imports."""
        if node.with_context:
            self.unoptimize_scope(frame)
        self.writeline('l_%s = ' % node.target, node)
        if frame.toplevel:
            self.write('context.vars[%r] = ' % node.target)
        self.write('environment.get_template(')
        self.visit(node.template, frame)
        self.write(', %r).' % self.name)
        if node.with_context:
            self.write('make_module(context.parent, True, locals())')
        else:
            self.write('module')
        if frame.toplevel and not node.target.startswith('_'):
            self.writeline('context.exported_vars.discard(%r)' % node.target)
        frame.assigned_names.add(node.target)

    def visit_FromImport(self, node, frame):
        """Visit named imports."""
        self.newline(node)
        self.write('included_template = environment.get_template(')
        self.visit(node.template, frame)
        self.write(', %r).' % self.name)
        if node.with_context:
            self.write('make_module(context.parent, True)')
        else:
            self.write('module')

        var_names = []
        discarded_names = []
        for name in node.names:
            if isinstance(name, tuple):
                name, alias = name
            else:
                alias = name
            self.writeline('l_%s = getattr(included_template, '
                           '%r, missing)' % (alias, name))
            self.writeline('if l_%s is missing:' % alias)
            self.indent()
            self.writeline('l_%s = environment.undefined(%r %% '
                           'included_template.__name__, '
                           'name=%r)' %
                           (alias, 'the template %%r (imported on %s) does '
                           'not export the requested name %s' % (
                                self.position(node),
                                repr(name)
                           ), name))
            self.outdent()
            if frame.toplevel:
                var_names.append(alias)
                if not alias.startswith('_'):
                    discarded_names.append(alias)
            frame.assigned_names.add(alias)

        if var_names:
            if len(var_names) == 1:
                name = var_names[0]
                self.writeline('context.vars[%r] = l_%s' % (name, name))
            else:
                self.writeline('context.vars.update({%s})' % ', '.join(
                    '%r: l_%s' % (name, name) for name in var_names
                ))
        if discarded_names:
            if len(discarded_names) == 1:
                self.writeline('context.exported_vars.discard(%r)' %
                               discarded_names[0])
            else:
                self.writeline('context.exported_vars.difference_'
                               'update((%s))' % ', '.join(imap(repr, discarded_names)))

    def visit_For(self, node, frame):
        # when calculating the nodes for the inner frame we have to exclude
        # the iterator contents from it
        children = node.iter_child_nodes(exclude=('iter',))
        if node.recursive:
            loop_frame = self.function_scoping(node, frame, children,
                                               find_special=False)
        else:
            loop_frame = frame.inner()
            loop_frame.inspect(children)

        # try to figure out if we have an extended loop.  An extended loop
        # is necessary if the loop is in recursive mode if the special loop
        # variable is accessed in the body.
        extended_loop = node.recursive or 'loop' in \
                        find_undeclared(node.iter_child_nodes(
                            only=('body',)), ('loop',))

        # if we don't have an recursive loop we have to find the shadowed
        # variables at that point.  Because loops can be nested but the loop
        # variable is a special one we have to enforce aliasing for it.
        if not node.recursive:
            aliases = self.push_scope(loop_frame, ('loop',))

        # otherwise we set up a buffer and add a function def
        else:
            self.writeline('def loop(reciter, loop_render_func, depth=0):', node)
            self.indent()
            self.buffer(loop_frame)
            aliases = {}

        # make sure the loop variable is a special one and raise a template
        # assertion error if a loop tries to write to loop
        if extended_loop:
            self.writeline('l_loop = missing')
            loop_frame.identifiers.add_special('loop')
        for name in node.find_all(nodes.Name):
            if name.ctx == 'store' and name.name == 'loop':
                self.fail('Can\'t assign to special loop variable '
                          'in for-loop target', name.lineno)

        self.pull_locals(loop_frame)
        if node.else_:
            iteration_indicator = self.temporary_identifier()
            self.writeline('%s = 1' % iteration_indicator)

        # Create a fake parent loop if the else or test section of a
        # loop is accessing the special loop variable and no parent loop
        # exists.
        if 'loop' not in aliases and 'loop' in find_undeclared(
           node.iter_child_nodes(only=('else_', 'test')), ('loop',)):
            self.writeline("l_loop = environment.undefined(%r, name='loop')" %
                ("'loop' is undefined. the filter section of a loop as well "
                 "as the else block don't have access to the special 'loop'"
                 " variable of the current loop.  Because there is no parent "
                 "loop it's undefined.  Happened in loop on %s" %
                 self.position(node)))

        self.writeline('for ', node)
        self.visit(node.target, loop_frame)
        self.write(extended_loop and ', l_loop in LoopContext(' or ' in ')

        # if we have an extened loop and a node test, we filter in the
        # "outer frame".
        if extended_loop and node.test is not None:
            self.write('(')
            self.visit(node.target, loop_frame)
            self.write(' for ')
            self.visit(node.target, loop_frame)
            self.write(' in ')
            if node.recursive:
                self.write('reciter')
            else:
                self.visit(node.iter, loop_frame)
            self.write(' if (')
            test_frame = loop_frame.copy()
            self.visit(node.test, test_frame)
            self.write('))')

        elif node.recursive:
            self.write('reciter')
        else:
            self.visit(node.iter, loop_frame)

        if node.recursive:
            self.write(', loop_render_func, depth):')
        else:
            self.write(extended_loop and '):' or ':')

        # tests in not extended loops become a continue
        if not extended_loop and node.test is not None:
            self.indent()
            self.writeline('if not ')
            self.visit(node.test, loop_frame)
            self.write(':')
            self.indent()
            self.writeline('continue')
            self.outdent(2)

        self.indent()
        self.blockvisit(node.body, loop_frame)
        if node.else_:
            self.writeline('%s = 0' % iteration_indicator)
        self.outdent()

        if node.else_:
            self.writeline('if %s:' % iteration_indicator)
            self.indent()
            self.blockvisit(node.else_, loop_frame)
            self.outdent()

        # reset the aliases if there are any.
        if not node.recursive:
            self.pop_scope(aliases, loop_frame)

        # if the node was recursive we have to return the buffer contents
        # and start the iteration code
        if node.recursive:
            self.return_buffer_contents(loop_frame)
            self.outdent()
            self.start_write(frame, node)
            self.write('loop(')
            self.visit(node.iter, frame)
            self.write(', loop)')
            self.end_write(frame)

    def visit_If(self, node, frame):
        if_frame = frame.soft()
        self.writeline('if ', node)
        self.visit(node.test, if_frame)
        self.write(':')
        self.indent()
        self.blockvisit(node.body, if_frame)
        self.outdent()
        if node.else_:
            self.writeline('else:')
            self.indent()
            self.blockvisit(node.else_, if_frame)
            self.outdent()

    def visit_Macro(self, node, frame):
        macro_frame = self.macro_body(node, frame)
        self.newline()
        if frame.toplevel:
            if not node.name.startswith('_'):
                self.write('context.exported_vars.add(%r)' % node.name)
            self.writeline('context.vars[%r] = ' % node.name)
        self.write('l_%s = ' % node.name)
        self.macro_def(node, macro_frame)
        frame.assigned_names.add(node.name)

    def visit_CallBlock(self, node, frame):
        children = node.iter_child_nodes(exclude=('call',))
        call_frame = self.macro_body(node, frame, children)
        self.writeline('caller = ')
        self.macro_def(node, call_frame)
        self.start_write(frame, node)
        self.visit_Call(node.call, call_frame, forward_caller=True)
        self.end_write(frame)

    def visit_FilterBlock(self, node, frame):
        filter_frame = frame.inner()
        filter_frame.inspect(node.iter_child_nodes())
        aliases = self.push_scope(filter_frame)
        self.pull_locals(filter_frame)
        self.buffer(filter_frame)
        self.blockvisit(node.body, filter_frame)
        self.start_write(frame, node)
        self.visit_Filter(node.filter, filter_frame)
        self.end_write(frame)
        self.pop_scope(aliases, filter_frame)

    def visit_ExprStmt(self, node, frame):
        self.newline(node)
        self.visit(node.node, frame)

    def visit_Output(self, node, frame):
        # if we have a known extends statement, we don't output anything
        # if we are in a require_output_check section
        if self.has_known_extends and frame.require_output_check:
            return

        if self.environment.finalize:
            finalize = lambda x: text_type(self.environment.finalize(x))
        else:
            finalize = text_type

        # if we are inside a frame that requires output checking, we do so
        outdent_later = False
        if frame.require_output_check:
            self.writeline('if parent_template is None:')
            self.indent()
            outdent_later = True

        # try to evaluate as many chunks as possible into a static
        # string at compile time.
        body = []
        for child in node.nodes:
            try:
                const = child.as_const(frame.eval_ctx)
            except nodes.Impossible:
                body.append(child)
                continue
            # the frame can't be volatile here, becaus otherwise the
            # as_const() function would raise an Impossible exception
            # at that point.
            try:
                if frame.eval_ctx.autoescape:
                    if hasattr(const, '__html__'):
                        const = const.__html__()
                    else:
                        const = escape(const)
                const = finalize(const)
            except Exception:
                # if something goes wrong here we evaluate the node
                # at runtime for easier debugging
                body.append(child)
                continue
            if body and isinstance(body[-1], list):
                body[-1].append(const)
            else:
                body.append([const])

        # if we have less than 3 nodes or a buffer we yield or extend/append
        if len(body) < 3 or frame.buffer is not None:
            if frame.buffer is not None:
                # for one item we append, for more we extend
                if len(body) == 1:
                    self.writeline('%s.append(' % frame.buffer)
                else:
                    self.writeline('%s.extend((' % frame.buffer)
                self.indent()
            for item in body:
                if isinstance(item, list):
                    val = repr(concat(item))
                    if frame.buffer is None:
                        self.writeline('yield ' + val)
                    else:
                        self.writeline(val + ', ')
                else:
                    if frame.buffer is None:
                        self.writeline('yield ', item)
                    else:
                        self.newline(item)
                    close = 1
                    if frame.eval_ctx.volatile:
                        self.write('(context.eval_ctx.autoescape and'
                                   ' escape or to_string)(')
                    elif frame.eval_ctx.autoescape:
                        self.write('escape(')
                    else:
                        self.write('to_string(')
                    if self.environment.finalize is not None:
                        self.write('environment.finalize(')
                        close += 1
                    self.visit(item, frame)
                    self.write(')' * close)
                    if frame.buffer is not None:
                        self.write(', ')
            if frame.buffer is not None:
                # close the open parentheses
                self.outdent()
                self.writeline(len(body) == 1 and ')' or '))')

        # otherwise we create a format string as this is faster in that case
        else:
            format = []
            arguments = []
            for item in body:
                if isinstance(item, list):
                    format.append(concat(item).replace('%', '%%'))
                else:
                    format.append('%s')
                    arguments.append(item)
            self.writeline('yield ')
            self.write(repr(concat(format)) + ' % (')
            idx = -1
            self.indent()
            for argument in arguments:
                self.newline(argument)
                close = 0
                if frame.eval_ctx.volatile:
                    self.write('(context.eval_ctx.autoescape and'
                               ' escape or to_string)(')
                    close += 1
                elif frame.eval_ctx.autoescape:
                    self.write('escape(')
                    close += 1
                if self.environment.finalize is not None:
                    self.write('environment.finalize(')
                    close += 1
                self.visit(argument, frame)
                self.write(')' * close + ', ')
            self.outdent()
            self.writeline(')')

        if outdent_later:
            self.outdent()

    def make_assignment_frame(self, frame):
        # toplevel assignments however go into the local namespace and
        # the current template's context.  We create a copy of the frame
        # here and add a set so that the Name visitor can add the assigned
        # names here.
        if not frame.toplevel:
            return frame
        assignment_frame = frame.copy()
        assignment_frame.toplevel_assignments = set()
        return assignment_frame

    def export_assigned_vars(self, frame, assignment_frame):
        if not frame.toplevel:
            return
        public_names = [x for x in assignment_frame.toplevel_assignments
                        if not x.startswith('_')]
        if len(assignment_frame.toplevel_assignments) == 1:
            name = next(iter(assignment_frame.toplevel_assignments))
            self.writeline('context.vars[%r] = l_%s' % (name, name))
        else:
            self.writeline('context.vars.update({')
            for idx, name in enumerate(assignment_frame.toplevel_assignments):
                if idx:
                    self.write(', ')
                self.write('%r: l_%s' % (name, name))
            self.write('})')
        if public_names:
            if len(public_names) == 1:
                self.writeline('context.exported_vars.add(%r)' %
                               public_names[0])
            else:
                self.writeline('context.exported_vars.update((%s))' %
                               ', '.join(imap(repr, public_names)))

    def visit_Assign(self, node, frame):
        self.newline(node)
        assignment_frame = self.make_assignment_frame(frame)
        self.visit(node.target, assignment_frame)
        self.write(' = ')
        self.visit(node.node, frame)
        self.export_assigned_vars(frame, assignment_frame)

    def visit_AssignBlock(self, node, frame):
        block_frame = frame.inner()
        block_frame.inspect(node.body)
        aliases = self.push_scope(block_frame)
        self.pull_locals(block_frame)
        self.buffer(block_frame)
        self.blockvisit(node.body, block_frame)
        self.pop_scope(aliases, block_frame)

        assignment_frame = self.make_assignment_frame(frame)
        self.newline(node)
        self.visit(node.target, assignment_frame)
        self.write(' = concat(%s)' % block_frame.buffer)
        self.export_assigned_vars(frame, assignment_frame)

    # -- Expression Visitors

    def visit_Name(self, node, frame):
        if node.ctx == 'store' and frame.toplevel:
            frame.toplevel_assignments.add(node.name)
        self.write('l_' + node.name)
        frame.assigned_names.add(node.name)

    def visit_Const(self, node, frame):
        val = node.value
        if isinstance(val, float):
            self.write(str(val))
        else:
            self.write(repr(val))

    def visit_TemplateData(self, node, frame):
        try:
            self.write(repr(node.as_const(frame.eval_ctx)))
        except nodes.Impossible:
            self.write('(context.eval_ctx.autoescape and Markup or identity)(%r)'
                       % node.data)

    def visit_Tuple(self, node, frame):
        self.write('(')
        idx = -1
        for idx, item in enumerate(node.items):
            if idx:
                self.write(', ')
            self.visit(item, frame)
        self.write(idx == 0 and ',)' or ')')

    def visit_List(self, node, frame):
        self.write('[')
        for idx, item in enumerate(node.items):
            if idx:
                self.write(', ')
            self.visit(item, frame)
        self.write(']')

    def visit_Dict(self, node, frame):
        self.write('{')
        for idx, item in enumerate(node.items):
            if idx:
                self.write(', ')
            self.visit(item.key, frame)
            self.write(': ')
            self.visit(item.value, frame)
        self.write('}')

    def binop(operator, interceptable=True):
        def visitor(self, node, frame):
            if self.environment.sandboxed and \
               operator in self.environment.intercepted_binops:
                self.write('environment.call_binop(context, %r, ' % operator)
                self.visit(node.left, frame)
                self.write(', ')
                self.visit(node.right, frame)
            else:
                self.write('(')
                self.visit(node.left, frame)
                self.write(' %s ' % operator)
                self.visit(node.right, frame)
            self.write(')')
        return visitor

    def uaop(operator, interceptable=True):
        def visitor(self, node, frame):
            if self.environment.sandboxed and \
               operator in self.environment.intercepted_unops:
                self.write('environment.call_unop(context, %r, ' % operator)
                self.visit(node.node, frame)
            else:
                self.write('(' + operator)
                self.visit(node.node, frame)
            self.write(')')
        return visitor

    visit_Add = binop('+')
    visit_Sub = binop('-')
    visit_Mul = binop('*')
    visit_Div = binop('/')
    visit_FloorDiv = binop('//')
    visit_Pow = binop('**')
    visit_Mod = binop('%')
    visit_And = binop('and', interceptable=False)
    visit_Or = binop('or', interceptable=False)
    visit_Pos = uaop('+')
    visit_Neg = uaop('-')
    visit_Not = uaop('not ', interceptable=False)
    del binop, uaop

    def visit_Concat(self, node, frame):
        if frame.eval_ctx.volatile:
            func_name = '(context.eval_ctx.volatile and' \
                        ' markup_join or unicode_join)'
        elif frame.eval_ctx.autoescape:
            func_name = 'markup_join'
        else:
            func_name = 'unicode_join'
        self.write('%s((' % func_name)
        for arg in node.nodes:
            self.visit(arg, frame)
            self.write(', ')
        self.write('))')

    def visit_Compare(self, node, frame):
        self.visit(node.expr, frame)
        for op in node.ops:
            self.visit(op, frame)

    def visit_Operand(self, node, frame):
        self.write(' %s ' % operators[node.op])
        self.visit(node.expr, frame)

    def visit_Getattr(self, node, frame):
        self.write('environment.getattr(')
        self.visit(node.node, frame)
        self.write(', %r)' % node.attr)

    def visit_Getitem(self, node, frame):
        # slices bypass the environment getitem method.
        if isinstance(node.arg, nodes.Slice):
            self.visit(node.node, frame)
            self.write('[')
            self.visit(node.arg, frame)
            self.write(']')
        else:
            self.write('environment.getitem(')
            self.visit(node.node, frame)
            self.write(', ')
            self.visit(node.arg, frame)
            self.write(')')

    def visit_Slice(self, node, frame):
        if node.start is not None:
            self.visit(node.start, frame)
        self.write(':')
        if node.stop is not None:
            self.visit(node.stop, frame)
        if node.step is not None:
            self.write(':')
            self.visit(node.step, frame)

    def visit_Filter(self, node, frame):
        self.write(self.filters[node.name] + '(')
        func = self.environment.filters.get(node.name)
        if func is None:
            self.fail('no filter named %r' % node.name, node.lineno)
        if getattr(func, 'contextfilter', False):
            self.write('context, ')
        elif getattr(func, 'evalcontextfilter', False):
            self.write('context.eval_ctx, ')
        elif getattr(func, 'environmentfilter', False):
            self.write('environment, ')

        # if the filter node is None we are inside a filter block
        # and want to write to the current buffer
        if node.node is not None:
            self.visit(node.node, frame)
        elif frame.eval_ctx.volatile:
            self.write('(context.eval_ctx.autoescape and'
                       ' Markup(concat(%s)) or concat(%s))' %
                       (frame.buffer, frame.buffer))
        elif frame.eval_ctx.autoescape:
            self.write('Markup(concat(%s))' % frame.buffer)
        else:
            self.write('concat(%s)' % frame.buffer)
        self.signature(node, frame)
        self.write(')')

    def visit_Test(self, node, frame):
        self.write(self.tests[node.name] + '(')
        if node.name not in self.environment.tests:
            self.fail('no test named %r' % node.name, node.lineno)
        self.visit(node.node, frame)
        self.signature(node, frame)
        self.write(')')

    def visit_CondExpr(self, node, frame):
        def write_expr2():
            if node.expr2 is not None:
                return self.visit(node.expr2, frame)
            self.write('environment.undefined(%r)' % ('the inline if-'
                       'expression on %s evaluated to false and '
                       'no else section was defined.' % self.position(node)))

        self.write('(')
        self.visit(node.expr1, frame)
        self.write(' if ')
        self.visit(node.test, frame)
        self.write(' else ')
        write_expr2()
        self.write(')')

    def visit_Call(self, node, frame, forward_caller=False):
        if self.environment.sandboxed:
            self.write('environment.call(context, ')
        else:
            self.write('context.call(')
        self.visit(node.node, frame)
        extra_kwargs = forward_caller and {'caller': 'caller'} or None
        self.signature(node, frame, extra_kwargs)
        self.write(')')

    def visit_Keyword(self, node, frame):
        self.write(node.key + '=')
        self.visit(node.value, frame)

    # -- Unused nodes for extensions

    def visit_MarkSafe(self, node, frame):
        self.write('Markup(')
        self.visit(node.expr, frame)
        self.write(')')

    def visit_MarkSafeIfAutoescape(self, node, frame):
        self.write('(context.eval_ctx.autoescape and Markup or identity)(')
        self.visit(node.expr, frame)
        self.write(')')

    def visit_EnvironmentAttribute(self, node, frame):
        self.write('environment.' + node.name)

    def visit_ExtensionAttribute(self, node, frame):
        self.write('environment.extensions[%r].%s' % (node.identifier, node.name))

    def visit_ImportedName(self, node, frame):
        self.write(self.import_aliases[node.importname])

    def visit_InternalName(self, node, frame):
        self.write(node.name)

    def visit_ContextReference(self, node, frame):
        self.write('context')

    def visit_Continue(self, node, frame):
        self.writeline('continue', node)

    def visit_Break(self, node, frame):
        self.writeline('break', node)

    def visit_Scope(self, node, frame):
        scope_frame = frame.inner()
        scope_frame.inspect(node.iter_child_nodes())
        aliases = self.push_scope(scope_frame)
        self.pull_locals(scope_frame)
        self.blockvisit(node.body, scope_frame)
        self.pop_scope(aliases, scope_frame)

    def visit_EvalContextModifier(self, node, frame):
        for keyword in node.options:
            self.writeline('context.eval_ctx.%s = ' % keyword.key)
            self.visit(keyword.value, frame)
            try:
                val = keyword.value.as_const(frame.eval_ctx)
            except nodes.Impossible:
                frame.eval_ctx.volatile = True
            else:
                setattr(frame.eval_ctx, keyword.key, val)

    def visit_ScopedEvalContextModifier(self, node, frame):
        old_ctx_name = self.temporary_identifier()
        safed_ctx = frame.eval_ctx.save()
        self.writeline('%s = context.eval_ctx.save()' % old_ctx_name)
        self.visit_EvalContextModifier(node, frame)
        for child in node.body:
            self.visit(child, frame)
        frame.eval_ctx.revert(safed_ctx)
        self.writeline('context.eval_ctx.revert(%s)' % old_ctx_name)