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