Commit | Line | Data |
e374d8da |
1 | package Template::Simple; |
2 | |
3 | use warnings; |
4 | use strict; |
5 | |
6 | use Carp ; |
7 | use Scalar::Util qw( reftype ) ; |
8 | use File::Slurp ; |
9 | |
10 | use Data::Dumper ; |
11 | |
12 | our $VERSION = '0.03'; |
13 | |
14 | my %opt_defaults = ( |
15 | |
16 | pre_delim => qr/\[%/, |
17 | post_delim => qr/%\]/, |
18 | greedy_chunk => 0, |
19 | # upper_case => 0, |
20 | # lower_case => 0, |
21 | include_paths => [ qw( templates ) ], |
22 | ) ; |
23 | |
24 | sub new { |
25 | |
26 | my( $class, %opts ) = @_ ; |
27 | |
28 | my $self = bless {}, $class ; |
29 | |
30 | # get all the options or defaults into the object |
31 | |
32 | while( my( $name, $default ) = each %opt_defaults ) { |
33 | |
34 | $self->{$name} = defined( $opts{$name} ) ? |
35 | $opts{$name} : $default ; |
36 | } |
37 | |
38 | # make up the regexes to parse the markup from templates |
39 | |
40 | # this matches scalar markups and grabs the name |
41 | |
42 | $self->{scalar_re} = qr{ |
43 | $self->{pre_delim} |
44 | \s* # optional leading whitespace |
45 | (\w+?) # grab scalar name |
46 | \s* # optional trailing whitespace |
47 | $self->{post_delim} |
48 | }xi ; # case insensitive |
49 | |
50 | #print "RE <$self->{scalar_re}>\n" ; |
51 | |
52 | # this grabs the body of a chunk in either greedy or non-greedy modes |
53 | |
54 | my $chunk_body = $self->{greedy_chunk} ? qr/.+/s : qr/.+?/s ; |
55 | |
56 | # this matches a marked chunk and grabs its name and text body |
57 | |
58 | $self->{chunk_re} = qr{ |
59 | $self->{pre_delim} |
60 | \s* # optional leading whitespace |
61 | START # required START token |
62 | \s+ # required whitespace |
63 | (\w+?) # grab the chunk name |
64 | \s* # optional trailing whitespace |
65 | $self->{post_delim} |
66 | ($chunk_body) # grab the chunk body |
67 | $self->{pre_delim} |
68 | \s* # optional leading whitespace |
69 | END # required END token |
70 | \s+ # required whitespace |
71 | \1 # match the grabbed chunk name |
72 | \s* # optional trailing whitespace |
73 | $self->{post_delim} |
74 | }xi ; # case insensitive |
75 | |
76 | #print "RE <$self->{chunk_re}>\n" ; |
77 | |
78 | # this matches a include markup and grabs its template name |
79 | |
80 | $self->{include_re} = qr{ |
81 | $self->{pre_delim} |
82 | \s* # optional leading whitespace |
83 | INCLUDE # required INCLUDE token |
84 | \s+ # required whitespace |
85 | (\w+?) # grab the included template name |
86 | \s* # optional trailing whitespace |
87 | $self->{post_delim} |
88 | }xi ; # case insensitive |
89 | |
90 | # load in any templates |
91 | |
92 | $self->add_templates( $opts{templates} ) ; |
93 | |
94 | return $self ; |
95 | } |
96 | |
59d7205c |
97 | sub compile { |
e374d8da |
98 | |
59d7205c |
99 | my( $self, $template_name ) = @_ ; |
100 | |
101 | my $tmpl_ref = eval { |
102 | $self->_get_template( $template_name ) ; |
103 | } ; |
104 | |
105 | croak "Template::Simple $@" if $@ ; |
106 | |
107 | # compile a copy of the template as it will be destroyed |
108 | |
109 | my $code_body = $self->_compile_chunk( '', "${$tmpl_ref}", "\t" ) ; |
110 | |
111 | $self->{source} = <<CODE ; |
112 | |
113 | no warnings ; |
114 | |
115 | sub { |
116 | my( \$data ) = \@_ ; |
117 | |
118 | my \$out = |
119 | $code_body ; |
120 | |
121 | return \\\$out ; |
122 | } |
123 | CODE |
124 | |
125 | $self->{source_cache}{$template_name} = $self->{source} ; |
126 | print $self->{source} ; |
127 | |
128 | my $code_ref = eval $self->{source} ; |
129 | |
130 | die $@ if $@ ; |
131 | |
132 | $self->{compiled_cache}{$template_name} = $code_ref ; |
133 | } |
134 | |
135 | |
136 | sub _compile_chunk { |
137 | |
138 | my( $self, $chunk_name, $template, $indent ) = @_ ; |
139 | |
140 | return '' unless length $template ; |
141 | |
142 | $indent .= "\t" ; |
143 | |
144 | my @parts ; |
145 | |
146 | # loop all nested chunks and the text separating them |
147 | |
148 | while( $template =~ m{$self->{chunk_re}}g ) { |
149 | |
150 | # grab the pre-chunk text and compile it for scalars and save all of its parts |
151 | |
152 | push @parts, $self->_compile_scalars( |
153 | substr( $template, 0, $-[0] ) ) ; |
154 | |
155 | # compile the nested chunk and save its parts |
156 | |
157 | push @parts, $self->_compile_chunk( $1, $2, $indent ) ; |
158 | |
159 | # chop off the pre-chunk and chunk |
160 | |
161 | substr( $template, 0, $+[0], '' ) ; |
162 | } |
163 | |
164 | # compile trailing text for scalars and save all of its parts |
165 | |
166 | push @parts, $self->_compile_scalars( $template ) ; |
167 | |
168 | # generate the code for this chunk |
169 | |
170 | # start it with a do{} block open |
171 | |
172 | my $code = "do {\n$indent" ; |
173 | |
174 | # generate a lookup in data for this chunk name (unless it is the top |
175 | # level). this descends down the data tree during rendering |
176 | |
177 | $code .= <<CODE . $indent if $chunk_name ; |
178 | my \$data = \$data->{$chunk_name} ; |
179 | CODE |
180 | |
181 | # now generate the code to output all the parts of this chunk. they |
182 | # are all concatentated by the . operator |
183 | |
184 | $code .= join( "\n$indent.\n$indent", @parts ) ; |
185 | |
186 | # now we close the do block |
187 | |
188 | chop $indent ; |
189 | $code .= "\n$indent}" ; |
190 | |
191 | return $code ; |
192 | } |
193 | |
194 | sub _compile_scalars { |
195 | |
196 | my( $self, $template ) = @_ ; |
197 | |
198 | # if the template is empty return no parts |
199 | |
200 | return unless length $template ; |
201 | |
202 | my @parts ; |
203 | |
204 | while( $template =~ m{$self->{scalar_re}}g ) { |
205 | |
206 | # keep the text before the scalar markup and the code to access the scalar |
207 | |
208 | push( @parts, |
209 | dump_text( substr( $template, 0, $-[0] ) ), |
210 | "\$data->{$1}" |
211 | ) ; |
212 | substr( $template, 0, $+[0], '' ) ; |
213 | } |
214 | |
215 | # keep any trailing text part |
216 | |
217 | push @parts, dump_text( $template ) ; |
218 | |
219 | return @parts ; |
220 | } |
221 | |
222 | use Data::Dumper ; |
223 | |
224 | sub dump_text { |
225 | |
226 | my( $text ) = @_ ; |
227 | |
228 | return unless length $text ; |
229 | |
230 | local( $Data::Dumper::Useqq ) = 1 ; |
231 | |
232 | my $dumped = Dumper $text ; |
233 | |
234 | $dumped =~ s/^[^"]+// ; |
235 | $dumped =~ s/;\n$// ; |
236 | |
237 | return $dumped ; |
238 | } |
e374d8da |
239 | |
240 | sub render { |
241 | |
59d7205c |
242 | my( $self, $template_name, $data ) = @_ ; |
243 | |
244 | # render with cached code if we precompiled this template |
245 | |
246 | if ( my $compiled = $self->{compiled_cache}{$template_name} ) { |
247 | |
248 | return $compiled->($data) ; |
249 | } |
e374d8da |
250 | |
59d7205c |
251 | # TODO: look for template by name |
252 | |
253 | my $template = eval{ $self->_get_template($1) } ; |
254 | |
255 | print "GOT [$template]\n" ; |
256 | |
257 | # force the template into a ref |
e374d8da |
258 | |
259 | my $tmpl_ref = ref $template eq 'SCALAR' ? $template : \$template ; |
260 | |
261 | my $rendered = $self->_render_includes( $tmpl_ref ) ; |
262 | |
263 | #print "INC EXP <$rendered>\n" ; |
264 | |
265 | $rendered = eval { |
266 | $self->_render_chunk( $rendered, $data ) ; |
267 | } ; |
268 | |
269 | croak "Template::Simple $@" if $@ ; |
270 | |
271 | return $rendered ; |
272 | } |
273 | |
274 | sub _render_includes { |
275 | |
276 | my( $self, $tmpl_ref ) = @_ ; |
277 | |
278 | # make a copy of the initial template so we can render it. |
279 | |
280 | my $rendered = ${$tmpl_ref} ; |
281 | |
282 | # loop until we can render no more include markups |
283 | |
284 | 1 while $rendered =~ |
285 | s{$self->{include_re}} |
286 | { ${ $self->_get_template($1) } |
287 | }e ; |
288 | |
289 | return \$rendered ; |
290 | } |
291 | |
292 | my %renderers = ( |
293 | |
294 | HASH => \&_render_hash, |
295 | ARRAY => \&_render_array, |
296 | CODE => \&_render_code, |
297 | # if no ref then data is a scalar so replace the template with just the data |
298 | '' => sub { \$_[2] }, |
299 | ) ; |
300 | |
301 | |
302 | sub _render_chunk { |
303 | |
304 | my( $self, $tmpl_ref, $data ) = @_ ; |
305 | |
306 | #print "T ref [$tmpl_ref] [$$tmpl_ref]\n" ; |
307 | #print "CHUNK ref [$tmpl_ref] TMPL\n<$$tmpl_ref>\n" ; |
308 | |
309 | #print Dumper $data ; |
310 | |
311 | return \'' unless defined $data ; |
312 | |
313 | # now render this chunk based on the type of data |
314 | |
315 | my $renderer = $renderers{reftype $data || ''} ; |
316 | |
317 | #print "EXP $renderer\nREF ", reftype $data, "\n" ; |
318 | |
319 | die "unknown template data type '$data'\n" unless defined $renderer ; |
320 | |
321 | return $self->$renderer( $tmpl_ref, $data ) ; |
322 | } |
323 | |
324 | sub _render_hash { |
325 | |
326 | my( $self, $tmpl_ref, $href ) = @_ ; |
327 | |
328 | return $tmpl_ref unless keys %{$href} ; |
329 | |
330 | # we need a local copy of the template to render |
331 | |
332 | my $rendered = ${$tmpl_ref} ; |
333 | |
334 | |
335 | # recursively render all top level chunks in this chunk |
336 | |
337 | $rendered =~ s{$self->{chunk_re}} |
338 | { |
339 | # print "CHUNK $1\nBODY\n----\n<$2>\n\n------\n" ; |
59d7205c |
340 | print "CHUNK $1\nBODY\n----\n<$2>\n\n------\n" ; |
341 | print "pre CHUNK [$`]\n" ; |
e374d8da |
342 | ${ $self->_render_chunk( \"$2", $href->{$1} ) } |
343 | }gex ; |
344 | |
345 | # now render scalars |
346 | |
347 | #print "HREF: ", Dumper $href ; |
348 | |
349 | $rendered =~ s{$self->{scalar_re}} |
350 | { |
351 | # print "SCALAR $1 VAL $href->{$1}\n" ; |
352 | defined $href->{$1} ? $href->{$1} : '' |
353 | }ge ; |
354 | |
355 | #print "HASH REND3\n<$rendered>\n" ; |
356 | |
357 | return \$rendered ; |
358 | } |
359 | |
360 | sub _render_array { |
361 | |
362 | my( $self, $tmpl_ref, $aref ) = @_ ; |
363 | |
364 | # render this $tmpl_ref for each element of the aref and join them |
365 | |
366 | my $rendered ; |
367 | |
368 | #print "AREF: ", Dumper $aref ; |
369 | |
370 | $rendered .= ${$self->_render_chunk( $tmpl_ref, $_ )} for @{$aref} ; |
371 | |
372 | return \$rendered ; |
373 | } |
374 | |
375 | sub _render_code { |
376 | |
377 | my( $self, $tmpl_ref, $cref ) = @_ ; |
378 | |
379 | my $rendered = $cref->( $tmpl_ref ) ; |
380 | |
381 | die <<DIE if ref $rendered ne 'SCALAR' ; |
382 | data callback to code didn't return a scalar or scalar reference |
383 | DIE |
384 | |
385 | return $rendered ; |
386 | } |
387 | |
388 | sub add_templates { |
389 | |
390 | my( $self, $tmpls ) = @_ ; |
391 | |
392 | #print Dumper $tmpls ; |
393 | return unless defined $tmpls ; |
394 | |
395 | ref $tmpls eq 'HASH' or croak "templates argument is not a hash ref" ; |
59d7205c |
396 | |
397 | # copy all the templates from the arg hash and force the values to be |
398 | # scalar refs |
e374d8da |
399 | |
59d7205c |
400 | @{ $self->{tmpl_cache}}{ keys %{$tmpls} } = |
e374d8da |
401 | map ref $_ eq 'SCALAR' ? \"${$_}" : \"$_", values %{$tmpls} ; |
402 | |
59d7205c |
403 | #print Dumper $self->{tmpl_cache} ; |
e374d8da |
404 | |
405 | return ; |
406 | } |
407 | |
408 | sub delete_templates { |
409 | |
410 | my( $self, @names ) = @_ ; |
411 | |
59d7205c |
412 | @names = keys %{$self->{tmpl_cache}} unless @names ; |
e374d8da |
413 | |
59d7205c |
414 | delete @{$self->{tmpl_cache}}{ @names } ; |
e374d8da |
415 | |
416 | delete @{$self->{template_paths}}{ @names } ; |
417 | |
418 | return ; |
419 | } |
420 | |
421 | sub _get_template { |
422 | |
423 | my( $self, $tmpl_name ) = @_ ; |
424 | |
425 | #print "INC $tmpl_name\n" ; |
426 | |
59d7205c |
427 | my $tmpls = $self->{tmpl_cache} ; |
e374d8da |
428 | |
429 | # get the template from the cache and send it back if it was found there |
430 | |
431 | my $template = $tmpls->{ $tmpl_name } ; |
432 | return $template if $template ; |
433 | |
434 | # not found, so find, slurp in and cache the template |
435 | |
436 | $template = $self->_find_template( $tmpl_name ) ; |
437 | $tmpls->{ $tmpl_name } = $template ; |
438 | |
439 | return $template ; |
440 | } |
441 | |
442 | sub _find_template { |
443 | |
444 | my( $self, $tmpl_name ) = @_ ; |
445 | |
446 | foreach my $dir ( @{$self->{include_paths}} ) { |
447 | |
448 | my $tmpl_path = "$dir/$tmpl_name.tmpl" ; |
449 | |
450 | #print "PATH: $tmpl_path\n" ; |
451 | next unless -r $tmpl_path ; |
452 | |
453 | # cache the path to this template |
454 | |
455 | $self->{template_paths}{$tmpl_name} = $tmpl_path ; |
456 | |
457 | # slurp in the template file and return it as a scalar ref |
458 | |
459 | return scalar read_file( $tmpl_path, scalar_ref => 1 ) ; |
460 | } |
461 | |
462 | die <<DIE ; |
463 | can't find template '$tmpl_name' in '@{$self->{include_paths}}' |
464 | DIE |
465 | |
466 | } |
467 | |
468 | 1; # End of Template::Simple |
469 | |
470 | __END__ |
471 | |
472 | =head1 NAME |
473 | |
474 | Template::Simple - A simple and fast template module |
475 | |
476 | =head1 VERSION |
477 | |
478 | Version 0.03 |
479 | |
480 | =head1 SYNOPSIS |
481 | |
482 | use Template::Simple; |
483 | |
484 | my $tmpl = Template::Simple->new(); |
485 | |
486 | my $template = <<TMPL ; |
487 | [%INCLUDE header%] |
488 | [%START row%] |
489 | [%first%] - [%second%] |
490 | [%END row%] |
491 | [%INCLUDE footer%] |
492 | TMPL |
493 | |
494 | my $data = { |
495 | header => { |
496 | date => 'Jan 1, 2008', |
497 | author => 'Me, myself and I', |
498 | }, |
499 | row => [ |
500 | { |
501 | first => 'row 1 value 1', |
502 | second => 'row 1 value 2', |
503 | }, |
504 | { |
505 | first => 'row 2 value 1', |
506 | second => 'row 2 value 2', |
507 | }, |
508 | ], |
509 | footer => { |
510 | modified => 'Aug 31, 2006', |
511 | }, |
512 | } ; |
513 | |
514 | my $rendered = $tmpl->render( $template, $data ) ; |
515 | |
516 | =head1 DESCRIPTION |
517 | |
518 | Template::Simple has these goals: |
519 | |
520 | =over 4 |
521 | |
522 | =item * Support most common template operations |
523 | |
524 | It can recursively include other templates, replace tokens (scalars), |
525 | recursively render nested chunks of text and render lists. By using |
526 | simple idioms you can get conditional renderings. |
527 | |
528 | =item * Complete isolation of template from program code |
529 | |
530 | This is very important as template design can be done by different |
531 | people than the program logic. It is rare that one person is well |
532 | skilled in both template design and also programming. |
533 | |
534 | =item * Very simple template markup (only 4 markups) |
535 | |
536 | The only markups are C<INCLUDE>, C<START>, C<END> and C<token>. See |
537 | MARKUP for more. |
538 | |
539 | =item * Easy to follow rendering rules |
540 | |
541 | Rendering of templates and chunks is driven from a data tree. The type |
542 | of the data element used in an rendering controls how the rendering |
543 | happens. The data element can be a scalar or scalar reference or an |
544 | array, hash or code reference. |
545 | |
546 | =item * Efficient template rendering |
547 | |
548 | Rendering is very simple and uses Perl's regular expressions |
549 | efficiently. Because the markup is so simple less processing is needed |
550 | than many other templaters. Precompiling templates is not supported |
551 | yet but that optimization is on the TODO list. |
552 | |
553 | =item * Easy user extensions |
554 | |
555 | User code can be called during an rendering so you can do custom |
556 | renderings and plugins. Closures can be used so the code can have its |
557 | own private data for use in rendering its template chunk. |
558 | |
559 | =back |
560 | |
561 | =head2 new() |
562 | |
563 | You create a Template::Simple by calling the class method new: |
564 | |
565 | my $tmpl = Template::Simple->new() ; |
566 | |
567 | All the arguments to C<new()> are key/value options that change how |
568 | the object will do renderings. |
569 | |
570 | =over 4 |
571 | |
572 | =item pre_delim |
573 | |
574 | This option sets the string or regex that is the starting delimiter |
575 | for all markups. You can use a plain string or a qr// but you need to |
576 | escape (with \Q or \) any regex metachars if you want them to be plain |
577 | chars. The default is qr/\[%/. |
578 | |
579 | my $tmpl = Template::Simple->new( |
580 | pre_delim => '<%', |
581 | ); |
582 | |
583 | my $rendered = $tmpl->render( '<%FOO%]', 'bar' ) ; |
584 | |
585 | =item post_delim |
586 | |
587 | This option sets the string or regex that is the ending delimiter |
588 | for all markups. You can use a plain string or a qr// but you need to |
589 | escape (with \Q or \) any regex metachars if you want them to be plain |
590 | chars. The default is qr/%]/. |
591 | |
592 | my $tmpl = Template::Simple->new( |
593 | post_delim => '%>', |
594 | ); |
595 | |
596 | my $rendered = $tmpl->render( '[%FOO%>', 'bar' ) ; |
597 | |
598 | =item greedy_chunk |
599 | |
600 | This boolean option will cause the regex that grabs a chunk of text |
601 | between the C<START/END> markups to become greedy (.+). The default is |
602 | a not-greedy grab of the chunk text. (UNTESTED) |
603 | |
604 | =item templates |
605 | |
606 | This option lets you load templates directly into the cache of the |
607 | Template::Simple object. This cache will be searched by the C<INCLUDE> |
608 | markup which will be replaced by the template if found. The option |
609 | value is a hash reference which has template names (the name in the |
610 | C<INCLUDE> markup) for keys and their template text as their |
611 | values. You can delete or clear templates from the object cache with |
612 | the C<delete_template> method. |
613 | |
614 | |
615 | my $tmpl = Template::Simple->new( |
616 | templates => { |
617 | |
618 | foo => <<FOO, |
619 | [%baz%] is a [%quux%] |
620 | FOO |
621 | bar => <<BAR, |
622 | [%user%] is not a [%fool%] |
623 | BAR |
624 | }, |
625 | ); |
626 | |
627 | my $template = <<TMPL ; |
628 | [%INCLUDE foo %] |
629 | TMPL |
630 | |
631 | my $rendered = $tmpl->render( |
632 | $template, |
633 | { |
634 | baz => 'blue', |
635 | quux => 'color, |
636 | } |
637 | ) ; |
638 | |
639 | =item include_paths |
640 | |
641 | Template::Simple can also load C<INCLUDE> templates from files. This |
642 | option lets you set the directory paths to search for those |
643 | files. Note that the template name in the C<INCLUDE> markup has the |
644 | .tmpl suffix appended to it when searched for in one of these |
645 | paths. The loaded file is cached inside the Template::Simple object |
646 | along with any loaded by the C<templates> option. |
647 | |
648 | =back |
649 | |
650 | =head1 METHODS |
651 | |
652 | =head2 render |
653 | |
654 | This method is passed a template and a data tree and it renders it and |
655 | returns a reference to the resulting string. The template argument can |
656 | be a scalar or a scalar reference. The data tree argument can be any |
657 | value allowed by Template::Simple when rendering a template. It can |
658 | also be a blessed reference (Perl object) since |
659 | C<Scalar::Util::reftype> is used instead of C<ref> to determine the |
660 | data type. |
661 | |
662 | Note that the author recommends against passing in an object as this |
663 | breaks encapsulation and forces your object to be (most likely) a |
664 | hash. It would be better to create a simple method that copies the |
665 | object contents to a hash reference and pass that. But current |
666 | templaters allow passing in objects so that is supported here as well. |
667 | |
668 | my $rendered = $tmpl->render( $template, $data ) ; |
669 | |
670 | =head2 add_templates |
671 | |
672 | This method adds templates to the object cache. It takes a list of template names and texts just like the C<templates> constructor option. |
673 | |
674 | $tmpl->add_templates( |
675 | { |
676 | foo => \$foo_template, |
677 | bar => '[%include bar%]', |
678 | } |
679 | ) ; |
680 | |
681 | =head2 delete_templates |
682 | |
683 | This method takes a list of template names and will delete them from |
684 | the template cache in the object. If you pass in an empty list then |
685 | all the templates will be deleted. This can be used when you know a |
686 | template file has been updated and you want to get it loaded back into |
687 | the cache. Note that you can delete templates that were loaded |
688 | directly (via the C<templates> constructor option or the |
689 | C<add_templates> method) or loaded from a file. |
690 | |
691 | # this deletes only the foo and bar templates from the object cache |
692 | |
693 | $tmpl->delete_templates( qw( foo bar ) ; |
694 | |
695 | # this deletes all of templates from the object cache |
696 | |
697 | $tmpl->delete_templates() ; |
698 | |
699 | =head2 get_dependencies |
700 | |
701 | This method render the only C<INCLUDE> markups of a template and it |
702 | returns a list of the file paths that were found and loaded. It is |
703 | meant to be used to build up a dependency list of included templates |
704 | for a main template. Typically this can be called from a script (see |
705 | TODO) that will do this for a set of main templates and will generate |
706 | Makefile dependencies for them. Then you can regenerate rendered |
707 | templates only when any of their included templates have changed. It |
708 | takes a single argument of a template. |
709 | |
710 | UNKNOWN: will this require a clearing of the cache or will it do the |
711 | right thing on its own? or will it use the file path cache? |
712 | |
713 | my @dependencies = |
714 | $tmpl->get_dependencies( '[%INCLUDE top_level%]' ); |
715 | |
716 | =head1 MARKUP |
717 | |
718 | All the markups in Template::Simple use the same delimiters which are |
719 | C<[%> and C<%]>. You can change the delimiters with the C<pre_delim> |
720 | and C<post_delim> options in the C<new()> constructor. |
721 | |
722 | =head2 Tokens |
723 | |
724 | A token is a single markup with a C<\w+> Perl word inside. The token |
725 | can have optional whitespace before and after it. A token is replaced |
726 | by a value looked up in a hash with the token as the key. The hash |
727 | lookup keeps the same case as parsed from the token markup. |
728 | |
729 | [% foo %] [%BAR%] |
730 | |
731 | Those will be replaced by C<$href->{foo}> and C<$href->{BAR}> assuming |
732 | C<$href> is the current data for this rendering. Tokens are only |
733 | parsed out during hash data rendering so see Hash Data for more. |
734 | |
735 | =head2 Chunks |
736 | |
737 | Chunks are regions of text in a template that are marked off with a |
738 | start and end markers with the same name. A chunk start marker is |
739 | C<[%START name%]> and the end marker for that chunk is C<[%END |
740 | name%]>. C<name> is a C<\w+> Perl word which is the name of this |
741 | chunk. The whitespace between C<START/END> and C<name> is required and |
742 | there is optional whitespace before C<START/END> and after the |
743 | C<name>. C<START/END> are case insensitive but the C<name>'s case is |
744 | kept. C<name> must match in the C<START/END> pair and it used as a key |
745 | in a hash data rendering. Chunks are the primary way to markup |
746 | templates for structures (sets of tokens), nesting (hashes of hashes), |
747 | repeats (array references) and callbacks to user code. Chunks are only |
748 | parsed out during hash data rendering so see Hash Data for more. |
749 | |
750 | The body of text between the C<START/END> markups is grabbed with a |
751 | C<.+?> regular expression with the /s option enabled so it will match |
752 | all characters. By default it will be a non-greedy grab but you can |
753 | change that in the constructor by enabling the C<greedy_chunk> option. |
754 | |
755 | [%Start FOO%] |
756 | [% START bar %] |
757 | [% field %] |
758 | [% end bar %] |
759 | [%End FOO%] |
760 | |
761 | =head2 Includes |
762 | |
763 | =head1 RENDERING RULES |
764 | |
765 | Template::Simple has a short list of rendering rules and they are easy |
766 | to understand. There are two types of renderings, include rendering |
767 | and chunk rendering. In the C<render> method, the template is an |
768 | unnamed top level chunk of text and it first gets its C<INCLUDE> |
769 | markups rendered. The text then undergoes a chunk rendering and a |
770 | scalar reference to that rendered template is returned to the caller. |
771 | |
772 | =head2 Include Rendering |
773 | |
774 | Include rendering is performed one time on a top level template. When |
775 | it is done the template is ready for chunk rendering. Any markup of |
776 | the form C<[%INCLUDE name]%> will be replaced by the text found in the |
777 | template C<name>. The template name is looked up in the object's |
778 | template cache and if it is found there its text is used as the |
779 | replacement. |
780 | |
781 | If a template is not found in the cache, it will be searched for in |
782 | the list of directories in the C<include_paths> option. The file name |
783 | will be a directory in that list appended with the template name and |
784 | the C<.tmpl> suffix. The first template file found will be read in and |
785 | stored in the cache. Its path is also saved and those will be returned |
786 | in the C<get_dependencies> method. See the C<add_templates> and |
787 | C<delete_templates> methods and the C<include_paths> option. |
788 | |
789 | Rendered include text can contain more C<INCLUDE> markups and they |
790 | will also be rendered. The include rendering phase ends where there |
791 | are no more C<INCLUDE> found. |
792 | |
793 | =head2 Chunk Rendering |
794 | |
795 | A chunk is the text found between C<START> and C<END> markups and it |
796 | gets its named from the C<START> markup. The top level template is |
797 | considered an unamed chunk and also gets chunk rendered. |
798 | |
799 | The data for a chunk determines how it will be rendered. The data can |
800 | be a scalar or scalar reference or an array, hash or code |
801 | reference. Since chunks can contain nested chunks, rendering will |
802 | recurse down the data tree as it renders the chunks. Each of these |
803 | renderings are explained below. Also see the IDIOMS and BEST PRACTICES |
804 | section for examples and used of these renderings. |
805 | |
806 | =head2 Scalar Data Rendering |
807 | |
808 | If the current data for a chunk is a scalar or scalar reference, the |
809 | chunk's text in the templated is replaced by the scalar's value. This |
810 | can be used to overwrite one default section of text with from the |
811 | data tree. |
812 | |
813 | =head2 Code Data Rendering |
814 | |
815 | If the current data for a chunk is a code reference (also called |
816 | anonymous sub) then the code reference is called and it is passed a |
817 | scalar reference to the that chunk's text. The code must return a |
818 | scalar or a scalar reference and its value replaces the chunk's text |
819 | in the template. If the code returns any other type of data it is a |
820 | fatal error. Code rendering is how you can do custom renderings and |
821 | plugins. A key idiom is to use closures as the data in code renderings |
822 | and keep the required outside data in the closure. |
823 | |
824 | =head2 Array Data Rendering |
825 | |
826 | If the current data for a chunk is an array reference do a full chunk |
827 | rendering for each value in the array. It will replace the original |
828 | chunk text with the joined list of rendered chunks. This is how you do |
829 | repeated sections in Template::Simple and why there is no need for any |
830 | loop markups. Note that this means that rendering a chunk with $data |
831 | and [ $data ] will do the exact same thing. A value of an empty array |
832 | C<[]> will cause the chunk to be replaced by the empty string. |
833 | |
834 | =head2 Hash Data Rendering |
835 | |
836 | If the current data for a chunk is a hash reference then two phases of |
837 | rendering happen, nested chunk rendering and token rendering. First |
838 | nested chunks are parsed of of this chunk along with their names. Each |
839 | parsed out chunk is rendered based on the value in the current hash |
840 | with the nested chunk's name as the key. |
841 | |
842 | If a value is not found (undefined), then the nested chunk is replaced |
843 | by the empty string. Otherwise the nested chunk is rendered according |
844 | to the type of its data (see chunk rendering) and it is replaced by |
845 | the rendered text. |
846 | |
847 | Chunk name and token lookup in the hash data is case sensitive (see |
848 | the TODO for cased lookups). |
849 | |
850 | Note that to keep a plain text chunk or to just have the all of its |
851 | markups (chunks and tokens) be deleted just pass in an empty hash |
852 | reference C<{}> as the data for the chunk. It will be rendered but all |
853 | markups will be replaced by the empty string. |
854 | |
855 | =head2 Token Rendering |
856 | |
857 | The second phase is token rendering. Markups of the form [%token%] are |
858 | replaced by the value of the hash element with the token as the |
859 | key. If a token's value is not defined it is replaced by the empty |
860 | string. This means if a token key is missing in the hash or its value |
861 | is undefined or its value is the empty string, the [%token%] markup |
862 | will be deleted in the rendering. |
863 | |
864 | =head1 IDIOMS and BEST PRACTICES |
865 | |
866 | With all template systems there are better ways to do things and |
867 | Template::Simple is no different. This section will show some ways to |
868 | handle typical template needs while using only the 4 markups in this |
869 | module. |
870 | |
871 | =head2 Conditionals |
872 | |
873 | This conditional idiom can be when building a fresh data tree or |
874 | modifying an existing one. |
875 | |
876 | $href->{$chunk_name} = $keep_chunk ? {} : '' ; |
877 | |
878 | If you are building a fresh data tree you can use this idiom to do a |
879 | conditional chunk: |
880 | |
881 | $href->{$chunk_name} = {} if $keep_chunk ; |
882 | |
883 | To handle an if/else conditional use two chunks, with the else chunk's |
884 | name prefixed with NOT_ (or use any name munging you want). Then you |
885 | set the data for either the true chunk (just the plain name) or the |
886 | false trunk with the NOT_ name. You can use a different name for the |
887 | else chunk if you want but keeping the names of the if/else chunks |
888 | related is a good idea. Here are two ways to set the if/else data. The |
889 | first one uses the same data for both the if and else chunks and the |
890 | second one uses different data so the it uses the full if/else code |
891 | for that. |
892 | |
893 | $href->{ ($boolean ? '' : 'NOT_') . $chunk_name} = $data |
894 | |
895 | if ( $boolean ) { |
896 | $href->{ $chunk_name} = $true_data ; |
897 | else { |
898 | $href->{ "NOT_$chunk_name" } = $false_data ; |
899 | } |
900 | |
901 | NOTE TO ALPHA USERS: i am also thinking that a non-existing key or |
902 | undefined hash value should leave the chunk as is. then you would need |
903 | to explicitly replace a chunk with the empty string if you wanted it |
904 | deleted. It does affect the list of styles idiom. Any thoughts on |
905 | this change of behavior? Since this hasn't been released it is the |
906 | time to decide this. |
907 | |
908 | =head2 Chunked Includes |
909 | |
910 | One of the benefits of using include templates is the ability to share |
911 | and reuse existing work. But if an included template has a top level |
912 | named chunk, then that name would also be the same everywhere where |
913 | this template is included. If a template included another template in |
914 | multiple places, its data tree would use the same name for each and |
915 | not allow unique data to be rendered for each include. A better way is |
916 | to have the current template wrap an include markup in a named chunk |
917 | markup. Then the data tree could use unique names for each included |
918 | template. Here is how it would look: |
919 | |
920 | [%START foo_prime%][%INCLUDE foo%][%START foo_prime%] |
921 | random noise |
922 | [%START foo_second%][%INCLUDE foo%][%START foo_second%] |
923 | |
924 | See the TODO section for some ideas on how to make this even more high level. |
925 | |
926 | =head2 Repeated Sections |
927 | |
928 | If you looked at the markup of Template::Simple you have noticed that |
929 | there is no loop or repeat construct. That is because there is no need |
930 | for one. Any chunk can be rendered in a loop just by having its |
931 | rendering data be an anonymous array. The renderer will loop over each |
932 | element of the array and do a fresh rendering of the chunk with this |
933 | data. A join (on '') of the list of renderings replaces the original |
934 | chunk and you have a repeated chunk. |
935 | |
936 | =head2 A List of Mixed Styles |
937 | |
938 | One formating style is to have a list of sections each which can have |
939 | its own style or content. Template::Simple can do this very easily |
940 | with just a 2 level nested chunk and an array of data for |
941 | rendering. The outer chunk includes (or contains) each of the desired |
942 | styles in any order. It looks like this: |
943 | |
944 | [%START para_styles%] |
945 | [%START main_style%] |
946 | [%INCLUDE para_style_main%] |
947 | [%END main_style%] |
948 | [%START sub_style%] |
949 | [%INCLUDE para_style_sub%] |
950 | [%END sub_style%] |
951 | [%START footer_style%] |
952 | [%INCLUDE para_style_footer%] |
953 | [%END footer_style%] |
954 | [%END para_styles%] |
955 | |
956 | The other part to make this work is in the data tree. The data for |
957 | para_styles should be a list of hashes. Each hash contains the data |
958 | for one pargraph style which is keyed by the style's chunk name. Since |
959 | the other styles's chunk names are not hash they are deleted. Only the |
960 | style which has its name as a key in the hash is rendered. The data |
961 | tree would look something like this: |
962 | |
963 | [ |
964 | { |
965 | main_style => $main_data, |
966 | }, |
967 | { |
968 | sub_style => $sub_data, |
969 | }, |
970 | { |
971 | sub_style => $other_sub_data, |
972 | }, |
973 | { |
974 | footer_style => $footer_data, |
975 | }, |
976 | ] |
977 | |
978 | =head1 TESTS |
979 | |
980 | The test scripts use a common test driver module in t/common.pl. It is |
981 | passed a list of hashes, each of which has the data for one test. A |
982 | test can create a ne Template::Simple object or use the one from the |
983 | previous test. The template source, the data tree and the expected |
984 | results are also important keys. See the test scripts for examples of |
985 | how to write tests using this common driver. |
986 | |
987 | =over 4 |
988 | |
989 | =item name |
990 | |
991 | This is the name of the test and is used by Test::More |
992 | |
993 | =item opts |
994 | |
995 | This is a hash ref of the options passed to the Template::Simple |
996 | constructor. The object is not built if the C<keep_obj> key is set. |
997 | |
998 | =item keep_obj |
999 | |
1000 | If set, this will make this test keep the Template::Simple object from |
1001 | the previous test and not build a new one. |
1002 | |
1003 | =item template |
1004 | |
1005 | This is the template to render for this test. If not set, the test |
1006 | driver will use the template from the previous test. This is useful to |
1007 | run a series of test variants with the same template. |
1008 | |
1009 | =item data |
1010 | |
1011 | This is the data tree for the rendering of the template. |
1012 | |
1013 | =item expected |
1014 | |
1015 | This is the text that is expected after the rendering. |
1016 | |
1017 | =item skip |
1018 | |
1019 | If set, this test is skipped. |
1020 | |
1021 | =back |
1022 | |
1023 | =head1 TODO |
1024 | |
1025 | Even though this template system is simple, that doesn't mean it can't |
1026 | be extended in many ways. Here are some features and designs that |
1027 | would be good extensions which add useful functionality without adding |
1028 | too much complexity. |
1029 | |
1030 | =head2 Compiled Templates |
1031 | |
1032 | A commonly performed optimization in template modules is to precompile |
1033 | (really preparse) templates into a internal form that will render |
1034 | faster. Precompiling is slower than rendering from the original |
1035 | template which means you won't want to do it for each rendering. This |
1036 | means it has a downside that you lose out when you want to render |
1037 | using templates which change often. Template::Simple makes it very |
1038 | easy to precompile as it already has the regexes to parse out the |
1039 | markup. So instead of calling subs to do actual rendering, a |
1040 | precompiler would call subs to generate a compiled rendering tree. |
1041 | The rendering tree can then be run or processes with rendering data |
1042 | passed to it. You can think of a precompiled template as having all |
1043 | the nested chunks be replaced by nested code that does the same |
1044 | rendering. It can still do the dynamic rendering of the data but it |
1045 | saves the time of parsing the template souice. There are three |
1046 | possible internal formats for the precompiled template: |
1047 | |
1048 | =over 4 |
1049 | |
1050 | =item Source code |
1051 | |
1052 | This precompiler will generate source code that can be stored and/or |
1053 | eval'ed. The eval'ed top level sub can then be called and passed the |
1054 | rendering data. |
1055 | |
1056 | =item Closure call tree |
1057 | |
1058 | The internal format can be a nested set of closures. Each closure would contain |
1059 | private data such as fixed text parts of the original template, lists |
1060 | of other closures to run, etc. It is trivial to write a basic closure |
1061 | generator which will make build this tree a simple task. |
1062 | |
1063 | =item Code ref call tree |
1064 | |
1065 | This format is a Perl data tree where the nodes have a code reference |
1066 | and its args (which can be nested instances of the same |
1067 | nodes). Instead of executing this directly, you will need a small |
1068 | interpreter to execute all the code refs as it runs through the tree. |
1069 | |
1070 | This would make for a challenging project to any intermediate Perl |
1071 | hacker. It just involves knowing recursion, data trees and code refs. |
1072 | Contact me if you are interested in doing this. |
1073 | |
1074 | =back |
1075 | |
1076 | =head2 Cased Hash Lookups |
1077 | |
1078 | One possible option is to allow hash renderings to always use upper or |
1079 | lower cased keys in their lookups. |
1080 | |
1081 | =head2 Render tokens before includes and chunks |
1082 | |
1083 | Currently tokens are rendered after includes and chunks. If tokens |
1084 | were rendered in a pass before the others, the include and chunk names |
1085 | could be dynamically set. This would make it harder to precompile |
1086 | templates as too much would be dynamic, i.e. you won't know what the |
1087 | fixed text to parse out is since anything can be included at render |
1088 | time. But the extra flexibility of changing the include and chunk |
1089 | names would be interesting. It could be done easily and enabled by an |
1090 | option. |
1091 | |
1092 | =head2 Plugins |
1093 | |
1094 | There are two different potential areas in Template::Simple that could |
1095 | use plugins. The first is with the rendering of chunkas and |
1096 | dispatching based on the data type. This dispatch table can easily be |
1097 | replaced by loaded modules which offer a different way to |
1098 | render. These include the precompiled renderers mentioned above. The |
1099 | other area is with code references as the data type. By defining a |
1100 | closure (or a closure making) API you can create different code refs |
1101 | for the rendering data. The range of plugins is endless some of the |
1102 | major template modules have noticed. One idea is to make a closure |
1103 | which contains a different Template::Simple object than the current |
1104 | one. This will allow rendering of a nested chunk with different rules |
1105 | than the current chunk being rendered. |
1106 | |
1107 | =head2 Data Escaping |
1108 | |
1109 | Some templaters have options to properly escape data for some types of |
1110 | text files such as html. this can be done with some variant of the |
1111 | _render_hash routine which also does the scalar rendering (which is |
1112 | where data is rendered). The rendering scalars code could be factored |
1113 | out into a set of subs one of which is used based on any escaping |
1114 | needs. |
1115 | |
1116 | =head2 Data Tree is an Object |
1117 | |
1118 | This is a concept I don't like but it was requested so it goes into |
1119 | the TODO file. Currently C<render> can only be passed a regular |
1120 | (unblessed) ref (or a scalar) for its data tree. Passing in an object |
1121 | would break encapsulation and force the object layout to be a hash |
1122 | tree that matches the layout of the template. I doubt that most |
1123 | objects will want to be organized to match a template. I have two |
1124 | ideas, one is that you add a method to that object that builds up a |
1125 | proper (unblessed) data tree to pass to C<render>. The other is by |
1126 | subclassing C<Template::Simple> and overriding C<render> with a sub |
1127 | that does take an object hash and it can unbless it or build a proper |
1128 | data tree and then call C<render> in SUPER::. A quick solution is to |
1129 | use C<reftype> (from Scalar::Utils) instead of C<ref> to allow object |
1130 | hashes to be passed in. |
1131 | |
1132 | =head2 Includes and Closure Synergy |
1133 | |
1134 | By pairing up an include template along with code that can generate |
1135 | the appropriate data tree for its rendering, you can create a higher |
1136 | level template framework (the synergy). Additional code can be |
1137 | associated with them that will handle input processing and |
1138 | verification for the templates (e.g. web forms) that need it. A key to |
1139 | this will be making all the closures for the data tree. This can be |
1140 | greatly simplified by using a closure maker sub that can create all |
1141 | the required closures. |
1142 | |
1143 | =head2 Metafields and UI Generation |
1144 | |
1145 | Taking the synergy up to a much higher level is the concept of meta |
1146 | knowledge of fields which can generate templates, output processing |
1147 | (data tree generation), input processing, DB backing and more. If you |
1148 | want to discuss such grandiose wacky application schemes in a long |
1149 | rambling mind bending conversation, please contact me. |
1150 | |
1151 | =head2 More Examples and Idioms |
1152 | |
1153 | As I convert several scripts over to this module (they all used the |
1154 | hack version), I will add them to an examples section or possibly put |
1155 | them in another (pod only) module. Similarly the Idioms section needs |
1156 | rendering and could be also put into a pod module. One goal requested |
1157 | by an early alpha tester is to keep the primary docs as simple as the |
1158 | markup itself. This means moving all the extra stuff (and plenty of |
1159 | that) into other pod modules. All the pod modules would be in the same |
1160 | cpan tarball so you get all the docs and examples when you install |
1161 | this. |
1162 | |
1163 | =head1 AUTHOR |
1164 | |
1165 | Uri Guttman, C<< <uri at sysarch.com> >> |
1166 | |
1167 | =head1 BUGS |
1168 | |
1169 | Please report any bugs or feature requests to |
1170 | C<bug-template-simple at rt.cpan.org>, or through the web interface at |
1171 | L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Template-Simple>. |
1172 | I will be notified, and then you'll automatically be notified of progress on |
1173 | your bug as I make changes. |
1174 | |
1175 | =head1 SUPPORT |
1176 | |
1177 | You can find documentation for this module with the perldoc command. |
1178 | |
1179 | perldoc Template::Simple |
1180 | |
1181 | You can also look for information at: |
1182 | |
1183 | =over 4 |
1184 | |
1185 | =item * RT: CPAN's request tracker |
1186 | |
1187 | L<http://rt.cpan.org/NoAuth/Bugs.html?Dist=Template-Simple> |
1188 | |
1189 | =item * Search CPAN |
1190 | |
1191 | L<http://search.cpan.org/dist/Template-Simple> |
1192 | |
1193 | =back |
1194 | |
1195 | =head1 ACKNOWLEDGEMENTS |
1196 | |
1197 | I wish to thank Turbo10 for their support in developing this module. |
1198 | |
1199 | =head1 COPYRIGHT & LICENSE |
1200 | |
1201 | Copyright 2006 Uri Guttman, all rights reserved. |
1202 | |
1203 | This program is free software; you can redistribute it and/or modify it |
1204 | under the same terms as Perl itself. |
1205 | |
1206 | =cut |
1207 | |
1208 | |
1209 | find templates and tests |
1210 | |
1211 | deep nesting tests |
1212 | |
1213 | greedy tests |
1214 | |
1215 | methods pod |
1216 | |
1217 | delete_templates test |
1218 | |
1219 | pod cleanup |
1220 | |
1221 | fine edit |
1222 | |
1223 | more tests |
1224 | |
1225 | slurp dependency in makefile.pl |
1226 | |