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
#![cfg_attr(
    feature = "custom_syntax",
    doc = "Documents the syntax for templates and provides ways to reconfigure it."
)]
#![cfg_attr(
    not(feature = "custom_syntax"),
    doc = "Documents the syntax for templates."
)]
//!
//! <details><summary><strong style="cursor: pointer">Table of Contents</strong></summary>
//!
//! - [Synopsis](#synopsis)
//! - [Trailing Newlines](#trailing-newlines)
//! - [Expressions](#expressions)
//!   - [Literals](#literals)
//!   - [Math](#math)
//!   - [Comparisons](#comparisons)
//!   - [Logic](#logic)
//!   - [Other Operators](#other-operators)
//!   - [If Expressions](#if-expressions)
//! - [Tags](#tags)
//!   - [`{% for %}`](#-for-)
//!   - [`{% if %}`](#-if-)
//!   - [`{% extends %}`](#-extends-)
//!   - [`{% block %}`](#-block-)
//!   - [`{% include %}`](#-include-)
//!   - [`{% import %}`](#-import-)
//!   - [`{% with %}`](#-with-)
//!   - [`{% set %}`](#-set-)
//!   - [`{% filter %}`](#-filter-)
//!   - [`{% macro %}`](#-macro-)
//!   - [`{% call %}`](#-call-)
//!   - [`{% do %}`](#-do-)
//!   - [`{% autoescape %}`](#-autoescape-)
//!   - [`{% raw %}`](#-raw-)
//!   - [`{% break %} / {% continue %}`](#-break----continue-)
#![cfg_attr(
    feature = "custom_syntax",
    doc = "- [Custom Delimiters](#custom-delimiters)"
)]
//! - [Whitespace Control](#whitespace-control)
//!
//! </details>
//!
//! # Synopsis
//!
//! A MiniJinja template is simply a text file.  MiniJinja can generate any text-based
//! format (HTML, XML, CSV, LaTeX, etc.).  A template doesn’t need to have a specific extension
//! and in fact MiniJinja does not understand much about the file system.  However the default
//! configuration for [auto escaping](crate::Environment::set_auto_escape_callback) uses file
//! extensions to configure the initial behavior.
//!
//! A template contains [**expressions**](#expressions), which get replaced with values when a
//! template is rendered; and [**tags**](#tags), which control the logic of the template.  The
//! template syntax is heavily inspired by Jinja2, Django and Python.
//!
//! This is a minimal template that illustrates a few basics:
//!
//! ```jinja
//! <!doctype html>
//! <title>{% block title %}My Website{% endblock %}</title>
//! <ul id="navigation">
//! {% for item in navigation %}
//!     <li><a href="{{ item.href }}">{{ item.caption }}</a></li>
//! {% endfor %}
//! </ul>
//!
//! <h1>My Webpage</h1>
//! {% block body %}{% endblock %}
//!
//! {# a comment #}
//! ```
//!
//! # Trailing Newlines
//!
//! MiniJinja, like Jinja2, will remove one trailing newline from the end of the file automatically
//! on parsing.  This lets templates produce a consistent output no matter if the editor adds a
//! trailing newline or not.  If one wants a trailing newline an extra newline can be added or the
//! code rendering it adds it manually.
//!
//! # Expressions
//!
//! MiniJinja allows basic expressions everywhere. These work largely as you expect from Jinja2.
//! Even if you have not used Jinja2 you should feel comfortable with it.  To output the result
//! of an expression wrap it in `{{ .. }}`.
//!
//! ## Literals
//!
//! The simplest form of expressions are literals. Literals are representations for
//! objects such as strings and numbers. The following literals exist:
//!
//! - `"Hello World"`: Everything between two double or single quotes is a string. They are
//!   useful whenever you need a string in the template (e.g. as arguments to function calls
//!   and filters, or just to extend or include a template).
//! - `42`: Integers are whole numbers without a decimal part.  They can be prefixed with
//!   `0b` to indicate binary, `0o` to indicate octal and `0x` to indicate hexadecimal.
//!   Underscores are tolerated (and ignored) everywhere a digit is except in the last place.
//! - `42.0`: Floating point numbers can be written using a `.` as a decimal mark.
//!   Underscores are tolerated (and ignored) everywhere a digit is except in the last place.
//! - `['list', 'of', 'objects']`: Everything between two brackets is a list. Lists are useful
//!   for storing sequential data to be iterated over.
//!   for compatibility with Jinja2 `('list', 'of', 'objects')` is also allowed.
//! - `{'map': 'of', 'key': 'and', 'value': 'pairs'}`: A map is a structure that combines keys
//!   and values. Keys must be unique and always have exactly one value. Maps are rarely
//!   created in templates.
//! - `true` / `false` / `none`: boolean values and the special `none` value which maps to the
//!   unit type in Rust.
//!
//! ## Math
//!
//! MiniJinja allows you to calculate with values.  The following operators are supported:
//!
//! - ``+``: Adds two numbers up. ``{{ 1 + 1 }}`` is ``2``.
//! - ``-``: Subtract the second number from the first one.  ``{{ 3 - 2 }}`` is ``1``.
//! - ``/``: Divide two numbers. ``{{ 1 / 2 }}`` is ``0.5``.  See note on divisions below.
//! - ``//``: Integer divide two numbers. ``{{ 5 // 3 }}`` is ``1``.  See note on divisions below.
//! - ``%``: Calculate the remainder of an integer division.  ``{{ 11 % 7 }}`` is ``4``.
//! - ``*``: Multiply the left operand with the right one.  ``{{ 2 * 2 }}`` would return ``4``.
//! - ``**``: Raise the left operand to the power of the right operand.  ``{{ 2**3 }}``
//!   would return ``8``.
//!
//! Note on divisions: divisions in Jinja2 are flooring, divisions in MiniJinja
//! are at present using euclidean division.  They are almost the same but not quite.
//!
//! ## Comparisons
//!  
//! - ``==``: Compares two objects for equality.
//! - ``!=``: Compares two objects for inequality.
//! - ``>``: ``true`` if the left hand side is greater than the right hand side.
//! - ``>=``: ``true`` if the left hand side is greater or equal to the right hand side.
//! - ``<``:``true`` if the left hand side is less than the right hand side.
//! - ``<=``: ``true`` if the left hand side is less or equal to the right hand side.
//!
//! ## Logic
//!
//! For ``if`` statements it can be useful to combine multiple expressions:
//!
//! - ``and``: Return true if the left and the right operand are true.
//! - ``or``: Return true if the left or the right operand are true.
//! - ``not``: negate a statement (see below).
//! - ``(expr)``: Parentheses group an expression.
//!
//! ## Other Operators
//!
//! The following operators are very useful but don't fit into any of the other
//! two categories:
//!
//! - ``is``/``is not``: Performs a [test](crate::tests).
//! - ``in``/``not in``: Performs a containment check.
//! - ``|`` (pipe, vertical bar): Applies a [filter](crate::filters).
//! - ``~`` (tilde): Converts all operands into strings and concatenates them.
//!   ``{{ "Hello " ~ name ~ "!" }}`` would return (assuming `name` is set
//!   to ``'John'``) ``Hello John!``.
//! - ``()``: Call a callable: ``{{ super() }}``.  Inside of the parentheses you
//!   can use positional arguments.  Additionally keyword arguments are supported
//!   which are treated like a dict syntax.  Eg: `foo(a=1, b=2)` is the same as
//!   `foo({"a": 1, "b": 2})`.
//! - ``.`` / ``[]``: Get an attribute of an object.  If an object does not have a specific
//!   attribute or item then `undefined` is returned.  Accessing a property of an already
//!   undefined value will result in an error.
//! - ``[start:stop]`` / ``[start:stop:step]``: slices a list or string.  All three expressions
//!   are optional (`start`, `stop`, `step`).  For instance ``"Hello World"[:5]`` will return
//!   just `"Hello"`.  Likewise ``"Hello"[1:-1]`` will return `"ell"`.  The step component can
//!   be used to change the step size.  `"12345"[::2]` will return `"135"`.
//!
//! ### If Expressions
//!
//! It is also possible to use inline _if_ expressions. These are useful in some situations.
//! For example, you can use this to extend from one template if a variable is defined,
//! otherwise from the default layout template:
//!
//! ```jinja
//! {% extends layout_template if layout_template is defined else 'default.html' %}
//! ```
//!
//! The `else` part is optional. If not provided, the else block implicitly evaluates
//! into an undefined value:
//!
//! ```jinja
//! {{ title|upper if title }}
//! ```
//!
//! # Tags
//!
//! Tags control logic in templates.  The following tags exist:
//!
//! ## `{% for %}`
//!
//! The for tag loops over each item in a sequence.  For example, to display a list
//! of users provided in a variable called `users`:
//!
//! ```jinja
//! <h1>Members</h1>
//! <ul>
//! {% for user in users %}
//!   <li>{{ user.username }}</li>
//! {% endfor %}
//! </ul>
//! ```
//!
//! It's also possible to unpack tuples while iterating:
//!
//! ```jinja
//! <h1>Members</h1>
//! <ul>
//! {% for (key, value) in list_of_pairs %}
//!   <li>{{ key }}: {{ value }}</li>
//! {% endfor %}
//! </ul>
//! ```
//!
//! Inside of the for block you can access some special variables:
//!
//! - `loop.index`: The current iteration of the loop. (1 indexed)
//! - `loop.index0`: The current iteration of the loop. (0 indexed)
//! - `loop.revindex`: The number of iterations from the end of the loop (1 indexed)
//! - `loop.revindex0`: The number of iterations from the end of the loop (0 indexed)
//! - `loop.first`: True if this is the first iteration.
//! - `loop.last`: True if this is the last iteration.
//! - `loop.length`: The number of items in the sequence.
//! - `loop.cycle`: A helper function to cycle between a list of sequences. See the explanation below.
//! - `loop.depth`: Indicates how deep in a recursive loop the rendering currently is. Starts at level 1
//! - `loop.depth0`: Indicates how deep in a recursive loop the rendering currently is. Starts at level 0
//! - `loop.previtem`: The item from the previous iteration of the loop. `Undefined` during the first iteration.
//! - `loop.nextitem`: The item from the previous iteration of the loop. `Undefined` during the last iteration.
//! - `loop.changed(...args)`: Returns true if the passed values have changed since the last time it was called with the same arguments.
//! - `loop.cycle(...args)`: Returns a value from the passed sequence in a cycle.
//!
//! A special note on iterators: in the current version of MiniJinja, some sequences are actually
//! lazy iterators.  They behave a bit like sequences not not entirely.  They can be iterated over,
//! will happily serialize once into a a list etc.  However when iterating over an actual iterator,
//! `last`, `revindex` and `revindex0` will always be undefined.
//!
//! Within a for-loop, it’s possible to cycle among a list of strings/variables each time through
//! the loop by using the special `loop.cycle` helper:
//!
//! ```jinja
//! {% for row in rows %}
//!   <li class="{{ loop.cycle('odd', 'even') }}">{{ row }}</li>
//! {% endfor %}
//! ```
//!
//! A `loop.changed()` helper is also available which can be used to detect when
//! a value changes between the last iteration and the current one.  The method
//! takes one or more arguments that are all compared.
//!
//! ```jinja
//! {% for entry in entries %}
//!   {% if loop.changed(entry.category) %}
//!     <h2>{{ entry.category }}</h2>
//!   {% endif %}
//!   <p>{{ entry.message }}</p>
//! {% endfor %}
//! ```
//!
//! Unlike in Rust or Python, it’s not possible to break or continue in a loop. You can,
//! however, filter the sequence during iteration, which allows you to skip items.  The
//! following example skips all the users which are hidden:
//!
//! ```jinja
//! {% for user in users if not user.hidden %}
//!   <li>{{ user.username }}</li>
//! {% endfor %}
//! ```
//!
//! If no iteration took place because the sequence was empty or the filtering
//! removed all the items from the sequence, you can render a default block by
//! using else:
//!
//! ```jinja
//! <ul>
//! {% for user in users %}
//!   <li>{{ user.username }}</li>
//! {% else %}
//!   <li><em>no users found</em></li>
//! {% endfor %}
//! </ul>
//! ```
//!
//! It is also possible to use loops recursively. This is useful if you are
//! dealing with recursive data such as sitemaps. To use loops recursively, you
//! basically have to add the ``recursive`` modifier to the loop definition and
//! call the loop variable with the new iterable where you want to recurse.
//!
//! ```jinja
//! <ul class="menu">
//! {% for item in menu recursive %}
//!   <li><a href="{{ item.href }}">{{ item.title }}</a>
//!   {% if item.children %}
//!     <ul class="submenu">{{ loop(item.children) }}</ul>
//!   {% endif %}</li>
//! {% endfor %}
//! </ul>
//! ```
//!
//! **Special note:** the `previtem` and `nextitem` attributes are available by default
//! but can be disabled by removing the `adjacent_loop_items` crate feature.  Removing
//! these attributes can provide meaningful speedups for templates with a lot of loops.
//!
//! ## `{% if %}`
//!
//! The `if` statement is comparable with the Python if statement. In the simplest form,
//! you can use it to test if a variable is defined, not empty and not false:
//!
//! ```jinja
//! {% if users %}
//!   <ul>
//!   {% for user in users %}
//!     <li>{{ user.username }}</li>
//!   {% endfor %}
//!   </ul>
//! {% endif %}
//! ```
//!
//! For multiple branches, `elif` and `else` can be used like in Python.  You can use more
//! complex expressions there too:
//!
//! ```jinja
//! {% if kenny.sick %}
//!   Kenny is sick.
//! {% elif kenny.dead %}
//!   You killed Kenny!  You bastard!!!
//! {% else %}
//!   Kenny looks okay --- so far
//! {% endif %}
//! ```
//!
//! ## `{% extends %}`
//!
//! **Feature:** `multi_template` (included by default)
//!
//! The `extends` tag can be used to extend one template from another.  You can have multiple
//! `extends` tags in a file, but only one of them may be executed at a time.  For more
//! information see [block](#-block-).
//!
//! ## `{% block %}`
//!
//! Blocks are used for inheritance and act as both placeholders and replacements at the
//! same time:
//!
//! The most powerful part of MiniJinja is template inheritance. Template inheritance allows
//! you to build a base "skeleton" template that contains all the common elements of your
//! site and defines **blocks** that child templates can override.
//!
//! **Base Template:**
//!
//! This template, which we'll call ``base.html``, defines a simple HTML skeleton
//! document that you might use for a simple two-column page. It's the job of
//! "child" templates to fill the empty blocks with content:
//!
//! ```jinja
//! <!doctype html>
//! {% block head %}
//! <title>{% block title %}{% endblock %}</title>
//! {% endblock %}
//! {% block body %}{% endblock %}
//! ```
//!
//! **Child Template:**
//!
//! ```jinja
//! {% extends "base.html" %}
//! {% block title %}Index{% endblock %}
//! {% block head %}
//!   {{ super() }}
//!   <style type="text/css">
//!     .important { color: #336699; }
//!   </style>
//! {% endblock %}
//! {% block body %}
//!   <h1>Index</h1>
//!   <p class="important">
//!     Welcome to my awesome homepage.
//!   </p>
//! {% endblock %}
//! ```
//!
//! The ``{% extends %}`` tag is the key here. It tells the template engine that
//! this template "extends" another template.  When the template system evaluates
//! this template, it first locates the parent.  The extends tag should be the
//! first tag in the template.
//!
//! As you can see it's also possible to render the contents of the parent block by calling
//! ``super()``. You can’t define multiple ``{% block %}`` tags with the same name in
//! the same template. This limitation exists because a block tag works in “both”
//! directions. That is, a block tag doesn’t just provide a placeholder to fill -
//! it also defines the content that fills the placeholder in the parent. If
//! there were two similarly-named ``{% block %}`` tags in a template, that
//! template’s parent wouldn’t know which one of the blocks’ content to use.
//!
//! If you want to print a block multiple times, you can, however, use the
//! special self variable and call the block with that name:
//!
//! ```jinja
//! <title>{% block title %}{% endblock %}</title>
//! <h1>{{ self.title() }}</h1>
//! {% block body %}{% endblock %}
//! ```
//!
//! MiniJinja allows you to put the name of the block after the end tag for better
//! readability:
//!
//! ```jinja
//! {% block sidebar %}
//!   {% block inner_sidebar %}
//!     ...
//!   {% endblock inner_sidebar %}
//! {% endblock sidebar %}
//! ```
//!
//! However, the name after the `endblock` word must match the block name.
//!
//! ## `{% include %}`
//!
//! **Feature:** `multi_template` (included by default)
//!  
//! The `include` tag is useful to include a template and return the rendered contents of that file
//! into the current namespace:
//!  
//! ```jinja
//! {% include 'header.html' %}
//!   Body
//! {% include 'footer.html' %}
//! ```
//!
//! Optionally `ignore missing` can be added in which case non existing templates
//! are silently ignored.
//!
//! ```jinja
//! {% include 'customization.html' ignore missing %}
//! ```
//!
//! You can also provide a list of templates that are checked for existence
//! before inclusion. The first template that exists will be included. If `ignore
//! missing` is set, it will fall back to rendering nothing if none of the
//! templates exist, otherwise it will fail with an error.
//!
//! ```jinja
//! {% include ['page_detailed.html', 'page.html'] %}
//! {% include ['special_sidebar.html', 'sidebar.html'] ignore missing %}
//! ```
//!  
//! Included templates have access to the variables of the active context.
//!
//! ## `{% import %}`
//!
//! **Feature:** `multi_template` (included by default)
//!
//! MiniJinja supports the `{% import %}` and `{% from ... import ... %}`
//! syntax.  With it variables or macros can be included from other templates:
//!
//! ```jinja
//! {% from "my_template.html" import my_macro, my_variable %}
//! ```
//!
//! Imports can also be aliased:
//!
//! ```jinja
//! {% from "my_template.html" import my_macro as other_name %}
//! {{ other_name() }}
//! ```
//!
//! Full modules can be imported with `{% import ... as ... %}`:
//!
//! ```jinja
//! {% import "my_template.html" as helpers %}
//! {{ helpers.my_macro() }}
//! ```
//!
//! Note that unlike Jinja2, exported modules do not contain any template code.  Only
//! variables and macros that are defined can be imported.  Also imports unlike in Jinja2
//! are not cached and they get access to the full template context.
//!
//! ## `{% with %}`
//!
//! The with statement makes it possible to create a new inner scope.  Variables set within
//! this scope are not visible outside of the scope:
//!
//! ```jinja
//! {% with foo = 42 %}
//!   {{ foo }}           foo is 42 here
//! {% endwith %}
//! foo is not visible here any longer
//! ```
//!
//! Multiple variables can be set at once and unpacking is supported:
//!
//! ```jinja
//! {% with a = 1, (b, c) = [2, 3] %}
//!   {{ a }}, {{ b }}, {{ c }}  (outputs 1, 2, 3)
//! {% endwith %}
//! ```
//!
//! ## `{% set %}`
//!
//! The `set` statement can be used to assign to variables on the same scope.  This is
//! similar to how `with` works but it won't introduce a new scope.
//!
//! ```jinja
//! {% set navigation = [('index.html', 'Index'), ('about.html', 'About')] %}
//! ```
//!
//! Please keep in mind that it is not possible to set variables inside a block
//! and have them show up outside of it.  This also applies to loops.  The only
//! exception to that rule are if statements which do not introduce a scope.
//!
//! It's also possible to capture blocks of template code into a variable by using
//! the `set` statement as a block.   In that case, instead of using an equals sign
//! and a value, you just write the variable name and then everything until
//! `{% endset %}` is captured.
//!
//! ```jinja
//! {% set navigation %}
//! <li><a href="/">Index</a>
//! <li><a href="/downloads">Downloads</a>
//! {% endset %}
//! ```
//!
//! The `navigation` variable then contains the navigation HTML source.
//!
//! This can also be combined with applying a filter:
//!
//! ```jinja
//! {% set title | upper %}Title of the page{% endset %}
//! ```
//!
//! More complex use cases can be handled using namespace objects which allow
//! propagating of changes across scopes:
//!
//! ```jinja
//! {% set ns = namespace(found=false) %}
//! {% for item in items %}
//!   {% if item.check_something() %}
//!     {% set ns.found = true %}
//!   {% endif %}
//!   * {{ item.title }}
//! {% endfor %}
//! Found item having something: {{ ns.found }}
//! ```
//!
//! Note that the `obj.attr` notation in the set tag is only allowed for namespace
//! objects; attempting to assign an attribute on any other object will cause
//! an error.
//!
//! ## `{% filter %}`
//!
//! Filter sections allow you to apply regular [filters](crate::filters) on a
//! block of template data. Just wrap the code in the special filter block:
//!
//! ```jinja
//! {% filter upper %}
//!   This text becomes uppercase
//! {% endfilter %}
//! ```
//!
//! ## `{% macro %}`
//!
//! **Feature:** `macros` (included by default)
//!
//! MiniJinja has limited support for macros.  They allow you to write reusable
//! template functions.  They are useful to put often used idioms into reusable
//! functions so you don't repeat yourself (“DRY”).
//!
//! Here’s a small example of a macro that renders a form element:
//!
//! ```jinja
//! {% macro input(name, value="", type="text") -%}
//! <input type="{{ type }}" name="{{ name }}" value="{{ value }}">
//! {%- endmacro %}
//! ```
//!
//! The macro can then be called like a function in the namespace:
//!
//! ```jinja
//! <p>{{ input('username') }}</p>
//! <p>{{ input('password', type='password') }}</p>
//! ```
//!
//! The behavior of macros with regards to undefined variables is that they capture
//! them at macro declaration time (eg: they use a closure).
//!
//! Macros can be imported via `{% import %}` or `{% from ... import %}`.
//!
//! Macros also accept a hidden `caller` keyword argument for the use with
//! `{% call %}`.
//!
//! ## `{% call %}`
//!
//! **Feature:** `macros` (included by default)
//!
//! This tag functions similar to a macro that is passed to another macro.  You can
//! think of it as a way to declare an anonymous macro and pass it to another macro
//! with the `caller` keyword argument.  The following example shows a macro that
//! takes advantage of the call functionality and how it can be used:
//!
//! ```jinja
//! {% macro dialog(title) %}
//!   <div class="dialog">
//!     <h3>{{ title }}</h3>
//!     <div class="contents">{{ caller() }}</div>
//!   </div>
//! {% endmacro %}
//!
//! {% call dialog(title="Hello World") %}
//!   This is the dialog body.
//! {% endcall %}
//! ```
//!
//! <details><summary><strong style="cursor: pointer">Macro Alternative:</strong></summary>
//!
//! The above example is more or less equivalent with the following:
//!
//! ```jinja
//! {% macro dialog(title) %}
//!   <div class="dialog">
//!     <h3>{{ title }}</h3>
//!     <div class="contents">{{ caller() }}</div>
//!   </div>
//! {% endmacro %}
//!
//! {% macro caller() %}
//!   This is the dialog body.
//! {% endmacro %}
//! {{ dialog(title="Hello World", caller=caller) }}
//! ```
//!
//! </details>
//!
//! It’s also possible to pass arguments back to the call block.  This makes it
//! useful to build macros that behave like if statements or loops.  Arguments
//! are placed surrounded in parentheses right after the `call` keyword and
//! is followed by the macro to be called.
//!
//! ```jinja
//! {% macro render_user_list(users) %}
//! <ul>
//! {% for user in users %}
//!   <li><p>{{ user.username }}</p>{{ caller(user) }}</li>
//! {% endfor %}
//! </ul>
//! {% endmacro %}
//!
//! {% call(user) render_user_list(list_of_user) %}
//! <dl>
//!   <dt>Name</dt>
//!   <dd>{{ user.name }}</dd>
//!   <dt>E-Mail</dt>
//!   <dd>{{ user.email }}</dd>
//! </dl>
//! {% endcall %}
//! ```
//!
//! ## `{% do %}`
//!
//! The do tag has the same functionality as regular template tags (`{{ ... }}`);
//! except it doesn't output anything when called.
//!
//! This is useful if you have a function or macro that has a side-effect, and
//! you don’t want to display output in the template. The following example
//! shows a macro that uses the do functionality, and how it can be used:
//!
//! ```jinja
//! {% macro dialog(title) %}
//!   Dialog is {{ title }}
//! {% endmacro %}
//!
//! {% do dialog(title="Hello World") %} <- does not output anything
//! ```
//!
//! The above example will not output anything when using the `do` tag.
//!
//! This tag exists for consistency with Jinja2 and can be useful if you have
//! custom functionality in templates that uses side-effects.  For instance if
//! you expose a function to templates that can be used to log warnings:
//!
//! ```jinja
//! {% for user in users %}
//!   {% if user.deleted %}
//!     {% log warn("Found unexpected deleted user in template") %}
//!   {% endif %}
//!   ...
//! {% endfor %}
//! ```
//!
//! ## `{% autoescape %}`
//!
//! If you want you can activate and deactivate the autoescaping from within
//! the templates.
//!
//! Example:
//!
//! ```jinja
//! {% autoescape true %}
//!   Autoescaping is active within this block
//! {% endautoescape %}
//!
//! {% autoescape false %}
//!   Autoescaping is inactive within this block
//! {% endautoescape %}
//! ```
//!
//! After an `endautoescape` the behavior is reverted to what it was before.
//!
//! The exact auto escaping behavior is determined by the value of
//! [`AutoEscape`](crate::AutoEscape) set to the template.
//!
//! ## `{% raw %}`
//!
//! A raw block is a special construct that lets you ignore the embedded template
//! syntax.  This is particularly useful if a segment of template code would
//! otherwise require constant escaping with things like `{{ "{{" }}`:
//!
//! Example:
//!
//! ```jinja
//! {% raw %}
//! <ul>
//! {% for item in seq %}
//!     <li>{{ item }}</li>
//! {% endfor %}
//! </ul>
//! {% endraw %}
//! ```
//!
//! ## `{% break %}` / `{% continue %}`
//!
//! If MiniJinja was compiled with the `loop_controls` feature, it’s possible to
//! use `break`` and `continue`` in loops.  When break is reached, the loop is
//! terminated; if continue is reached, the processing is stopped and continues
//! with the next iteration.
//!
//! Here’s a loop that skips every second item:
//!
//! ```jinja
//! {% for user in users %}
//! {%- if loop.index is even %}{% continue %}{% endif %}
//! ...
//! {% endfor %}
//! ```
//!
//! Likewise, a loop that stops processing after the 10th iteration:
//!
//! ```jinja
//! {% for user in users %}
//! {%- if loop.index >= 10 %}{% break %}{% endif %}
//! {%- endfor %}
//! ```
//!
#![cfg_attr(
    feature = "custom_syntax",
    doc = r###"
# Custom Delimiters

When MiniJinja has been compiled with the `custom_syntax` feature (see
[`SyntaxConfig`]), it's possible to reconfigure the delimiters of the
templates.  This is generally not recommended but it's useful for situations
where Jinja templates are used to generate files with a syntax that would be
conflicting for Jinja.  With custom delimiters it can for instance be more
convenient to generate LaTeX files:

```
# use minijinja::{Environment, syntax::SyntaxConfig};
let mut environment = Environment::new();
environment.set_syntax(SyntaxConfig::builder()
    .block_delimiters("\\BLOCK{", "}")
    .variable_delimiters("\\VAR{", "}")
    .comment_delimiters("\\#{", "}")
    .build()
    .unwrap()
);
```

And then a template might look like this instead:

```latex
\begin{itemize}
\BLOCK{for item in sequence}
  \item \VAR{item}
\BLOCK{endfor}
\end{itemize}
```

# Line Statements and Comments

MiniJinja supports line statements and comments like Jinja2 does.  Line statements
and comments are an alternative syntax feature where blocks can be placed on their
own line if they are opened with a configured prefix.  They must appear on their own
line but can be prefixed with whitespace.  Line comments are similar but they can
also be trailing.  These syntax features need to be configured explicitly.
There are however small differences with regards to whitespace compared to
Jinja2.

To use line statements and comments the `custom_syntax` feature needs to be
enabled and they need to be configured (see [`SyntaxConfig`]).

```
# use minijinja::{Environment, syntax::SyntaxConfig};
let mut environment = Environment::new();
environment.set_syntax(SyntaxConfig::builder()
    .line_statement_prefix("#")
    .line_comment_prefix("##")
    .build()
    .unwrap()
);
```

With the above config you can render a template like this:

```jinja
## This block is
## completely removed
<ul>
  # for item in [1, 2]
    ## this is a comment that is also removed including leading whitespace
    <li>{{ item }}
  # endfor
</ul>
```

Renders into the following HTML:

```html
<ul>
    <li>1
    <li>2
</ul>
```

Note that this is slightly different than in Jinja2.  Specifically the following
rules apply with regards to whitespace:

* line statements remove all whitespace before and after including the newline
* line comments remove the trailing newline and leading whitespace.

This is different than in Jinja2 where empty lines can remain from line comments.
Additionally whitespace control is not available for line statements.
"###
)]
//! # Whitespace Control
//!
//! MiniJinja shares the same behavior with Jinja2 when it comes to
//! whitespace handling.  By default a single trailing newline is stripped if present
//! and all other whitespace is returned unchanged.
//!
//! If an application configures Jinja to [`trim_blocks`](crate::Environment::set_trim_blocks),
//! the first newline after a template tag is removed automatically (like in PHP).  The
//! [`lstrip_blocks`](crate::Environment::set_lstrip_blocks) option can also be set to strip
//! tabs and spaces from the beginning of a line to the start of a block. (Nothing will be
//! stripped if there are other characters before the start of the block.)
//!
//! With both `trim_blocks` and `lstrip_blocks` enabled, you can put block tags on their
//! own lines, and the entire block line will be removed when rendered, preserving the
//! whitespace of the contents.
//!
//! For example, without the `trim_blocks` and `lstrip_blocks` options, this template:
//!
//! ```jinja
//! <div>
//!   {% if True %}
//!     yay
//!   {% endif %}
//! </div>
//! ```
//!
//! gets rendered with blank lines inside the div:
//!
//! ```jinja
//! <div>
//!
//!     yay
//!
//! </div>
//! ```
//!
//! But with both `trim_blocks` and `lstrip_blocks` enabled, the template block lines
//! are removed and other whitespace is preserved:
//!
//! ```jinja
//! <div>
//!     yay
//! </div>
//! ````
//!
//! You can manually disable the `lstrip_blocks` behavior by putting a plus sign (`+`)
//! at the start of a block:
//!
//! ```jinja
//! <div>
//!   {%+ if something %}yay{% endif %}
//! </div>
//! ```
//!
//! Similarly, you can manually disable the `trim_blocks` behavior by putting a plus
//! sign (`+`) at the end of a block:
//!
//! ```jinja
//! <div>
//! {% if something +%}
//!     yay
//! {% endif %}
//! </div>
//! ```
//!
//! You can also strip whitespace in templates by hand. If you add a minus sign (`-`) to the
//! start or end of a block (e.g. a for tag), a comment, or a variable expression, the
//! whitespaces before or after that block will be removed:
//!
//! ```jinja
//! {% for item in range(1, 10) -%}
//! {{ item }}
//! {%- endfor %}
//! ```
//!
//! This will yield all elements without whitespace between them, in this case
//! the output would be `123456789`.
//!
//! By default, MiniJinja also removes trailing newlines.  To keep single trailing newlines,
//! configure MiniJinja to [`keep_trailing_newline`](crate::Environment::set_keep_trailing_newline).

#[cfg(feature = "custom_syntax")]
mod imp {
    use crate::compiler::lexer::StartMarker;
    use crate::error::{Error, ErrorKind};
    use aho_corasick::{AhoCorasick, PatternID};
    use std::borrow::Cow;
    use std::sync::Arc;

    #[derive(Debug, PartialEq, Clone)]
    pub(crate) struct Delims {
        block_start: Cow<'static, str>,
        block_end: Cow<'static, str>,
        variable_start: Cow<'static, str>,
        variable_end: Cow<'static, str>,
        comment_start: Cow<'static, str>,
        comment_end: Cow<'static, str>,
        line_statement_prefix: Cow<'static, str>,
        line_comment_prefix: Cow<'static, str>,
    }

    const DEFAULT_DELIMS: Delims = Delims {
        block_start: Cow::Borrowed("{%"),
        block_end: Cow::Borrowed("%}"),
        variable_start: Cow::Borrowed("{{"),
        variable_end: Cow::Borrowed("}}"),
        comment_start: Cow::Borrowed("{#"),
        comment_end: Cow::Borrowed("#}"),
        line_statement_prefix: Cow::Borrowed(""),
        line_comment_prefix: Cow::Borrowed(""),
    };

    impl Delims {
        fn validated_start_delims(&self) -> Result<Vec<&str>, Error> {
            let mut delims = Vec::with_capacity(5);
            for (delim, required) in [
                (&self.variable_start, true),
                (&self.block_start, true),
                (&self.comment_start, true),
                (&self.line_statement_prefix, false),
                (&self.line_comment_prefix, false),
            ] {
                let delim = delim as &str;
                if delim.is_empty() {
                    if required {
                        return Err(ErrorKind::InvalidDelimiter.into());
                    }
                } else if delims.contains(&delim) {
                    return Err(ErrorKind::InvalidDelimiter.into());
                } else {
                    delims.push(delim);
                }
            }

            Ok(delims)
        }
    }

    /// Builder helper to reconfigure the syntax.
    ///
    /// A new builder is returned by [`SyntaxConfig::builder`].
    #[derive(Debug)]
    #[cfg_attr(docsrs, doc(cfg(feature = "custom_syntax")))]
    pub struct SyntaxConfigBuilder {
        delims: Arc<Delims>,
    }

    impl SyntaxConfigBuilder {
        /// Sets the block start and end delimiters.
        pub fn block_delimiters<S, E>(&mut self, s: S, e: E) -> &mut Self
        where
            S: Into<Cow<'static, str>>,
            E: Into<Cow<'static, str>>,
        {
            let delims = Arc::make_mut(&mut self.delims);
            delims.block_start = s.into();
            delims.block_end = e.into();
            self
        }

        /// Sets the variable start and end delimiters.
        pub fn variable_delimiters<S, E>(&mut self, s: S, e: E) -> &mut Self
        where
            S: Into<Cow<'static, str>>,
            E: Into<Cow<'static, str>>,
        {
            let delims = Arc::make_mut(&mut self.delims);
            delims.variable_start = s.into();
            delims.variable_end = e.into();
            self
        }

        /// Sets the comment start and end delimiters.
        pub fn comment_delimiters<S, E>(&mut self, s: S, e: E) -> &mut Self
        where
            S: Into<Cow<'static, str>>,
            E: Into<Cow<'static, str>>,
        {
            let delims = Arc::make_mut(&mut self.delims);
            delims.comment_start = s.into();
            delims.comment_end = e.into();
            self
        }

        /// Sets the line statement prefix.
        ///
        /// By default this is the empty string which disables the line
        /// statement prefix feature.
        pub fn line_statement_prefix<S>(&mut self, s: S) -> &mut Self
        where
            S: Into<Cow<'static, str>>,
        {
            let delims = Arc::make_mut(&mut self.delims);
            delims.line_statement_prefix = s.into();
            self
        }

        /// Sets the line comment prefix.
        ///
        /// By default this is the empty string which disables the line
        /// comment prefix feature.
        pub fn line_comment_prefix<S>(&mut self, s: S) -> &mut Self
        where
            S: Into<Cow<'static, str>>,
        {
            let delims = Arc::make_mut(&mut self.delims);
            delims.line_comment_prefix = s.into();
            self
        }

        /// Builds the final syntax config.
        pub fn build(&self) -> Result<SyntaxConfig, Error> {
            let delims = self.delims.clone();
            if *delims == DEFAULT_DELIMS {
                return Ok(SyntaxConfig::default());
            }
            let aho_corasick = ok!(AhoCorasick::builder()
                .build(ok!(delims.validated_start_delims()))
                .map_err(|_| ErrorKind::InvalidDelimiter.into()));
            Ok(SyntaxConfig {
                delims,
                aho_corasick: Some(aho_corasick),
            })
        }
    }

    /// The delimiter configuration for the environment and the parser.
    ///
    /// Custom syntax configurations require the `custom_syntax` feature.
    /// Otherwise just the default syntax is available.
    ///
    /// You can  override the syntax configuration for templates by setting different
    /// delimiters.  The end markers can be shared, but the start markers need to be
    /// distinct.  It would thus not be valid to configure `{{` to be the marker for
    /// both variables and blocks.
    ///
    /// ```
    /// # use minijinja::{Environment, syntax::SyntaxConfig};
    /// let mut environment = Environment::new();
    /// environment.set_syntax(
    ///     SyntaxConfig::builder()
    ///         .block_delimiters("\\BLOCK{", "}")
    ///         .variable_delimiters("\\VAR{", "}")
    ///         .comment_delimiters("\\#{", "}")
    ///         .build()
    ///         .unwrap()
    /// );
    #[derive(Clone, Debug)]
    pub struct SyntaxConfig {
        delims: Arc<Delims>,
        pub(crate) aho_corasick: Option<aho_corasick::AhoCorasick>,
    }

    impl Default for SyntaxConfig {
        fn default() -> Self {
            Self {
                delims: Arc::new(DEFAULT_DELIMS),
                aho_corasick: None,
            }
        }
    }

    impl SyntaxConfig {
        /// Creates a syntax builder.
        #[cfg_attr(docsrs, doc(cfg(feature = "custom_syntax")))]
        pub fn builder() -> SyntaxConfigBuilder {
            SyntaxConfigBuilder {
                delims: Arc::new(DEFAULT_DELIMS),
            }
        }

        /// Returns the block delimiters.
        #[inline(always)]
        pub fn block_delimiters(&self) -> (&str, &str) {
            (&self.delims.block_start, &self.delims.block_end)
        }

        /// Returns the variable delimiters.
        #[inline(always)]
        pub fn variable_delimiters(&self) -> (&str, &str) {
            (&self.delims.variable_start, &self.delims.variable_end)
        }

        /// Returns the comment delimiters.
        #[inline(always)]
        pub fn comment_delimiters(&self) -> (&str, &str) {
            (&self.delims.comment_start, &self.delims.comment_end)
        }

        /// Returns the line statement prefix.
        #[inline(always)]
        pub fn line_statement_prefix(&self) -> Option<&str> {
            if self.delims.line_statement_prefix.is_empty() {
                None
            } else {
                Some(&self.delims.line_statement_prefix)
            }
        }

        /// Returns the line comment prefix.
        #[inline(always)]
        pub fn line_comment_prefix(&self) -> Option<&str> {
            if self.delims.line_comment_prefix.is_empty() {
                None
            } else {
                Some(&self.delims.line_comment_prefix)
            }
        }

        /// Reverse resolves the pattern to a start marker.
        pub(crate) fn pattern_to_marker(&self, pattern: PatternID) -> StartMarker {
            match pattern.as_usize() {
                0 => StartMarker::Variable,
                1 => StartMarker::Block,
                2 => StartMarker::Comment,
                3 => {
                    if self.line_statement_prefix().is_some() {
                        StartMarker::LineStatement
                    } else {
                        StartMarker::LineComment
                    }
                }
                4 => StartMarker::LineComment,
                _ => unreachable!(),
            }
        }
    }
}

#[cfg(not(feature = "custom_syntax"))]
mod imp {
    /// The default delimiter configuration for the environment and the parser.
    #[derive(Clone, Default, Debug)]
    pub struct SyntaxConfig;

    impl SyntaxConfig {
        /// Returns the block delimiters.
        #[inline(always)]
        pub fn block_delimiters(&self) -> (&str, &str) {
            ("{%", "%}")
        }

        /// Returns the variable delimiters.
        #[inline(always)]
        pub fn variable_delimiters(&self) -> (&str, &str) {
            ("{{", "}}")
        }

        /// Returns the comment delimiters.
        #[inline(always)]
        pub fn comment_delimiters(&self) -> (&str, &str) {
            ("{#", "#}")
        }

        /// Returns the line statement prefix.
        #[inline(always)]
        pub fn line_statement_prefix(&self) -> Option<&str> {
            None
        }

        /// Returns the line comment prefix.
        #[inline(always)]
        pub fn line_comment_prefix(&self) -> Option<&str> {
            None
        }
    }
}

pub use self::imp::*;