1Twig(3) User Contributed Perl Documentation Twig(3)
2
6 XML::Twig - A perl module for processing huge XML documents in tree
7 mode.
8
10 Note that this documentation is intended as a reference to the module.
11 Complete docs, including a tutorial, examples, an easier to use HTML
13 version, a quick reference card and a FAQ are available at
14 <http://www.xmltwig.org/xmltwig>
15 Small documents (loaded in memory as a tree):
17 my $twig=XML::Twig->new(); # create the twig
19 $twig->parsefile( 'doc.xml'); # build it
20 my_process( $twig); # use twig methods to process it
21 $twig->print; # output the twig
22 Huge documents (processed in combined stream/tree mode):
24 # at most one div will be loaded in memory
26 my $twig=XML::Twig->new(
27 twig_handlers =>
28 { title => sub { $_->set_tag( 'h2') }, # change title tags to h2
29 # $_ is the current element
30 para => sub { $_->set_tag( 'p') }, # change para to p
31 hidden => sub { $_->delete; }, # remove hidden elements
32 list => \&my_list_process, # process list elements
33 div => sub { $_[0]->flush; }, # output and free memory
34 },
35 pretty_print => 'indented', # output will be nicely formatted
36 empty_tags => 'html', # outputs <empty_tag />
37 );
38 $twig->parsefile( 'my_big.xml');
39 sub my_list_process
41 { my( $twig, $list)= @_;
42 # ...
43 }
44 See XML::Twig 101 for other ways to use the module, as a filter for
46 example.
47
49 This module provides a way to process XML documents. It is build on top
50 of "XML::Parser".
51 The module offers a tree interface to the document, while allowing you
53 to output the parts of it that have been completely processed.
54 It allows minimal resource (CPU and memory) usage by building the tree
56 only for the parts of the documents that need actual processing,
57 through the use of the "twig_roots " and "twig_print_outside_roots "
58 options. The "finish " and "finish_print " methods also help to
59 increase performances.
60 XML::Twig tries to make simple things easy so it tries its best to
62 takes care of a lot of the (usually) annoying (but sometimes necessary)
63 features that come with XML and XML::Parser.
64
66 XML::Twig comes with a few command-line utilities:
67 xml_pp - xml pretty-printer
69 XML pretty printer using XML::Twig
70 xml_grep - grep XML files looking for specific elements
72 "xml_grep" does a grep on XML files. Instead of using regular
73 expressions it uses XPath expressions (in fact the subset of XPath
74 supported by XML::Twig).
75 xml_split - cut a big XML file into smaller chunks
77 "xml_split" takes a (presumably big) XML file and split it in several
78 smaller files, based on various criteria (level in the tree, size or an
79 XPath expression)
80 xml_merge - merge back XML files split with xml_split
82 "xml_merge" takes several xml files that have been split using
83 "xml_split" and recreates a single file.
84 xml_spellcheck - spellcheck XML files
86 "xml_spellcheck" lets you spell check the content of an XML file. It
87 extracts the text (the content of elements and optionally of
88 attributes), call a spell checker on it and then recreates the XML
89 document.
90
92 XML::Twig can be used either on "small" XML documents (that fit in
93 memory) or on huge ones, by processing parts of the document and
94 outputting or discarding them once they are processed.
95 Loading an XML document and processing it
97 my $t= XML::Twig->new();
98 $t->parse( '<d><title>title</title><para>p 1</para><para>p 2</para></d>');
99 my $root= $t->root;
100 $root->set_tag( 'html'); # change doc to html
101 $title= $root->first_child( 'title'); # get the title
102 $title->set_tag( 'h1'); # turn it into h1
103 my @para= $root->children( 'para'); # get the para children
104 foreach my $para (@para)
105 { $para->set_tag( 'p'); } # turn them into p
106 $t->print; # output the document
107 Other useful methods include:
109 att: "$elt->{'att'}->{'foo'}" return the "foo" attribute for an
111 element,
112 set_att : "$elt->set_att( foo => "bar")" sets the "foo" attribute to
114 the "bar" value,
115 next_sibling: "$elt->{next_sibling}" return the next sibling in the
117 document (in the example "$title->{next_sibling}" is the first "para",
118 you can also (and actually should) use "$elt->next_sibling( 'para')" to
119 get it
120 The document can also be transformed through the use of the cut, copy,
122 paste and move methods: "$title->cut; $title->paste( after => $p);" for
123 example
124 And much, much more, see XML::Twig::Elt.
126 Processing an XML document chunk by chunk
128 One of the strengths of XML::Twig is that it let you work with files
129 that do not fit in memory (BTW storing an XML document in memory as a
130 tree is quite memory-expensive, the expansion factor being often around
131 10).
132 To do this you can define handlers, that will be called once a specific
134 element has been completely parsed. In these handlers you can access
135 the element and process it as you see fit, using the navigation and the
136 cut-n-paste methods, plus lots of convenient ones like "prefix ". Once
137 the element is completely processed you can then "flush " it, which
138 will output it and free the memory. You can also "purge " it if you
139 don't need to output it (if you are just extracting some data from the
140 document for example). The handler will be called again once the next
141 relevant element has been parsed.
142 my $t= XML::Twig->new( twig_handlers =>
144 { section => \§ion,
145 para => sub { $_->set_tag( 'p'); }
146 },
147 );
148 $t->parsefile( 'doc.xml');
149 # the handler is called once a section is completely parsed, ie when
151 # the end tag for section is found, it receives the twig itself and
152 # the element (including all its sub-elements) as arguments
153 sub section
154 { my( $t, $section)= @_; # arguments for all twig_handlers
155 $section->set_tag( 'div'); # change the tag name
156 # let's use the attribute nb as a prefix to the title
157 my $title= $section->first_child( 'title'); # find the title
158 my $nb= $title->{'att'}->{'nb'}; # get the attribute
159 $title->prefix( "$nb - "); # easy isn't it?
160 $section->flush; # outputs the section and frees memory
161 }
162 There is of course more to it: you can trigger handlers on more
164 elaborate conditions than just the name of the element, "section/title"
165 for example.
166 my $t= XML::Twig->new( twig_handlers =>
168 { 'section/title' => sub { $_->print } }
169 )
170 ->parsefile( 'doc.xml');
171 Here "sub { $_->print }" simply prints the current element ($_ is
173 aliased to the element in the handler).
174 You can also trigger a handler on a test on an attribute:
176 my $t= XML::Twig->new( twig_handlers =>
178 { 'section[@level="1"]' => sub { $_->print } }
179 );
180 ->parsefile( 'doc.xml');
181 You can also use "start_tag_handlers " to process an element as soon as
183 the start tag is found. Besides "prefix " you can also use "suffix ",
184 Processing just parts of an XML document
186 The twig_roots mode builds only the required sub-trees from the
187 document Anything outside of the twig roots will just be ignored:
188 my $t= XML::Twig->new(
190 # the twig will include just the root and selected titles
191 twig_roots => { 'section/title' => \&print_n_purge,
192 'annex/title' => \&print_n_purge
193 }
194 );
195 $t->parsefile( 'doc.xml');
196 sub print_n_purge
198 { my( $t, $elt)= @_;
199 print $elt->text; # print the text (including sub-element texts)
200 $t->purge; # frees the memory
201 }
202 You can use that mode when you want to process parts of a documents but
204 are not interested in the rest and you don't want to pay the price,
205 either in time or memory, to build the tree for the it.
206 Building an XML filter
208 You can combine the "twig_roots" and the "twig_print_outside_roots"
209 options to build filters, which let you modify selected elements and
210 will output the rest of the document as is.
211 This would convert prices in $ to prices in Euro in a document:
213 my $t= XML::Twig->new(
215 twig_roots => { 'price' => \&convert, }, # process prices
216 twig_print_outside_roots => 1, # print the rest
217 );
218 $t->parsefile( 'doc.xml');
219 sub convert
221 { my( $t, $price)= @_;
222 my $currency= $price->{'att'}->{'currency'}; # get the currency
223 if( $currency eq 'USD')
224 { $usd_price= $price->text; # get the price
225 # %rate is just a conversion table
226 my $euro_price= $usd_price * $rate{usd2euro};
227 $price->set_text( $euro_price); # set the new price
228 $price->set_att( currency => 'EUR'); # don't forget this!
229 }
230 $price->print; # output the price
231 }
232 XML::Twig and various versions of Perl, XML::Parser and expat:
234 XML::Twig is a lot more sensitive to variations in versions of perl,
235 XML::Parser and expat than to the OS, so this should cover some
236 reasonable configurations.
237 The "recommended configuration" is perl 5.8.3+ (for good Unicode
239 support), XML::Parser 2.31+ and expat 1.95.5+
240 See <http://testers.cpan.org/search?request=dist&dist=XML-Twig> for the
242 CPAN testers reports on XML::Twig, which list all tested
243 configurations.
244 An Atom feed of the CPAN Testers results is available at
246 <http://xmltwig.org/rss/twig_testers.rss>
247 Finally:
249 XML::Twig does NOT work with expat 1.95.4
251 XML::Twig only works with XML::Parser 2.27 in perl 5.6.*
252 Note that I can't compile XML::Parser 2.27 anymore, so I can't
253 guarantee that it still works
254 XML::Parser 2.28 does not really work
256 When in doubt, upgrade expat, XML::Parser and Scalar::Util
258 Finally, for some optional features, XML::Twig depends on some
260 additional modules. The complete list, which depends somewhat on the
261 version of Perl that you are running, is given by running
262 "t/zz_dump_config.t"
263
265 Whitespaces
266 Whitespaces that look non-significant are discarded, this behaviour
267 can be controlled using the "keep_spaces ", "keep_spaces_in " and
268 "discard_spaces_in " options.
269 Encoding
271 You can specify that you want the output in the same encoding as
272 the input (provided you have valid XML, which means you have to
273 specify the encoding either in the document or when you create the
274 Twig object) using the "keep_encoding " option
275 You can also use "output_encoding" to convert the internal UTF-8
277 format to the required encoding.
278 Comments and Processing Instructions (PI)
280 Comments and PI's can be hidden from the processing, but still
281 appear in the output (they are carried by the "real" element closer
282 to them)
283 Pretty Printing
285 XML::Twig can output the document pretty printed so it is easier to
286 read for us humans.
287 Surviving an untimely death
289 XML parsers are supposed to react violently when fed improper XML.
290 XML::Parser just dies.
291 XML::Twig provides the "safe_parse " and the "safe_parsefile "
293 methods which wrap the parse in an eval and return either the
294 parsed twig or 0 in case of failure.
295 Private attributes
297 Attributes with a name starting with # (illegal in XML) will not be
298 output, so you can safely use them to store temporary values during
299 processing. Note that you can store anything in a private
300 attribute, not just text, it's just a regular Perl variable, so a
301 reference to an object or a huge data structure is perfectly fine.
302
304 XML::Twig uses a very limited number of classes. The ones you are most
305 likely to use are "XML::Twig" of course, which represents a complete
306 XML document, including the document itself (the root of the document
307 itself is "root"), its handlers, its input or output filters... The
308 other main class is "XML::Twig::Elt", which models an XML element.
309 Element here has a very wide definition: it can be a regular element,
310 or but also text, with an element "tag" of "#PCDATA" (or "#CDATA"), an
311 entity (tag is "#ENT"), a Processing Instruction ("#PI"), a comment
312 ("#COMMENT").
313 Those are the 2 commonly used classes.
315 You might want to look the "elt_class" option if you want to subclass
317 "XML::Twig::Elt".
318 Attributes are just attached to their parent element, they are not
320 objects per se. (Please use the provided methods "att" and "set_att" to
321 access them, if you access them as a hash, then your code becomes
322 implementation dependent and might break in the future).
323 Other classes that are seldom used are "XML::Twig::Entity_list" and
325 "XML::Twig::Entity".
326 If you use "XML::Twig::XPath" instead of "XML::Twig", elements are then
328 created as "XML::Twig::XPath::Elt"
329
331 XML::Twig
332 A twig is a subclass of XML::Parser, so all XML::Parser methods can be
333 called on a twig object, including parse and parsefile. "setHandlers"
334 on the other hand cannot be used, see "BUGS "
335 new This is a class method, the constructor for XML::Twig. Options are
337 passed as keyword value pairs. Recognized options are the same as
338 XML::Parser, plus some (in fact a lot!) XML::Twig specifics.
339 New Options:
341 twig_handlers
343 This argument consists of a hash "{ expression =" \&handler}>
344 where expression is a an XPath-like expression (+ some others).
345 XPath expressions are limited to using the child and descendant
347 axis (indeed you can't specify an axis), and predicates cannot
348 be nested. You can use the "string", or "string(<tag>)"
349 function (except in "twig_roots" triggers).
350 Additionally you can use regexps (/ delimited) to match
352 attribute and string values.
353 Examples:
355 foo
357 foo/bar
358 foo//bar
359 /foo/bar
360 /foo//bar
361 /foo/bar[@att1 = "val1" and @att2 = "val2"]/baz[@a >= 1]
362 foo[string()=~ /^duh!+/]
363 /foo[string(bar)=~ /\d+/]/baz[@att != 3]
364 #CDATA can be used to call a handler for a CDATA section.
366 #COMMENT can be used to call a handler for comments
367 Some additional (non-XPath) expressions are also provided for
369 convenience:
370 processing instructions
372 '?' or '#PI' triggers the handler for any processing
373 instruction, and '?<target>' or '#PI <target>' triggers a
374 handler for processing instruction with the given target(
375 ex: '#PI xml-stylesheet').
376 level(<level>)
378 Triggers the handler on any element at that level in the
379 tree (root is level 1)
380 _all_
382 Triggers the handler for all elements in the tree
383 _default_
385 Triggers the handler for each element that does NOT have
386 any other handler.
387 Expressions are evaluated against the input document. Which
389 means that even if you have changed the tag of an element
390 (changing the tag of a parent element from a handler for
391 example) the change will not impact the expression evaluation.
392 There is an exception to this: "private" attributes (which name
393 start with a '#', and can only be created during the parsing,
394 as they are not valid XML) are checked against the current
395 twig.
396 Handlers are triggered in fixed order, sorted by their type
398 (xpath expressions first, then regexps, then level), then by
399 whether they specify a full path (starting at the root element)
400 or not, then by number of steps in the expression, then number
401 of predicates, then number of tests in predicates. Handlers
402 where the last step does not specify a step ("foo/bar/*") are
403 triggered after other XPath handlers. Finally "_all_" handlers
404 are triggered last.
405 Important: once a handler has been triggered if it returns 0
407 then no other handler is called, except a "_all_" handler which
408 will be called anyway.
409 If a handler returns a true value and other handlers apply,
411 then the next applicable handler will be called. Repeat, rinse,
412 lather..; The exception to that rule is when the
413 "do_not_chain_handlers" option is set, in which case only the
414 first handler will be called.
415 Note that it might be a good idea to explicitly return a short
417 true value (like 1) from handlers: this ensures that other
418 applicable handlers are called even if the last statement for
419 the handler happens to evaluate to false. This might also
420 speedup the code by avoiding the result of the last statement
421 of the code to be copied and passed to the code managing
422 handlers. It can really pay to have 1 instead of a long string
423 returned.
424 When the closing tag for an element is parsed the corresponding
426 handler is called, with 2 arguments: the twig and the "Element
427 ". The twig includes the document tree that has been built so
428 far, the element is the complete sub-tree for the element. The
429 fact that the handler is called only when the closing tag for
430 the element is found means that handlers for inner elements are
431 called before handlers for outer elements.
432 $_ is also set to the element, so it is easy to write inline
434 handlers like
435 para => sub { $_->set_tag( 'p'); }
437 Text is stored in elements whose tag name is #PCDATA (due to
439 mixed content, text and sub-element in an element there is no
440 way to store the text as just an attribute of the enclosing
441 element, this is similar to the DOM model).
442 Warning: if you have used purge or flush on the twig the
444 element might not be complete, some of its children might have
445 been entirely flushed or purged, and the start tag might even
446 have been printed (by "flush") already, so changing its tag
447 might not give the expected result.
448 twig_roots
450 This argument let's you build the tree only for those elements
451 you are interested in.
452 Example: my $t= XML::Twig->new( twig_roots => { title => 1, subtitle => 1});
454 $t->parsefile( file);
455 my $t= XML::Twig->new( twig_roots => { 'section/title' => 1});
456 $t->parsefile( file);
457 return a twig containing a document including only "title" and
459 "subtitle" elements, as children of the root element.
460 You can use generic_attribute_condition, attribute_condition,
462 full_path, partial_path, tag, tag_regexp, _default_ and _all_
463 to trigger the building of the twig. string_condition and
464 regexp_condition cannot be used as the content of the element,
465 and the string, have not yet been parsed when the condition is
466 checked.
467 WARNING: path are checked for the document. Even if the
469 "twig_roots" option is used they will be checked against the
470 full document tree, not the virtual tree created by XML::Twig
471 WARNING: twig_roots elements should NOT be nested, that would
473 hopelessly confuse XML::Twig ;--(
474 Note: you can set handlers (twig_handlers) using twig_roots
476 Example: my $t= XML::Twig->new( twig_roots =>
477 { title => sub {
478 $_[1]->print;},
479 subtitle =>
480 \&process_subtitle
481 }
482 );
483 $t->parsefile( file);
484 twig_print_outside_roots
486 To be used in conjunction with the "twig_roots" argument. When
487 set to a true value this will print the document outside of the
488 "twig_roots" elements.
489 Example: my $t= XML::Twig->new( twig_roots => { title => \&number_title },
491 twig_print_outside_roots => 1,
492 );
493 $t->parsefile( file);
494 { my $nb;
495 sub number_title
496 { my( $twig, $title);
497 $nb++;
498 $title->prefix( "$nb ");
499 $title->print;
500 }
501 }
502 This example prints the document outside of the title element,
504 calls "number_title" for each "title" element, prints it, and
505 then resumes printing the document. The twig is built only for
506 the "title" elements.
507 If the value is a reference to a file handle then the document
509 outside the "twig_roots" elements will be output to this file
510 handle:
511 open( my $out, '>', 'out_file.xml') or die "cannot open out file.xml out_file:$!";
513 my $t= XML::Twig->new( twig_roots => { title => \&number_title },
514 # default output to $out
515 twig_print_outside_roots => $out,
516 );
517 { my $nb;
519 sub number_title
520 { my( $twig, $title);
521 $nb++;
522 $title->prefix( "$nb ");
523 $title->print( $out); # you have to print to \*OUT here
524 }
525 }
526 start_tag_handlers
528 A hash "{ expression =" \&handler}>. Sets element handlers that
529 are called when the element is open (at the end of the
530 XML::Parser "Start" handler). The handlers are called with 2
531 params: the twig and the element. The element is empty at that
532 point, its attributes are created though.
533 You can use generic_attribute_condition, attribute_condition,
535 full_path, partial_path, tag, tag_regexp, _default_ and _all_
536 to trigger the handler.
537 string_condition and regexp_condition cannot be used as the
539 content of the element, and the string, have not yet been
540 parsed when the condition is checked.
541 The main uses for those handlers are to change the tag name
543 (you might have to do it as soon as you find the open tag if
544 you plan to "flush" the twig at some point in the element, and
545 to create temporary attributes that will be used when
546 processing sub-element with "twig_hanlders".
547 Note: "start_tag" handlers can be called outside of
549 "twig_roots" if this argument is used. Since the element object
550 is not built, in this case handlers are called with the
551 following arguments: $t (the twig), $tag (the tag of the
552 element) and %att (a hash of the attributes of the element).
553 If the "twig_print_outside_roots" argument is also used, if the
555 last handler called returns a "true" value, then the start tag
556 will be output as it appeared in the original document, if the
557 handler returns a "false" value then the start tag will not be
558 printed (so you can print a modified string yourself for
559 example).
560 Note that you can use the ignore method in "start_tag_handlers"
562 (and only there).
563 end_tag_handlers
565 A hash "{ expression =" \&handler}>. Sets element handlers that
566 are called when the element is closed (at the end of the
567 XML::Parser "End" handler). The handlers are called with 2
568 params: the twig and the tag of the element.
569 twig_handlers are called when an element is completely parsed,
571 so why have this redundant option? There is only one use for
572 "end_tag_handlers": when using the "twig_roots" option, to
573 trigger a handler for an element outside the roots. It is for
574 example very useful to number titles in a document using nested
575 sections:
576 my @no= (0);
578 my $no;
579 my $t= XML::Twig->new(
580 start_tag_handlers =>
581 { section => sub { $no[$#no]++; $no= join '.', @no; push @no, 0; } },
582 twig_roots =>
583 { title => sub { $_->prefix( $no); $_->print; } },
584 end_tag_handlers => { section => sub { pop @no; } },
585 twig_print_outside_roots => 1
586 );
587 $t->parsefile( $file);
588 Using the "end_tag_handlers" argument without "twig_roots" will
590 result in an error.
591 do_not_chain_handlers
593 If this option is set to a true value, then only one handler
594 will be called for each element, even if several satisfy the
595 condition
596 Note that the "_all_" handler will still be called regardless
598 ignore_elts
600 This option lets you ignore elements when building the twig.
601 This is useful in cases where you cannot use "twig_roots" to
602 ignore elements, for example if the element to ignore is a
603 sibling of elements you are interested in.
604 Example:
606 my $twig= XML::Twig->new( ignore_elts => { elt => 'discard' });
608 $twig->parsefile( 'doc.xml');
609 This will build the complete twig for the document, except that
611 all "elt" elements (and their children) will be left out.
612 The keys in the hash are triggers, limited to the same subset
614 as "start_tag_handlers". The values can be "discard", to
615 discard the element, "print", to output the element as-is,
616 "string" to store the text of the ignored element(s), including
617 markup, in a field of the twig: "$t->{twig_buffered_string}" or
618 a reference to a scalar, in which case the text of the ignored
619 element(s), including markup, will be stored in the scalar. Any
620 other value will be treated as "discard".
621 char_handler
623 A reference to a subroutine that will be called every time
624 "PCDATA" is found.
625 The subroutine receives the string as argument, and returns the
627 modified string:
628 # WE WANT ALL STRINGS IN UPPER CASE
630 sub my_char_handler
631 { my( $text)= @_;
632 $text= uc( $text);
633 return $text;
634 }
635 elt_class
637 The name of a class used to store elements. this class should
638 inherit from "XML::Twig::Elt" (and by default it is
639 "XML::Twig::Elt"). This option is used to subclass the element
640 class and extend it with new methods.
641 This option is needed because during the parsing of the XML,
643 elements are created by "XML::Twig", without any control from
644 the user code.
645 keep_atts_order
647 Setting this option to a true value causes the attribute hash
648 to be tied to a "Tie::IxHash" object. This means that
649 "Tie::IxHash" needs to be installed for this option to be
650 available. It also means that the hash keeps its order, so you
651 will get the attributes in order. This allows outputting the
652 attributes in the same order as they were in the original
653 document.
654 keep_encoding
656 This is a (slightly?) evil option: if the XML document is not
657 UTF-8 encoded and you want to keep it that way, then setting
658 keep_encoding will use the"Expat" original_string method for
659 character, thus keeping the original encoding, as well as the
660 original entities in the strings.
661 See the "t/test6.t" test file to see what results you can
663 expect from the various encoding options.
664 WARNING: if the original encoding is multi-byte then attribute
666 parsing will be EXTREMELY unsafe under any Perl before 5.6, as
667 it uses regular expressions which do not deal properly with
668 multi-byte characters. You can specify an alternate function to
669 parse the start tags with the "parse_start_tag" option (see
670 below)
671 WARNING: this option is NOT used when parsing with XML::Parser
673 non-blocking parser ("parse_start", "parse_more", "parse_done"
674 methods) which you probably should not use with XML::Twig
675 anyway as they are totally untested!
676 output_encoding
678 This option generates an output_filter using "Encode",
679 "Text::Iconv" or "Unicode::Map8" and "Unicode::Strings", and
680 sets the encoding in the XML declaration. This is the easiest
681 way to deal with encodings, if you need more sophisticated
682 features, look at "output_filter" below
683 output_filter
685 This option is used to convert the character encoding of the
686 output document. It is passed either a string corresponding to
687 a predefined filter or a subroutine reference. The filter will
688 be called every time a document or element is processed by the
689 "print" functions ("print", "sprint", "flush").
690 Pre-defined filters:
692 latin1
694 uses either "Encode", "Text::Iconv" or "Unicode::Map8" and
695 "Unicode::String" or a regexp (which works only with
696 XML::Parser 2.27), in this order, to convert all characters
697 to ISO-8859-15 (usually latin1 is synonym to ISO-8859-1,
698 but in practice it seems that ISO-8859-15, which includes
699 the euro sign, is more useful and probably what most people
700 want).
701 html
703 does the same conversion as "latin1", plus encodes entities
704 using "HTML::Entities" (oddly enough you will need to have
705 HTML::Entities installed for it to be available). This
706 should only be used if the tags and attribute names
707 themselves are in US-ASCII, or they will be converted and
708 the output will not be valid XML any more
709 safe
711 converts the output to ASCII (US) only plus character
712 entities ("&#nnn;") this should be used only if the tags
713 and attribute names themselves are in US-ASCII, or they
714 will be converted and the output will not be valid XML any
715 more
716 safe_hex
718 same as "safe" except that the character entities are in
719 hex ("&#xnnn;")
720 encode_convert ($encoding)
722 Return a subref that can be used to convert utf8 strings to
723 $encoding). Uses "Encode".
724 my $conv = XML::Twig::encode_convert( 'latin1');
726 my $t = XML::Twig->new(output_filter => $conv);
727 iconv_convert ($encoding)
729 this function is used to create a filter subroutine that
730 will be used to convert the characters to the target
731 encoding using "Text::Iconv" (which needs to be installed,
732 look at the documentation for the module and for the
733 "iconv" library to find out which encodings are available
734 on your system, "iconv -l" should give you a list of
735 available encodings)
736 my $conv = XML::Twig::iconv_convert( 'latin1');
738 my $t = XML::Twig->new(output_filter => $conv);
739 unicode_convert ($encoding)
741 this function is used to create a filter subroutine that
742 will be used to convert the characters to the target
743 encoding using "Unicode::Strings" and "Unicode::Map8"
744 (which need to be installed, look at the documentation for
745 the modules to find out which encodings are available on
746 your system)
747 my $conv = XML::Twig::unicode_convert( 'latin1');
749 my $t = XML::Twig->new(output_filter => $conv);
750 The "text" and "att" methods do not use the filter, so their
752 result are always in unicode.
753 Those predeclared filters are based on subroutines that can be
755 used by themselves (as "XML::Twig::foo").
756 html_encode ($string)
758 Use "HTML::Entities" to encode a utf8 string
759 safe_encode ($string)
761 Use either a regexp (perl < 5.8) or "Encode" to encode non-
762 ascii characters in the string in "&#<nnnn>;" format
763 safe_encode_hex ($string)
765 Use either a regexp (perl < 5.8) or "Encode" to encode non-
766 ascii characters in the string in "&#x<nnnn>;" format
767 regexp2latin1 ($string)
769 Use a regexp to encode a utf8 string into latin 1
770 (ISO-8859-1). Does not work with Perl 5.8.0!
771 output_text_filter
773 same as output_filter, except it doesn't apply to the brackets
774 and quotes around attribute values. This is useful for all
775 filters that could change the tagging, basically anything that
776 does not just change the encoding of the output. "html", "safe"
777 and "safe_hex" are better used with this option.
778 input_filter
780 This option is similar to "output_filter" except the filter is
781 applied to the characters before they are stored in the twig,
782 at parsing time.
783 remove_cdata
785 Setting this option to a true value will force the twig to
786 output CDATA sections as regular (escaped) PCDATA
787 parse_start_tag
789 If you use the "keep_encoding" option then this option can be
790 used to replace the default parsing function. You should
791 provide a coderef (a reference to a subroutine) as the
792 argument, this subroutine takes the original tag (given by
793 XML::Parser::Expat "original_string()" method) and returns a
794 tag and the attributes in a hash (or in a list
795 attribute_name/attribute value).
796 no_xxe
798 prevents external entities to be parsed.
799 This is a security feature, in case the input XML cannot be
801 trusted. With this option set to a true value defining external
802 entities in the document will cause the parse to fail.
803 This prevents an entity like "<!ENTITY xxe PUBLIC "bar"
805 "/etc/passwd">" to make the password fiel available in the
806 document.
807 expand_external_ents
809 When this option is used external entities (that are defined)
810 are expanded when the document is output using "print"
811 functions such as "print ", "sprint ", "flush " and "xml_string
812 ". Note that in the twig the entity will be stored as an
813 element with a tag '"#ENT"', the entity will not be expanded
814 there, so you might want to process the entities before
815 outputting it.
816 If an external entity is not available, then the parse will
818 fail.
819 A special case is when the value of this option is -1. In that
821 case a missing entity will not cause the parser to die, but its
822 "name", "sysid" and "pubid" will be stored in the twig as
823 "$twig->{twig_missing_system_entities}" (a reference to an
824 array of hashes { name => <name>, sysid => <sysid>, pubid =>
825 <pubid> }). Yes, this is a bit of a hack, but it's useful in
826 some cases.
827 load_DTD
829 If this argument is set to a true value, "parse" or "parsefile"
830 on the twig will load the DTD information. This information
831 can then be accessed through the twig, in a "DTD_handler" for
832 example. This will load even an external DTD.
833 Default and fixed values for attributes will also be filled,
835 based on the DTD.
836 Note that to do this the module will generate a temporary file
838 in the current directory. If this is a problem let me know and
839 I will add an option to specify an alternate directory.
840 See "DTD Handling" for more information
842 DTD_base <path_to_DTD_directory>
844 If the DTD is in a different directory, looks for it there,
845 useful to make up somewhat for the lack of catalog suport in
846 "expat". You still need a SYSTEM declaration
847 DTD_handler
849 Set a handler that will be called once the doctype (and the
850 DTD) have been loaded, with 2 arguments, the twig and the DTD.
851 no_prolog
853 Does not output a prolog (XML declaration and DTD)
854 id This optional argument gives the name of an attribute that can
856 be used as an ID in the document. Elements whose ID is known
857 can be accessed through the elt_id method. id defaults to 'id'.
858 See "BUGS "
859 discard_spaces
861 If this optional argument is set to a true value then spaces
862 are discarded when they look non-significant: strings
863 containing only spaces and at least one line feed are
864 discarded. This argument is set to true by default.
865 The exact algorithm to drop spaces is: strings including only
867 spaces (perl \s) and at least one \n right before an open or
868 close tag are dropped.
869 discard_all_spaces
871 If this argument is set to a true value, spaces are discarded
872 more aggressively than with "discard_spaces": strings not
873 including a \n are also dropped. This option is appropriate for
874 data-oriented XML.
875 keep_spaces
877 If this optional argument is set to a true value then all
878 spaces in the document are kept, and stored as "PCDATA".
879 Warning: adding this option can result in changes in the twig
881 generated: space that was previously discarded might end up in
882 a new text element. see the difference by calling the following
883 code with 0 and 1 as arguments:
884 perl -MXML::Twig -e'print XML::Twig->new( keep_spaces => shift)->parse( "<d> \n<e/></d>")->_dump'
886 "keep_spaces" and "discard_spaces" cannot be both set.
888 discard_spaces_in
890 This argument sets "keep_spaces" to true but will cause the
891 twig builder to discard spaces in the elements listed.
892 The syntax for using this argument is:
894 XML::Twig->new( discard_spaces_in => [ 'elt1', 'elt2']);
896 keep_spaces_in
898 This argument sets "discard_spaces" to true but will cause the
899 twig builder to keep spaces in the elements listed.
900 The syntax for using this argument is:
902 XML::Twig->new( keep_spaces_in => [ 'elt1', 'elt2']);
904 Warning: adding this option can result in changes in the twig
906 generated: space that was previously discarded might end up in
907 a new text element.
908 pretty_print
910 Set the pretty print method, amongst '"none"' (default),
911 '"nsgmls"', '"nice"', '"indented"', '"indented_c"',
912 '"indented_a"', '"indented_close_tag"', '"cvs"', '"wrapped"',
913 '"record"' and '"record_c"'
914 pretty_print formats:
916 none
918 The document is output as one ling string, with no line
919 breaks except those found within text elements
920 nsgmls
922 Line breaks are inserted in safe places: that is within
923 tags, between a tag and an attribute, between attributes
924 and before the > at the end of a tag.
925 This is quite ugly but better than "none", and it is very
927 safe, the document will still be valid (conforming to its
928 DTD).
929 This is how the SGML parser "sgmls" splits documents, hence
931 the name.
932 nice
934 This option inserts line breaks before any tag that does
935 not contain text (so element with textual content are not
936 broken as the \n is the significant).
937 WARNING: this option leaves the document well-formed but
939 might make it invalid (not conformant to its DTD). If you
940 have elements declared as
941 <!ELEMENT foo (#PCDATA|bar)>
943 then a "foo" element including a "bar" one will be printed
945 as
946 <foo>
948 <bar>bar is just pcdata</bar>
949 </foo>
950 This is invalid, as the parser will take the line break
952 after the "foo" tag as a sign that the element contains
953 PCDATA, it will then die when it finds the "bar" tag. This
954 may or may not be important for you, but be aware of it!
955 indented
957 Same as "nice" (and with the same warning) but indents
958 elements according to their level
959 indented_c
961 Same as "indented" but a little more compact: the closing
962 tags are on the same line as the preceding text
963 indented_close_tag
965 Same as "indented" except that the closing tag is also
966 indented, to line up with the tags within the element
967 idented_a
969 This formats XML files in a line-oriented version control
970 friendly way. The format is described in
971 <http://tinyurl.com/2kwscq> (that's an Oracle document with
972 an insanely long URL).
973 Note that to be totaly conformant to the "spec", the order
975 of attributes should not be changed, so if they are not
976 already in alphabetical order you will need to use the
977 "keep_atts_order" option.
978 cvs Same as "idented_a".
980 wrapped
982 Same as "indented_c" but lines are wrapped using
983 Text::Wrap::wrap. The default length for lines is the
984 default for $Text::Wrap::columns, and can be changed by
985 changing that variable.
986 record
988 This is a record-oriented pretty print, that display data
989 in records, one field per line (which looks a LOT like
990 "indented")
991 record_c
993 Stands for record compact, one record per line
994 empty_tags
996 Set the empty tag display style ('"normal"', '"html"' or
997 '"expand"').
998 "normal" outputs an empty tag '"<tag/>"', "html" adds a space
1000 '"<tag />"' for elements that can be empty in XHTML and
1001 "expand" outputs '"<tag></tag>"'
1002 quote
1004 Set the quote character for attributes ('"single"' or
1005 '"double"').
1006 escape_gt
1008 By default XML::Twig does not escape the character > in its
1009 output, as it is not mandated by the XML spec. With this option
1010 on, > will be replaced by ">"
1011 comments
1013 Set the way comments are processed: '"drop"' (default),
1014 '"keep"' or '"process"'
1015 Comments processing options:
1017 drop
1019 drops the comments, they are not read, nor printed to the
1020 output
1021 keep
1023 comments are loaded and will appear on the output, they are
1024 not accessible within the twig and will not interfere with
1025 processing though
1026 Note: comments in the middle of a text element such as
1028 <p>text <!-- comment --> more text --></p>
1030 are kept at their original position in the text. Using
1032 ˝"print" methods like "print" or "sprint" will return the
1033 comments in the text. Using "text" or "field" on the other
1034 hand will not.
1035 Any use of "set_pcdata" on the "#PCDATA" element (directly
1037 or through other methods like "set_content") will delete
1038 the comment(s).
1039 process
1041 comments are loaded in the twig and will be treated as
1042 regular elements (their "tag" is "#COMMENT") this can
1043 interfere with processing if you expect
1044 "$elt->{first_child}" to be an element but find a comment
1045 there. Validation will not protect you from this as
1046 comments can happen anywhere. You can use
1047 "$elt->first_child( 'tag')" (which is a good habit anyway)
1048 to get where you want.
1049 Consider using "process" if you are outputting SAX events
1051 from XML::Twig.
1052 pi Set the way processing instructions are processed: '"drop"',
1054 '"keep"' (default) or '"process"'
1055 Note that you can also set PI handlers in the "twig_handlers"
1057 option:
1058 '?' => \&handler
1060 '?target' => \&handler 2
1061 The handlers will be called with 2 parameters, the twig and the
1063 PI element if "pi" is set to "process", and with 3, the twig,
1064 the target and the data if "pi" is set to "keep". Of course
1065 they will not be called if "pi" is set to "drop".
1066 If "pi" is set to "keep" the handler should return a string
1068 that will be used as-is as the PI text (it should look like ""
1069 <?target data?" >" or '' if you want to remove the PI),
1070 Only one handler will be called, "?target" or "?" if no
1072 specific handler for that target is available.
1073 map_xmlns
1075 This option is passed a hashref that maps uri's to prefixes.
1076 The prefixes in the document will be replaced by the ones in
1077 the map. The mapped prefixes can (actually have to) be used to
1078 trigger handlers, navigate or query the document.
1079 Here is an example:
1081 my $t= XML::Twig->new( map_xmlns => {'http://www.w3.org/2000/svg' => "svg"},
1083 twig_handlers =>
1084 { 'svg:circle' => sub { $_->set_att( r => 20) } },
1085 pretty_print => 'indented',
1086 )
1087 ->parse( '<doc xmlns:gr="http://www.w3.org/2000/svg">
1088 <gr:circle cx="10" cy="90" r="10"/>
1089 </doc>'
1090 )
1091 ->print;
1092 This will output:
1094 <doc xmlns:svg="http://www.w3.org/2000/svg">
1096 <svg:circle cx="10" cy="90" r="20"/>
1097 </doc>
1098 keep_original_prefix
1100 When used with "map_xmlns" this option will make "XML::Twig"
1101 use the original namespace prefixes when outputting a document.
1102 The mapped prefix will still be used for triggering handlers
1103 and in navigation and query methods.
1104 my $t= XML::Twig->new( map_xmlns => {'http://www.w3.org/2000/svg' => "svg"},
1106 twig_handlers =>
1107 { 'svg:circle' => sub { $_->set_att( r => 20) } },
1108 keep_original_prefix => 1,
1109 pretty_print => 'indented',
1110 )
1111 ->parse( '<doc xmlns:gr="http://www.w3.org/2000/svg">
1112 <gr:circle cx="10" cy="90" r="10"/>
1113 </doc>'
1114 )
1115 ->print;
1116 This will output:
1118 <doc xmlns:gr="http://www.w3.org/2000/svg">
1120 <gr:circle cx="10" cy="90" r="20"/>
1121 </doc>
1122 original_uri ($prefix)
1124 called within a handler, this will return the uri bound to the
1125 namespace prefix in the original document.
1126 index ($arrayref or $hashref)
1128 This option creates lists of specific elements during the
1129 parsing of the XML. It takes a reference to either a list of
1130 triggering expressions or to a hash name => expression, and for
1131 each one generates the list of elements that match the
1132 expression. The list can be accessed through the "index"
1133 method.
1134 example:
1136 # using an array ref
1138 my $t= XML::Twig->new( index => [ 'div', 'table' ])
1139 ->parsefile( "foo.xml");
1140 my $divs= $t->index( 'div');
1141 my $first_div= $divs->[0];
1142 my $last_table= $t->index( table => -1);
1143 # using a hashref to name the indexes
1145 my $t= XML::Twig->new( index => { email => 'a[@href=~/^ \s*mailto:/]'})
1146 ->parsefile( "foo.xml");
1147 my $last_emails= $t->index( email => -1);
1148 Note that the index is not maintained after the parsing. If
1150 elements are deleted, renamed or otherwise hurt during
1151 processing, the index is NOT updated. (changing the id element
1152 OTOH will update the index)
1153 att_accessors <list of attribute names>
1155 creates methods that give direct access to attribute:
1156 my $t= XML::Twig->new( att_accessors => [ 'href', 'src'])
1158 ->parsefile( $file);
1159 my $first_href= $t->first_elt( 'img')->src; # same as ->att( 'src')
1160 $t->first_elt( 'img')->src( 'new_logo.png') # changes the attribute value
1161 elt_accessors
1163 creates methods that give direct access to the first child
1164 element (in scalar context) or the list of elements (in list
1165 context):
1166 the list of accessors to create can be given 1 2 different
1168 ways: in an array, or in a hash alias => expression
1169 my $t= XML::Twig->new( elt_accessors => [ 'head'])
1170 ->parsefile( $file);
1171 my $title_text= $t->root->head->field( 'title');
1172 # same as $title_text= $t->root->first_child( 'head')->field(
1173 'title');
1174 my $t= XML::Twig->new( elt_accessors => { warnings => 'p[@class="warning"]', d2 => 'div[2]'}, )
1176 ->parsefile( $file);
1177 my $body= $t->first_elt( 'body');
1178 my @warnings= $body->warnings; # same as $body->children( 'p[@class="warning"]');
1179 my $s2= $body->d2; # same as $body->first_child( 'div[2]')
1180 field_accessors
1182 creates methods that give direct access to the first child
1183 element text:
1184 my $t= XML::Twig->new( field_accessors => [ 'h1'])
1186 ->parsefile( $file);
1187 my $div_title_text= $t->first_elt( 'div')->title;
1188 # same as $title_text= $t->first_elt( 'div')->field( 'title');
1189 use_tidy
1191 set this option to use HTML::Tidy instead of HTML::TreeBuilder
1192 to convert HTML to XML. HTML, especially real (real "crap")
1193 HTML found in the wild, so depending on the data, one module or
1194 the other does a better job at the conversion. Also, HTML::Tidy
1195 can be a bit difficult to install, so XML::Twig offers both
1196 option. TIMTOWTDI
1197 output_html_doctype
1199 when using HTML::TreeBuilder to convert HTML, this option
1200 causes the DOCTYPE declaration to be output, which may be
1201 important for some legacy browsers. Without that option the
1202 DOCTYPE definition is NOT output. Also if the definition is
1203 completely wrong (ie not easily parsable), it is not output
1204 either.
1205 Note: I _HATE_ the Java-like name of arguments used by most XML
1207 modules. So in pure TIMTOWTDI fashion all arguments can be written
1208 either as "UglyJavaLikeName" or as "readable_perl_name":
1209 "twig_print_outside_roots" or "TwigPrintOutsideRoots" (or even
1210 "twigPrintOutsideRoots" {shudder}). XML::Twig normalizes them
1211 before processing them.
1212 parse ( $source)
1214 The $source parameter should either be a string containing the
1215 whole XML document, or it should be an open "IO::Handle" (aka a
1216 filehandle).
1217 A die call is thrown if a parse error occurs. Otherwise it will
1219 return the twig built by the parse. Use "safe_parse" if you want
1220 the parsing to return even when an error occurs.
1221 If this method is called as a class method ("XML::Twig->parse(
1223 $some_xml_or_html)") then an XML::Twig object is created, using the
1224 parameters except the last one (eg "XML::Twig->parse( pretty_print
1225 => 'indented', $some_xml_or_html)") and "xparse" is called on it.
1226 Note that when parsing a filehandle, the handle should NOT be open
1228 with an encoding (ie open with "open( my $in, '<', $filename)". The
1229 file will be parsed by "expat", so specifying the encoding actually
1230 causes problems for the parser (as in: it can crash it, see
1231 https://rt.cpan.org/Ticket/Display.html?id=78877). For parsing a
1232 file it is actually recommended to use "parsefile" on the file
1233 name, instead of <parse> on the open file.
1234 parsestring
1236 This is just an alias for "parse" for backwards compatibility.
1237 parsefile (FILE [, OPT => OPT_VALUE [...]])
1239 Open "FILE" for reading, then call "parse" with the open handle.
1240 The file is closed no matter how "parse" returns.
1241 A "die" call is thrown if a parse error occurs. Otherwise it will
1243 return the twig built by the parse. Use "safe_parsefile" if you
1244 want the parsing to return even when an error occurs.
1245 parsefile_inplace ( $file, $optional_extension)
1247 Parse and update a file "in place". It does this by creating a temp
1248 file, selecting it as the default for print() statements (and
1249 methods), then parsing the input file. If the parsing is
1250 successful, then the temp file is moved to replace the input file.
1251 If an extension is given then the original file is backed-up (the
1253 rules for the extension are the same as the rule for the -i option
1254 in perl).
1255 parsefile_html_inplace ( $file, $optional_extension)
1257 Same as parsefile_inplace, except that it parses HTML instead of
1258 XML
1259 parseurl ($url $optional_user_agent)
1261 Gets the data from $url and parse it. The data is piped to the
1262 parser in chunks the size of the XML::Parser::Expat buffer, so
1263 memory consumption and hopefully speed are optimal.
1264 For most (read "small") XML it is probably as efficient (and easier
1266 to debug) to just "get" the XML file and then parse it as a string.
1267 use XML::Twig;
1269 use LWP::Simple;
1270 my $twig= XML::Twig->new();
1271 $twig->parse( LWP::Simple::get( $URL ));
1272 or
1274 use XML::Twig;
1276 my $twig= XML::Twig->nparse( $URL);
1277 If the $optional_user_agent argument is used then it is used,
1279 otherwise a new one is created.
1280 safe_parse ( SOURCE [, OPT => OPT_VALUE [...]])
1282 This method is similar to "parse" except that it wraps the parsing
1283 in an "eval" block. It returns the twig on success and 0 on failure
1284 (the twig object also contains the parsed twig). $@ contains the
1285 error message on failure.
1286 Note that the parsing still stops as soon as an error is detected,
1288 there is no way to keep going after an error.
1289 safe_parsefile (FILE [, OPT => OPT_VALUE [...]])
1291 This method is similar to "parsefile" except that it wraps the
1292 parsing in an "eval" block. It returns the twig on success and 0 on
1293 failure (the twig object also contains the parsed twig) . $@
1294 contains the error message on failure
1295 Note that the parsing still stops as soon as an error is detected,
1297 there is no way to keep going after an error.
1298 safe_parseurl ($url $optional_user_agent)
1300 Same as "parseurl" except that it wraps the parsing in an "eval"
1301 block. It returns the twig on success and 0 on failure (the twig
1302 object also contains the parsed twig) . $@ contains the error
1303 message on failure
1304 parse_html ($string_or_fh)
1306 parse an HTML string or file handle (by converting it to XML using
1307 HTML::TreeBuilder, which needs to be available).
1308 This works nicely, but some information gets lost in the process:
1310 newlines are removed, and (at least on the version I use), comments
1311 get an extra CDATA section inside ( <!-- foo --> becomes <!--
1312 <![CDATA[ foo ]]> -->
1313 parsefile_html ($file)
1315 parse an HTML file (by converting it to XML using
1316 HTML::TreeBuilder, which needs to be available, or HTML::Tidy if
1317 the "use_tidy" option was used). The file is loaded completely in
1318 memory and converted to XML before being parsed.
1319 this method is to be used with caution though, as it doesn't know
1321 about the file encoding, it is usually better to use "parse_html",
1322 which gives you a chance to open the file with the proper encoding
1323 layer.
1324 parseurl_html ($url $optional_user_agent)
1326 parse an URL as html the same way "parse_html" does
1327 safe_parseurl_html ($url $optional_user_agent)
1329 Same as "parseurl_html"> except that it wraps the parsing in an
1330 "eval" block. It returns the twig on success and 0 on failure (the
1331 twig object also contains the parsed twig) . $@ contains the error
1332 message on failure
1333 safe_parsefile_html ($file $optional_user_agent)
1335 Same as "parsefile_html"> except that it wraps the parsing in an
1336 "eval" block. It returns the twig on success and 0 on failure (the
1337 twig object also contains the parsed twig) . $@ contains the error
1338 message on failure
1339 safe_parse_html ($string_or_fh)
1341 Same as "parse_html" except that it wraps the parsing in an "eval"
1342 block. It returns the twig on success and 0 on failure (the twig
1343 object also contains the parsed twig) . $@ contains the error
1344 message on failure
1345 xparse ($thing_to_parse)
1347 parse the $thing_to_parse, whether it is a filehandle, a string, an
1348 HTML file, an HTML URL, an URL or a file.
1349 Note that this is mostly a convenience method for one-off scripts.
1351 For example files that end in '.htm' or '.html' are parsed first as
1352 XML, and if this fails as HTML. This is certainly not the most
1353 efficient way to do this in general.
1354 nparse ($optional_twig_options, $thing_to_parse)
1356 create a twig with the $optional_options, and parse the
1357 $thing_to_parse, whether it is a filehandle, a string, an HTML
1358 file, an HTML URL, an URL or a file.
1359 Examples:
1361 XML::Twig->nparse( "file.xml");
1363 XML::Twig->nparse( error_context => 1, "file://file.xml");
1364 nparse_pp ($optional_twig_options, $thing_to_parse)
1366 same as "nparse" but also sets the "pretty_print" option to
1367 "indented".
1368 nparse_e ($optional_twig_options, $thing_to_parse)
1370 same as "nparse" but also sets the "error_context" option to 1.
1371 nparse_ppe ($optional_twig_options, $thing_to_parse)
1373 same as "nparse" but also sets the "pretty_print" option to
1374 "indented" and the "error_context" option to 1.
1375 parser
1377 This method returns the "expat" object (actually the
1378 XML::Parser::Expat object) used during parsing. It is useful for
1379 example to call XML::Parser::Expat methods on it. To get the line
1380 of a tag for example use "$t->parser->current_line".
1381 setTwigHandlers ($handlers)
1383 Set the twig_handlers. $handlers is a reference to a hash similar
1384 to the one in the "twig_handlers" option of new. All previous
1385 handlers are unset. The method returns the reference to the
1386 previous handlers.
1387 setTwigHandler ($exp $handler)
1389 Set a single twig_handler for elements matching $exp. $handler is a
1390 reference to a subroutine. If the handler was previously set then
1391 the reference to the previous handler is returned.
1392 setStartTagHandlers ($handlers)
1394 Set the start_tag handlers. $handlers is a reference to a hash
1395 similar to the one in the "start_tag_handlers" option of new. All
1396 previous handlers are unset. The method returns the reference to
1397 the previous handlers.
1398 setStartTagHandler ($exp $handler)
1400 Set a single start_tag handlers for elements matching $exp.
1401 $handler is a reference to a subroutine. If the handler was
1402 previously set then the reference to the previous handler is
1403 returned.
1404 setEndTagHandlers ($handlers)
1406 Set the end_tag handlers. $handlers is a reference to a hash
1407 similar to the one in the "end_tag_handlers" option of new. All
1408 previous handlers are unset. The method returns the reference to
1409 the previous handlers.
1410 setEndTagHandler ($exp $handler)
1412 Set a single end_tag handlers for elements matching $exp. $handler
1413 is a reference to a subroutine. If the handler was previously set
1414 then the reference to the previous handler is returned.
1415 setTwigRoots ($handlers)
1417 Same as using the "twig_roots" option when creating the twig
1418 setCharHandler ($exp $handler)
1420 Set a "char_handler"
1421 setIgnoreEltsHandler ($exp)
1423 Set a "ignore_elt" handler (elements that match $exp will be
1424 ignored
1425 setIgnoreEltsHandlers ($exp)
1427 Set all "ignore_elt" handlers (previous handlers are replaced)
1428 dtd Return the dtd (an XML::Twig::DTD object) of a twig
1430 xmldecl
1432 Return the XML declaration for the document, or a default one if it
1433 doesn't have one
1434 doctype
1436 Return the doctype for the document
1437 doctype_name
1439 returns the doctype of the document from the doctype declaration
1440 system_id
1442 returns the system value of the DTD of the document from the
1443 doctype declaration
1444 public_id
1446 returns the public doctype of the document from the doctype
1447 declaration
1448 internal_subset
1450 returns the internal subset of the DTD
1451 dtd_text
1453 Return the DTD text
1454 dtd_print
1456 Print the DTD
1457 model ($tag)
1459 Return the model (in the DTD) for the element $tag
1460 root
1462 Return the root element of a twig
1463 set_root ($elt)
1465 Set the root of a twig
1466 first_elt ($optional_condition)
1468 Return the first element matching $optional_condition of a twig, if
1469 no condition is given then the root is returned
1470 last_elt ($optional_condition)
1472 Return the last element matching $optional_condition of a twig, if
1473 no condition is given then the last element of the twig is returned
1474 elt_id ($id)
1476 Return the element whose "id" attribute is $id
1477 getEltById
1479 Same as "elt_id"
1480 index ($index_name, $optional_index)
1482 If the $optional_index argument is present, return the
1483 corresponding element in the index (created using the "index"
1484 option for "XML::Twig-"new>)
1485 If the argument is not present, return an arrayref to the index
1487 normalize
1489 merge together all consecutive pcdata elements in the document (if
1490 for example you have turned some elements into pcdata using
1491 "erase", this will give you a "clean" document in which there all
1492 text elements are as long as possible).
1493 encoding
1495 This method returns the encoding of the XML document, as defined by
1496 the "encoding" attribute in the XML declaration (ie it is "undef"
1497 if the attribute is not defined)
1498 set_encoding
1500 This method sets the value of the "encoding" attribute in the XML
1501 declaration. Note that if the document did not have a declaration
1502 it is generated (with an XML version of 1.0)
1503 xml_version
1505 This method returns the XML version, as defined by the "version"
1506 attribute in the XML declaration (ie it is "undef" if the attribute
1507 is not defined)
1508 set_xml_version
1510 This method sets the value of the "version" attribute in the XML
1511 declaration. If the declaration did not exist it is created.
1512 standalone
1514 This method returns the value of the "standalone" declaration for
1515 the document
1516 set_standalone
1518 This method sets the value of the "standalone" attribute in the XML
1519 declaration. Note that if the document did not have a declaration
1520 it is generated (with an XML version of 1.0)
1521 set_output_encoding
1523 Set the "encoding" "attribute" in the XML declaration
1524 set_doctype ($name, $system, $public, $internal)
1526 Set the doctype of the element. If an argument is "undef" (or not
1527 present) then its former value is retained, if a false ('' or 0)
1528 value is passed then the former value is deleted;
1529 entity_list
1531 Return the entity list of a twig
1532 entity_names
1534 Return the list of all defined entities
1535 entity ($entity_name)
1537 Return the entity
1538 notation_list
1540 Return the notation list of a twig
1541 notation_names
1543 Return the list of all defined notations
1544 notation ($notation_name)
1546 Return the notation
1547 change_gi ($old_gi, $new_gi)
1549 Performs a (very fast) global change. All elements $old_gi are now
1550 $new_gi. This is a bit dangerous though and should be avoided if <
1551 possible, as the new tag might be ignored in subsequent processing.
1552 See "BUGS "
1554 flush ($optional_filehandle, %options)
1556 Flushes a twig up to (and including) the current element, then
1557 deletes all unnecessary elements from the tree that's kept in
1558 memory. "flush" keeps track of which elements need to be
1559 open/closed, so if you flush from handlers you don't have to worry
1560 about anything. Just keep flushing the twig every time you're done
1561 with a sub-tree and it will come out well-formed. After the whole
1562 parsing don't forget to"flush" one more time to print the end of
1563 the document. The doctype and entity declarations are also
1564 printed.
1565 flush take an optional filehandle as an argument.
1567 If you use "flush" at any point during parsing, the document will
1569 be flushed one last time at the end of the parsing, to the proper
1570 filehandle.
1571 options: use the "update_DTD" option if you have updated the
1573 (internal) DTD and/or the entity list and you want the updated DTD
1574 to be output
1575 The "pretty_print" option sets the pretty printing of the document.
1577 Example: $t->flush( Update_DTD => 1);
1579 $t->flush( $filehandle, pretty_print => 'indented');
1580 $t->flush( \*FILE);
1581 flush_up_to ($elt, $optional_filehandle, %options)
1583 Flushes up to the $elt element. This allows you to keep part of the
1584 tree in memory when you "flush".
1585 options: see flush.
1587 purge
1589 Does the same as a "flush" except it does not print the twig. It
1590 just deletes all elements that have been completely parsed so far.
1591 purge_up_to ($elt)
1593 Purges up to the $elt element. This allows you to keep part of the
1594 tree in memory when you "purge".
1595 print ($optional_filehandle, %options)
1597 Prints the whole document associated with the twig. To be used only
1598 AFTER the parse.
1599 options: see "flush".
1601 print_to_file ($filename, %options)
1603 Prints the whole document associated with the twig to file
1604 $filename. To be used only AFTER the parse.
1605 options: see "flush".
1607 safe_print_to_file ($filename, %options)
1609 Prints the whole document associated with the twig to file
1610 $filename. This variant, which probably only works on *nix prints
1611 to a temp file, then move the temp file to overwrite the original
1612 file.
1613 This is a bit safer when 2 processes an potentiallywrite the same
1615 file: only the last one will succeed, but the file won't be
1616 corruted. I often use this for cron jobs, so testing the code
1617 doesn't interfere with the cron job running at the same time.
1618 options: see "flush".
1620 sprint
1622 Return the text of the whole document associated with the twig. To
1623 be used only AFTER the parse.
1624 options: see "flush".
1626 trim
1628 Trim the document: gets rid of initial and trailing spaces, and
1629 replaces multiple spaces by a single one.
1630 toSAX1 ($handler)
1632 Send SAX events for the twig to the SAX1 handler $handler
1633 toSAX2 ($handler)
1635 Send SAX events for the twig to the SAX2 handler $handler
1636 flush_toSAX1 ($handler)
1638 Same as flush, except that SAX events are sent to the SAX1 handler
1639 $handler instead of the twig being printed
1640 flush_toSAX2 ($handler)
1642 Same as flush, except that SAX events are sent to the SAX2 handler
1643 $handler instead of the twig being printed
1644 ignore
1646 This method should be called during parsing, usually in
1647 "start_tag_handlers". It causes the element to be skipped during
1648 the parsing: the twig is not built for this element, it will not be
1649 accessible during parsing or after it. The element will not take up
1650 any memory and parsing will be faster.
1651 Note that this method can also be called on an element. If the
1653 element is a parent of the current element then this element will
1654 be ignored (the twig will not be built any more for it and what has
1655 already been built will be deleted).
1656 set_pretty_print ($style)
1658 Set the pretty print method, amongst '"none"' (default),
1659 '"nsgmls"', '"nice"', '"indented"', "indented_c", '"wrapped"',
1660 '"record"' and '"record_c"'
1661 WARNING: the pretty print style is a GLOBAL variable, so once set
1663 it's applied to ALL "print"'s (and "sprint"'s). Same goes if you
1664 use XML::Twig with "mod_perl" . This should not be a problem as the
1665 XML that's generated is valid anyway, and XML processors (as well
1666 as HTML processors, including browsers) should not care. Let me
1667 know if this is a big problem, but at the moment the
1668 performance/cleanliness trade-off clearly favors the global
1669 approach.
1670 set_empty_tag_style ($style)
1672 Set the empty tag display style ('"normal"', '"html"' or
1673 '"expand"'). As with "set_pretty_print" this sets a global flag.
1674 "normal" outputs an empty tag '"<tag/>"', "html" adds a space
1676 '"<tag />"' for elements that can be empty in XHTML and "expand"
1677 outputs '"<tag></tag>"'
1678 set_remove_cdata ($flag)
1680 set (or unset) the flag that forces the twig to output CDATA
1681 sections as regular (escaped) PCDATA
1682 print_prolog ($optional_filehandle, %options)
1684 Prints the prolog (XML declaration + DTD + entity declarations) of
1685 a document.
1686 options: see "flush".
1688 prolog ($optional_filehandle, %options)
1690 Return the prolog (XML declaration + DTD + entity declarations) of
1691 a document.
1692 options: see "flush".
1694 finish
1696 Call Expat "finish" method. Unsets all handlers (including
1697 internal ones that set context), but expat continues parsing to the
1698 end of the document or until it finds an error. It should finish
1699 up a lot faster than with the handlers set.
1700 finish_print
1702 Stops twig processing, flush the twig and proceed to finish
1703 printing the document as fast as possible. Use this method when
1704 modifying a document and the modification is done.
1705 finish_now
1707 Stops twig processing, does not finish parsing the document (which
1708 could actually be not well-formed after the point where
1709 "finish_now" is called). Execution resumes after the "Lparse"> or
1710 "parsefile" call. The content of the twig is what has been parsed
1711 so far (all open elements at the time "finish_now" is called are
1712 considered closed).
1713 set_expand_external_entities
1715 Same as using the "expand_external_ents" option when creating the
1716 twig
1717 set_input_filter
1719 Same as using the "input_filter" option when creating the twig
1720 set_keep_atts_order
1722 Same as using the "keep_atts_order" option when creating the twig
1723 set_keep_encoding
1725 Same as using the "keep_encoding" option when creating the twig
1726 escape_gt
1728 usually XML::Twig does not escape > in its output. Using this
1729 option makes it replace > by >
1730 do_not_escape_gt
1732 reverts XML::Twig behavior to its default of not escaping > in its
1733 output.
1734 set_output_filter
1736 Same as using the "output_filter" option when creating the twig
1737 set_output_text_filter
1739 Same as using the "output_text_filter" option when creating the
1740 twig
1741 add_stylesheet ($type, @options)
1743 Adds an external stylesheet to an XML document.
1744 Supported types and options:
1746 xsl option: the url of the stylesheet
1748 Example:
1750 $t->add_stylesheet( xsl => "xsl_style.xsl");
1752 will generate the following PI at the beginning of the
1754 document:
1755 <?xml-stylesheet type="text/xsl" href="xsl_style.xsl"?>
1757 css option: the url of the stylesheet
1759 active_twig
1761 a class method that returns the last processed twig, so you
1762 don't necessarily need the object to call methods on it.
1763 Methods inherited from XML::Parser::Expat
1765 A twig inherits all the relevant methods from XML::Parser::Expat.
1766 These methods can only be used during the parsing phase (they will
1767 generate a fatal error otherwise).
1768 Inherited methods are:
1770 depth
1772 Returns the size of the context list.
1773 in_element
1775 Returns true if NAME is equal to the name of the innermost cur‐
1776 rently opened element. If namespace processing is being used
1777 and you want to check against a name that may be in a
1778 namespace, then use the generate_ns_name method to create the
1779 NAME argument.
1780 within_element
1782 Returns the number of times the given name appears in the
1783 context list. If namespace processing is being used and you
1784 want to check against a name that may be in a namespace, then
1785 use the gener‐ ate_ns_name method to create the NAME argument.
1786 context
1788 Returns a list of element names that represent open elements,
1789 with the last one being the innermost. Inside start and end tag
1790 han‐ dlers, this will be the tag of the parent element.
1791 current_line
1793 Returns the line number of the current position of the parse.
1794 current_column
1796 Returns the column number of the current position of the parse.
1797 current_byte
1799 Returns the current position of the parse.
1800 position_in_context
1802 Returns a string that shows the current parse position. LINES
1803 should be an integer >= 0 that represents the number of lines
1804 on either side of the current parse line to place into the
1805 returned string.
1806 base ([NEWBASE])
1808 Returns the current value of the base for resolving relative
1809 URIs. If NEWBASE is supplied, changes the base to that value.
1810 current_element
1812 Returns the name of the innermost currently opened element.
1813 Inside start or end handlers, returns the parent of the element
1814 associated with those tags.
1815 element_index
1817 Returns an integer that is the depth-first visit order of the
1818 cur‐ rent element. This will be zero outside of the root
1819 element. For example, this will return 1 when called from the
1820 start handler for the root element start tag.
1821 recognized_string
1823 Returns the string from the document that was recognized in
1824 order to call the current handler. For instance, when called
1825 from a start handler, it will give us the start-tag string. The
1826 string is encoded in UTF-8. This method doesn't return a
1827 meaningful string inside declaration handlers.
1828 original_string
1830 Returns the verbatim string from the document that was
1831 recognized in order to call the current handler. The string is
1832 in the original document encoding. This method doesn't return a
1833 meaningful string inside declaration handlers.
1834 xpcroak
1836 Concatenate onto the given message the current line number
1837 within the XML document plus the message implied by
1838 ErrorContext. Then croak with the formed message.
1839 xpcarp
1841 Concatenate onto the given message the current line number
1842 within the XML document plus the message implied by
1843 ErrorContext. Then carp with the formed message.
1844 xml_escape(TEXT [, CHAR [, CHAR ...]])
1846 Returns TEXT with markup characters turned into character
1847 entities. Any additional characters provided as arguments are
1848 also turned into character references where found in TEXT.
1849 (this method is broken on some versions of expat/XML::Parser)
1851 path ( $optional_tag)
1853 Return the element context in a form similar to XPath's short form:
1854 '"/root/tag1/../tag"'
1855 get_xpath ( $optional_array_ref, $xpath, $optional_offset)
1857 Performs a "get_xpath" on the document root (see <Elt|"Elt">)
1858 If the $optional_array_ref argument is used the array must contain
1860 elements. The $xpath expression is applied to each element in turn
1861 and the result is union of all results. This way a first query can
1862 be refined in further steps.
1863 find_nodes ( $optional_array_ref, $xpath, $optional_offset)
1865 same as "get_xpath"
1866 findnodes ( $optional_array_ref, $xpath, $optional_offset)
1868 same as "get_xpath" (similar to the XML::LibXML method)
1869 findvalue ( $optional_array_ref, $xpath, $optional_offset)
1871 Return the "join" of all texts of the results of applying
1872 "get_xpath" to the node (similar to the XML::LibXML method)
1873 findvalues ( $optional_array_ref, $xpath, $optional_offset)
1875 Return an array of all texts of the results of applying "get_xpath"
1876 to the node
1877 subs_text ($regexp, $replace)
1879 subs_text does text substitution on the whole document, similar to
1880 perl's " s///" operator.
1881 dispose
1883 Useful only if you don't have "Scalar::Util" or "WeakRef"
1884 installed.
1885 Reclaims properly the memory used by an XML::Twig object. As the
1887 object has circular references it never goes out of scope, so if
1888 you want to parse lots of XML documents then the memory leak
1889 becomes a problem. Use "$twig->dispose" to clear this problem.
1890 att_accessors (list_of_attribute_names)
1892 A convenience method that creates l-valued accessors for
1893 attributes. So "$twig->create_accessors( 'foo')" will create a
1894 "foo" method that can be called on elements:
1895 $elt->foo; # equivalent to $elt->{'att'}->{'foo'};
1897 $elt->foo( 'bar'); # equivalent to $elt->set_att( foo => 'bar');
1898 The methods are l-valued only under those perl's that support this
1900 feature (5.6 and above)
1901 create_accessors (list_of_attribute_names)
1903 Same as att_accessors
1904 elt_accessors (list_of_attribute_names)
1906 A convenience method that creates accessors for elements. So
1907 "$twig->create_accessors( 'foo')" will create a "foo" method that
1908 can be called on elements:
1909 $elt->foo; # equivalent to $elt->first_child( 'foo');
1911 field_accessors (list_of_attribute_names)
1913 A convenience method that creates accessors for element values
1914 ("field"). So "$twig->create_accessors( 'foo')" will create a
1915 "foo" method that can be called on elements:
1916 $elt->foo; # equivalent to $elt->field( 'foo');
1918 set_do_not_escape_amp_in_atts
1920 An evil method, that I only document because Test::Pod::Coverage
1921 complaints otherwise, but really, you don't want to know about it.
1922 XML::Twig::Elt
1924 new ($optional_tag, $optional_atts, @optional_content)
1925 The "tag" is optional (but then you can't have a content ), the
1926 $optional_atts argument is a reference to a hash of attributes, the
1927 content can be just a string or a list of strings and element. A
1928 content of '"#EMPTY"' creates an empty element;
1929 Examples: my $elt= XML::Twig::Elt->new();
1931 my $elt= XML::Twig::Elt->new( para => { align => 'center' });
1932 my $elt= XML::Twig::Elt->new( para => { align => 'center' }, 'foo');
1933 my $elt= XML::Twig::Elt->new( br => '#EMPTY');
1934 my $elt= XML::Twig::Elt->new( 'para');
1935 my $elt= XML::Twig::Elt->new( para => 'this is a para');
1936 my $elt= XML::Twig::Elt->new( para => $elt3, 'another para');
1937 The strings are not parsed, the element is not attached to any
1939 twig.
1940 WARNING: if you rely on ID's then you will have to set the id
1942 yourself. At this point the element does not belong to a twig yet,
1943 so the ID attribute is not known so it won't be stored in the ID
1944 list.
1945 Note that "#COMMENT", "#PCDATA" or "#CDATA" are valid tag names,
1947 that will create text elements.
1948 To create an element "foo" containing a CDATA section:
1950 my $foo= XML::Twig::Elt->new( '#CDATA' => "content of the CDATA section")
1952 ->wrap_in( 'foo');
1953 An attribute of '#CDATA', will create the content of the element as
1955 CDATA:
1956 my $elt= XML::Twig::Elt->new( 'p' => { '#CDATA' => 1}, 'foo < bar');
1958 creates an element
1960 <p><![CDATA[foo < bar]]></>
1962 parse ($string, %args)
1964 Creates an element from an XML string. The string is actually
1965 parsed as a new twig, then the root of that twig is returned. The
1966 arguments in %args are passed to the twig. As always if the parse
1967 fails the parser will die, so use an eval if you want to trap
1968 syntax errors.
1969 As obviously the element does not exist beforehand this method has
1971 to be called on the class:
1972 my $elt= parse XML::Twig::Elt( "<a> string to parse, with <sub/>
1974 <elements>, actually tons of </elements>
1975 h</a>");
1976 set_inner_xml ($string)
1978 Sets the content of the element to be the tree created from the
1979 string
1980 set_inner_html ($string)
1982 Sets the content of the element, after parsing the string with an
1983 HTML parser (HTML::Parser)
1984 set_outer_xml ($string)
1986 Replaces the element with the tree created from the string
1987 print ($optional_filehandle, $optional_pretty_print_style)
1989 Prints an entire element, including the tags, optionally to a
1990 $optional_filehandle, optionally with a $pretty_print_style.
1991 The print outputs XML data so base entities are escaped.
1993 print_to_file ($filename, %options)
1995 Prints the element to file $filename.
1996 options: see "flush". =item sprint ($elt,
1998 $optional_no_enclosing_tag)
1999 Return the xml string for an entire element, including the tags.
2001 If the optional second argument is true then only the string inside
2002 the element is returned (the start and end tag for $elt are not).
2003 The text is XML-escaped: base entities (& and < in text, & < and "
2004 in attribute values) are turned into entities.
2005 gi Return the gi of the element (the gi is the "generic identifier"
2007 the tag name in SGML parlance).
2008 "tag" and "name" are synonyms of "gi".
2010 tag Same as "gi"
2012 name
2014 Same as "tag"
2015 set_gi ($tag)
2017 Set the gi (tag) of an element
2018 set_tag ($tag)
2020 Set the tag (="tag") of an element
2021 set_name ($name)
2023 Set the name (="tag") of an element
2024 root
2026 Return the root of the twig in which the element is contained.
2027 twig
2029 Return the twig containing the element.
2030 parent ($optional_condition)
2032 Return the parent of the element, or the first ancestor matching
2033 the $optional_condition
2034 first_child ($optional_condition)
2036 Return the first child of the element, or the first child matching
2037 the $optional_condition
2038 has_child ($optional_condition)
2040 Return the first child of the element, or the first child matching
2041 the $optional_condition (same as first_child)
2042 has_children ($optional_condition)
2044 Return the first child of the element, or the first child matching
2045 the $optional_condition (same as first_child)
2046 first_child_text ($optional_condition)
2048 Return the text of the first child of the element, or the first
2049 child
2050 matching the $optional_condition If there is no first_child then
2051 returns ''. This avoids getting the child, checking for its
2052 existence then getting the text for trivial cases.
2053 Similar methods are available for the other navigation methods:
2055 last_child_text
2057 prev_sibling_text
2058 next_sibling_text
2059 prev_elt_text
2060 next_elt_text
2061 child_text
2062 parent_text
2063 All this methods also exist in "trimmed" variant:
2065 first_child_trimmed_text
2067 last_child_trimmed_text
2068 prev_sibling_trimmed_text
2069 next_sibling_trimmed_text
2070 prev_elt_trimmed_text
2071 next_elt_trimmed_text
2072 child_trimmed_text
2073 parent_trimmed_text
2074 field ($condition)
2075 Same method as "first_child_text" with a different name
2076 fields ($condition_list)
2078 Return the list of field (text of first child matching the
2079 conditions), missing fields are returned as the empty string.
2080 Same method as "first_child_text" with a different name
2082 trimmed_field ($optional_condition)
2084 Same method as "first_child_trimmed_text" with a different name
2085 set_field ($condition, $optional_atts, @list_of_elt_and_strings)
2087 Set the content of the first child of the element that matches
2088 $condition, the rest of the arguments is the same as for
2089 "set_content"
2090 If no child matches $condition _and_ if $condition is a valid XML
2092 element name, then a new element by that name is created and
2093 inserted as the last child.
2094 first_child_matches ($optional_condition)
2096 Return the element if the first child of the element (if it exists)
2097 passes the $optional_condition "undef" otherwise
2098 if( $elt->first_child_matches( 'title')) ...
2100 is equivalent to
2102 if( $elt->{first_child} && $elt->{first_child}->passes( 'title'))
2104 "first_child_is" is an other name for this method
2106 Similar methods are available for the other navigation methods:
2108 last_child_matches
2110 prev_sibling_matches
2111 next_sibling_matches
2112 prev_elt_matches
2113 next_elt_matches
2114 child_matches
2115 parent_matches
2116 is_first_child ($optional_condition)
2117 returns true (the element) if the element is the first child of its
2118 parent (optionally that satisfies the $optional_condition)
2119 is_last_child ($optional_condition)
2121 returns true (the element) if the element is the last child of its
2122 parent (optionally that satisfies the $optional_condition)
2123 prev_sibling ($optional_condition)
2125 Return the previous sibling of the element, or the previous sibling
2126 matching $optional_condition
2127 next_sibling ($optional_condition)
2129 Return the next sibling of the element, or the first one matching
2130 $optional_condition.
2131 next_elt ($optional_elt, $optional_condition)
2133 Return the next elt (optionally matching $optional_condition) of
2134 the element. This is defined as the next element which opens after
2135 the current element opens. Which usually means the first child of
2136 the element. Counter-intuitive as it might look this allows you to
2137 loop through the whole document by starting from the root.
2138 The $optional_elt is the root of a subtree. When the "next_elt" is
2140 out of the subtree then the method returns undef. You can then walk
2141 a sub-tree with:
2142 my $elt= $subtree_root;
2144 while( $elt= $elt->next_elt( $subtree_root))
2145 { # insert processing code here
2146 }
2147 prev_elt ($optional_condition)
2149 Return the previous elt (optionally matching $optional_condition)
2150 of the element. This is the first element which opens before the
2151 current one. It is usually either the last descendant of the
2152 previous sibling or simply the parent
2153 next_n_elt ($offset, $optional_condition)
2155 Return the $offset-th element that matches the $optional_condition
2156 following_elt
2158 Return the following element (as per the XPath following axis)
2159 preceding_elt
2161 Return the preceding element (as per the XPath preceding axis)
2162 following_elts
2164 Return the list of following elements (as per the XPath following
2165 axis)
2166 preceding_elts
2168 Return the list of preceding elements (as per the XPath preceding
2169 axis)
2170 children ($optional_condition)
2172 Return the list of children (optionally which matches
2173 $optional_condition) of the element. The list is in document order.
2174 children_count ($optional_condition)
2176 Return the number of children of the element (optionally which
2177 matches $optional_condition)
2178 children_text ($optional_condition)
2180 In array context, returns an array containing the text of children
2181 of the element (optionally which matches $optional_condition)
2182 In scalar context, returns the concatenation of the text of
2184 children of the element
2185 children_trimmed_text ($optional_condition)
2187 In array context, returns an array containing the trimmed text of
2188 children of the element (optionally which matches
2189 $optional_condition)
2190 In scalar context, returns the concatenation of the trimmed text of
2192 children of the element
2193 children_copy ($optional_condition)
2195 Return a list of elements that are copies of the children of the
2196 element, optionally which matches $optional_condition
2197 descendants ($optional_condition)
2199 Return the list of all descendants (optionally which matches
2200 $optional_condition) of the element. This is the equivalent of the
2201 "getElementsByTagName" of the DOM (by the way, if you are really a
2202 DOM addict, you can use "getElementsByTagName" instead)
2203 getElementsByTagName ($optional_condition)
2205 Same as "descendants"
2206 find_by_tag_name ($optional_condition)
2208 Same as "descendants"
2209 descendants_or_self ($optional_condition)
2211 Same as "descendants" except that the element itself is included in
2212 the list if it matches the $optional_condition
2213 first_descendant ($optional_condition)
2215 Return the first descendant of the element that matches the
2216 condition
2217 last_descendant ($optional_condition)
2219 Return the last descendant of the element that matches the
2220 condition
2221 ancestors ($optional_condition)
2223 Return the list of ancestors (optionally matching
2224 $optional_condition) of the element. The list is ordered from the
2225 innermost ancestor to the outermost one
2226 NOTE: the element itself is not part of the list, in order to
2228 include it you will have to use ancestors_or_self
2229 ancestors_or_self ($optional_condition)
2231 Return the list of ancestors (optionally matching
2232 $optional_condition) of the element, including the element (if it
2233 matches the condition>). The list is ordered from the innermost
2234 ancestor to the outermost one
2235 passes ($condition)
2237 Return the element if it passes the $condition
2238 att ($att)
2240 Return the value of attribute $att or "undef"
2241 latt ($att)
2243 Return the value of attribute $att or "undef"
2244 this method is an lvalue, so you can do "$elt->latt( 'foo')= 'bar'"
2246 or "$elt->latt( 'foo')++;"
2247 set_att ($att, $att_value)
2249 Set the attribute of the element to the given value
2250 You can actually set several attributes this way:
2252 $elt->set_att( att1 => "val1", att2 => "val2");
2254 del_att ($att)
2256 Delete the attribute for the element
2257 You can actually delete several attributes at once:
2259 $elt->del_att( 'att1', 'att2', 'att3');
2261 att_exists ($att)
2263 Returns true if the attribute $att exists for the element, false
2264 otherwise
2265 cut Cut the element from the tree. The element still exists, it can be
2267 copied or pasted somewhere else, it is just not attached to the
2268 tree anymore.
2269 Note that the "old" links to the parent, previous and next siblings
2271 can still be accessed using the former_* methods
2272 former_next_sibling
2274 Returns the former next sibling of a cut node (or undef if the node
2275 has not been cut)
2276 This makes it easier to write loops where you cut elements:
2278 my $child= $parent->first_child( 'achild');
2280 while( $child->{'att'}->{'cut'})
2281 { $child->cut; $child= ($child->{former} && $child->{former}->{next_sibling}); }
2282 former_prev_sibling
2284 Returns the former previous sibling of a cut node (or undef if the
2285 node has not been cut)
2286 former_parent
2288 Returns the former parent of a cut node (or undef if the node has
2289 not been cut)
2290 cut_children ($optional_condition)
2292 Cut all the children of the element (or all of those which satisfy
2293 the $optional_condition).
2294 Return the list of children
2296 cut_descendants ($optional_condition)
2298 Cut all the descendants of the element (or all of those which
2299 satisfy the $optional_condition).
2300 Return the list of descendants
2302 copy ($elt)
2304 Return a copy of the element. The copy is a "deep" copy: all sub-
2305 elements of the element are duplicated.
2306 paste ($optional_position, $ref)
2308 Paste a (previously "cut" or newly generated) element. Die if the
2309 element already belongs to a tree.
2310 Note that the calling element is pasted:
2312 $child->paste( first_child => $existing_parent);
2314 $new_sibling->paste( after => $this_sibling_is_already_in_the_tree);
2315 or
2317 my $new_elt= XML::Twig::Elt->new( tag => $content);
2319 $new_elt->paste( $position => $existing_elt);
2320 Example:
2322 my $t= XML::Twig->new->parse( 'doc.xml')
2324 my $toc= $t->root->new( 'toc');
2325 $toc->paste( $t->root); # $toc is pasted as first child of the root
2326 foreach my $title ($t->findnodes( '/doc/section/title'))
2327 { my $title_toc= $title->copy;
2328 # paste $title_toc as the last child of toc
2329 $title_toc->paste( last_child => $toc)
2330 }
2331 Position options:
2333 first_child (default)
2335 The element is pasted as the first child of $ref
2336 last_child
2338 The element is pasted as the last child of $ref
2339 before
2341 The element is pasted before $ref, as its previous sibling.
2342 after
2344 The element is pasted after $ref, as its next sibling.
2345 within
2347 In this case an extra argument, $offset, should be supplied.
2348 The element will be pasted in the reference element (or in its
2349 first text child) at the given offset. To achieve this the
2350 reference element will be split at the offset.
2351 Note that you can call directly the underlying method:
2353 paste_before
2355 paste_after
2356 paste_first_child
2357 paste_last_child
2358 paste_within
2359 move ($optional_position, $ref)
2360 Move an element in the tree. This is just a "cut" then a "paste".
2361 The syntax is the same as "paste".
2362 replace ($ref)
2364 Replaces an element in the tree. Sometimes it is just not possible
2365 to"cut" an element then "paste" another in its place, so "replace"
2366 comes in handy. The calling element replaces $ref.
2367 replace_with (@elts)
2369 Replaces the calling element with one or more elements
2370 delete
2372 Cut the element and frees the memory.
2373 prefix ($text, $optional_option)
2375 Add a prefix to an element. If the element is a "PCDATA" element
2376 the text is added to the pcdata, if the elements first child is a
2377 "PCDATA" then the text is added to it's pcdata, otherwise a new
2378 "PCDATA" element is created and pasted as the first child of the
2379 element.
2380 If the option is "asis" then the prefix is added asis: it is
2382 created in a separate "PCDATA" element with an "asis" property. You
2383 can then write:
2384 $elt1->prefix( '<b>', 'asis');
2386 to create a "<b>" in the output of "print".
2388 suffix ($text, $optional_option)
2390 Add a suffix to an element. If the element is a "PCDATA" element
2391 the text is added to the pcdata, if the elements last child is a
2392 "PCDATA" then the text is added to it's pcdata, otherwise a new
2393 PCDATA element is created and pasted as the last child of the
2394 element.
2395 If the option is "asis" then the suffix is added asis: it is
2397 created in a separate "PCDATA" element with an "asis" property. You
2398 can then write:
2399 $elt2->suffix( '</b>', 'asis');
2401 trim
2403 Trim the element in-place: spaces at the beginning and at the end
2404 of the element are discarded and multiple spaces within the element
2405 (or its descendants) are replaced by a single space.
2406 Note that in some cases you can still end up with multiple spaces,
2408 if they are split between several elements:
2409 <doc> text <b> hah! </b> yep</doc>
2411 gets trimmed to
2413 <doc>text <b> hah! </b> yep</doc>
2415 This is somewhere in between a bug and a feature.
2417 normalize
2419 merge together all consecutive pcdata elements in the element (if
2420 for example you have turned some elements into pcdata using
2421 "erase", this will give you a "clean" element in which there all
2422 text fragments are as long as possible).
2423 simplify (%options)
2425 Return a data structure suspiciously similar to XML::Simple's.
2426 Options are identical to XMLin options, see XML::Simple doc for
2427 more details (or use DATA::dumper or YAML to dump the data
2428 structure)
2429 Note: there is no magic here, if you write "$twig->parsefile( $file
2431 )->simplify();" then it will load the entire document in memory. I
2432 am afraid you will have to put some work into it to get just the
2433 bits you want and discard the rest. Look at the synopsis or the
2434 XML::Twig 101 section at the top of the docs for more information.
2435 content_key
2437 forcearray
2438 keyattr
2439 noattr
2440 normalize_space
2441 aka normalise_space
2442 variables (%var_hash)
2444 %var_hash is a hash { name => value }
2445 This option allows variables in the XML to be expanded when the
2447 file is read. (there is no facility for putting the variable
2448 names back if you regenerate XML using XMLout).
2449 A 'variable' is any text of the form ${name} (or $name) which
2451 occurs in an attribute value or in the text content of an
2452 element. If 'name' matches a key in the supplied hashref,
2453 ${name} will be replaced with the corresponding value from the
2454 hashref. If no matching key is found, the variable will not be
2455 replaced.
2456 var_att ($attribute_name)
2458 This option gives the name of an attribute that will be used to
2459 create variables in the XML:
2460 <dirs>
2462 <dir name="prefix">/usr/local</dir>
2463 <dir name="exec_prefix">$prefix/bin</dir>
2464 </dirs>
2465 use "var => 'name'" to get $prefix replaced by /usr/local in
2467 the generated data structure
2468 By default variables are captured by the following regexp:
2470 /$(\w+)/
2471 var_regexp (regexp)
2473 This option changes the regexp used to capture variables. The
2474 variable name should be in $1
2475 group_tags { grouping tag => grouped tag, grouping tag 2 => grouped
2477 tag 2...}
2478 Option used to simplify the structure: elements listed will not
2479 be used. Their children will be, they will be considered
2480 children of the element parent.
2481 If the element is:
2483 <config host="laptop.xmltwig.org">
2485 <server>localhost</server>
2486 <dirs>
2487 <dir name="base">/home/mrodrigu/standards</dir>
2488 <dir name="tools">$base/tools</dir>
2489 </dirs>
2490 <templates>
2491 <template name="std_def">std_def.templ</template>
2492 <template name="dummy">dummy</template>
2493 </templates>
2494 </config>
2495 Then calling simplify with "group_tags => { dirs => 'dir',
2497 templates => 'template'}" makes the data structure be exactly
2498 as if the start and end tags for "dirs" and "templates" were
2499 not there.
2500 A YAML dump of the structure
2502 base: '/home/mrodrigu/standards'
2504 host: laptop.xmltwig.org
2505 server: localhost
2506 template:
2507 - std_def.templ
2508 - dummy.templ
2509 tools: '$base/tools'
2510 split_at ($offset)
2512 Split a text ("PCDATA" or "CDATA") element in 2 at $offset, the
2513 original element now holds the first part of the string and a new
2514 element holds the right part. The new element is returned
2515 If the element is not a text element then the first text child of
2517 the element is split
2518 split ( $optional_regexp, $tag1, $atts1, $tag2, $atts2...)
2520 Split the text descendants of an element in place, the text is
2521 split using the $regexp, if the regexp includes () then the matched
2522 separators will be wrapped in elements. $1 is wrapped in $tag1,
2523 with attributes $atts1 if $atts1 is given (as a hashref), $2 is
2524 wrapped in $tag2...
2525 if $elt is "<p>tati tata <b>tutu tati titi</b> tata tati tata</p>"
2527 $elt->split( qr/(ta)ti/, 'foo', {type => 'toto'} )
2529 will change $elt to
2531 <p><foo type="toto">ta</foo> tata <b>tutu <foo type="toto">ta</foo>
2533 titi</b> tata <foo type="toto">ta</foo> tata</p>
2534 The regexp can be passed either as a string or as "qr//" (perl
2536 5.005 and later), it defaults to \s+ just as the "split" built-in
2537 (but this would be quite a useless behaviour without the
2538 $optional_tag parameter)
2539 $optional_tag defaults to PCDATA or CDATA, depending on the initial
2541 element type
2542 The list of descendants is returned (including un-touched original
2544 elements and newly created ones)
2545 mark ( $regexp, $optional_tag, $optional_attribute_ref)
2547 This method behaves exactly as split, except only the newly created
2548 elements are returned
2549 wrap_children ( $regexp_string, $tag, $optional_attribute_hashref)
2551 Wrap the children of the element that match the regexp in an
2552 element $tag. If $optional_attribute_hashref is passed then the
2553 new element will have these attributes.
2554 The $regexp_string includes tags, within pointy brackets, as in
2556 "<title><para>+" and the usual Perl modifiers (+*?...). Tags can
2557 be further qualified with attributes: "<para type="warning"
2558 classif="cosmic_secret">+". The values for attributes should be
2559 xml-escaped: "<candy type="M&Ms">*" ("<", "&" ">" and """
2560 should be escaped).
2561 Note that elements might get extra "id" attributes in the process.
2563 See add_id. Use strip_att to remove unwanted id's.
2564 Here is an example:
2566 If the element $elt has the following content:
2568 <elt>
2570 <p>para 1</p>
2571 <l_l1_1>list 1 item 1 para 1</l_l1_1>
2572 <l_l1>list 1 item 1 para 2</l_l1>
2573 <l_l1_n>list 1 item 2 para 1 (only para)</l_l1_n>
2574 <l_l1_n>list 1 item 3 para 1</l_l1_n>
2575 <l_l1>list 1 item 3 para 2</l_l1>
2576 <l_l1>list 1 item 3 para 3</l_l1>
2577 <l_l1_1>list 2 item 1 para 1</l_l1_1>
2578 <l_l1>list 2 item 1 para 2</l_l1>
2579 <l_l1_n>list 2 item 2 para 1 (only para)</l_l1_n>
2580 <l_l1_n>list 2 item 3 para 1</l_l1_n>
2581 <l_l1>list 2 item 3 para 2</l_l1>
2582 <l_l1>list 2 item 3 para 3</l_l1>
2583 </elt>
2584 Then the code
2586 $elt->wrap_children( q{<l_l1_1><l_l1>*} , li => { type => "ul1" });
2588 $elt->wrap_children( q{<l_l1_n><l_l1>*} , li => { type => "ul" });
2589 $elt->wrap_children( q{<li type="ul1"><li type="ul">+}, "ul");
2591 $elt->strip_att( 'id');
2592 $elt->strip_att( 'type');
2593 $elt->print;
2594 will output:
2596 <elt>
2598 <p>para 1</p>
2599 <ul>
2600 <li>
2601 <l_l1_1>list 1 item 1 para 1</l_l1_1>
2602 <l_l1>list 1 item 1 para 2</l_l1>
2603 </li>
2604 <li>
2605 <l_l1_n>list 1 item 2 para 1 (only para)</l_l1_n>
2606 </li>
2607 <li>
2608 <l_l1_n>list 1 item 3 para 1</l_l1_n>
2609 <l_l1>list 1 item 3 para 2</l_l1>
2610 <l_l1>list 1 item 3 para 3</l_l1>
2611 </li>
2612 </ul>
2613 <ul>
2614 <li>
2615 <l_l1_1>list 2 item 1 para 1</l_l1_1>
2616 <l_l1>list 2 item 1 para 2</l_l1>
2617 </li>
2618 <li>
2619 <l_l1_n>list 2 item 2 para 1 (only para)</l_l1_n>
2620 </li>
2621 <li>
2622 <l_l1_n>list 2 item 3 para 1</l_l1_n>
2623 <l_l1>list 2 item 3 para 2</l_l1>
2624 <l_l1>list 2 item 3 para 3</l_l1>
2625 </li>
2626 </ul>
2627 </elt>
2628 subs_text ($regexp, $replace)
2630 subs_text does text substitution, similar to perl's " s///"
2631 operator.
2632 $regexp must be a perl regexp, created with the "qr" operator.
2634 $replace can include "$1, $2"... from the $regexp. It can also be
2636 used to create element and entities, by using "&elt( tag => { att
2637 => val }, text)" (similar syntax as "new") and "&ent( name)".
2638 Here is a rather complex example:
2640 $elt->subs_text( qr{(?<!do not )link to (http://([^\s,]*))},
2642 'see &elt( a =>{ href => $1 }, $2)'
2643 );
2644 This will replace text like link to http://www.xmltwig.org by see
2646 <a href="www.xmltwig.org">www.xmltwig.org</a>, but not do not link
2647 to...
2648 Generating entities (here replacing spaces with ):
2650 $elt->subs_text( qr{ }, '&ent( " ")');
2652 or, using a variable:
2654 my $ent=" ";
2656 $elt->subs_text( qr{ }, "&ent( '$ent')");
2657 Note that the substitution is always global, as in using the "g"
2659 modifier in a perl substitution, and that it is performed on all
2660 text descendants of the element.
2661 Bug: in the $regexp, you can only use "\1", "\2"... if the
2663 replacement expression does not include elements or attributes. eg
2664 $t->subs_text( qr/((t[aiou])\2)/, '$2'); # ok, replaces toto, tata, titi, tutu by to, ta, ti, tu
2666 $t->subs_text( qr/((t[aiou])\2)/, '&elt(p => $1)' ); # NOK, does not find toto...
2667 add_id ($optional_coderef)
2669 Add an id to the element.
2670 The id is an attribute, "id" by default, see the "id" option for
2672 XML::Twig "new" to change it. Use an id starting with "#" to get an
2673 id that's not output by print, flush or sprint, yet that allows you
2674 to use the elt_id method to get the element easily.
2675 If the element already has an id, no new id is generated.
2677 By default the method create an id of the form "twig_id_<nnnn>",
2679 where "<nnnn>" is a number, incremented each time the method is
2680 called successfully.
2681 set_id_seed ($prefix)
2683 by default the id generated by "add_id" is "twig_id_<nnnn>",
2684 "set_id_seed" changes the prefix to $prefix and resets the number
2685 to 1
2686 strip_att ($att)
2688 Remove the attribute $att from all descendants of the element
2689 (including the element)
2690 Return the element
2692 change_att_name ($old_name, $new_name)
2694 Change the name of the attribute from $old_name to $new_name. If
2695 there is no attribute $old_name nothing happens.
2696 lc_attnames
2698 Lower cases the name all the attributes of the element.
2699 sort_children_on_value( %options)
2701 Sort the children of the element in place according to their text.
2702 All children are sorted.
2703 Return the element, with its children sorted.
2705 %options are
2707 type : numeric | alpha (default: alpha)
2709 order : normal | reverse (default: normal)
2710 Return the element, with its children sorted
2712 sort_children_on_att ($att, %options)
2714 Sort the children of the element in place according to attribute
2715 $att. %options are the same as for "sort_children_on_value"
2716 Return the element.
2718 sort_children_on_field ($tag, %options)
2720 Sort the children of the element in place, according to the field
2721 $tag (the text of the first child of the child with this tag).
2722 %options are the same as for "sort_children_on_value".
2723 Return the element, with its children sorted
2725 sort_children( $get_key, %options)
2727 Sort the children of the element in place. The $get_key argument is
2728 a reference to a function that returns the sort key when passed an
2729 element.
2730 For example:
2732 $elt->sort_children( sub { $_[0]->{'att'}->{"nb"} + $_[0]->text },
2734 type => 'numeric', order => 'reverse'
2735 );
2736 field_to_att ($cond, $att)
2738 Turn the text of the first sub-element matched by $cond into the
2739 value of attribute $att of the element. If $att is omitted then
2740 $cond is used as the name of the attribute, which makes sense only
2741 if $cond is a valid element (and attribute) name.
2742 The sub-element is then cut.
2744 att_to_field ($att, $tag)
2746 Take the value of attribute $att and create a sub-element $tag as
2747 first child of the element. If $tag is omitted then $att is used as
2748 the name of the sub-element.
2749 get_xpath ($xpath, $optional_offset)
2751 Return a list of elements satisfying the $xpath. $xpath is an
2752 XPATH-like expression.
2753 A subset of the XPATH abbreviated syntax is covered:
2755 tag
2757 tag[1] (or any other positive number)
2758 tag[last()]
2759 tag[@att] (the attribute exists for the element)
2760 tag[@att="val"]
2761 tag[@att=~ /regexp/]
2762 tag[att1="val1" and att2="val2"]
2763 tag[att1="val1" or att2="val2"]
2764 tag[string()="toto"] (returns tag elements which text (as per the text method)
2765 is toto)
2766 tag[string()=~/regexp/] (returns tag elements which text (as per the text
2767 method) matches regexp)
2768 expressions can start with / (search starts at the document root)
2769 expressions can start with . (search starts at the current element)
2770 // can be used to get all descendants instead of just direct children
2771 * matches any tag
2772 So the following examples from the XPath
2774 recommendation<http://www.w3.org/TR/xpath.html#path-abbrev> work:
2775 para selects the para element children of the context node
2777 * selects all element children of the context node
2778 para[1] selects the first para child of the context node
2779 para[last()] selects the last para child of the context node
2780 */para selects all para grandchildren of the context node
2781 /doc/chapter[5]/section[2] selects the second section of the fifth chapter
2782 of the doc
2783 chapter//para selects the para element descendants of the chapter element
2784 children of the context node
2785 //para selects all the para descendants of the document root and thus selects
2786 all para elements in the same document as the context node
2787 //olist/item selects all the item elements in the same document as the
2788 context node that have an olist parent
2789 .//para selects the para element descendants of the context node
2790 .. selects the parent of the context node
2791 para[@type="warning"] selects all para children of the context node that have
2792 a type attribute with value warning
2793 employee[@secretary and @assistant] selects all the employee children of the
2794 context node that have both a secretary attribute and an assistant
2795 attribute
2796 The elements will be returned in the document order.
2798 If $optional_offset is used then only one element will be returned,
2800 the one with the appropriate offset in the list, starting at 0
2801 Quoting and interpolating variables can be a pain when the Perl
2803 syntax and the XPATH syntax collide, so use alternate quoting
2804 mechanisms like q or qq (I like q{} and qq{} myself).
2805 Here are some more examples to get you started:
2807 my $p1= "p1";
2809 my $p2= "p2";
2810 my @res= $t->get_xpath( qq{p[string( "$p1") or string( "$p2")]});
2811 my $a= "a1";
2813 my @res= $t->get_xpath( qq{//*[@att="$a"]});
2814 my $val= "a1";
2816 my $exp= qq{//p[ \@att='$val']}; # you need to use \@ or you will get a warning
2817 my @res= $t->get_xpath( $exp);
2818 Note that the only supported regexps delimiters are / and that you
2820 must backslash all / in regexps AND in regular strings.
2821 XML::Twig does not provide natively full XPATH support, but you can
2823 use "XML::Twig::XPath" to get "findnodes" to use "XML::XPath" as
2824 the XPath engine, with full coverage of the spec.
2825 "XML::Twig::XPath" to get "findnodes" to use "XML::XPath" as the
2827 XPath engine, with full coverage of the spec.
2828 find_nodes
2830 same as"get_xpath"
2831 findnodes
2833 same as "get_xpath"
2834 text @optional_options
2836 Return a string consisting of all the "PCDATA" and "CDATA" in an
2837 element, without any tags. The text is not XML-escaped: base
2838 entities such as "&" and "<" are not escaped.
2839 The '"no_recurse"' option will only return the text of the element,
2841 not of any included sub-elements (same as "text_only").
2842 text_only
2844 Same as "text" except that the text returned doesn't include the
2845 text of sub-elements.
2846 trimmed_text
2848 Same as "text" except that the text is trimmed: leading and
2849 trailing spaces are discarded, consecutive spaces are collapsed
2850 set_text ($string)
2852 Set the text for the element: if the element is a "PCDATA", just
2853 set its text, otherwise cut all the children of the element and
2854 create a single "PCDATA" child for it, which holds the text.
2855 merge ($elt2)
2857 Move the content of $elt2 within the element
2858 insert ($tag1, [$optional_atts1], $tag2, [$optional_atts2],...)
2860 For each tag in the list inserts an element $tag as the only child
2861 of the element. The element gets the optional attributes
2862 in"$optional_atts<n>." All children of the element are set as
2863 children of the new element. The upper level element is returned.
2864 $p->insert( table => { border=> 1}, 'tr', 'td')
2866 put $p in a table with a visible border, a single "tr" and a single
2868 "td" and return the "table" element:
2869 <p><table border="1"><tr><td>original content of p</td></tr></table></p>
2871 wrap_in (@tag)
2873 Wrap elements in @tag as the successive ancestors of the element,
2874 returns the new element. "$elt->wrap_in( 'td', 'tr', 'table')"
2875 wraps the element as a single cell in a table for example.
2876 Optionally each tag can be followed by a hashref of attributes,
2878 that will be set on the wrapping element:
2879 $elt->wrap_in( p => { class => "advisory" }, div => { class => "intro", id => "div_intro" });
2881 insert_new_elt ($opt_position, $tag, $opt_atts_hashref, @opt_content)
2883 Combines a "new " and a "paste ": creates a new element using $tag,
2884 $opt_atts_hashref and @opt_content which are arguments similar to
2885 those for "new", then paste it, using $opt_position or
2886 'first_child', relative to $elt.
2887 Return the newly created element
2889 erase
2891 Erase the element: the element is deleted and all of its children
2892 are pasted in its place.
2893 set_content ( $optional_atts, @list_of_elt_and_strings) (
2895 $optional_atts, '#EMPTY')
2896 Set the content for the element, from a list of strings and
2897 elements. Cuts all the element children, then pastes the list
2898 elements as the children. This method will create a "PCDATA"
2899 element for any strings in the list.
2900 The $optional_atts argument is the ref of a hash of attributes. If
2902 this argument is used then the previous attributes are deleted,
2903 otherwise they are left untouched.
2904 WARNING: if you rely on ID's then you will have to set the id
2906 yourself. At this point the element does not belong to a twig yet,
2907 so the ID attribute is not known so it won't be stored in the ID
2908 list.
2909 A content of '"#EMPTY"' creates an empty element;
2911 namespace ($optional_prefix)
2913 Return the URI of the namespace that $optional_prefix or the
2914 element name belongs to. If the name doesn't belong to any
2915 namespace, "undef" is returned.
2916 local_name
2918 Return the local name (without the prefix) for the element
2919 ns_prefix
2921 Return the namespace prefix for the element
2922 current_ns_prefixes
2924 Return a list of namespace prefixes valid for the element. The
2925 order of the prefixes in the list has no meaning. If the default
2926 namespace is currently bound, '' appears in the list.
2927 inherit_att ($att, @optional_tag_list)
2929 Return the value of an attribute inherited from parent tags. The
2930 value returned is found by looking for the attribute in the element
2931 then in turn in each of its ancestors. If the @optional_tag_list is
2932 supplied only those ancestors whose tag is in the list will be
2933 checked.
2934 all_children_are ($optional_condition)
2936 return 1 if all children of the element pass the
2937 $optional_condition, 0 otherwise
2938 level ($optional_condition)
2940 Return the depth of the element in the twig (root is 0). If
2941 $optional_condition is given then only ancestors that match the
2942 condition are counted.
2943 WARNING: in a tree created using the "twig_roots" option this will
2945 not return the level in the document tree, level 0 will be the
2946 document root, level 1 will be the "twig_roots" elements. During
2947 the parsing (in a "twig_handler") you can use the "depth" method on
2948 the twig object to get the real parsing depth.
2949 in ($potential_parent)
2951 Return true if the element is in the potential_parent
2952 ($potential_parent is an element)
2953 in_context ($cond, $optional_level)
2955 Return true if the element is included in an element which passes
2956 $cond optionally within $optional_level levels. The returned value
2957 is the including element.
2958 pcdata
2960 Return the text of a "PCDATA" element or "undef" if the element is
2961 not "PCDATA".
2962 pcdata_xml_string
2964 Return the text of a "PCDATA" element or undef if the element is
2965 not "PCDATA". The text is "XML-escaped" ('&' and '<' are replaced
2966 by '&' and '<')
2967 set_pcdata ($text)
2969 Set the text of a "PCDATA" element. This method does not check that
2970 the element is indeed a "PCDATA" so usually you should use
2971 "set_text" instead.
2972 append_pcdata ($text)
2974 Add the text at the end of a "PCDATA" element.
2975 is_cdata
2977 Return 1 if the element is a "CDATA" element, returns 0 otherwise.
2978 is_text
2980 Return 1 if the element is a "CDATA" or "PCDATA" element, returns 0
2981 otherwise.
2982 cdata
2984 Return the text of a "CDATA" element or "undef" if the element is
2985 not "CDATA".
2986 cdata_string
2988 Return the XML string of a "CDATA" element, including the opening
2989 and closing markers.
2990 set_cdata ($text)
2992 Set the text of a "CDATA" element.
2993 append_cdata ($text)
2995 Add the text at the end of a "CDATA" element.
2996 remove_cdata
2998 Turns all "CDATA" sections in the element into regular "PCDATA"
2999 elements. This is useful when converting XML to HTML, as browsers
3000 do not support CDATA sections.
3001 extra_data
3003 Return the extra_data (comments and PI's) attached to an element
3004 set_extra_data ($extra_data)
3006 Set the extra_data (comments and PI's) attached to an element
3007 append_extra_data ($extra_data)
3009 Append extra_data to the existing extra_data before the element (if
3010 no previous extra_data exists then it is created)
3011 set_asis
3013 Set a property of the element that causes it to be output without
3014 being XML escaped by the print functions: if it contains "a < b" it
3015 will be output as such and not as "a < b". This can be useful to
3016 create text elements that will be output as markup. Note that all
3017 "PCDATA" descendants of the element are also marked as having the
3018 property (they are the ones that are actually impacted by the
3019 change).
3020 If the element is a "CDATA" element it will also be output asis,
3022 without the "CDATA" markers. The same goes for any "CDATA"
3023 descendant of the element
3024 set_not_asis
3026 Unsets the "asis" property for the element and its text
3027 descendants.
3028 is_asis
3030 Return the "asis" property status of the element ( 1 or "undef")
3031 closed
3033 Return true if the element has been closed. Might be useful if you
3034 are somewhere in the tree, during the parse, and have no idea
3035 whether a parent element is completely loaded or not.
3036 get_type
3038 Return the type of the element: '"#ELT"' for "real" elements, or
3039 '"#PCDATA"', '"#CDATA"', '"#COMMENT"', '"#ENT"', '"#PI"'
3040 is_elt
3042 Return the tag if the element is a "real" element, or 0 if it is
3043 "PCDATA", "CDATA"...
3044 contains_only_text
3046 Return 1 if the element does not contain any other "real" element
3047 contains_only ($exp)
3049 Return the list of children if all children of the element match
3050 the expression $exp
3051 if( $para->contains_only( 'tt')) { ... }
3053 contains_a_single ($exp)
3055 If the element contains a single child that matches the expression
3056 $exp returns that element. Otherwise returns 0.
3057 is_field
3059 same as "contains_only_text"
3060 is_pcdata
3062 Return 1 if the element is a "PCDATA" element, returns 0 otherwise.
3063 is_ent
3065 Return 1 if the element is an entity (an unexpanded entity)
3066 element, return 0 otherwise.
3067 is_empty
3069 Return 1 if the element is empty, 0 otherwise
3070 set_empty
3072 Flags the element as empty. No further check is made, so if the
3073 element is actually not empty the output will be messed. The only
3074 effect of this method is that the output will be "<tag
3075 att="value""/>".
3076 set_not_empty
3078 Flags the element as not empty. if it is actually empty then the
3079 element will be output as "<tag att="value""></tag>"
3080 is_pi
3082 Return 1 if the element is a processing instruction ("#PI")
3083 element, return 0 otherwise.
3084 target
3086 Return the target of a processing instruction
3087 set_target ($target)
3089 Set the target of a processing instruction
3090 data
3092 Return the data part of a processing instruction
3093 set_data ($data)
3095 Set the data of a processing instruction
3096 set_pi ($target, $data)
3098 Set the target and data of a processing instruction
3099 pi_string
3101 Return the string form of a processing instruction ("<?target
3102 data?>")
3103 is_comment
3105 Return 1 if the element is a comment ("#COMMENT") element, return 0
3106 otherwise.
3107 set_comment ($comment_text)
3109 Set the text for a comment
3110 comment
3112 Return the content of a comment (just the text, not the "<!--" and
3113 "-->")
3114 comment_string
3116 Return the XML string for a comment ("<!-- comment -->")
3117 Note that an XML comment cannot start or end with a '-', or include
3119 '--' (http://www.w3.org/TR/2008/REC-xml-20081126/#sec-comments), if
3120 that is the case (because you have created the comment yourself
3121 presumably, as it could not be in the input XML), then a space will
3122 be inserted before an initial '-', after a trailing one or between
3123 two '-' in the comment (which could presumably mangle javascript
3124 "hidden" in an XHTML comment);
3125 set_ent ($entity)
3127 Set an (non-expanded) entity ("#ENT"). $entity) is the entity text
3128 ("&ent;")
3129 ent Return the entity for an entity ("#ENT") element ("&ent;")
3131 ent_name
3133 Return the entity name for an entity ("#ENT") element ("ent")
3134 ent_string
3136 Return the entity, either expanded if the expanded version is
3137 available, or non-expanded ("&ent;") otherwise
3138 child ($offset, $optional_condition)
3140 Return the $offset-th child of the element, optionally the
3141 $offset-th child that matches $optional_condition. The children are
3142 treated as a list, so "$elt->child( 0)" is the first child, while
3143 "$elt->child( -1)" is the last child.
3144 child_text ($offset, $optional_condition)
3146 Return the text of a child or "undef" if the sibling does not
3147 exist. Arguments are the same as child.
3148 last_child ($optional_condition)
3150 Return the last child of the element, or the last child matching
3151 $optional_condition (ie the last of the element children matching
3152 the condition).
3153 last_child_text ($optional_condition)
3155 Same as "first_child_text" but for the last child.
3156 sibling ($offset, $optional_condition)
3158 Return the next or previous $offset-th sibling of the element, or
3159 the $offset-th one matching $optional_condition. If $offset is
3160 negative then a previous sibling is returned, if $offset is
3161 positive then a next sibling is returned. "$offset=0" returns the
3162 element if there is no condition or if the element matches the
3163 condition>, "undef" otherwise.
3164 sibling_text ($offset, $optional_condition)
3166 Return the text of a sibling or "undef" if the sibling does not
3167 exist. Arguments are the same as "sibling".
3168 prev_siblings ($optional_condition)
3170 Return the list of previous siblings (optionally matching
3171 $optional_condition) for the element. The elements are ordered in
3172 document order.
3173 next_siblings ($optional_condition)
3175 Return the list of siblings (optionally matching
3176 $optional_condition) following the element. The elements are
3177 ordered in document order.
3178 siblings ($optional_condition)
3180 Return the list of siblings (optionally matching
3181 $optional_condition) of the element (excluding the element itself).
3182 The elements are ordered in document order.
3183 pos ($optional_condition)
3185 Return the position of the element in the children list. The first
3186 child has a position of 1 (as in XPath).
3187 If the $optional_condition is given then only siblings that match
3189 the condition are counted. If the element itself does not match the
3190 condition then 0 is returned.
3191 atts
3193 Return a hash ref containing the element attributes
3194 set_atts ({ att1=>$att1_val, att2=> $att2_val... })
3196 Set the element attributes with the hash ref supplied as the
3197 argument. The previous attributes are lost (ie the attributes set
3198 by "set_atts" replace all of the attributes of the element).
3199 You can also pass a list instead of a hashref: "$elt->set_atts(
3201 att1 => 'val1',...)"
3202 del_atts
3204 Deletes all the element attributes.
3205 att_nb
3207 Return the number of attributes for the element
3208 has_atts
3210 Return true if the element has attributes (in fact return the
3211 number of attributes, thus being an alias to "att_nb"
3212 has_no_atts
3214 Return true if the element has no attributes, false (0) otherwise
3215 att_names
3217 return a list of the attribute names for the element
3218 att_xml_string ($att, $options)
3220 Return the attribute value, where '&', '<' and quote (" or the
3221 value of the quote option at twig creation) are XML-escaped.
3222 The options are passed as a hashref, setting "escape_gt" to a true
3224 value will also escape '>' ($elt( 'myatt', { escape_gt => 1 });
3225 set_id ($id)
3227 Set the "id" attribute of the element to the value. See "elt_id "
3228 to change the id attribute name
3229 id Gets the id attribute value
3231 del_id ($id)
3233 Deletes the "id" attribute of the element and remove it from the id
3234 list for the document
3235 class
3237 Return the "class" attribute for the element (methods on the
3238 "class" attribute are quite convenient when dealing with XHTML, or
3239 plain XML that will eventually be displayed using CSS)
3240 lclass
3242 same as class, except that this method is an lvalue, so you can do
3243 "$elt->lclass= "foo""
3244 set_class ($class)
3246 Set the "class" attribute for the element to $class
3247 add_class ($class)
3249 Add $class to the element "class" attribute: the new class is added
3250 only if it is not already present.
3251 Note that classes are then sorted alphabetically, so the "class"
3253 attribute can be changed even if the class is already there
3254 remove_class ($class)
3256 Remove $class from the element "class" attribute.
3257 Note that classes are then sorted alphabetically, so the "class"
3259 attribute can be changed even if the class is already there
3260 add_to_class ($class)
3262 alias for add_class
3263 att_to_class ($att)
3265 Set the "class" attribute to the value of attribute $att
3266 add_att_to_class ($att)
3268 Add the value of attribute $att to the "class" attribute of the
3269 element
3270 move_att_to_class ($att)
3272 Add the value of attribute $att to the "class" attribute of the
3273 element and delete the attribute
3274 tag_to_class
3276 Set the "class" attribute of the element to the element tag
3277 add_tag_to_class
3279 Add the element tag to its "class" attribute
3280 set_tag_class ($new_tag)
3282 Add the element tag to its "class" attribute and sets the tag to
3283 $new_tag
3284 in_class ($class)
3286 Return true (1) if the element is in the class $class (if $class is
3287 one of the tokens in the element "class" attribute)
3288 tag_to_span
3290 Change the element tag tp "span" and set its class to the old tag
3291 tag_to_div
3293 Change the element tag tp "div" and set its class to the old tag
3294 DESTROY
3296 Frees the element from memory.
3297 start_tag
3299 Return the string for the start tag for the element, including the
3300 "/>" at the end of an empty element tag
3301 end_tag
3303 Return the string for the end tag of an element. For an empty
3304 element, this returns the empty string ('').
3305 xml_string @optional_options
3307 Equivalent to "$elt->sprint( 1)", returns the string for the entire
3308 element, excluding the element's tags (but nested element tags are
3309 present)
3310 The '"no_recurse"' option will only return the text of the element,
3312 not of any included sub-elements (same as "xml_text_only").
3313 inner_xml
3315 Another synonym for xml_string
3316 outer_xml
3318 An other synonym for sprint
3319 xml_text
3321 Return the text of the element, encoded (and processed by the
3322 current "output_filter" or "output_encoding" options, without any
3323 tag.
3324 xml_text_only
3326 Same as "xml_text" except that the text returned doesn't include
3327 the text of sub-elements.
3328 set_pretty_print ($style)
3330 Set the pretty print method, amongst '"none"' (default),
3331 '"nsgmls"', '"nice"', '"indented"', '"record"' and '"record_c"'
3332 pretty_print styles:
3334 none
3336 the default, no "\n" is used
3337 nsgmls
3339 nsgmls style, with "\n" added within tags
3340 nice
3342 adds "\n" wherever possible (NOT SAFE, can lead to invalid XML)
3343 indented
3345 same as "nice" plus indents elements (NOT SAFE, can lead to
3346 invalid XML)
3347 record
3349 table-oriented pretty print, one field per line
3350 record_c
3352 table-oriented pretty print, more compact than "record", one
3353 record per line
3354 set_empty_tag_style ($style)
3356 Set the method to output empty tags, amongst '"normal"' (default),
3357 '"html"', and '"expand"',
3358 "normal" outputs an empty tag '"<tag/>"', "html" adds a space
3360 '"<tag />"' for elements that can be empty in XHTML and "expand"
3361 outputs '"<tag></tag>"'
3362 set_remove_cdata ($flag)
3364 set (or unset) the flag that forces the twig to output CDATA
3365 sections as regular (escaped) PCDATA
3366 set_indent ($string)
3368 Set the indentation for the indented pretty print style (default is
3369 2 spaces)
3370 set_quote ($quote)
3372 Set the quotes used for attributes. can be '"double"' (default) or
3373 '"single"'
3374 cmp ($elt)
3376 Compare the order of the 2 elements in a twig.
3377 C<$a> is the <A>..</A> element, C<$b> is the <B>...</B> element
3379 document $a->cmp( $b)
3381 <A> ... </A> ... <B> ... </B> -1
3382 <A> ... <B> ... </B> ... </A> -1
3383 <B> ... </B> ... <A> ... </A> 1
3384 <B> ... <A> ... </A> ... </B> 1
3385 $a == $b 0
3386 $a and $b not in the same tree undef
3387 before ($elt)
3389 Return 1 if $elt starts before the element, 0 otherwise. If the 2
3390 elements are not in the same twig then return "undef".
3391 if( $a->cmp( $b) == -1) { return 1; } else { return 0; }
3393 after ($elt)
3395 Return 1 if $elt starts after the element, 0 otherwise. If the 2
3396 elements are not in the same twig then return "undef".
3397 if( $a->cmp( $b) == -1) { return 1; } else { return 0; }
3399 other comparison methods
3401 lt
3402 le
3403 gt
3404 ge
3405 path
3406 Return the element context in a form similar to XPath's short form:
3407 '"/root/tag1/../tag"'
3408 xpath
3410 Return a unique XPath expression that can be used to find the
3411 element again.
3412 It looks like "/doc/sect[3]/title": unique elements do not have an
3414 index, the others do.
3415 flush
3417 flushes the twig up to the current element (strictly equivalent to
3418 "$elt->root->flush")
3419 private methods
3421 Low-level methods on the twig:
3422 set_parent ($parent)
3424 set_first_child ($first_child)
3425 set_last_child ($last_child)
3426 set_prev_sibling ($prev_sibling)
3427 set_next_sibling ($next_sibling)
3428 set_twig_current
3429 del_twig_current
3430 twig_current
3431 contains_text
3432 Those methods should not be used, unless of course you find some
3434 creative and interesting, not to mention useful, ways to do it.
3435 cond
3437 Most of the navigation functions accept a condition as an optional
3438 argument The first element (or all elements for "children " or
3439 "ancestors ") that passes the condition is returned.
3440 The condition is a single step of an XPath expression using the XPath
3442 subset defined by "get_xpath". Additional conditions are:
3443 The condition can be
3445 #ELT
3447 return a "real" element (not a PCDATA, CDATA, comment or pi
3448 element)
3449 #TEXT
3451 return a PCDATA or CDATA element
3452 regular expression
3454 return an element whose tag matches the regexp. The regexp has to
3455 be created with "qr//" (hence this is available only on perl 5.005
3456 and above)
3457 code reference
3459 applies the code, passing the current element as argument, if the
3460 code returns true then the element is returned, if it returns false
3461 then the code is applied to the next candidate.
3462 XML::Twig::XPath
3464 XML::Twig implements a subset of XPath through the "get_xpath" method.
3465 If you want to use the whole XPath power, then you can use
3467 "XML::Twig::XPath" instead. In this case "XML::Twig" uses "XML::XPath"
3468 to execute XPath queries. You will of course need "XML::XPath"
3469 installed to be able to use "XML::Twig::XPath".
3470 See XML::XPath for more information.
3472 The methods you can use are:
3474 findnodes ($path)
3476 return a list of nodes found by $path.
3477 findnodes_as_string ($path)
3479 return the nodes found reproduced as XML. The result is not
3480 guaranteed to be valid XML though.
3481 findvalue ($path)
3483 return the concatenation of the text content of the result nodes
3484 In order for "XML::XPath" to be used as the XPath engine the following
3486 methods are included in "XML::Twig":
3487 in XML::Twig
3489 getRootNode
3491 getParentNode
3492 getChildNodes
3493 in XML::Twig::Elt
3495 string_value
3497 toString
3498 getName
3499 getRootNode
3500 getNextSibling
3501 getPreviousSibling
3502 isElementNode
3503 isTextNode
3504 isPI
3505 isPINode
3506 isProcessingInstructionNode
3507 isComment
3508 isCommentNode
3509 getTarget
3510 getChildNodes
3511 getElementById
3512 XML::Twig::XPath::Elt
3514 The methods you can use are the same as on "XML::Twig::XPath" elements:
3515 findnodes ($path)
3517 return a list of nodes found by $path.
3518 findnodes_as_string ($path)
3520 return the nodes found reproduced as XML. The result is not
3521 guaranteed to be valid XML though.
3522 findvalue ($path)
3524 return the concatenation of the text content of the result nodes
3525 XML::Twig::Entity_list
3527 new Create an entity list.
3528 add ($ent)
3530 Add an entity to an entity list.
3531 add_new_ent ($name, $val, $sysid, $pubid, $ndata, $param)
3533 Create a new entity and add it to the entity list
3534 delete ($ent or $tag).
3536 Delete an entity (defined by its name or by the Entity object) from
3537 the list.
3538 print ($optional_filehandle)
3540 Print the entity list.
3541 list
3543 Return the list as an array
3544 XML::Twig::Entity
3546 new ($name, $val, $sysid, $pubid, $ndata, $param)
3547 Same arguments as the Entity handler for XML::Parser.
3548 print ($optional_filehandle)
3550 Print an entity declaration.
3551 name
3553 Return the name of the entity
3554 val Return the value of the entity
3556 sysid
3558 Return the system id for the entity (for NDATA entities)
3559 pubid
3561 Return the public id for the entity (for NDATA entities)
3562 ndata
3564 Return true if the entity is an NDATA entity
3565 param
3567 Return true if the entity is a parameter entity
3568 text
3570 Return the entity declaration text.
3571 XML::Twig::Notation_list
3573 new Create an notation list.
3574 add ($notation)
3576 Add an notation to an notation list.
3577 add_new_notation ($name, $base, $sysid, $pubid)
3579 Create a new notation and add it to the notation list
3580 delete ($notation or $tag).
3582 Delete an notation (defined by its name or by the Notation object)
3583 from the list.
3584 print ($optional_filehandle)
3586 Print the notation list.
3587 list
3589 Return the list as an array
3590 XML::Twig::Notation
3592 new ($name, $base, $sysid, $pubid)
3593 Same argumnotations as the Notation handler for XML::Parser.
3594 print ($optional_filehandle)
3596 Print an notation declaration.
3597 name
3599 Return the name of the notation
3600 base
3602 Return the base to be used for resolving a relative URI
3603 sysid
3605 Return the system id for the notation
3606 pubid
3608 Return the public id for the notation
3609 text
3611 Return the notation declaration text.
3612
3614 Additional examples (and a complete tutorial) can be found on the
3615 XML::Twig Page<http://www.xmltwig.org/xmltwig/>
3616 To figure out what flush does call the following script with an XML
3618 file and an element name as arguments
3619 use XML::Twig;
3621 my ($file, $elt)= @ARGV;
3623 my $t= XML::Twig->new( twig_handlers =>
3624 { $elt => sub {$_[0]->flush; print "\n[flushed here]\n";} });
3625 $t->parsefile( $file, ErrorContext => 2);
3626 $t->flush;
3627 print "\n";
3628
3630 Subclassing XML::Twig
3631 Useful methods:
3632 elt_class
3634 In order to subclass "XML::Twig" you will probably need to subclass
3635 also "XML::Twig::Elt". Use the "elt_class" option when you create
3636 the "XML::Twig" object to get the elements created in a different
3637 class (which should be a subclass of "XML::Twig::Elt".
3638 add_options
3640 If you inherit "XML::Twig" new method but want to add more options
3641 to it you can use this method to prevent XML::Twig to issue
3642 warnings for those additional options.
3643 DTD Handling
3645 There are 3 possibilities here. They are:
3646 No DTD
3648 No doctype, no DTD information, no entity information, the world is
3649 simple...
3650 Internal DTD
3652 The XML document includes an internal DTD, and maybe entity
3653 declarations.
3654 If you use the load_DTD option when creating the twig the DTD
3656 information and the entity declarations can be accessed.
3657 The DTD and the entity declarations will be "flush"'ed (or
3659 "print"'ed) either as is (if they have not been modified) or as
3660 reconstructed (poorly, comments are lost, order is not kept, due to
3661 it's content this DTD should not be viewed by anyone) if they have
3662 been modified. You can also modify them directly by changing the
3663 "$twig->{twig_doctype}->{internal}" field (straight from
3664 XML::Parser, see the "Doctype" handler doc)
3665 External DTD
3667 The XML document includes a reference to an external DTD, and maybe
3668 entity declarations.
3669 If you use the "load_DTD" when creating the twig the DTD
3671 information and the entity declarations can be accessed. The entity
3672 declarations will be "flush"'ed (or "print"'ed) either as is (if
3673 they have not been modified) or as reconstructed (badly, comments
3674 are lost, order is not kept).
3675 You can change the doctype through the "$twig->set_doctype" method
3677 and print the dtd through the "$twig->dtd_text" or
3678 "$twig->dtd_print"
3679 methods.
3680 If you need to modify the entity list this is probably the easiest
3682 way to do it.
3683 Flush
3685 Remember that element handlers are called when the element is CLOSED,
3686 so if you have handlers for nested elements the inner handlers will be
3687 called first. It makes it for example trickier than it would seem to
3688 number nested sections (or clauses, or divs), as the titles in the
3689 inner sections are handled before the outer sections.
3690
3692 segfault during parsing
3693 This happens when parsing huge documents, or lots of small ones,
3694 with a version of Perl before 5.16.
3695 This is due to a bug in the way weak references are handled in Perl
3697 itself.
3698 The fix is either to upgrade to Perl 5.16 or later ("perlbrew" is a
3700 great tool to manage several installations of perl on the same
3701 machine).
3702 An other, NOT RECOMMENDED, way of fixing the problem, is to switch
3704 off weak references by writing "XML::Twig::_set_weakrefs( 0);" at
3705 the top of the code. This is totally unsupported, and may lead to
3706 other problems though,
3707 entity handling
3709 Due to XML::Parser behaviour, non-base entities in attribute values
3710 disappear if they are not declared in the document:
3711 "att="val&ent;"" will be turned into "att => val", unless you use
3712 the "keep_encoding" argument to "XML::Twig->new"
3713 DTD handling
3715 The DTD handling methods are quite bugged. No one uses them and it
3716 seems very difficult to get them to work in all cases, including
3717 with several slightly incompatible versions of XML::Parser and of
3718 libexpat.
3719 Basically you can read the DTD, output it back properly, and update
3721 entities, but not much more.
3722 So use XML::Twig with standalone documents, or with documents
3724 referring to an external DTD, but don't expect it to properly parse
3725 and even output back the DTD.
3726 memory leak
3728 If you use a REALLY old Perl (5.005!) and a lot of twigs you might
3729 find that you leak quite a lot of memory (about 2Ks per twig). You
3730 can use the "dispose " method to free that memory after you are
3731 done.
3732 If you create elements the same thing might happen, use the
3734 "delete" method to get rid of them.
3735 Alternatively installing the "Scalar::Util" (or "WeakRef") module
3737 on a version of Perl that supports it (>5.6.0) will get rid of the
3738 memory leaks automagically.
3739 ID list
3741 The ID list is NOT updated when elements are cut or deleted.
3742 change_gi
3744 This method will not function properly if you do:
3745 $twig->change_gi( $old1, $new);
3747 $twig->change_gi( $old2, $new);
3748 $twig->change_gi( $new, $even_newer);
3749 sanity check on XML::Parser method calls
3751 XML::Twig should really prevent calls to some XML::Parser methods,
3752 especially the "setHandlers" method.
3753 pretty printing
3755 Pretty printing (at least using the '"indented"' style) is hard to
3756 get right! Only elements that belong to the document will be
3757 properly indented. Printing elements that do not belong to the twig
3758 makes it impossible for XML::Twig to figure out their depth, and
3759 thus their indentation level.
3760 Also there is an unavoidable bug when using "flush" and pretty
3762 printing for elements with mixed content that start with an
3763 embedded element:
3764 <elt><b>b</b>toto<b>bold</b></elt>
3766 will be output as
3768 <elt>
3770 <b>b</b>toto<b>bold</b></elt>
3771 if you flush the twig when you find the "<b>" element
3773
3775 These are the things that can mess up calling code, especially if
3776 threaded. They might also cause problem under mod_perl.
3777 Exported constants
3779 Whether you want them or not you get them! These are subroutines to
3780 use as constant when creating or testing elements
3781 PCDATA return '#PCDATA'
3783 CDATA return '#CDATA'
3784 PI return '#PI', I had the choice between PROC and PI :--(
3785 Module scoped values: constants
3787 these should cause no trouble:
3788 %base_ent= ( '>' => '>',
3790 '<' => '<',
3791 '&' => '&',
3792 "'" => ''',
3793 '"' => '"',
3794 );
3795 CDATA_START = "<![CDATA[";
3796 CDATA_END = "]]>";
3797 PI_START = "<?";
3798 PI_END = "?>";
3799 COMMENT_START = "<!--";
3800 COMMENT_END = "-->";
3801 pretty print styles
3803 ( $NSGMLS, $NICE, $INDENTED, $INDENTED_C, $WRAPPED, $RECORD1, $RECORD2)= (1..7);
3805 empty tag output style
3807 ( $HTML, $EXPAND)= (1..2);
3809 Module scoped values: might be changed
3811 Most of these deal with pretty printing, so the worst that can
3812 happen is probably that XML output does not look right, but is
3813 still valid and processed identically by XML processors.
3814 $empty_tag_style can mess up HTML bowsers though and changing $ID
3816 would most likely create problems.
3817 $pretty=0; # pretty print style
3819 $quote='"'; # quote for attributes
3820 $INDENT= ' '; # indent for indented pretty print
3821 $empty_tag_style= 0; # how to display empty tags
3822 $ID # attribute used as an id ('id' by default)
3823 Module scoped values: definitely changed
3825 These 2 variables are used to replace tags by an index, thus saving
3826 some space when creating a twig. If they really cause you too much
3827 trouble, let me know, it is probably possible to create either a
3828 switch or at least a version of XML::Twig that does not perform
3829 this optimization.
3830 %gi2index; # tag => index
3832 @index2gi; # list of tags
3833 If you need to manipulate all those values, you can use the following
3835 methods on the XML::Twig object:
3836 global_state
3838 Return a hashref with all the global variables used by XML::Twig
3839 The hash has the following fields: "pretty", "quote", "indent",
3841 "empty_tag_style", "keep_encoding", "expand_external_entities",
3842 "output_filter", "output_text_filter", "keep_atts_order"
3843 set_global_state ($state)
3845 Set the global state, $state is a hashref
3846 save_global_state
3848 Save the current global state
3849 restore_global_state
3851 Restore the previously saved (using "Lsave_global_state"> state
3852
3854 SAX handlers
3855 Allowing XML::Twig to work on top of any SAX parser
3856 multiple twigs are not well supported
3858 A number of twig features are just global at the moment. These
3859 include the ID list and the "tag pool" (if you use "change_gi" then
3860 you change the tag for ALL twigs).
3861 A future version will try to support this while trying not to be to
3863 hard on performance (at least when a single twig is used!).
3864
3866 Michel Rodriguez <mirod@cpan.org>
3867
3869 This library is free software; you can redistribute it and/or modify it
3870 under the same terms as Perl itself.
3871 Bug reports should be sent using: RT
3873 <http://rt.cpan.org/NoAuth/Bugs.html?Dist=XML-Twig>
3874 Comments can be sent to mirod@cpan.org
3876 The XML::Twig page is at <http://www.xmltwig.org/xmltwig/> It includes
3878 the development version of the module, a slightly better version of the
3879 documentation, examples, a tutorial and a: Processing XML efficiently
3880 with Perl and XML::Twig:
3881 <http://www.xmltwig.org/xmltwig/tutorial/index.html>
3882
3884 Complete docs, including a tutorial, examples, an easier to use HTML
3885 version of the docs, a quick reference card and a FAQ are available at
3886 <http://www.xmltwig.org/xmltwig/>
3887 git repository at <http://github.com/mirod/xmltwig>
3889 XML::Parser, XML::Parser::Expat, XML::XPath, Encode, Text::Iconv,
3891 Scalar::Utils
3892 Alternative Modules
3894 XML::Twig is not the only XML::Processing module available on CPAN (far
3895 from it!).
3896 The main alternative I would recommend is XML::LibXML.
3898 Here is a quick comparison of the 2 modules:
3900 XML::LibXML, actually "libxml2" on which it is based, sticks to the
3902 standards, and implements a good number of them in a rather strict way:
3903 XML, XPath, DOM, RelaxNG, I must be forgetting a couple (XInclude?). It
3904 is fast and rather frugal memory-wise.
3905 XML::Twig is older: when I started writing it XML::Parser/expat was the
3907 only game in town. It implements XML and that's about it (plus a subset
3908 of XPath, and you can use XML::Twig::XPath if you have XML::XPathEngine
3909 installed for full support). It is slower and requires more memory for
3910 a full tree than XML::LibXML. On the plus side (yes, there is a plus
3911 side!) it lets you process a big document in chunks, and thus let you
3912 tackle documents that couldn't be loaded in memory by XML::LibXML, and
3913 it offers a lot (and I mean a LOT!) of higher-level methods, for
3914 everything, from adding structure to "low-level" XML, to shortcuts for
3915 XHTML conversions and more. It also DWIMs quite a bit, getting comments
3916 and non-significant whitespaces out of the way but preserving them in
3917 the output for example. As it does not stick to the DOM, is also
3918 usually leads to shorter code than in XML::LibXML.
3919 Beyond the pure features of the 2 modules, XML::LibXML seems to be
3921 preferred by "XML-purists", while XML::Twig seems to be more used by
3922 Perl Hackers who have to deal with XML. As you have noted, XML::Twig
3923 also comes with quite a lot of docs, but I am sure if you ask for help
3924 about XML::LibXML here or on Perlmonks you will get answers.
3925 Note that it is actually quite hard for me to compare the 2 modules: on
3927 one hand I know XML::Twig inside-out and I can get it to do pretty much
3928 anything I need to (or I improve it ;--), while I have a very basic
3929 knowledge of XML::LibXML. So feature-wise, I'd rather use XML::Twig
3930 ;--). On the other hand, I am painfully aware of some of the
3931 deficiencies, potential bugs and plain ugly code that lurk in
3932 XML::Twig, even though you are unlikely to be affected by them (unless
3933 for example you need to change the DTD of a document programmatically),
3934 while I haven't looked much into XML::LibXML so it still looks shinny
3935 and clean to me.
3936 That said, if you need to process a document that is too big to fit
3938 memory and XML::Twig is too slow for you, my reluctant advice would be
3939 to use "bare" XML::Parser. It won't be as easy to use as XML::Twig:
3940 basically with XML::Twig you trade some speed (depending on what you do
3941 from a factor 3 to... none) for ease-of-use, but it will be easier IMHO
3942 than using SAX (albeit not standard), and at this point a LOT faster
3943 (see the last test in
3944 <http://www.xmltwig.org/article/simple_benchmark/>).
3945perl v5.32.1 2021-01-27 Twig(3)