1Data::Stag(3) User Contributed Perl Documentation Data::Stag(3)
2
6 Data::Stag - Structured Tags datastructures
7
9 # PROCEDURAL USAGE
10 use Data::Stag qw(:all);
11 $doc = stag_parse($file);
12 @persons = stag_find($doc, "person");
13 foreach $p (@persons) {
14 printf "%s, %s phone: %s\n",
15 stag_sget($p, "family_name"),
16 stag_sget($p, "given_name"),
17 stag_sget($p, "phone_no"),
18 ;
19 }
20 # OBJECT-ORIENTED USAGE
22 use Data::Stag;
23 $doc = Data::Stag->parse($file);
24 @persons = $doc->find("person");
25 foreach $p (@person) {
26 printf "%s, %s phone:%s\n",
27 $p->sget("family_name"),
28 $p->sget("given_name"),
29 $p->sget("phone_no"),
30 ;
31 }
32
34 This module is for manipulating data as hierarchical tag/value pairs
35 (Structured TAGs or Simple Tree AGgreggates). These datastructures can
36 be represented as nested arrays, which have the advantage of being
37 native to perl. A simple example is shown below:
38 [ person=> [ [ family_name => $family_name ],
40 [ given_name => $given_name ],
41 [ phone_no => $phone_no ] ] ],
42 Data::Stag uses a subset of XML for import and export. This means the
44 module can also be used as a general XML parser/writer (with certain
45 caveats).
46 The above set of structured tags can be represented in XML as
48 <person>
50 <family_name>...</family_name>
51 <given_name>...</given_name>
52 <phone_no>...</phone_no>
53 </person>
54 This datastructure can be examined, manipulated and exported using Stag
56 functions or methods:
57 $document = Data::Stag->parse($file);
59 @persons = $document->find('person');
60 foreach my $person (@person) {
61 $person->set('full_name',
62 $person->sget('given_name') . ' ' .
63 $person->sget('family_name'));
64 }
65 Advanced querying is performed by passing functions, for example:
67 # get all people in dataset with name starting 'A'
69 @persons =
70 $document->where('person',
71 sub {shift->sget('family_name') =~ /^A/});
72 One of the things that marks this module out against other XML modules
74 is this emphasis on a functional approach as an obect-oriented or
75 procedural approach.
76 For full information on the stag project, see
78 <http://stag.sourceforge.net>
79 PROCEDURAL VS OBJECT-ORIENTED USAGE
81 Depending on your preference, this module can be used a set of
82 procedural subroutine calls, or as method calls upon Data::Stag
83 objects, or both.
84 In procedural mode, all the subroutine calls are prefixed "stag_" to
86 avoid namespace clashes. The following three calls are equivalent:
87 $person = stag_find($doc, "person");
89 $person = $doc->find("person");
90 $person = $doc->find_person;
91 In object mode, you can treat any tree element as if it is an object
93 with automatically defined methods for getting/setting the tag values.
94 USE OF XML
96 Nested arrays can be imported and exported as XML, as well as other
97 formats. XML can be slurped into memory all at once (using less memory
98 than an equivalent DOM tree), or a simplified SAX style event handling
99 model can be used. Similarly, data can be exported all at once, or as a
100 series of events.
101 Although this module can be used as a general XML tool, it is intended
103 primarily as a tool for manipulating hierarchical data using nested
104 tag/value pairs.
105 This module is more suited to dealing with data-oriented documents than
107 text-oriented documents.
108 By using a simpler subset of XML equivalent to a basic data tree
110 structure, we can write simpler, cleaner code.
111 This module is ideally suited to element-only XML (that is, XML without
113 attributes or mixed elements).
114 If you are using attributes or mixed elements, it is useful to know
116 what is going on under the hood.
117 All attributes are turned into elements; they are nested inside an
119 element with name '@'.
120 For example, the following piece of XML
122 <foo id="x">
124 <bar>ugh</bar>
125 </foo>
126 Gets represented internally as
128 <foo>
130 <@>
131 <id>x</id>
132 </@>
133 <bar>ugh</bar>
134 </foo>
135 Of course, this is not valid XML. However, it is just an internal
137 representation - when exporting back to XML it will look like normal
138 XML with attributes again.
139 Mixed content cannot be represented in a simple tree format, so this is
141 also expanded.
142 The following piece of XML
144 <paragraph id="1" color="green">
146 example of <bold>mixed</bold>content
147 </paragraph>
148 gets parsed as if it were actually:
150 <paragraph>
152 <@>
153 <id>1</id>
154 <color>green</color>
155 </@>
156 <.>example of</.>
157 <bold>mixed</bold>
158 <.>content</.>
159 </paragraph>
160 When using stag with attribute or mixed attribute xml, you can treat
162 '@' and '.' as normal elements
163 SAX
165 This module can also be used as part of a SAX-style event generation /
167 handling framework - see Data::Stag::BaseHandler
168 PERL REPRESENTATION
170 Because nested arrays are native to perl, we can specify an XML
172 datastructure directly in perl without going through multiple object
173 calls.
174 For example, instead of using XML::Writer for the lengthy
176 $obj->startTag("record");
178 $obj->startTag("field1");
179 $obj->characters("foo");
180 $obj->endTag("field1");
181 $obj->startTag("field2");
182 $obj->characters("bar");
183 $obj->endTag("field2");
184 $obj->end("record");
185 We can instead write
187 $struct = [ record => [
189 [ field1 => 'foo'],
190 [ field2 => 'bar']]];
191 PARSING
193 The following example is for parsing out subsections of a tree and
195 changing sub-elements
196 use Data::Stag qw(:all);
198 my $tree = stag_parse($xmlfile);
199 my ($subtree) = stag_findnode($tree, $element);
200 stag_set($element, $sub_element, $new_val);
201 print stag_xml($subtree);
202 OBJECT ORIENTED
204 The same can be done in a more OO fashion
206 use Data::Stag qw(:all);
208 my $tree = Data::Stag->parse($xmlfile);
209 my ($subtree) = $tree->findnode($element);
210 $element->set($sub_element, $new_val);
211 print $subtree->xml;
212 IN A STREAM
214 Rather than parsing in a whole file into memory all at once (which may
216 not be suitable for very large files), you can take an event handling
217 approach. The easiest way to do this to register which nodes in the
218 file you are interested in using the makehandler method. The parser
219 will sweep through the file, building objects as it goes, and handing
220 the object to a subroutine that you specify.
221 For example:
223 use Data::Stag;
225 # catch the end of 'person' elements
226 my $h = Data::Stag->makehandler( person=> sub {
227 my ($self, $person) = @_;
228 printf "name:%s phone:%s\n",
229 $person->get_name,
230 $person->get_phone;
231 return; # clear node
232 });
233 Data::Stag->parse(-handler=>$h,
234 -file=>$f);
235 see Data::Stag::BaseHandler for writing handlers
237 See the Stag website at <http://stag.sourceforge.net> for more
239 examples.
240 STRUCTURED TAGS TREE DATA STRUCTURE
242 A tree of structured tags is represented as a recursively nested array,
243 the elements of the array represent nodes in the tree.
244 A node is a name/data pair, that can represent tags and values. A node
246 is represented using a reference to an array, where the first element
247 of the array is the tagname, or element, and the second element is the
248 data
249 This can be visualised as a box:
251 +-----------+
253 |Name | Data|
254 +-----------+
255 In perl, we represent this pair as a reference to an array
257 [ Name => $Data ]
259 The Data can either be a list of child nodes (subtrees), or a data
261 value.
262 The terminal nodes (leafs of the tree) contain data values; this is
264 represented in perl using primitive scalars.
265 For example:
267 [ Name => 'Fred' ]
269 For non-terminal nodes, the Data is a reference to an array, where each
271 element of the the array is a new node.
272 +-----------+
274 |Name | Data|
275 +-----------+
276 ||| +-----------+
277 ||+-->|Name | Data|
278 || +-----------+
279 ||
280 || +-----------+
281 |+--->|Name | Data|
282 | +-----------+
283 |
284 | +-----------+
285 +---->|Name | Data|
286 +-----------+
287 In perl this would be:
289 [ Name => [
291 [Name1 => $Data1],
292 [Name2 => $Data2],
293 [Name3 => $Data3],
294 ]
295 ];
296 The extra level of nesting is required to be able to store any node in
298 the tree using a single variable. This representation has lots of
299 advantages over others, eg hashes and mixed hash/array structures.
300 MANIPULATION AND QUERYING
302 The following example is taken from biology; we have a list of species
303 (mouse, human, fly) and a list of genes found in that species. These
304 are cross-referenced by an identifier called tax_id. We can do a
305 relational-style inner join on this identifier, as follows -
306 use Data::Stag qw(:all);
308 my $tree =
309 Data::Stag->new(
310 'db' => [
311 [ 'species_set' => [
312 [ 'species' => [
313 [ 'common_name' => 'house mouse' ],
314 [ 'binomial' => 'Mus musculus' ],
315 [ 'tax_id' => '10090' ]]],
316 [ 'species' => [
317 [ 'common_name' => 'fruit fly' ],
318 [ 'binomial' => 'Drosophila melanogaster' ],
319 [ 'tax_id' => '7227' ]]],
320 [ 'species' => [
321 [ 'common_name' => 'human' ],
322 [ 'binomial' => 'Homo sapiens' ],
323 [ 'tax_id' => '9606' ]]]]],
324 [ 'gene_set' => [
325 [ 'gene' => [
326 [ 'symbol' => 'HGNC' ],
327 [ 'tax_id' => '9606' ],
328 [ 'phenotype' => 'Hemochromatosis' ],
329 [ 'phenotype' => 'Porphyria variegata' ],
330 [ 'GO_term' => 'iron homeostasis' ],
331 [ 'map' => '6p21.3' ]]],
332 [ 'gene' => [
333 [ 'symbol' => 'Hfe' ],
334 [ 'synonym' => 'MR2' ],
335 [ 'tax_id' => '10090' ],
336 [ 'GO_term' => 'integral membrane protein' ],
337 [ 'map' => '13 A2-A4' ]]]]]]
338 );
339 # inner join of species and gene parts of tree,
341 # based on 'tax_id' element
342 my $gene_set = $tree->find("gene_set"); # get <gene_set> element
343 my $species_set = $tree->find("species_set"); # get <species_set> element
344 $gene_set->ijoin("gene", "tax_id", $species_set); # INNER JOIN
345 print "Reorganised data:\n";
347 print $gene_set->xml;
348 # find all genes starting with letter 'H' in where species/common_name=human
350 my @genes =
351 $gene_set->where('gene',
352 sub { my $g = shift;
353 $g->get_symbol =~ /^H/ &&
354 $g->findval("common_name") eq ('human')});
355 print "Human genes beginning 'H'\n";
357 print $_->xml foreach @genes;
358 S-Expression (Lisp) representation
360 The data represented using this module can be represented as Lisp-style
361 S-Expressions.
362 See Data::Stag::SxprParser and Data::Stag::SxprWriter
364 If we execute this code on the XML from the example above
366 $stag = Data::Stag->parse($xmlfile);
368 print $stag->sxpr;
369 The following S-Expression will be printed:
371 '(db
373 (species_set
374 (species
375 (common_name "house mouse")
376 (binomial "Mus musculus")
377 (tax_id "10090"))
378 (species
379 (common_name "fruit fly")
380 (binomial "Drosophila melanogaster")
381 (tax_id "7227"))
382 (species
383 (common_name "human")
384 (binomial "Homo sapiens")
385 (tax_id "9606")))
386 (gene_set
387 (gene
388 (symbol "HGNC")
389 (tax_id "9606")
390 (phenotype "Hemochromatosis")
391 (phenotype "Porphyria variegata")
392 (GO_term "iron homeostasis")
393 (map
394 (cytological
395 (chromosome "6")
396 (band "p21.3"))))
397 (gene
398 (symbol "Hfe")
399 (synonym "MR2")
400 (tax_id "10090")
401 (GO_term "integral membrane protein")))
402 (similarity_set
403 (pair
404 (symbol "HGNC")
405 (symbol "Hfe"))
406 (pair
407 (symbol "WNT3A")
408 (symbol "Wnt3a"))))
409 TIPS FOR EMACS USERS AND LISP PROGRAMMERS
411 If you use emacs, you can save this as a file with the ".el" suffix and
413 get syntax highlighting for editing this file. Quotes around the
414 terminal node data items are optional.
415 If you know emacs lisp or any other lisp, this also turns out to be a
417 very nice language for manipulating these datastructures. Try copying
418 and pasting the above s-expression to the emacs scratch buffer and
419 playing with it in lisp.
420 INDENTED TEXT REPRESENTATION
422 Data::Stag has its own text format for writing data trees. Again, this
423 is only possible because we are working with a subset of XML (no
424 attributes, no mixed elements). The data structure above can be written
425 as follows -
426 db:
428 species_set:
429 species:
430 common_name: house mouse
431 binomial: Mus musculus
432 tax_id: 10090
433 species:
434 common_name: fruit fly
435 binomial: Drosophila melanogaster
436 tax_id: 7227
437 species:
438 common_name: human
439 binomial: Homo sapiens
440 tax_id: 9606
441 gene_set:
442 gene:
443 symbol: HGNC
444 tax_id: 9606
445 phenotype: Hemochromatosis
446 phenotype: Porphyria variegata
447 GO_term: iron homeostasis
448 map: 6p21.3
449 gene:
450 symbol: Hfe
451 synonym: MR2
452 tax_id: 10090
453 GO_term: integral membrane protein
454 map: 13 A2-A4
455 similarity_set:
456 pair:
457 symbol: HGNC
458 symbol: Hfe
459 pair:
460 symbol: WNT3A
461 symbol: Wnt3a
462 See Data::Stag::ITextParser and Data::Stag::ITextWriter
464 NESTED ARRAY SPECIFICATION II
466 To avoid excessive square bracket usage, you can specify a structure
467 like this:
468 use Data::Stag qw(:all);
470 *N = \&stag_new;
472 my $tree =
473 N(top=>[
474 N('personset'=>[
475 N('person'=>[
476 N('name'=>'davey'),
477 N('address'=>'here'),
478 N('description'=>[
479 N('hair'=>'green'),
480 N('eyes'=>'two'),
481 N('teeth'=>5),
482 ]
483 ),
484 N('pets'=>[
485 N('petname'=>'igor'),
486 N('petname'=>'ginger'),
487 ]
488 ),
489 ],
491 ),
492 N('person'=>[
493 N('name'=>'shuggy'),
494 N('address'=>'there'),
495 N('description'=>[
496 N('hair'=>'red'),
497 N('eyes'=>'three'),
498 N('teeth'=>1),
499 ]
500 ),
501 N('pets'=>[
502 N('petname'=>'thud'),
503 N('petname'=>'spud'),
504 ]
505 ),
506 ]
507 ),
508 ]
509 ),
510 N('animalset'=>[
511 N('animal'=>[
512 N('name'=>'igor'),
513 N('class'=>'rat'),
514 N('description'=>[
515 N('fur'=>'white'),
516 N('eyes'=>'red'),
517 N('teeth'=>50),
518 ],
519 ),
520 ],
521 ),
522 ]
523 ),
524 ]
526 );
527 # find all people
529 my @persons = stag_find($tree, 'person');
530 # write xml for all red haired people
532 foreach my $p (@persons) {
533 print stag_xml($p)
534 if stag_tmatch($p, "hair", "red");
535 } ;
536 # find all people that have name == shuggy
538 my @p =
539 stag_qmatch($tree,
540 "person",
541 "name",
542 "shuggy");
543
545 As well as the methods listed below, a node can be treated as if it is
546 a data object of a class determined by the element.
547 For example, the following are equivalent.
549 $node->get_name;
551 $node->get('name');
552 $node->set_name('fred');
554 $node->set('name', 'fred');
555 This is really just syntactic sugar. The autoloaded methods are not
557 checked against any schema, although this may be added in future.
558
560 A stag tree can be indexed as a hash for direct retrieval; see
561 Data::Stag::HashDB
562 This index can be made persistent as a DB file; see Data::Stag::StagDB
564 If you wish to use Stag in conjunction with a relational database, you
566 should install DBIx::DBStag
567
569 All method calls are also available as procedural subroutine calls;
570 unless otherwise noted, the subroutine call is the same as the method
571 call, but with the string stag_ prefixed to the method name. The first
572 argument should be a Data::Stag datastructure.
573 To import all subroutines into the current namespace, use this idiom:
575 use Data::Stag qw(:all);
577 $doc = stag_parse($file);
578 @persons = stag_find($doc, 'person');
579 If you wish to use this module procedurally, and you are too lazy to
581 prefix all calls with stag_, use this idiom:
582 use Data::Stag qw(:lazy);
584 $doc = parse($file);
585 @persons = find($doc, 'person');
586 But beware of clashes!
588 Most method calls also have a handy short mnemonic. Use of these is
590 optional. Software engineering types prefer longer names, in the belief
591 that this leads to clearer code. Hacker types prefer shorter names, as
592 this requires less keystrokes, and leads to a more compact
593 representation of the code. It is expected that if you do use this
594 module, then its usage will be fairly ubiquitous within your code, and
595 the mnemonics will become familiar, much like the qw and s/ operators
596 in perl. As always with perl, the decision is yours.
597 Some methods take a single parameter or list of parameters; some have
599 large lists of parameters that can be passed in any order. If the
600 documentation states:
601 Args: [x str], [y int], [z ANY]
603 Then the method can be called like this:
605 $stag->foo("this is x", 55, $ref);
607 or like this:
609 $stag->foo(-z=>$ref, -x=>"this is x", -y=>55);
611 INITIALIZATION METHODS
613 new
614 Title: new
616 Args: element str, data STAG-DATA
618 Returns: Data::Stag node
619 Example: $node = stag_new();
620 Example: $node = Data::Stag->new;
621 Example: $node = Data::Stag->new(person => [[name=>$n], [phone=>$p]]);
622 creates a new instance of a Data::Stag node
624 stagify (nodify)
626 Title: stagify
628 Synonym: nodify
629 Args: data ARRAY-REF
630 Returns: Data::Stag node
631 Example: $node = stag_stagify([person => [[name=>$n], [phone=>$p]]]);
632 turns a perl array reference into a Data::Stag node.
634 similar to new
636 parse
638 Title: parse
640 Args: [file str], [format str], [handler obj], [fh FileHandle]
642 Returns: Data::Stag node
643 Example: $node = stag_parse($fn);
644 Example: $node = stag_parse(-fh=>$fh, -handler=>$h, -errhandler=>$eh);
645 Example: $node = Data::Stag->parse(-file=>$fn, -handler=>$myhandler);
646 slurps a file or string into a Data::Stag node structure. Will guess
648 the format (xml, sxpr, itext, indent) from the suffix if it is not
649 given.
650 The format can also be the name of a parsing module, or an actual
652 parser object;
653 The handler is any object that can take nested Stag events
655 (start_event, end_event, evbody) which are generated from the parse. If
656 the handler is omitted, all events will be cached and the resulting
657 tree will be returned.
658 See Data::Stag::BaseHandler for writing your own handlers
660 See Data::Stag::BaseGenerator for details on parser classes, and error
662 handling
663 parsestr
665 Title: parsestr
667 Args: [str str], [format str], [handler obj]
669 Returns: Data::Stag node
670 Example: $node = stag_parsestr('(a (b (c "1")))');
671 Example: $node = Data::Stag->parsestr(-str=>$str, -handler=>$myhandler);
672 Similar to parse(), except the first argument is a string
674 from
676 Title: from
678 Args: format str, source str
680 Returns: Data::Stag node
681 Example: $node = stag_from('xml', $fn);
682 Example: $node = stag_from('xmlstr', q[<top><x>1</x></top>]);
683 Example: $node = Data::Stag->from($parser, $fn);
684 Similar to parse
686 slurps a file or string into a Data::Stag node structure.
688 The format can also be the name of a parsing module, or an actual
690 parser object
691 unflatten
693 Title: unflatten
695 Args: data array
697 Returns: Data::Stag node
698 Example: $node = stag_unflatten(person=>[name=>$n, phone=>$p, address=>[street=>$s, city=>$c]]);
699 Creates a node structure from a semi-flattened representation, in which
701 children of a node are represented as a flat list of data rather than a
702 list of array references.
703 This means a structure can be specified as:
705 person=>[name=>$n,
707 phone=>$p,
708 address=>[street=>$s,
709 city=>$c]]
710 Instead of:
712 [person=>[ [name=>$n],
714 [phone=>$p],
715 [address=>[ [street=>$s],
716 [city=>$c] ] ]
717 ]
718 ]
719 The former gets converted into the latter for the internal
721 representation
722 makehandler
724 Title: makehandler
726 Args: hash of CODEREFs keyed by element name
728 OR a string containing the name of a module
729 Returns: L<Data::Stag::BaseHandler>
730 Example: $h = Data::Stag->makehandler(%subs);
731 Example: $h = Data::Stag->makehandler("My::FooHandler");
732 Example: $h = Data::Stag->makehandler('xml');
733 This creates a Stag event handler. The argument is a hash of
735 subroutines keyed by element/node name. After each node is fired by the
736 parser/generator, the subroutine is called, passing the handler object
737 and the stag node as arguments. whatever the subroutine returns is
738 placed back into the tree
739 For example, for a a parser/generator that fires events with the
741 following tree form
742 <person>
744 <name>foo</name>
745 ...
746 </person>
747 we can create a handler that writes person/name like this:
749 $h = Data::Stag->makehandler(
751 person => sub { my ($self,$stag) = @_;
752 print $stag->name;
753 return $stag; # dont change tree
754 });
755 $stag = Data::Stag->parse(-str=>"(...)", -handler=>$h)
756 See Data::Stag::BaseHandler for details on handlers
758 getformathandler
760 Title: getformathandler
762 Args: format str OR L<Data::Stag::BaseHandler>
764 Returns: L<Data::Stag::BaseHandler>
765 Example: $h = Data::Stag->getformathandler('xml');
766 $h->file("my.xml");
767 Data::Stag->parse(-fn=>$fn, -handler=>$h);
768 Creates a Stag event handler - this handler can be passed to an event
770 generator / parser. Built in handlers include:
771 xml Generates xml tags from events
773 sxpr
775 Generates S-Expressions from events
776 itext
778 Generates itext format from events
779 indent
781 Generates indent format from events
782 All the above are kinds of Data::Stag::Writer
784 chainhandler
786 Title: chainhandler
788 Args: blocked events - str or str[]
790 initial handler - handler object
791 final handler - handler object
792 Returns:
793 Example: $h = Data::Stag->chainhandler('foo', $processor, 'xml')
794 chains handlers together - for example, you may want to make transforms
796 on an event stream, and then pass the event stream to another handler -
797 for example, and xml handler
798 $processor = Data::Stag->makehandler(
800 a => sub { my ($self,$stag) = @_;
801 $stag->set_foo("bar");
802 return $stag
803 },
804 b => sub { my ($self,$stag) = @_;
805 $stag->set_blah("eek");
806 return $stag
807 },
808 );
809 $chainh = Data::Stag->chainhandler(['a', 'b'], $processor, 'xml');
810 $stag = Data::Stag->parse(-str=>"(...)", -handler=>$chainh)
811 If the inner handler has a method CONSUMES(), this method will
813 determine the blocked events if none are specified.
814 see also the script stag-handle.pl
816 RECURSIVE SEARCHING
818 find (f)
819 Title: find
821 Synonym: f
822 Args: element str
824 Returns: node[] or ANY
825 Example: @persons = stag_find($struct, 'person');
826 Example: @persons = $struct->find('person');
827 recursively searches tree for all elements of the given type, and
829 returns all nodes or data elements found.
830 if the element found is a non-terminal node, will return the node if
832 the element found is a terminal (leaf) node, will return the data value
833 the element argument can be a path
835 @names = $struct->find('department/person/name');
837 will find name in the nested structure below:
839 (department
841 (person
842 (name "foo")))
843 findnode (fn)
845 Title: findnode
847 Synonym: fn
848 Args: element str
850 Returns: node[]
851 Example: @persons = stag_findnode($struct, 'person');
852 Example: @persons = $struct->findnode('person');
853 recursively searches tree for all elements of the given type, and
855 returns all nodes found.
856 paths can also be used (see find)
858 findval (fv)
860 Title: findval
862 Synonym: fv
863 Args: element str
865 Returns: ANY[] or ANY
866 Example: @names = stag_findval($struct, 'name');
867 Example: @names = $struct->findval('name');
868 Example: $firstname = $struct->findval('name');
869 recursively searches tree for all elements of the given type, and
871 returns all data values found. the data values could be primitive
872 scalars or nodes.
873 paths can also be used (see find)
875 sfindval (sfv)
877 Title: sfindval
879 Synonym: sfv
880 Args: element str
882 Returns: ANY
883 Example: $name = stag_sfindval($struct, 'name');
884 Example: $name = $struct->sfindval('name');
885 as findval, but returns the first value found
887 paths can also be used (see find)
889 findvallist (fvl)
891 Title: findvallist
893 Synonym: fvl
894 Args: element str[]
896 Returns: ANY[]
897 Example: ($name, $phone) = stag_findvallist($personstruct, 'name', 'phone');
898 Example: ($name, $phone) = $personstruct->findvallist('name', 'phone');
899 recursively searches tree for all elements in the list
901 DEPRECATED
903 DATA ACCESSOR METHODS
905 these allow getting and setting of elements directly underneath the
906 current one
907 get (g)
909 Title: get
911 Synonym: g
912 Args: element str
914 Return: node[] or ANY
915 Example: $name = $person->get('name');
916 Example: @phone_nos = $person->get('phone_no');
917 gets the value of the named sub-element
919 if the sub-element is a non-terminal, will return a node(s) if the sub-
921 element is a terminal (leaf) it will return the data value(s)
922 the examples above would work on a data structure like this:
924 [person => [ [name => 'fred'],
926 [phone_no => '1-800-111-2222'],
927 [phone_no => '1-415-555-5555']]]
928 will return an array or single value depending on the context
930 [equivalent to findval(), except that only direct children (as opposed
932 to all descendents) are checked]
933 paths can also be used, like this:
935 @phones_nos = $struct->get('person/phone_no')
937 sget (sg)
939 Title: sget
941 Synonym: sg
942 Args: element str
944 Return: ANY
945 Example: $name = $person->sget('name');
946 Example: $phone = $person->sget('phone_no');
947 Example: $phone = $person->sget('department/person/name');
948 as get but always returns a single value
950 [equivalent to sfindval(), except that only direct children (as opposed
952 to all descendents) are checked]
953 getl (gl getlist)
955 Title: gl
957 Synonym: getl
958 Synonym: getlist
959 Args: element str[]
961 Return: node[] or ANY[]
962 Example: ($name, @phone) = $person->getl('name', 'phone_no');
963 returns the data values for a list of sub-elements of a node
965 [equivalent to findvallist(), except that only direct children (as
967 opposed to all descendents) are checked]
968 getn (gn getnode)
970 Title: getn
972 Synonym: gn
973 Synonym: getnode
974 Args: element str
976 Return: node[]
977 Example: $namestruct = $person->getn('name');
978 Example: @pstructs = $person->getn('phone_no');
979 as get but returns the whole node rather than just the data value
981 [equivalent to findnode(), except that only direct children (as opposed
983 to all descendents) are checked]
984 sgetmap (sgm)
986 Title: sgetmap
988 Synonym: sgm
989 Args: hash
991 Return: hash
992 Example: %h = $person->sgetmap('social-security-no'=>'id',
993 'name' =>'label',
994 'job' =>0,
995 'address' =>'location');
996 returns a hash of key/val pairs based on the values of the data values
998 of the subnodes in the current element; keys are mapped according to
999 the hash passed (a value of '' or 0 will map an identical key/val).
1000 no multivalued data elements are allowed
1002 set (s)
1004 Title: set
1006 Synonym: s
1007 Args: element str, datavalue ANY (list)
1009 Return: ANY
1010 Example: $person->set('name', 'fred'); # single val
1011 Example: $person->set('phone_no', $cellphone, $homephone);
1012 sets the data value of an element for any node. if the element is
1014 multivalued, all the old values will be replaced with the new ones
1015 specified.
1016 ordering will be preserved, unless the element specified does not
1018 exist, in which case, the new tag/value pair will be placed at the end.
1019 for example, if we have a stag node $person
1021 person:
1023 name: shuggy
1024 job: bus driver
1025 if we do this
1027 $person->set('name', ());
1029 we will end up with
1031 person:
1033 job: bus driver
1034 then if we do this
1036 $person->set('name', 'shuggy');
1038 the 'name' node will be placed as the last attribute
1040 person:
1042 job: bus driver
1043 name: shuggy
1044 You can also use magic methods, for example
1046 $person->set_name('shuggy');
1048 $person->set_job('bus driver', 'poet');
1049 print $person->itext;
1050 will print
1052 person:
1054 name: shuggy
1055 job: bus driver
1056 job: poet
1057 note that if the datavalue is a non-terminal node as opposed to a
1059 primitive value, then you have to do it like this:
1060 $people = Data::Stag->new(people=>[
1062 [person=>[[name=>'Sherlock Holmes']]],
1063 [person=>[[name=>'Moriarty']]],
1064 ]);
1065 $address = Data::Stag->new(address=>[
1066 [address_line=>"221B Baker Street"],
1067 [city=>"London"],
1068 [country=>"Great Britain"]]);
1069 ($person) = $people->qmatch('person', (name => "Sherlock Holmes"));
1070 $person->set("address", $address->data);
1071 If you are using XML data, you can set attributes like this:
1073 $person->set('@'=>[[id=>$id],[foo=>$foo]]);
1075 unset (u)
1077 Title: unset
1079 Synonym: u
1080 Args: element str, datavalue ANY
1082 Return: ANY
1083 Example: $person->unset('name');
1084 Example: $person->unset('phone_no');
1085 prunes all nodes of the specified element from the current node
1087 You can use magic methods, like this
1089 $person->unset_name;
1091 $person->unset_phone_no;
1092 free
1094 Title: free
1096 Synonym: u
1097 Args:
1099 Return:
1100 Example: $person->free;
1101 removes all data from a node. If that node is a subnode of another
1103 node, it is removed altogether
1104 for instance, if we had the data below:
1106 <person>
1108 <name>fred</name>
1109 <address>
1110 ..
1111 </address>
1112 </person>
1113 and called
1115 $person->get_address->free
1117 then the person node would look like this:
1119 <person>
1121 <name>fred</name>
1122 </person>
1123 add (a)
1125 Title: add
1127 Synonym: a
1128 Args: element str, datavalues ANY[]
1130 OR
1131 Data::Stag
1132 Return: ANY
1133 Example: $person->add('phone_no', $cellphone, $homephone);
1134 Example: $person->add_phone_no('1-555-555-5555');
1135 Example: $dataset->add($person)
1136 adds a datavalue or list of datavalues. appends if already existing,
1138 creates new element value pairs if not already existing.
1139 if the argument is a stag node, it will add this node under the current
1141 one.
1142 For example, if we have the following node in $dataset
1144 <dataset>
1146 <person>
1147 <name>jim</name>
1148 </person>
1149 </dataset>
1150 And then we add data to it:
1152 ($person) = $dataset->qmatch('person', name=>'jim');
1154 $person->add('phone_no', '555-1111', '555-2222');
1155 We will be left with:
1157 <dataset>
1159 <person>
1160 <name>jim</name>
1161 <phone_no>555-1111</phone_no>
1162 <phone_no>555-2222</phone_no>
1163 </person>
1164 </dataset>
1165 The above call is equivalent to:
1167 $person->add_phone_no('555-1111', '555-2222');
1169 As well as adding data values, we can add whole nodes:
1171 $dataset->add(person=>[[name=>"fred"],
1173 [phone_no=>"555-3333"]]);
1174 Which is equivalent to
1176 $dataset->add_person([[name=>"fred"],
1178 [phone_no=>"555-3333"]]);
1179 Remember, the value has to be specified as an array reference of nodes.
1181 In general, you should use the addkid() method to add nodes and used
1182 add() to add values
1183 element (e name)
1185 Title: element
1187 Synonym: e
1188 Synonym: name
1189 Args:
1191 Return: element str
1192 Example: $element = $struct->element
1193 returns the element name of the current node.
1195 This is illustrated in the different representation formats below
1197 sxpr
1199 (element "data")
1200 or
1202 (element
1204 (sub_element "..."))
1205 xml
1207 <element>data</element>
1208 or
1210 <element>
1212 <sub_element>...</sub_element>
1213 </element>
1214 perl
1216 [element => $data ]
1217 or
1219 [element => [
1221 [sub_element => "..." ]]]
1222 itext
1224 element: data
1225 or
1227 element:
1229 sub_element: ...
1230 indent
1232 element "data"
1233 or
1235 element
1237 sub_element "..."
1238 kids (k children)
1240 Title: kids
1242 Synonym: k
1243 Synonym: children
1244 Args:
1246 Return: ANY or ANY[]
1247 Example: @nodes = $person->kids
1248 Example: $name = $namestruct->kids
1249 returns the data value(s) of the current node; if it is a terminal
1251 node, returns a single value which is the data. if it is non-terminal,
1252 returns an array of nodes
1253 addkid (ak addchild)
1255 Title: addkid
1257 Synonym: ak
1258 Synonym: addchild
1259 Args: kid node
1261 Return: ANY
1262 Example: $person->addkid($job);
1263 adds a new child node to a non-terminal node, after all the existing
1265 child nodes
1266 You can use this method/procedure to add XML attribute data to a node:
1268 $person->addkid(['@'=>[[id=>$id]]]);
1270 subnodes
1272 Title: subnodes
1274 Args:
1276 Return: ANY[]
1277 Example: @nodes = $person->subnodes
1278 returns the child nodes; returns empty list if this is a terminal node
1280 ntnodes
1282 Title: ntnodes
1284 Args:
1286 Return: ANY[]
1287 Example: @nodes = $person->ntnodes
1288 returns all non-terminal children of current node
1290 tnodes
1292 Title: tnodes
1294 Args:
1296 Return: ANY[]
1297 Example: @nodes = $person->tnodes
1298 returns all terminal children of current node
1300 QUERYING AND ADVANCED DATA MANIPULATION
1302 ijoin (j)
1303 Title: ijoin
1305 Synonym: j
1306 Synonym: ij
1307 Args: element str, key str, data Node
1309 Return: undef
1310 does a relational style inner join - see previous example in this doc
1312 key can either be a single node name that must be shared (analagous to
1314 SQL INNER JOIN .. USING), or a key1=key2 equivalence relation
1315 (analagous to SQL INNER JOIN ... ON)
1316 qmatch (qm)
1318 Title: qmatch
1320 Synonym: qm
1321 Args: return-element str, match-element str, match-value str
1323 Return: node[]
1324 Example: @persons = $s->qmatch('person', 'name', 'fred');
1325 Example: @persons = $s->qmatch('person', (job=>'bus driver'));
1326 queries the node tree for all elements that satisfy the specified
1328 key=val match - see previous example in this doc
1329 for those inclined to thinking relationally, this can be thought of as
1331 a query that returns a stag object:
1332 SELECT <return-element> FROM <stag-node> WHERE <match-element> = <match-value>
1334 this always returns an array; this means that calling in a scalar
1336 context will return the number of elements; for example
1337 $n = $s->qmatch('person', (name=>'fred'));
1339 the value of $n will be equal to the number of persons called fred
1341 tmatch (tm)
1343 Title: tmatch
1345 Synonym: tm
1346 Args: element str, value str
1348 Return: bool
1349 Example: @persons = grep {$_->tmatch('name', 'fred')} @persons
1350 returns true if the the value of the specified element matches - see
1352 previous example in this doc
1353 tmatchhash (tmh)
1355 Title: tmatchhash
1357 Synonym: tmh
1358 Args: match hashref
1360 Return: bool
1361 Example: @persons = grep {$_->tmatchhash({name=>'fred', hair_colour=>'green'})} @persons
1362 returns true if the node matches a set of constraints, specified as
1364 hash.
1365 tmatchnode (tmn)
1367 Title: tmatchnode
1369 Synonym: tmn
1370 Args: match node
1372 Return: bool
1373 Example: @persons = grep {$_->tmatchnode([person=>[[name=>'fred'], [hair_colour=>'green']]])} @persons
1374 returns true if the node matches a set of constraints, specified as
1376 node
1377 cmatch (cm)
1379 Title: cmatch
1381 Synonym: cm
1382 Args: element str, value str
1384 Return: bool
1385 Example: $n_freds = $personset->cmatch('name', 'fred');
1386 counts the number of matches
1388 where (w)
1390 Title: where
1392 Synonym: w
1393 Args: element str, test CODE
1395 Return: Node[]
1396 Example: @rich_persons = $data->where('person', sub {shift->get_salary > 100000});
1397 the tree is queried for all elements of the specified type that satisfy
1399 the coderef (must return a boolean)
1400 my @rich_dog_or_cat_owners =
1402 $data->where('person',
1403 sub {my $p = shift;
1404 $p->get_salary > 100000 &&
1405 $p->where('pet',
1406 sub {shift->get_type =~ /(dog|cat)/})});
1407 iterate (i)
1409 Title: iterate
1411 Synonym: i
1412 Args: CODE
1414 Return: Node[]
1415 Example: $data->iterate(sub {
1416 my $stag = shift;
1417 my $parent = shift;
1418 if ($stag->element eq 'pet') {
1419 $parent->set_pet_name($stag->get_name);
1420 }
1421 });
1422 iterates through whole tree calling the specified subroutine.
1424 the first arg passed to the subroutine is the stag node representing
1426 the tree at that point; the second arg is for the parent.
1427 for instance, the example code above would turn this
1429 (person
1431 (name "jim")
1432 (pet
1433 (name "fluffy")))
1434 into this
1436 (person
1438 (name "jim")
1439 (pet_name "fluffy")
1440 (pet
1441 (name "fluffy")))
1442 maptree
1444 Title: maptree
1446 Args: CODE
1448 Return: Node[]
1449 Example: $data->maptree(sub {
1450 my $stag = shift;
1451 my $parent = shift;
1452 if ($stag->element eq 'pet') {
1453 [pet=>$stag->sget_foo]
1454 }
1455 else {
1456 $stag
1457 }
1458 });
1459 MISCELLANEOUS METHODS
1461 duplicate (d)
1462 Title: duplicate
1464 Synonym: d
1465 Args:
1467 Return: Node
1468 Example: $node2 = $node->duplicate;
1469 does a deep copy of a stag structure
1471 isanode
1473 Title: isanode
1475 Args:
1477 Return: bool
1478 Example: if (stag_isanode($node)) { ... }
1479 hash
1481 Title: hash
1483 Args:
1485 Return: hash
1486 Example: $h = $node->hash;
1487 turns a tree into a hash. all data values will be arrayrefs
1489 pairs
1491 Title: pairs
1493 turns a tree into a hash. all data values will be scalar (IMPORTANT:
1495 this means duplicate values will be lost)
1496 write
1498 Title: write
1500 Args: filename str, format str[optional]
1502 Return:
1503 Example: $node->write("myfile.xml");
1504 Example: $node->write("myfile", "itext");
1505 will try and guess the format from the extension if not specified
1507 xml
1509 Title: xml
1511 Args: filename str, format str[optional]
1513 Return:
1514 Example: $node->write("myfile.xml");
1515 Example: $node->write("myfile", "itext");
1516 Args:
1519 Return: xml str
1520 Example: print $node->xml;
1521 XML METHODS
1523 xslt
1524 Title: xslt
1526 Args: xslt_file str
1528 Return: Node
1529 Example: $new_stag = $stag->xslt('mytransform.xsl');
1530 transforms a stag tree using XSLT
1532 xsltstr
1534 Title: xsltstr
1536 Args: xslt_file str
1538 Return: str
1539 Example: print $stag->xsltstr('mytransform.xsl');
1540 As above, but returns the string of the resulting transform, rather
1542 than a stag tree
1543 sax
1545 Title: sax
1547 Args: saxhandler SAX-CLASS
1549 Return:
1550 Example: $node->sax($mysaxhandler);
1551 turns a tree into a series of SAX events
1553 xpath (xp tree2xpath)
1555 Title: xpath
1557 Synonym: xp
1558 Synonym: tree2xpath
1559 Args:
1561 Return: xpath object
1562 Example: $xp = $node->xpath; $q = $xp->find($xpathquerystr);
1563 xpquery (xpq xpathquery)
1565 Title: xpquery
1567 Synonym: xpq
1568 Synonym: xpathquery
1569 Args: xpathquery str
1571 Return: Node[]
1572 Example: @nodes = $node->xqp($xpathquerystr);
1573
1575 The following scripts come with the stag module
1576 stag-autoschema.pl
1578 writes the implicit stag-schema for a stag file
1579 stag-db.pl
1581 persistent storage and retrieval for stag data (xml, sxpr, itext)
1582 stag-diff.pl
1584 finds the difference between two stag files
1585 stag-drawtree.pl
1587 draws a stag file (xml, itext, sxpr) as a PNG diagram
1588 stag-filter.pl
1590 filters a stag file (xml, itext, sxpr) for nodes of interest
1591 stag-findsubtree.pl
1593 finds nodes in a stag file
1594 stag-flatten.pl
1596 turns stag data into a flat table
1597 stag-grep.pl
1599 filters a stag file (xml, itext, sxpr) for nodes of interest
1600 stag-handle.pl
1602 streams a stag file through a handler into a writer
1603 stag-join.pl
1605 joins two stag files together based around common key
1606 stag-mogrify.pl
1608 mangle stag files
1609 stag-parse.pl
1611 parses a file and fires events (e.g. sxpr to xml)
1612 stag-query.pl
1614 aggregare queries
1615 stag-split.pl
1617 splits a stag file (xml, itext, sxpr) into multiple files
1618 stag-splitter.pl
1620 splits a stag file into multiple files
1621 stag-view.pl
1623 draws an expandable Tk tree diagram showing stag data
1624 To get more documentation, type
1626 stag_<script> -h
1628
1630 none known so far, possibly quite a few undocumented features!
1631 Not a bug, but the underlying default datastructure of nested arrays is
1633 more heavyweight than it needs to be. More lightweight implementations
1634 are possible. Some time I will write a C implementation.
1635
1637 <http://stag.sourceforge.net>
1638
1640 Chris Mungall <cjm AT fruitfly DOT org>
1641
1643 Copyright (c) 2004 Chris Mungall
1644 This module is free software. You may distribute this module under the
1646 same terms as perl itself
1647perl v5.34.0 2021-07-22 Data::Stag(3)