1Text::Xslate::Syntax::KUosleorn(C3o)ntributed Perl DocumTeenxtta:t:iXosnlate::Syntax::Kolon(3)
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6 Text::Xslate::Syntax::Kolon - The default template syntax
7
9 use Text::Xslate;
10 my $tx = Text::Xslate->new(
11 syntax => 'Kolon', # optional
12 );
13 print $tx->render_string(
15 'Hello, <: $dialect :> world!',
16 { dialect => 'Kolon' }
17 );
18
20 Kolon is the default syntax, using "<: ... :>" tags and ": ..." line
21 code. In this syntax all the features in Xslate are available.
22
24 Variable access
25 Variable access:
26 <: $var :>
28 Field access:
30 <: $var.0 :>
32 <: $var.field :>
33 <: $var.accessor :>
34 <: $var["field"] :>
36 <: $var[0] :>
37 Variables may be HASH references, ARRAY references, or objects.
39 Because "$var.field" and $var["field"] are the same semantics,
40 $obj["accessor"] syntax may be call object methods.
41 Literals
43 Special:
44 : nil # as undef, indicating "nothing"
46 : true # as the integer 1
47 : false # as the integer 0
48 String:
50 : "foo\n" # the same as perl
52 : 'foo\n' # the same as perl
53 Number:
55 : 42
57 : 3.14
58 : 0xFF # hex
59 : 0777 # octal
60 : 0b1010 # binary
61 Array:
63 : for [1, 2, 3] -> $i { ... }
65 Hash:
67 : foo({ foo => "bar" })
69 Note that "{ ... }" is always parsed as hash literals, so you don't
71 need to use the <+> prefix as Perl sometimes requires:
72 : {}.kv(); # ok
74 : +{}.kv(); # also ok
75 Expressions
77 Conditional operator ("?:"):
78 : $var.value == nil ? "nil" : $var.value
80 Relational operators ("== != < <= > >="):
82 : $var == 10 ? "10" : "not 10"
84 : $var != 10 ? "not 10" : "10"
85 Note that "==" and "!=" are similar to Perl's "eq" and "ne" except that
87 "$var == nil" is true iff $var is uninitialized, while other relational
88 operators are numerical.
89 Arithmetic operators ("+ - * / % min max"):
91 : $var * 10_000
93 : ($var % 10) == 0
94 : 10 min 20 min 30 # 10
95 : 10 max 20 max 30 # 30
96 Bitwise operators ("prefix:<+^> +& +| +^")
98 : 0x1010 +| 0x3200 # bitwise or: 0x3210
100 : 0x1010 +& 0x3200 # bitwise and: 0x1000
101 : 0x1010 +^ 0x3200 # bitwise xor: 0x0210
102 : +^0x1010 # bitwise neg: 0xFFFFEFEF (on 32 bit system)
103 Logical operators ("! && || // not and or")
105 : $var >= 0 && $var <= 10 ? "ok" : "too smaller or too larger"
107 : $var // "foo" # as a default value
108 String operators ("~")
110 : "[" ~ $var ~ "]" # concatenation
112 The operator precedence is very like Perl's:
114 . () []
116 prefix:<!> prefix:<+> prefix:<-> prefix:<+^>
117 * / % x +&
118 + - ~ +| +^
119 prefix:<defined>
120 < <= > >=
121 == !=
122 |
123 &&
124 || // min max
125 ?:
126 not
127 and
128 or
129 Constants (or binding)
131 You can define lexical constants with "constant", which requires a bare
132 word, and "my", which requires a variable name.
133 : constant FOO = 42;
135 : my $foo = 42;
136 These two statements has the same semantics, so you cannot modify $foo.
138 : my $foo = 42; $foo = 3.14; # compile error!
140 Loops
142 There are "for" loops that are like Perl's "foreach".
143 : # iterate over an ARRAY reference
145 : for $data -> $item {
146 [<: $item.field :>]
147 : }
148 : # iterate over a HASH reference
150 : # You must specify how to iterate it (.keys(), .values() or .kv())
151 : for $data.keys() -> $key {
152 <: $key :>=<: $data[$key] :>
153 : }
154 And the "for" statement can take an "else" block:
156 : for $data -> $item {
158 [<: $item.field :>]
159 : }
160 : else {
161 Nothing in data
162 : }
163 The "else" block is executed if $data is an empty array or nil.
165 You can get the iterator index in "for" statements as "$~ITERATOR_VAR":
167 : for $data -> $item {
169 : if ($~item % 2) == 0 {
170 Even (0, 2, 4, ...)
171 : }
172 : else {
173 Odd (1, 3, 5, ...)
174 : }
175 : }
176 "$~ITERATOR_VAR" is a pseudo object, so you can access its elements via
178 the dot-name syntax.
179 : for $data -> $i {
181 : $~i # 0-origin iterator index (0, 1, 2, ...)
182 : $~i.index # the same as $~i
183 : $~i.count # the same as $~i + 1
184 : if ($~i.index % 2) == 0 {
186 even
187 : }
188 : else {
189 odd
190 : }
191 : $~i.cycle("even", "odd") # => "even" -> "odd" -> "even" -> "odd" ...
192 : }
193 Supported iterator elements are "index :Int", "count :Int", "body :
195 ArrayRef", "size : Int", "max_index :Int", "is_first :Bool", "is_last
196 :Bool", "peek_next :Any", "peek_prev :Any", "cycle(...) :Any".
197 "while" loops are also supported in the same semantics as Perl's:
199 : # $obj might be an iteratable object
201 : while $dbh.fetch() -> $item {
202 [<: $item.field :>]
203 : }
204 "while defined expr -> $item" is interpreted as "while defined(my $item
206 = expr)" for convenience.
207 : while defined $dbh.fetch() -> $item {
209 [<: $item # $item can be false-but-defined :>]
210 : }
211 Loop control statements, namely "next" and "last", are also supported
213 in both "for" and "while" loops.
214 : for $data -> $item {
216 : last if $item == 42
217 ...
218 : }
219 Conditional statements
221 There are "if-else" and "given-when" conditional statements.
222 "if-else":
224 : if $var == nil {
226 $var is nil.
227 : }
228 : else if $var != "foo" { # elsif is okay
229 $var is not nil nor "foo".
230 : }
231 : else {
232 $var is "foo".
233 : }
234 : if( $var >= 1 && $var <= 10 ) {
236 $var is 1 .. 10
237 : }
238 Note that "if" doesn't require parens, so the following code is okay:
240 : if ($var + 10) == 20 { } # OK
242 "given-when"(also known as switch statement):
244 : given $var {
246 : when "foo" {
247 it is foo.
248 : }
249 : when ["bar", "baz" ] {
250 it is either bar or baz.
251 : }
252 : default {
253 it is not foo nor bar.
254 }
255 : }
256 You can specify the topic variable.
258 : given $var -> $it {
260 : when "foo" {
261 it is foo.
262 : }
263 : when $it == "bar" or $it == "baz" {
264 it is either bar or baz.
265 : }
266 : }
267 Functions and filters
269 You can register functions via "function" or "module" options for
270 "Text::Xslate->new()".
271 Once you have registered functions, you can call them with the "()"
273 operator. "infix:<|>" is also supported as a syntactic sugar to "()".
274 : f() # without args
276 : f(1, 2, 3) # with args
277 : 42 | f # the same as f(42)
278 Functions are just Perl's subroutines, so you can define dynamic
280 functions (a.k.a. dynamic filters), which is a subroutine that returns
281 another subroutine:
282 # code
284 sub mk_indent {
285 my($prefix) = @_;
286 return sub {
287 my($str) = @_;
288 $str =~ s/^/$prefix/xmsg;
289 return $str;
290 }
291 }
292 my $tx = Text::Xslate->new(
293 function => {
294 indent => \&mk_indent,
295 },
296 );
297 :# template
299 : $value | indent("> ") # Template-Toolkit like
300 : indent("> ")($value) # This is also valid
301 "example/dynamic_functions.tx" has examples of dynamic functions being
303 used with block, function and filter syntax, and with scalar, hash and
304 array objects.
305 There are several builtin functions, which you cannot redefine:
307 : $var | mark_raw # marks it as a raw string
309 : $var | raw # synonym to mark_raw
310 : $var | unmark_raw # removes "raw" marker from it
311 : $var | html # does html-escape to it and marks it as raw
312 : $var | dump # dumps it with Data::Dumper
313 Note that you should not use "mark_raw" in templates because it can
315 make security hole easily just like as type casts in C. If you want to
316 generate HTML components dynamically, e.g. by HTML form builders,
317 application code should be responsible to make strings as marked "raw".
318 Methods
320 When $var is an object instance, you can call its methods with the dot
321 operator.
322 <: $var.method() :>
324 <: $var.method(1, 2, 3) :>
325 <: $var.method( foo => [ 1, 2, 3 ] ) :>
326 There is an autoboxing mechanism that provides primitive types with
328 builtin methods. See Text::Xslate::Manual::Builtin for details.
329 You can define more primitive methods with the "function" option. See
331 Text::Xslate.
332 Template inclusion
334 Template inclusion is a traditional way to extend templates.
335 : include "foo.tx";
337 : include "foo.tx" { var1 => value1, var2 => value2, ... };
338 : include "foo.tx" {$vars}; # use $vars as the params
339 if a var exist in the {$vars} and __ROOT__, the one in {$vars} will
341 win.
342 also, be careful about the order of vars.
344 : include "foo.tx" { var1 => $id, id => $var, var2 => $id }
346 var1 and var2 will be replaced by $id, var2 will be replaced by $var,
348 because the value of id is changed
349 As "cascade" does, "include" allows barewords:
351 : include foo # the same as 'foo.tx'
353 : include foo::bar # the same as 'foo/bar.tx'
354 Xslate templates may be recursively included, but the including depth
356 is limited to 100.
357 Template cascading
359 Template cascading is another way to extend templates other than
360 "include".
361 First, make base templates myapp/base.tx:
363 : block title -> { # with default
365 [My Template!]
366 : }
367 : block body -> { } # without default
369 Then extend from base templates with the "cascade" keyword:
371 : cascade myapp::base
373 : cascade myapp::base { var1 => value1, var2 => value2, ...}
374 : cascade myapp::base with myapp::role1, myapp::role2
375 : cascade with myapp::role1, myapp::role2
376 In derived templates, you may extend templates (e.g. myapp/foo.tx) with
378 block modifiers "before", "around" (or "override") and "after".
379 : # cascade "myapp/base.tx" is also okay
381 : cascade myapp::base
382 : # use default title
383 : around body -> {
384 My template body!
385 : }
386 And, make yet another derived template myapp/bar.tx:
388 : cascade myapp::foo
390 : around title -> {
391 --------------
392 : super
393 --------------
394 : }
395 : before body -> {
396 Before body!
397 : }
398 : after body -> {
399 After body!
400 : }
401 Then render it as usual.
403 my $tx = Text::Xslate->new( file => 'myapp/bar.tx' );
405 $tx->render({});
406 The result is something like this:
408 --------------
410 [My Template!]
411 --------------
412 Before body!
414 My template body!
415 After body!
416 You can also cascade templates just like Moose's roles:
418 : cascade myapp::base with myapp::role1, myapp::role2
420 You can omit the base template.
422 Given a file myapp/hello.tx:
424 : around hello -> {
426 --------------
427 : super
428 --------------
429 : }
430 Then the main template:
432 : cascade with myapp::hello
434 : block hello -> {
436 Hello, world!
437 : }
438 Output:
440 --------------
442 Hello, world!
443 --------------
444 In fact, you can omit the base template, and components can include any
446 macros.
447 Given a file common.tx
449 : macro hello -> $lang {
451 Hello, <: $lang :> world!
452 : }
453 : around title -> {
455 --------------
456 : super
457 --------------
458 : }
459 The main template:
461 : cascade with common
463 : block title -> {
465 Hello, world!
466 : }
467 : hello("Xslate")
468 Output:
470 --------------
472 Hello, world!
473 --------------
474 Hello, Xslate world!
475 There is a limitation that you cannot pass variables to the "cascade"
477 keyword, because template cascading is statically processed.
478 Macro blocks
480 Macros are supported, which are called in the same way as functions and
481 return a "raw" string. Macros return what their bodies render, so they
482 cannot return references or objects, including other macros.
483 : macro add ->($x, $y) {
485 : $x + $y;
486 : }
487 : add(10, 20)
488 : macro signature -> {
490 This is foo version <: $VERSION :>
491 : }
492 : signature()
493 : macro factorial -> $x {
495 : $x == 0 ? 1 : $x * factorial($x-1)
496 : }
497 : factorial(1) # as a function
498 : 1 | factorial # as a filter
499 If you want to html-escape the return values of macros, you can use
501 "unmark_raw" to remove "raw-ness" from the values.
502 : macro em -> $s {
504 <em><: $s :></em>
505 : }
506 : em("foo") # renders "<em>foo</em>"
507 : em("foo") | unmark_raw # renders "<em>foo<em>"
508 Because macros are first-class objects, you can bind them to symbols.
510 <: macro foo -> { "foo" }
512 macro bar -> { "bar" }
513 my $dispatcher = {
514 foo => foo,
515 bar => bar,
516 }; -:>
517 : $dispatcher{$key}()
518 Anonymous macros are also supported, although they can return only
520 strings. They might be useful for callbacks to high-level functions or
521 methods.
522 <: -> $x, $y { $x + $y }(1, 2) # => 3 :>
524 The "block" keyword is used to make a group of template code, and you
526 can apply filters to that block with "infix:<|>". Here is an example
527 to embed HTML source code into templates.
528 Template:
530 : block source | unmark_raw -> {
532 <em>Hello, world!</em>
533 : }
534 Output:
536 <em>Hello, world!</em>
538 See also "Using FillInForm" in Text::Xslate::Manual::Cookbook for
540 another example to use this block filter syntax.
541 Note that closures are not supported.
543 Chomping newlines
545 You can add "-" to the immediate start or end of a directive tag to
546 control the newline chomping options to keep the output clean. The
547 starting "-" removes leading newlines and the ending "-" removes
548 trailing ones.
549 Special keywords
551 There are special keywords:
552 __FILE__
554 Indicates the current file name. Equivalent to
555 "Text::Xslate->current_file".
556 __LINE__
558 Indicates the current line number. Equivalent to
559 "Text::Xslate->current_line".
560 __ROOT__
562 Means the root of the parameters. Equivalent to
563 "Text::Xslate->current_vars".
564 Comments
566 Comments start from "#" to a new line or semicolon.
567 :# this is a comment
569 <:
570 # this is also a comment
571 $foo # $foo is rendered
572 :>
573 <: $bar # this is ok :>
575 <: # this is comment; $baz # $baz is rendered :>
576
578 Text::Xslate
579perl v5.30.1 2019-11-26 Text::Xslate::Syntax::Kolon(3)