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
use std::collections::HashMap;
use std::fmt;
use std::fs::File;
use std::io::prelude::*;
use std::path::Path;
use std::sync::Arc;

use globwalk::glob_builder;

use crate::builtins::filters::{array, common, number, object, string, Filter};
use crate::builtins::functions::{self, Function};
use crate::builtins::testers::{self, Test};
use crate::context::Context;
use crate::errors::{Error, Result};
use crate::renderer::Renderer;
use crate::template::Template;
use crate::utils::escape_html;

/// Default template name used for `Tera::render_str` and `Tera::one_off`.
const ONE_OFF_TEMPLATE_NAME: &str = "__tera_one_off";

/// The escape function type definition
pub type EscapeFn = fn(&str) -> String;

/// The main point of interaction in this library.
#[derive(Clone)]
pub struct Tera {
    // The glob used in `Tera::new`, None if Tera was instantiated differently
    #[doc(hidden)]
    glob: Option<String>,
    #[doc(hidden)]
    pub templates: HashMap<String, Template>,
    #[doc(hidden)]
    pub filters: HashMap<String, Arc<dyn Filter>>,
    #[doc(hidden)]
    pub testers: HashMap<String, Arc<dyn Test>>,
    #[doc(hidden)]
    pub functions: HashMap<String, Arc<dyn Function>>,
    // Which extensions does Tera automatically autoescape on.
    // Defaults to [".html", ".htm", ".xml"]
    #[doc(hidden)]
    pub autoescape_suffixes: Vec<&'static str>,
    #[doc(hidden)]
    escape_fn: EscapeFn,
}

impl Tera {
    fn create(dir: &str, parse_only: bool) -> Result<Tera> {
        if dir.find('*').is_none() {
            return Err(Error::msg(format!(
                "Tera expects a glob as input, no * were found in `{}`",
                dir
            )));
        }

        let mut tera = Tera {
            glob: Some(dir.to_string()),
            templates: HashMap::new(),
            filters: HashMap::new(),
            functions: HashMap::new(),
            testers: HashMap::new(),
            autoescape_suffixes: vec![".html", ".htm", ".xml"],
            escape_fn: escape_html,
        };

        tera.load_from_glob()?;
        if !parse_only {
            tera.build_inheritance_chains()?;
            tera.check_macro_files()?;
        }
        tera.register_tera_filters();
        tera.register_tera_testers();
        tera.register_tera_functions();
        Ok(tera)
    }

    /// Create a new instance of Tera, containing all the parsed templates found in the `dir` glob
    ///
    ///```no_compile
    ///match Tera::new("templates/**/*") {
    ///    Ok(t) => t,
    ///    Err(e) => {
    ///        println!("Parsing error(s): {}", e);
    ///        ::std::process::exit(1);
    ///    }
    ///}
    ///```
    pub fn new(dir: &str) -> Result<Tera> {
        Self::create(dir, false)
    }

    /// Create a new instance of Tera, containing all the parsed templates found in the `dir` glob
    /// The difference with `Tera::new` is that it won't build the inheritance chains automatically
    /// so you are free to modify the templates if you need to.
    /// You will NOT get a working Tera instance using `Tera::parse`, you will need to call
    /// `tera.build_inheritance_chains()` to make it usable
    ///
    ///```no_compile
    ///let mut tera = match Tera::parse("templates/**/*") {
    ///    Ok(t) => t,
    ///    Err(e) => {
    ///        println!("Parsing error(s): {}", e);
    ///        ::std::process::exit(1);
    ///    }
    ///};
    ///tera.build_inheritance_chains()?;
    ///```
    pub fn parse(dir: &str) -> Result<Tera> {
        Self::create(dir, true)
    }

    /// Loads all the templates found in the glob that was given to Tera::new
    fn load_from_glob(&mut self) -> Result<()> {
        let glob = match &self.glob {
            Some(g) => g,
            None => return Err(Error::msg("Tera can only load from glob if a glob is provided")),
        };

        // We want to preserve templates that have been added through
        // Tera::extend so we only keep those
        self.templates = self
            .templates
            .iter()
            .filter(|&(_, t)| t.from_extend)
            .map(|(n, t)| (n.clone(), t.clone())) // TODO: avoid that clone
            .collect();

        let mut errors = String::new();

        // Need to canonicalize the glob path because globwalk always returns
        // an empty list for paths starting with `./` or `../`.
        // See https://github.com/Keats/tera/issues/574 for the Tera discussion
        // and https://github.com/Gilnaa/globwalk/issues/28 for the upstream issue.
        let (parent_dir, glob_end) = glob.split_at(glob.find('*').unwrap());
        let parent_dir = std::fs::canonicalize(parent_dir)?;
        let dir = parent_dir.join(glob_end).into_os_string().into_string().unwrap();

        // We are parsing all the templates on instantiation
        for entry in glob_builder(&dir)
            .follow_links(true)
            .build()
            .unwrap()
            .filter_map(std::result::Result::ok)
        {
            let mut path = entry.into_path();
            // We only care about actual files
            if path.is_file() {
                if path.starts_with("./") {
                    path = path.strip_prefix("./").unwrap().to_path_buf();
                }

                let filepath = path
                    .strip_prefix(&parent_dir)
                    .unwrap()
                    .to_string_lossy()
                    // unify on forward slash
                    .replace('\\', "/");

                if let Err(e) = self.add_file(Some(&filepath), path) {
                    use std::error::Error;

                    errors += &format!("\n* {}", e);
                    let mut cause = e.source();
                    while let Some(e) = cause {
                        errors += &format!("\n{}", e);
                        cause = e.source();
                    }
                }
            }
        }

        if !errors.is_empty() {
            return Err(Error::msg(errors));
        }

        Ok(())
    }

    // Add a template from a path: reads the file and parses it.
    // This will return an error if the template is invalid and doesn't check the validity of
    // inheritance chains.
    fn add_file<P: AsRef<Path>>(&mut self, name: Option<&str>, path: P) -> Result<()> {
        let path = path.as_ref();
        let tpl_name = name.unwrap_or_else(|| path.to_str().unwrap());

        let mut f = File::open(path)
            .map_err(|e| Error::chain(format!("Couldn't open template '{:?}'", path), e))?;

        let mut input = String::new();
        f.read_to_string(&mut input)
            .map_err(|e| Error::chain(format!("Failed to read template '{:?}'", path), e))?;

        let tpl = Template::new(tpl_name, Some(path.to_str().unwrap().to_string()), &input)
            .map_err(|e| Error::chain(format!("Failed to parse {:?}", path), e))?;

        self.templates.insert(tpl_name.to_string(), tpl);
        Ok(())
    }

    /// We need to know the hierarchy of templates to be able to render multiple extends level
    /// This happens at compile-time to avoid checking it every time we want to render a template
    /// This also checks for soundness issues in the inheritance chains, such as missing template or
    /// circular extends.
    /// It also builds the block inheritance chain and detects when super() is called in a place
    /// where it can't possibly work
    ///
    /// You generally don't need to call that yourself, unless you used `Tera::parse`
    pub fn build_inheritance_chains(&mut self) -> Result<()> {
        // Recursive fn that finds all the parents and put them in an ordered Vec from closest to first parent
        // parent template
        fn build_chain(
            templates: &HashMap<String, Template>,
            start: &Template,
            template: &Template,
            mut parents: Vec<String>,
        ) -> Result<Vec<String>> {
            if !parents.is_empty() && start.name == template.name {
                return Err(Error::circular_extend(&start.name, parents));
            }

            match template.parent {
                Some(ref p) => match templates.get(p) {
                    Some(parent) => {
                        parents.push(parent.name.clone());
                        build_chain(templates, start, parent, parents)
                    }
                    None => Err(Error::missing_parent(&template.name, p)),
                },
                None => Ok(parents),
            }
        }

        // TODO: if we can rewrite the 2 loops below to be only one loop, that'd be great
        let mut tpl_parents = HashMap::new();
        let mut tpl_block_definitions = HashMap::new();
        for (name, template) in &self.templates {
            if template.parent.is_none() && template.blocks.is_empty() {
                continue;
            }

            let parents = build_chain(&self.templates, template, template, vec![])?;

            let mut blocks_definitions = HashMap::new();
            for (block_name, def) in &template.blocks {
                // push our own block first
                let mut definitions = vec![(template.name.clone(), def.clone())];

                // and then see if our parents have it
                for parent in &parents {
                    let t = self.get_template(parent)?;

                    if let Some(b) = t.blocks.get(block_name) {
                        definitions.push((t.name.clone(), b.clone()));
                    }
                }
                blocks_definitions.insert(block_name.clone(), definitions);
            }
            tpl_parents.insert(name.clone(), parents);
            tpl_block_definitions.insert(name.clone(), blocks_definitions);
        }

        for template in self.templates.values_mut() {
            // Simple template: no inheritance or blocks -> nothing to do
            if template.parent.is_none() && template.blocks.is_empty() {
                continue;
            }

            template.parents = match tpl_parents.remove(&template.name) {
                Some(parents) => parents,
                None => vec![],
            };
            template.blocks_definitions = match tpl_block_definitions.remove(&template.name) {
                Some(blocks) => blocks,
                None => HashMap::new(),
            };
        }

        Ok(())
    }

    /// We keep track of macro files loaded in each Template so we can know whether one or them
    /// is missing and error accordingly before the user tries to render a template.
    ///
    /// As with `self::build_inheritance_chains`, you don't usually need to call that yourself.
    pub fn check_macro_files(&self) -> Result<()> {
        for template in self.templates.values() {
            for (tpl_name, _) in &template.imported_macro_files {
                if !self.templates.contains_key(tpl_name) {
                    return Err(Error::msg(format!(
                        "Template `{}` loads macros from `{}` which isn't present in Tera",
                        template.name, tpl_name
                    )));
                }
            }
        }

        Ok(())
    }

    /// Renders a Tera template given a `tera::Context`,
    ///
    /// To render a template with an empty context, simply pass a new `tera::Context` object
    ///
    /// ```no_compile
    /// // Rendering a template with a normal context
    /// let mut context = Context::new();
    /// context.insert("age", 18);
    /// tera.render("hello.html", context);
    /// // Rendering a template with an empty context
    /// let output = tera.render("hello.html", Context::new());
    /// ```
    pub fn render(&self, template_name: &str, context: &Context) -> Result<String> {
        let template = self.get_template(template_name)?;
        let renderer = Renderer::new(template, self, context);
        renderer.render()
    }

    /// Renders a Tera template given a `tera::Context` to a [std::io::Write],
    ///
    /// The only difference from [Self::render] is that this version doesn't convert buffer to a String,
    /// allowing to render directly to anything that implements [std::io::Write].
    ///
    /// Any i/o error will be reported in the result.
    ///
    /// ```no_compile
    /// // Rendering a template to an internal buffer
    /// let mut buffer = Vec::new();
    /// let mut context = Context::new();
    /// context.insert("age", 18);
    /// tera.render_to("hello.html", context, &mut buffer);
    /// ```
    pub fn render_to(
        &self,
        template_name: &str,
        context: &Context,
        write: impl Write,
    ) -> Result<()> {
        let template = self.get_template(template_name)?;
        let renderer = Renderer::new(template, self, context);
        renderer.render_to(write)
    }

    /// Renders a one off template (for example a template coming from a user
    /// input) given a `Context` and an instance of Tera. This allows you to
    /// render templates using custom filters or functions.
    ///
    /// Any errors will mention the `__tera_one_off` template: this is the name
    /// given to the template by Tera.
    ///
    /// ```no_compile
    /// let mut context = Context::new();
    /// context.insert("greeting", &"Hello");
    /// let string = tera.render_str("{{ greeting }} World!", &context)?;
    /// assert_eq!(string, "Hello World!");
    /// ```
    pub fn render_str(&mut self, input: &str, context: &Context) -> Result<String> {
        self.add_raw_template(ONE_OFF_TEMPLATE_NAME, input)?;
        let result = self.render(ONE_OFF_TEMPLATE_NAME, context);
        self.templates.remove(ONE_OFF_TEMPLATE_NAME);
        result
    }

    /// Renders a one off template (for example a template coming from a user input) given a `Context`
    ///
    /// This creates a separate instance of Tera with no possibilities of adding custom filters
    /// or testers, parses the template and render it immediately.
    /// Any errors will mention the `__tera_one_off` template: this is the name given to the template by
    /// Tera
    ///
    /// ```no_compile
    /// let mut context = Context::new();
    /// context.insert("greeting", &"hello");
    /// Tera::one_off("{{ greeting }} world", &context, true);
    /// ```
    pub fn one_off(input: &str, context: &Context, autoescape: bool) -> Result<String> {
        let mut tera = Tera::default();

        if autoescape {
            tera.autoescape_on(vec![ONE_OFF_TEMPLATE_NAME]);
        }

        tera.render_str(input, context)
    }

    #[doc(hidden)]
    #[inline]
    pub fn get_template(&self, template_name: &str) -> Result<&Template> {
        match self.templates.get(template_name) {
            Some(tpl) => Ok(tpl),
            None => Err(Error::template_not_found(template_name)),
        }
    }

    /// Returns an iterator over the names of all registered templates in an
    /// unspecified order.
    ///
    /// # Example
    ///
    /// ```rust
    /// use tera::Tera;
    ///
    /// let mut tera = Tera::default();
    /// tera.add_raw_template("foo", "{{ hello }}");
    /// tera.add_raw_template("another-one.html", "contents go here");
    ///
    /// let names: Vec<_> = tera.get_template_names().collect();
    /// assert_eq!(names.len(), 2);
    /// assert!(names.contains(&"foo"));
    /// assert!(names.contains(&"another-one.html"));
    /// ```
    #[inline]
    pub fn get_template_names(&self) -> impl Iterator<Item = &str> {
        self.templates.keys().map(|s| s.as_str())
    }

    /// Add a single template to the Tera instance
    ///
    /// This will error if the inheritance chain can't be built, such as adding a child
    /// template without the parent one.
    /// If you want to add several templates, use [Tera::add_templates](struct.Tera.html#method.add_raw_templates)
    ///
    /// ```no_compile
    /// tera.add_raw_template("new.html", "Blabla");
    /// ```
    pub fn add_raw_template(&mut self, name: &str, content: &str) -> Result<()> {
        let tpl = Template::new(name, None, content)
            .map_err(|e| Error::chain(format!("Failed to parse '{}'", name), e))?;
        self.templates.insert(name.to_string(), tpl);
        self.build_inheritance_chains()?;
        self.check_macro_files()?;
        Ok(())
    }

    /// Add all the templates given to the Tera instance
    ///
    /// This will error if the inheritance chain can't be built, such as adding a child
    /// template without the parent one.
    ///
    /// ```no_compile
    /// tera.add_raw_templates(vec![
    ///     ("new.html", "blabla"),
    ///     ("new2.html", "hello"),
    /// ]);
    /// ```
    pub fn add_raw_templates<I, N, C>(&mut self, templates: I) -> Result<()>
    where
        I: IntoIterator<Item = (N, C)>,
        N: AsRef<str>,
        C: AsRef<str>,
    {
        for (name, content) in templates {
            let name = name.as_ref();
            let tpl = Template::new(name, None, content.as_ref())
                .map_err(|e| Error::chain(format!("Failed to parse '{}'", name), e))?;
            self.templates.insert(name.to_string(), tpl);
        }
        self.build_inheritance_chains()?;
        self.check_macro_files()?;
        Ok(())
    }

    /// Add a single template from a path to the Tera instance. The default name for the template is
    /// the path given, but this can be renamed with the `name` parameter
    ///
    /// This will error if the inheritance chain can't be built, such as adding a child
    /// template without the parent one.
    /// If you want to add several file, use [Tera::add_template_files](struct.Tera.html#method.add_template_files)
    ///
    /// ```no_compile
    /// // Use path as name
    /// tera.add_template_file(path, None);
    /// // Rename
    /// tera.add_template_file(path, Some("index"));
    /// ```
    pub fn add_template_file<P: AsRef<Path>>(&mut self, path: P, name: Option<&str>) -> Result<()> {
        self.add_file(name, path)?;
        self.build_inheritance_chains()?;
        self.check_macro_files()?;
        Ok(())
    }

    /// Add several templates from paths to the Tera instance. The default name for the template is
    /// the path given, but this can be renamed with the second parameter of the tuple
    ///
    /// This will error if the inheritance chain can't be built, such as adding a child
    /// template without the parent one.
    ///
    /// ```no_compile
    /// tera.add_template_files(vec![
    ///     (path1, None), // this template will have the value of path1 as name
    ///     (path2, Some("hey")), // this template will have `hey` as name
    /// ]);
    /// ```
    pub fn add_template_files<I, P, N>(&mut self, files: I) -> Result<()>
    where
        I: IntoIterator<Item = (P, Option<N>)>,
        P: AsRef<Path>,
        N: AsRef<str>,
    {
        for (path, name) in files {
            self.add_file(name.as_ref().map(AsRef::as_ref), path)?;
        }
        self.build_inheritance_chains()?;
        self.check_macro_files()?;
        Ok(())
    }

    #[doc(hidden)]
    #[inline]
    pub fn get_filter(&self, filter_name: &str) -> Result<&dyn Filter> {
        match self.filters.get(filter_name) {
            Some(fil) => Ok(&**fil),
            None => Err(Error::filter_not_found(filter_name)),
        }
    }

    /// Register a filter with Tera.
    ///
    /// If a filter with that name already exists, it will be overwritten
    ///
    /// ```no_compile
    /// tera.register_filter("upper", string::upper);
    /// ```
    pub fn register_filter<F: Filter + 'static>(&mut self, name: &str, filter: F) {
        self.filters.insert(name.to_string(), Arc::new(filter));
    }

    #[doc(hidden)]
    #[inline]
    pub fn get_tester(&self, tester_name: &str) -> Result<&dyn Test> {
        match self.testers.get(tester_name) {
            Some(t) => Ok(&**t),
            None => Err(Error::test_not_found(tester_name)),
        }
    }

    /// Register a tester with Tera.
    ///
    /// If a tester with that name already exists, it will be overwritten
    ///
    /// ```no_compile
    /// tera.register_tester("odd", testers::odd);
    /// ```
    pub fn register_tester<T: Test + 'static>(&mut self, name: &str, tester: T) {
        self.testers.insert(name.to_string(), Arc::new(tester));
    }

    #[doc(hidden)]
    #[inline]
    pub fn get_function(&self, fn_name: &str) -> Result<&dyn Function> {
        match self.functions.get(fn_name) {
            Some(t) => Ok(&**t),
            None => Err(Error::function_not_found(fn_name)),
        }
    }

    /// Register a function with Tera.
    ///
    /// If a function with that name already exists, it will be overwritten
    ///
    /// ```no_compile
    /// tera.register_function("range", range);
    /// ```
    pub fn register_function<F: Function + 'static>(&mut self, name: &str, function: F) {
        self.functions.insert(name.to_string(), Arc::new(function));
    }

    fn register_tera_filters(&mut self) {
        self.register_filter("upper", string::upper);
        self.register_filter("lower", string::lower);
        self.register_filter("trim", string::trim);
        self.register_filter("trim_start", string::trim_start);
        self.register_filter("trim_end", string::trim_end);
        self.register_filter("trim_start_matches", string::trim_start_matches);
        self.register_filter("trim_end_matches", string::trim_end_matches);
        self.register_filter("truncate", string::truncate);
        self.register_filter("wordcount", string::wordcount);
        self.register_filter("replace", string::replace);
        self.register_filter("capitalize", string::capitalize);
        self.register_filter("title", string::title);
        self.register_filter("linebreaksbr", string::linebreaksbr);
        self.register_filter("indent", string::indent);
        self.register_filter("striptags", string::striptags);
        self.register_filter("spaceless", string::spaceless);
        #[cfg(feature = "urlencode")]
        self.register_filter("urlencode", string::urlencode);
        #[cfg(feature = "urlencode")]
        self.register_filter("urlencode_strict", string::urlencode_strict);
        self.register_filter("escape", string::escape_html);
        self.register_filter("escape_xml", string::escape_xml);
        #[cfg(feature = "builtins")]
        self.register_filter("slugify", string::slugify);
        self.register_filter("addslashes", string::addslashes);
        self.register_filter("split", string::split);
        self.register_filter("int", string::int);
        self.register_filter("float", string::float);

        self.register_filter("first", array::first);
        self.register_filter("last", array::last);
        self.register_filter("nth", array::nth);
        self.register_filter("join", array::join);
        self.register_filter("sort", array::sort);
        self.register_filter("unique", array::unique);
        self.register_filter("slice", array::slice);
        self.register_filter("group_by", array::group_by);
        self.register_filter("filter", array::filter);
        self.register_filter("map", array::map);
        self.register_filter("concat", array::concat);

        self.register_filter("abs", number::abs);
        self.register_filter("pluralize", number::pluralize);
        self.register_filter("round", number::round);

        #[cfg(feature = "builtins")]
        self.register_filter("filesizeformat", number::filesizeformat);

        self.register_filter("length", common::length);
        self.register_filter("reverse", common::reverse);
        #[cfg(feature = "builtins")]
        self.register_filter("date", common::date);
        self.register_filter("json_encode", common::json_encode);
        self.register_filter("as_str", common::as_str);

        self.register_filter("get", object::get);
    }

    fn register_tera_testers(&mut self) {
        self.register_tester("defined", testers::defined);
        self.register_tester("undefined", testers::undefined);
        self.register_tester("odd", testers::odd);
        self.register_tester("even", testers::even);
        self.register_tester("string", testers::string);
        self.register_tester("number", testers::number);
        self.register_tester("divisibleby", testers::divisible_by);
        self.register_tester("iterable", testers::iterable);
        self.register_tester("object", testers::object);
        self.register_tester("starting_with", testers::starting_with);
        self.register_tester("ending_with", testers::ending_with);
        self.register_tester("containing", testers::containing);
        self.register_tester("matching", testers::matching);
    }

    fn register_tera_functions(&mut self) {
        self.register_function("range", functions::range);
        #[cfg(feature = "builtins")]
        self.register_function("now", functions::now);
        self.register_function("throw", functions::throw);
        #[cfg(feature = "builtins")]
        self.register_function("get_random", functions::get_random);
        self.register_function("get_env", functions::get_env);
    }

    /// Select which suffix(es) to automatically do HTML escaping on,
    ///`[".html", ".htm", ".xml"]` by default.
    ///
    /// Only call this function if you wish to change the defaults.
    ///
    ///
    ///```no_compile
    /// // escape only files ending with `.php.html`
    /// tera.autoescape_on(vec![".php.html"]);
    /// // disable autoescaping completely
    /// tera.autoescape_on(vec![]);
    ///```
    pub fn autoescape_on(&mut self, suffixes: Vec<&'static str>) {
        self.autoescape_suffixes = suffixes;
    }

    #[doc(hidden)]
    #[inline]
    pub fn get_escape_fn(&self) -> &EscapeFn {
        &self.escape_fn
    }

    /// Set user-defined function which applied to a rendered content.
    ///
    ///```no_compile
    /// fn escape_c_string(input: &str) -> String { ... }
    ///
    /// // make valid C string literal
    /// tera.set_escape_fn(escape_c_string);
    /// tera.add_raw_template("foo", "\"{{ content }}\"").unwrap();
    /// tera.autoescape_on(vec!["foo"]);
    /// let mut context = Context::new();
    /// context.insert("content", &"Hello\n\'world\"!");
    /// let result = tera.render("foo", &context).unwrap();
    /// assert_eq!(result, r#""Hello\n\'world\"!""#);
    ///```
    pub fn set_escape_fn(&mut self, function: EscapeFn) {
        self.escape_fn = function;
    }

    /// Reset escape function to default `tera::escape_html`.
    pub fn reset_escape_fn(&mut self) {
        self.escape_fn = escape_html;
    }

    /// Re-parse all templates found in the glob given to Tera
    /// Use this when you are watching a directory and want to reload everything,
    /// for example when a file is added.
    ///
    /// If you are adding templates without using a glob, we can't know when a template
    /// is deleted, which would result in an error if we are trying to reload that file
    pub fn full_reload(&mut self) -> Result<()> {
        if self.glob.is_some() {
            self.load_from_glob()?;
        } else {
            return Err(Error::msg("Reloading is only available if you are using a glob"));
        }

        self.build_inheritance_chains()?;
        self.check_macro_files()
    }

    /// Use that method when you want to add a given Tera instance templates/filters/testers/functions
    /// to your own. If a template/filter/tester/function with the same name already exists in your instance,
    /// it will not be overwritten.
    ///
    ///```no_compile
    /// // add all the templates from FRAMEWORK_TERA
    /// // except the ones that have an identical name to the ones in `my_tera`
    /// my_tera.extend(&FRAMEWORK_TERA);
    ///```
    pub fn extend(&mut self, other: &Tera) -> Result<()> {
        for (name, template) in &other.templates {
            if !self.templates.contains_key(name) {
                let mut tpl = template.clone();
                tpl.from_extend = true;
                self.templates.insert(name.to_string(), tpl);
            }
        }

        for (name, filter) in &other.filters {
            if !self.filters.contains_key(name) {
                self.filters.insert(name.to_string(), filter.clone());
            }
        }

        for (name, tester) in &other.testers {
            if !self.testers.contains_key(name) {
                self.testers.insert(name.to_string(), tester.clone());
            }
        }

        for (name, function) in &other.functions {
            if !self.functions.contains_key(name) {
                self.functions.insert(name.to_string(), function.clone());
            }
        }

        self.build_inheritance_chains()?;
        self.check_macro_files()
    }
}

impl Default for Tera {
    fn default() -> Tera {
        let mut tera = Tera {
            glob: None,
            templates: HashMap::new(),
            filters: HashMap::new(),
            testers: HashMap::new(),
            functions: HashMap::new(),
            autoescape_suffixes: vec![".html", ".htm", ".xml"],
            escape_fn: escape_html,
        };

        tera.register_tera_filters();
        tera.register_tera_testers();
        tera.register_tera_functions();
        tera
    }
}

// Needs a manual implementation since borrows in Fn's don't implement Debug.
impl fmt::Debug for Tera {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "Tera {{")?;
        writeln!(f, "\n\ttemplates: [")?;

        for template in self.templates.keys() {
            writeln!(f, "\t\t{},", template)?;
        }
        write!(f, "\t]")?;
        writeln!(f, "\n\tfilters: [")?;

        for filter in self.filters.keys() {
            writeln!(f, "\t\t{},", filter)?;
        }
        write!(f, "\t]")?;
        writeln!(f, "\n\ttesters: [")?;

        for tester in self.testers.keys() {
            writeln!(f, "\t\t{},", tester)?;
        }
        writeln!(f, "\t]")?;

        writeln!(f, "}}")
    }
}

#[cfg(test)]
mod tests {
    use tempfile::tempdir;

    use std::collections::HashMap;
    use std::fs::File;

    use super::Tera;
    use crate::context::Context;
    use serde_json::{json, Value as JsonValue};

    #[test]
    fn test_get_inheritance_chain() {
        let mut tera = Tera::default();
        tera.add_raw_templates(vec![
            ("a", "{% extends \"b\" %}"),
            ("b", "{% extends \"c\" %}"),
            ("c", "{% extends \"d\" %}"),
            ("d", ""),
        ])
        .unwrap();

        assert_eq!(
            tera.get_template("a").unwrap().parents,
            vec!["b".to_string(), "c".to_string(), "d".to_string()]
        );
        assert_eq!(tera.get_template("b").unwrap().parents, vec!["c".to_string(), "d".to_string()]);
        assert_eq!(tera.get_template("c").unwrap().parents, vec!["d".to_string()]);
        assert_eq!(tera.get_template("d").unwrap().parents.len(), 0);
    }

    #[test]
    fn test_missing_parent_template() {
        let mut tera = Tera::default();
        assert_eq!(
            tera.add_raw_template("a", "{% extends \"b\" %}").unwrap_err().to_string(),
            "Template \'a\' is inheriting from \'b\', which doesn\'t exist or isn\'t loaded."
        );
    }

    #[test]
    fn test_circular_extends() {
        let mut tera = Tera::default();
        let err = tera
            .add_raw_templates(vec![("a", "{% extends \"b\" %}"), ("b", "{% extends \"a\" %}")])
            .unwrap_err();

        assert!(err.to_string().contains("Circular extend detected for template"));
    }

    #[test]
    fn test_get_parent_blocks_definition() {
        let mut tera = Tera::default();
        tera.add_raw_templates(vec![
            (
                "grandparent",
                "{% block hey %}hello{% endblock hey %} {% block ending %}sincerely{% endblock ending %}",
            ),
            (
                "parent",
                "{% extends \"grandparent\" %}{% block hey %}hi and grandma says {{ super() }}{% endblock hey %}",
            ),
            (
                "child",
                "{% extends \"parent\" %}{% block hey %}dad says {{ super() }}{% endblock hey %}{% block ending %}{{ super() }} with love{% endblock ending %}",
            ),
        ]).unwrap();

        let hey_definitions =
            tera.get_template("child").unwrap().blocks_definitions.get("hey").unwrap();
        assert_eq!(hey_definitions.len(), 3);

        let ending_definitions =
            tera.get_template("child").unwrap().blocks_definitions.get("ending").unwrap();
        assert_eq!(ending_definitions.len(), 2);
    }

    #[test]
    fn test_get_parent_blocks_definition_nested_block() {
        let mut tera = Tera::default();
        tera.add_raw_templates(vec![
            ("grandparent", "{% block hey %}hello{% endblock hey %}"),
            (
                "parent",
                "{% extends \"grandparent\" %}{% block hey %}hi and grandma says {{ super() }} {% block ending %}sincerely{% endblock ending %}{% endblock hey %}",
            ),
            (
                "child",
                "{% extends \"parent\" %}{% block hey %}dad says {{ super() }}{% endblock hey %}{% block ending %}{{ super() }} with love{% endblock ending %}",
            ),
        ]).unwrap();

        let hey_definitions =
            tera.get_template("child").unwrap().blocks_definitions.get("hey").unwrap();
        assert_eq!(hey_definitions.len(), 3);

        let ending_definitions =
            tera.get_template("parent").unwrap().blocks_definitions.get("ending").unwrap();
        assert_eq!(ending_definitions.len(), 1);
    }

    #[test]
    fn test_can_autoescape_one_off_template() {
        let mut context = Context::new();
        context.insert("greeting", &"<p>");
        let result = Tera::one_off("{{ greeting }} world", &context, true).unwrap();

        assert_eq!(result, "&lt;p&gt; world");
    }

    #[test]
    fn test_can_disable_autoescape_one_off_template() {
        let mut context = Context::new();
        context.insert("greeting", &"<p>");
        let result = Tera::one_off("{{ greeting }} world", &context, false).unwrap();

        assert_eq!(result, "<p> world");
    }

    #[test]
    fn test_set_escape_function() {
        let escape_c_string: super::EscapeFn = |input| {
            let mut output = String::with_capacity(input.len() * 2);
            for c in input.chars() {
                match c {
                    '\'' => output.push_str("\\'"),
                    '\"' => output.push_str("\\\""),
                    '\\' => output.push_str("\\\\"),
                    '\n' => output.push_str("\\n"),
                    '\r' => output.push_str("\\r"),
                    '\t' => output.push_str("\\t"),
                    _ => output.push(c),
                }
            }
            output
        };
        let mut tera = Tera::default();
        tera.add_raw_template("foo", "\"{{ content }}\"").unwrap();
        tera.autoescape_on(vec!["foo"]);
        tera.set_escape_fn(escape_c_string);
        let mut context = Context::new();
        context.insert("content", &"Hello\n\'world\"!");
        let result = tera.render("foo", &context).unwrap();
        assert_eq!(result, r#""Hello\n\'world\"!""#);
    }

    #[test]
    fn test_reset_escape_function() {
        let no_escape: super::EscapeFn = |input| input.to_string();
        let mut tera = Tera::default();
        tera.add_raw_template("foo", "{{ content }}").unwrap();
        tera.autoescape_on(vec!["foo"]);
        tera.set_escape_fn(no_escape);
        tera.reset_escape_fn();
        let mut context = Context::new();
        context.insert("content", &"Hello\n\'world\"!");
        let result = tera.render("foo", &context).unwrap();
        assert_eq!(result, "Hello\n&#x27;world&quot;!");
    }

    #[test]
    fn test_value_one_off_template() {
        let m = json!({
            "greeting": "Good morning"
        });
        let result =
            Tera::one_off("{{ greeting }} world", &Context::from_value(m).unwrap(), true).unwrap();

        assert_eq!(result, "Good morning world");
    }

    #[test]
    fn test_render_str_with_custom_function() {
        let mut tera = Tera::default();
        tera.register_function("echo", |args: &HashMap<_, JsonValue>| {
            Ok(args.get("greeting").map(JsonValue::to_owned).unwrap())
        });

        let result =
            tera.render_str("{{ echo(greeting='Hello') }} world", &Context::default()).unwrap();

        assert_eq!(result, "Hello world");
    }

    #[test]
    fn test_render_map_with_dotted_keys() {
        let mut my_tera = Tera::default();
        my_tera
            .add_raw_templates(vec![
                ("dots", r#"{{ map["a.b.c"] }}"#),
                ("urls", r#"{{ map["https://example.com"] }}"#),
            ])
            .unwrap();

        let mut map = HashMap::new();
        map.insert("a.b.c", "success");
        map.insert("https://example.com", "success");

        let mut tera_context = Context::new();
        tera_context.insert("map", &map);

        my_tera.render("dots", &tera_context).unwrap();
        my_tera.render("urls", &tera_context).unwrap();
    }

    #[test]
    fn test_extend_no_overlap() {
        let mut my_tera = Tera::default();
        my_tera
            .add_raw_templates(vec![
                ("one", "{% block hey %}1{% endblock hey %}"),
                ("two", "{% block hey %}2{% endblock hey %}"),
                ("three", "{% block hey %}3{% endblock hey %}"),
            ])
            .unwrap();

        let mut framework_tera = Tera::default();
        framework_tera.add_raw_templates(vec![("four", "Framework X")]).unwrap();

        my_tera.extend(&framework_tera).unwrap();
        assert_eq!(my_tera.templates.len(), 4);
        let result = my_tera.render("four", &Context::default()).unwrap();
        assert_eq!(result, "Framework X");
    }

    #[test]
    fn test_extend_with_overlap() {
        let mut my_tera = Tera::default();
        my_tera
            .add_raw_templates(vec![
                ("one", "MINE"),
                ("two", "{% block hey %}2{% endblock hey %}"),
                ("three", "{% block hey %}3{% endblock hey %}"),
            ])
            .unwrap();

        let mut framework_tera = Tera::default();
        framework_tera
            .add_raw_templates(vec![("one", "FRAMEWORK"), ("four", "Framework X")])
            .unwrap();

        my_tera.extend(&framework_tera).unwrap();
        assert_eq!(my_tera.templates.len(), 4);
        let result = my_tera.render("one", &Context::default()).unwrap();
        assert_eq!(result, "MINE");
    }

    #[test]
    fn test_extend_new_filter() {
        let mut my_tera = Tera::default();
        let mut framework_tera = Tera::default();
        framework_tera.register_filter("hello", |_: &JsonValue, _: &HashMap<String, JsonValue>| {
            Ok(JsonValue::Number(10.into()))
        });
        my_tera.extend(&framework_tera).unwrap();
        assert!(my_tera.filters.contains_key("hello"));
    }

    #[test]
    fn test_extend_new_tester() {
        let mut my_tera = Tera::default();
        let mut framework_tera = Tera::default();
        framework_tera.register_tester("hello", |_: Option<&JsonValue>, _: &[JsonValue]| Ok(true));
        my_tera.extend(&framework_tera).unwrap();
        assert!(my_tera.testers.contains_key("hello"));
    }

    #[test]
    fn can_load_from_glob() {
        let tera = Tera::new("examples/basic/templates/**/*").unwrap();
        assert!(tera.get_template("base.html").is_ok());
    }

    #[test]
    fn can_load_from_glob_with_patterns() {
        let tera = Tera::new("examples/basic/templates/**/*.{html, xml}").unwrap();
        assert!(tera.get_template("base.html").is_ok());
    }

    #[test]
    fn full_reload_with_glob() {
        let mut tera = Tera::new("examples/basic/templates/**/*").unwrap();
        tera.full_reload().unwrap();

        assert!(tera.get_template("base.html").is_ok());
    }

    #[test]
    fn full_reload_with_glob_after_extending() {
        let mut tera = Tera::new("examples/basic/templates/**/*").unwrap();
        let mut framework_tera = Tera::default();
        framework_tera
            .add_raw_templates(vec![("one", "FRAMEWORK"), ("four", "Framework X")])
            .unwrap();
        tera.extend(&framework_tera).unwrap();
        tera.full_reload().unwrap();

        assert!(tera.get_template("base.html").is_ok());
        assert!(tera.get_template("one").is_ok());
    }

    #[should_panic]
    #[test]
    fn test_can_only_parse_templates() {
        let mut tera = Tera::parse("examples/basic/templates/**/*").unwrap();
        for tpl in tera.templates.values_mut() {
            tpl.name = format!("a-theme/templates/{}", tpl.name);
            if let Some(ref parent) = tpl.parent.clone() {
                tpl.parent = Some(format!("a-theme/templates/{}", parent));
            }
        }
        // Will panic here as we changed the parent and it won't be able
        // to build the inheritance chain in this case
        tera.build_inheritance_chains().unwrap();
    }

    // https://github.com/Keats/tera/issues/380
    #[test]
    fn glob_work_with_absolute_paths() {
        let tmp_dir = tempdir().expect("create temp dir");
        let cwd = tmp_dir.path().canonicalize().unwrap();
        File::create(cwd.join("hey.html")).expect("Failed to create a test file");
        File::create(cwd.join("ho.html")).expect("Failed to create a test file");
        let glob = cwd.join("*.html").into_os_string().into_string().unwrap();
        let tera = Tera::new(&glob).expect("Couldn't build Tera instance");
        assert_eq!(tera.templates.len(), 2);
    }

    #[test]
    fn glob_work_with_absolute_paths_and_double_star() {
        let tmp_dir = tempdir().expect("create temp dir");
        let cwd = tmp_dir.path().canonicalize().unwrap();
        File::create(cwd.join("hey.html")).expect("Failed to create a test file");
        File::create(cwd.join("ho.html")).expect("Failed to create a test file");
        let glob = cwd.join("**").join("*.html").into_os_string().into_string().unwrap();
        let tera = Tera::new(&glob).expect("Couldn't build Tera instance");
        assert_eq!(tera.templates.len(), 2);
    }

    // Test for https://github.com/Keats/tera/issues/574
    #[test]
    fn glob_work_with_paths_starting_with_dots() {
        use std::path::PathBuf;

        let this_dir = std::env::current_dir()
            .expect("Could not retrieve the executable's current directory.");

        let scratch_dir = tempfile::Builder::new()
            .prefix("tera_test_scratchspace")
            .tempdir_in(&this_dir)
            .expect(&format!(
                "Could not create temporary directory for test in current directory ({}).",
                this_dir.display()
            ));
        dbg!(&scratch_dir.path().display());

        File::create(scratch_dir.path().join("hey.html")).expect("Failed to create a test file");
        File::create(scratch_dir.path().join("ho.html")).expect("Failed to create a test file");
        let glob = PathBuf::from("./")
            .join(scratch_dir.path().file_name().unwrap())
            .join("**")
            .join("*.html")
            .into_os_string()
            .into_string()
            .unwrap();
        let tera = Tera::new(&glob).expect("Couldn't build Tera instance.");
        assert_eq!(tera.templates.len(), 2);
    }

    // https://github.com/Keats/tera/issues/396
    #[test]
    fn issues_found_fuzzing_expressions_are_fixed() {
        let samples: Vec<(&str, Option<&str>)> = vec![
            // sample, expected result if it isn't an error
            ("{{0%0}}", None),
            ("{{W>W>vv}}{", None),
            ("{{22220222222022222220}}", None),
            ("{_{{W~1+11}}k{", None),
            ("{{n~n<n.11}}}", None),
            ("{{266314325266577770*4167}}7}}7", None),
            ("{{0~1~``~0~0~177777777777777777777~``~0~0~h}}", None),
        ];

        for (sample, expected_output) in samples {
            let res = Tera::one_off(sample, &Context::new(), true);
            if let Some(output) = expected_output {
                assert!(res.is_ok());
                assert_eq!(res.unwrap(), output);
            } else {
                assert!(res.is_err());
            }
        }
    }

    #[test]
    fn issues_found_fuzzing_conditions_are_fixed() {
        let samples: Vec<(&str, Option<&str>)> = vec![
            // (sample, expected result if it isn't an error)
            ("C~Q", None),
            ("s is V*0", None),
            ("x0x::N()", None),
            // this is an issue in pest itself: https://github.com/pest-parser/pest/issues/402
            //            ("_(p=__(p=[_(p=__(p=[_(p=[_(p=[_1", None),
        ];

        for (sample, expected_output) in samples {
            println!("{}, {:?}", sample, expected_output);
            let res = Tera::one_off(
                &format!("{{% if {} %}}true{{% endif %}}", sample),
                &Context::new(),
                true,
            );
            if let Some(output) = expected_output {
                assert!(res.is_ok());
                assert_eq!(res.unwrap(), output);
            } else {
                assert!(res.is_err());
            }
        }
    }

    // https://github.com/Keats/tera/issues/819
    #[test]
    fn doesnt_panic_on_invalid_glob() {
        let tera = Tera::new("\\dev/null/*");
        println!("{:?}", tera);
        assert!(tera.is_err());
    }
}