NAME Data::Stag - Structured Tags datastructures SYNOPSIS # PROCEDURAL USAGE use Data::Stag qw(:all); $doc = stag_parse($file); @persons = stag_find($doc, "person"); foreach $p (@persons) { printf "%s, %s phone: %s\n", stag_sget($p, "family_name"), stag_sget($p, "given_name"), stag_sget($p, "phone_no"), ; } # OBJECT-ORIENTED USAGE use Data::Stag; $doc = Data::Stag->parse($file); @persons = $doc->find("person"); foreach $p (@person) { printf "%s, %s phone:%s\n", $p->sget("family_name"), $p->sget("given_name"), $p->sget("phone_no"), ; } DESCRIPTION This module is for manipulating data as hierarchical tag/value pairs (Structured TAGs or Simple Tree AGgreggates). These datastructures can be represented as nested arrays, which have the advantage of being native to perl. A simple example is shown below: [ person=> [ [ family_name => $family_name ], [ given_name => $given_name ], [ phone_no => $phone_no ] ] ], the Data::Stag manpage uses a subset of XML for import and export. This means the module can also be used as a general XML parser/writer (with certain caveats). The above set of structured tags can be represented in XML as ... ... ... This datastructure can be examined, manipulated and exported using Stag functions or methods: $document = Data::Stag->parse($file); @persons = $document->find('person'); foreach my $person (@person) { $person->set('full_name', $person->sget('given_name') . ' ' . $person->sget('family_name')); } Advanced querying is performed by passing functions, for example: # get all people in dataset with name starting 'A' @persons = $document->where('person', sub {shift->sget('family_name') =~ /^A/}); One of the things that marks this module out against other XML modules is this emphasis on a functional approach as an obect-oriented or procedural approach. PROCEDURAL VS OBJECT-ORIENTED USAGE Depending on your preference, this module can be used a set of procedural subroutine calls, or as method calls upon Data::Stag objects, or both. In procedural mode, all the subroutine calls are prefixed "stag_" to avoid namespace clashes. The following three calls are equivalent: $person = stag_find($doc, "person"); $person = $doc->find("person"); $person = $doc->find_person; In object mode, you can treat any tree element as if it is an object with automatically defined methods for getting/setting the tag values. USE OF XML Nested arrays can be imported and exported as XML, as well as other formats. XML can be slurped into memory all at once (using less memory than an equivalent DOM tree), or a simplified SAX style event handling model can be used. Similarly, data can be exported all at once, or as a series of events. Although this module can be used as a general XML tool, it is intended primarily as a tool for manipulating hierarchical data using nested tag/value pairs. By using a simpler subset of XML equivalent to a basic data tree structure, we can write simpler, cleaner code. This simplicity comes at a price - this module is not very suitable for XML with attributes or mixed content. All attributes are turned into elements. This means that it will not round-trip a piece of xml with attributes in it. For some applications this is acceptable, for others it is not. Mixed content cannot be represented in a simple tree format, so this is also expanded. The following piece of XML example of mixedcontent gets parsed as if it were actually: 1 example of mixed content This module is more suited to dealing with data-oriented documents than text-oriented documents. It can also be used as part of a SAX-style event generation / handling framework - see the Data::Stag::BaseHandler manpage Because nested arrays are native to perl, we can specify an XML datastructure directly in perl without going through multiple object calls. For example, instead of the lengthy $obj->startTag("record"); $obj->startTag("field1"); $obj->characters("foo"); $obj->endTag("field1"); $obj->startTag("field2"); $obj->characters("bar"); $obj->endTag("field2"); $obj->end("record"); We can instead write $struct = [ record => [ [ field1 => 'foo'], [ field2 => 'bar']]]; PARSING The following example is for parsing out subsections of a tree and changing sub-elements use Data::Stag qw(:all); my $tree = stag_parse($xmlfile); my ($subtree) = stag_findnode($tree, $element); stag_set($element, $sub_element, $new_val); print stag_xml($subtree); OBJECT ORIENTED The same can be done in a more OO fashion use Data::Stag qw(:all); my $tree = Data::Stag->parse($xmlfile); my ($subtree) = $tree->findnode($element); $element->set($sub_element, $new_val); print $subtree->xml; IN A STREAM Rather than parsing in a whole file into memory all at once (which may not be suitable for very large files), you can take an event handling approach. The easiest way to do this to register which nodes in the file you are interested in using the makehandler method. The parser will sweep through the file, building objects as it goes, and handing the object to a subroutine that you specify. For example: use Data::Stag; # catch the end of 'person' elements my $h = Data::Stag->makehandler( person=> sub { my ($self, $person) = @_; printf "name:%s phone:%s\n", $person->get_name, $person->get_phone; return; # clear node }); Data::Stag->parse(-handler=>$h, -file=>$f); see the Data::Stag::BaseHandler manpage for writing handlers See the Stag website at http://stag.sourceforge.net for more examples. STRUCTURED TAGS TREE DATA STRUCTURE A tree of structured tags is represented as a recursively nested array, the elements of the array represent nodes in the tree. A node is a name/data pair, that can represent tags and values. A node is represented using a reference to an array, where the first element of the array is the tagname, or element, and the second element is the data This can be visualised as a box: +-----------+ |Name | Data| +-----------+ In perl, we represent this pair as a reference to an array [ Name => $Data ] The Data can either be a list of child nodes (subtrees), or a data value. The terminal nodes (leafs of the tree) contain data values; this is represented in perl using primitive scalars. For example: [ Name => 'Fred' ] For non-terminal nodes, the Data is a reference to an array, where each element of the the array is a new node. +-----------+ |Name | Data| +-----------+ ||| +-----------+ ||+-->|Name | Data| || +-----------+ || || +-----------+ |+--->|Name | Data| | +-----------+ | | +-----------+ +---->|Name | Data| +-----------+ In perl this would be: [ Name => [ [Name1 => $Data1], [Name2 => $Data2], [Name3 => $Data3], ] ]; The extra level of nesting is required to be able to store any node in the tree using a single variable. This representation has lots of advantages over others, eg hashes and mixed hash/array structures. MANIPULATION AND QUERYING The following example is taken from biology; we have a list of species (mouse, human, fly) and a list of genes found in that species. These are cross-referenced by an identifier called tax_id. We can do a relational-style inner join on this identifier, as follows - use Data::Stag qw(:all); my $tree = Data::Stag->new( 'db' => [ [ 'species_set' => [ [ 'species' => [ [ 'common_name' => 'house mouse' ], [ 'binomial' => 'Mus musculus' ], [ 'tax_id' => '10090' ]]], [ 'species' => [ [ 'common_name' => 'fruit fly' ], [ 'binomial' => 'Drosophila melanogaster' ], [ 'tax_id' => '7227' ]]], [ 'species' => [ [ 'common_name' => 'human' ], [ 'binomial' => 'Homo sapiens' ], [ 'tax_id' => '9606' ]]]]], [ 'gene_set' => [ [ 'gene' => [ [ 'symbol' => 'HGNC' ], [ 'tax_id' => '9606' ], [ 'phenotype' => 'Hemochromatosis' ], [ 'phenotype' => 'Porphyria variegata' ], [ 'GO_term' => 'iron homeostasis' ], [ 'map' => '6p21.3' ]]], [ 'gene' => [ [ 'symbol' => 'Hfe' ], [ 'synonym' => 'MR2' ], [ 'tax_id' => '10090' ], [ 'GO_term' => 'integral membrane protein' ], [ 'map' => '13 A2-A4' ]]]]]] ); # inner join of species and gene parts of tree, # based on 'tax_id' element my $gene_set = $tree->find("gene_set"); # get element my $species_set = $tree->find("species_set"); # get element $gene_set->ijoin("gene", "tax_id", $species_set); # INNER JOIN print "Reorganised data:\n"; print $gene_set->xml; # find all genes starting with letter 'H' in where species/common_name=human my @genes = $gene_set->where('gene', sub { my $g = shift; $g->get_symbol =~ /^H/ && $g->findval("common_name") eq ('human')}); print "Human genes beginning 'H'\n"; print $_->xml foreach @genes; S-Expression (Lisp) representation The data represented using this module can be represented as Lisp-style S-Expressions. See the Data::Stag::SxprParser manpage and the Data::Stag::SxprWriter manpage If we execute this code on the XML from the example above $stag = Data::Stag->parse($xmlfile); print $stag->sxpr; The following S-Expression will be printed: '(db (species_set (species (common_name "house mouse") (binomial "Mus musculus") (tax_id "10090")) (species (common_name "fruit fly") (binomial "Drosophila melanogaster") (tax_id "7227")) (species (common_name "human") (binomial "Homo sapiens") (tax_id "9606"))) (gene_set (gene (symbol "HGNC") (tax_id "9606") (phenotype "Hemochromatosis") (phenotype "Porphyria variegata") (GO_term "iron homeostasis") (map (cytological (chromosome "6") (band "p21.3")))) (gene (symbol "Hfe") (synonym "MR2") (tax_id "10090") (GO_term "integral membrane protein"))) (similarity_set (pair (symbol "HGNC") (symbol "Hfe")) (pair (symbol "WNT3A") (symbol "Wnt3a")))) TIPS FOR EMACS USERS AND LISP PROGRAMMERS If you use emacs, you can save this as a file with the ".el" suffix and get syntax highlighting for editing this file. Quotes around the terminal node data items are optional. If you know emacs lisp or any other lisp, this also turns out to be a very nice language for manipulating these datastructures. Try copying and pasting the above s-expression to the emacs scratch buffer and playing with it in lisp. INDENTED TEXT REPRESENTATION Data::Stag has its own text format for writing data trees. Again, this is only possible because we are working with a subset of XML (no attributes, no mixed elements). The data structure above can be written as follows - db: species_set: species: common_name: house mouse binomial: Mus musculus tax_id: 10090 species: common_name: fruit fly binomial: Drosophila melanogaster tax_id: 7227 species: common_name: human binomial: Homo sapiens tax_id: 9606 gene_set: gene: symbol: HGNC tax_id: 9606 phenotype: Hemochromatosis phenotype: Porphyria variegata GO_term: iron homeostasis map: 6p21.3 gene: symbol: Hfe synonym: MR2 tax_id: 10090 GO_term: integral membrane protein map: 13 A2-A4 similarity_set: pair: symbol: HGNC symbol: Hfe pair: symbol: WNT3A symbol: Wnt3a See the Data::Stag::ITextParser manpage and the Data::Stag::ITextWriter manpage NESTED ARRAY SPECIFICATION II To avoid excessive square bracket usage, you can specify a structure like this: use Data::Stag qw(:all); *N = \&stag_new; my $tree = N(top=>[ N('personset'=>[ N('person'=>[ N('name'=>'davey'), N('address'=>'here'), N('description'=>[ N('hair'=>'green'), N('eyes'=>'two'), N('teeth'=>5), ] ), N('pets'=>[ N('petname'=>'igor'), N('petname'=>'ginger'), ] ), ], ), N('person'=>[ N('name'=>'shuggy'), N('address'=>'there'), N('description'=>[ N('hair'=>'red'), N('eyes'=>'three'), N('teeth'=>1), ] ), N('pets'=>[ N('petname'=>'thud'), N('petname'=>'spud'), ] ), ] ), ] ), N('animalset'=>[ N('animal'=>[ N('name'=>'igor'), N('class'=>'rat'), N('description'=>[ N('fur'=>'white'), N('eyes'=>'red'), N('teeth'=>50), ], ), ], ), ] ), ] ); # find all people my @persons = stag_find($tree, 'person'); # write xml for all red haired people foreach my $p (@persons) { print stag_xml($p) if stag_tmatch($p, "hair", "red"); } ; # find all people that have name == shuggy my @p = stag_qmatch($tree, "person", "name", "shuggy"); NODES AS DATA OBJECTS As well as the methods listed below, a node can be treated as if it is a data object of a class determined by the element. For example, the following are equivalent. $node->get_name; $node->get('name'); $node->set_name('fred'); $node->set('name', 'fred'); This is really just syntactic sugar. The autoloaded methods are not checked against any schema, although this may be added in future. STAG METHODS All method calls are also available as procedural subroutine calls; unless otherwise noted, the subroutine call is the same as the method call, but with the string stag_ prefixed to the method name. The first argument should be a Data::Stag datastructure. To import all subroutines into the current namespace, use this idiom: use Data::Stag qw(:all); $doc = stag_parse($file); @persons = stag_find($doc, 'person'); If you wish to use this module procedurally, and you are too lazy to prefix all calls with stag_, use this idiom: use Data::Stag qw(:lazy); $doc = parse($file); @persons = find($doc, 'person'); But beware of clashes! Most method calls also have a handy short mnemonic. Use of these is optional. Software engineering types prefer longer names, in the belief that this leads to clearer code. Hacker types prefer shorter names, as this requires less keystrokes, and leads to a more compact representation of the code. It is expected that if you do use this module, then its usage will be fairly ubiquitous within your code, and the mnemonics will become familiar, much like the qw and s/ operators in perl. As always with perl, the decision is yours. Some methods take a single parameter or list of parameters; some have large lists of parameters that can be passed in any order. If the documentation states: Args: [x str], [y int], [z ANY] Then the method can be called like this: $stag->foo("this is x", 55, $ref); or like this: $stag->foo(-z=>$ref, -x=>"this is x", -y=>55); INITIALIZATION METHODS new Title: new Args: element str, data STAG-DATA Returns: Data::Stag node Example: $node = stag_new(); Example: $node = Data::Stag->new; Example: $node = Data::Stag->new(person => [[name=>$n], [phone=>$p]]); creates a new instance of a Data::Stag node stagify (nodify) Title: stagify Synonym: nodify Args: data ARRAY-REF Returns: Data::Stag node Example: $node = stag_stagify([person => [[name=>$n], [phone=>$p]]]); turns a perl array reference into a Data::Stag node. similar to new parse Title: parse Args: [file str], [format str], [handler obj], [fh FileHandle] Returns: Data::Stag node Example: $node = stag_parse($fn); Example: $node = stag_parse(-fh=>$fh, -handler=>$h, -errhandler=>$eh); Example: $node = Data::Stag->parse(-file=>$fn, -handler=>$myhandler); slurps a file or string into a Data::Stag node structure. Will guess the format (xml, sxpr, itext) from the suffix if it is not given. The format can also be the name of a parsing module, or an actual parser object; The handler is any object that can take nested Stag events (start_event, end_event, evbody) which are generated from the parse. If the handler is omitted, all events will be cached and the resulting tree will be returned. See the Data::Stag::BaseHandler manpage for writing your own handlers See the Data::Stag::BaseGenerator manpage for details on parser classes, and error handling parsestr Title: parsestr Args: [str str], [format str], [handler obj] Returns: Data::Stag node Example: $node = stag_parsestr('(a (b (c "1")))'); Example: $node = Data::Stag->parsestr(-str=>$str, -handler=>$myhandler); Similar to parse(), except the first argument is a string from Title: from Args: format str, source str Returns: Data::Stag node Example: $node = stag_from('xml', $fn); Example: $node = stag_from('xmlstr', q[1]); Example: $node = Data::Stag->from($parser, $fn); Similar to parse slurps a file or string into a Data::Stag node structure. The format can also be the name of a parsing module, or an actual parser object unflatten Title: unflatten Args: data array Returns: Data::Stag node Example: $node = stag_unflatten(person=>[name=>$n, phone=>$p, address=>[street=>$s, city=>$c]]); Creates a node structure from a semi-flattened representation, in which children of a node are represented as a flat list of data rather than a list of array references. This means a structure can be specified as: person=>[name=>$n, phone=>$p, address=>[street=>$s, city=>$c]] Instead of: [person=>[ [name=>$n], [phone=>$p], [address=>[ [street=>$s], [city=>$c] ] ] ] ] The former gets converted into the latter for the internal representation makehandler Title: makehandler Args: hash of CODEREFs keyed by element name OR a string containing the name of a module Returns: L Example: $h = Data::Stag->makehandler(%subs); Example: $h = Data::Stag->makehandler("My::FooHandler"); This creates a Stag event handler. The argument is a hash of subroutines keyed by element/node name. After each node is fired by the parser/generator, the subroutine is called, passing the handler object and the stag node as arguments. whatever the subroutine returns is placed back into the tree For example, for a a parser/generator that fires events with the following tree form foo ... we can create a handler that writes person/name like this: $h = Data::Stag->makehandler( person => sub { my ($self,$stag) = @_; print $stag->name; return $stag; # dont change tree }); $stag = Data::Stag->parse(-str=>"(...)", -handler=>$h) See the Data::Stag::BaseHandler manpage for details on handlers getformathandler Title: getformathandler Args: format str OR L Returns: L Example: $h = Data::Stag->getformathandler('xml'); $h->file("my.xml"); Data::Stag->parse(-fn=>$fn, -handler=>$h); Creates a Stag event handler - this handler can be passed to an event generator / parser. Built in handlers include: xml Generates xml tags from events sxpr Generates S-Expressions from events itext Generates indented text from events All the above are kinds of the Data::Stag::Writer manpage chainhandler Title: chainhandler Args: blocked events - str or str[] initial handler - handler object final handler - handler object Returns: Example: $h = Data::Stag->chainhandler('foo', $processor, 'xml') chains handlers together - for example, you may want to make transforms on an event stream, and then pass the event stream to another handler - for example, and xml handler $processor = Data::Stag->makehandler( a => sub { my ($self,$stag) = @_; $stag->set_foo("bar"); return $stag }, b => sub { my ($self,$stag) = @_; $stag->set_blah("eek"); return $stag }, ); $chainh = Data::Stag->chainhandler(['a', 'b'], $processor, 'xml'); $stag = Data::Stag->parse(-str=>"(...)", -handler=>$chainh) chains together two handlers (see also the script stag-handle.pl) RECURSIVE SEARCHING find (f) Title: find Synonym: f Args: element str Returns: node[] or ANY Example: @persons = stag_find($struct, 'person'); Example: @persons = $struct->find('person'); recursively searches tree for all elements of the given type, and returns all nodes or data elements found. if the element found is a non-terminal node, will return the node if the element found is a terminal (leaf) node, will return the data value the element argument can be a path @names = $struct->find('department/person/name'); will find name in the nested structure below: (department (person (name "foo"))) findnode (fn) Title: findnode Synonym: fn Args: element str Returns: node[] Example: @persons = stag_findnode($struct, 'person'); Example: @persons = $struct->findnode('person'); recursively searches tree for all elements of the given type, and returns all nodes found. paths can also be used (see find) findval (fv) Title: findval Synonym: fv Args: element str Returns: ANY[] or ANY Example: @names = stag_findval($struct, 'name'); Example: @names = $struct->findval('name'); Example: $firstname = $struct->findval('name'); recursively searches tree for all elements of the given type, and returns all data values found. the data values could be primitive scalars or nodes. paths can also be used (see find) sfindval (sfv) Title: sfindval Synonym: sfv Args: element str Returns: ANY Example: $name = stag_sfindval($struct, 'name'); Example: $name = $struct->sfindval('name'); as findval, but returns the first value found paths can also be used (see find) findvallist (fvl) Title: findvallist Synonym: fvl Args: element str[] Returns: ANY[] Example: ($name, $phone) = stag_findvallist($personstruct, 'name', 'phone'); Example: ($name, $phone) = $personstruct->findvallist('name', 'phone'); recursively searches tree for all elements in the list DEPRECATED DATA ACCESSOR METHODS these allow getting and setting of elements directly underneath the current one get (g) Title: get Synonym: g Args: element str Return: node[] or ANY Example: $name = $person->get('name'); Example: @phone_nos = $person->get('phone_no'); gets the value of the named sub-element if the sub-element is a non-terminal, will return a node(s) if the sub-element is a terminal (leaf) it will return the data value(s) the examples above would work on a data structure like this: [person => [ [name => 'fred'], [phone_no => '1-800-111-2222'], [phone_no => '1-415-555-5555']]] will return an array or single value depending on the context [equivalent to findval(), except that only direct children (as opposed to all descendents) are checked] paths can also be used, like this: @phones_nos = $struct->get('person/phone_no') sget (sg) Title: sget Synonym: sg Args: element str Return: ANY Example: $name = $person->sget('name'); Example: $phone = $person->sget('phone_no'); Example: $phone = $person->sget('department/person/name'); as get but always returns a single value [equivalent to sfindval(), except that only direct children (as opposed to all descendents) are checked] getl (gl getlist) Title: gl Synonym: getl Synonym: getlist Args: element str[] Return: node[] or ANY[] Example: ($name, @phone) = $person->getl('name', 'phone_no'); returns the data values for a list of sub-elements of a node [equivalent to findvallist(), except that only direct children (as opposed to all descendents) are checked] getn (gn getnode) Title: getn Synonym: gn Synonym: getnode Args: element str Return: node[] Example: $namestruct = $person->getn('name'); Example: @pstructs = $person->getn('phone_no'); as get but returns the whole node rather than just the data value [equivalent to findnode(), except that only direct children (as opposed to all descendents) are checked] sgetmap (sgm) Title: sgetmap Synonym: sgm Args: hash Return: hash Example: %h = $person->sgetmap('social-security-no'=>'id', 'name' =>'label', 'job' =>0, 'address' =>'location'); returns a hash of key/val pairs based on the values of the data values of the subnodes in the current element; keys are mapped according to the hash passed (a value of '' or 0 will map an identical key/val). no multivalued data elements are allowed set (s) Title: set Synonym: s Args: element str, datavalue ANY (list) Return: ANY Example: $person->set('name', 'fred'); # single val Example: $person->set('phone_no', $cellphone, $homephone); sets the data value of an element for any node. if the element is multivalued, all the old values will be replaced with the new ones specified. ordering will be preserved, unless the element specified does not exist, in which case, the new tag/value pair will be placed at the end. for example, if we have a stag node $person person: name: shuggy job: bus driver if we do this $person->set('name', ()); we will end up with person: job: bus driver then if we do this $person->set('name', 'shuggy'); the 'name' node will be placed as the last attribute person: job: bus driver name: shuggy You can also use magic methods, for example $person->set_name('shuggy'); $person->set_job('bus driver', 'poet'); print $person->itext; will print person: name: shuggy job: bus driver job: poet note that if the datavalue is a non-terminal node as opposed to a primitive value, then you have to do it like this: $people = Data::Stag->new(people=>[ [person=>[[name=>'Sherlock Holmes']]], [person=>[[name=>'Moriarty']]], ]); $address = Data::Stag->new(address=>[ [address_line=>"221B Baker Street"], [city=>"London"], [country=>"Great Britain"]]); ($person) = $people->qmatch('person', (name => "Sherlock Holmes")); $person->set("address", $address->data); unset (u) Title: unset Synonym: u Args: element str, datavalue ANY Return: ANY Example: $person->unset('name'); Example: $person->unset('phone_no'); prunes all nodes of the specified element from the current node You can use magic methods, like this $person->unset_name; $person->unset_phone_no; free Title: free Synonym: u Args: Return: Example: $person->free; removes all data from a node. If that node is a subnode of another node, it is removed altogether for instance, if we had the data below: fred
..
and called $person->get_address->free then the person node would look like this: fred add (a) Title: add Synonym: a Args: element str, datavalues ANY[] OR Data::Stag Return: ANY Example: $person->add('phone_no', $cellphone, $homephone); Example: $person->add_phone_no('1-555-555-5555'); Example: $dataset->add($person) adds a datavalue or list of datavalues. appends if already existing, creates new element value pairs if not already existing. if the argument is a stag node, it will add this node under the current one element (e name) Title: element Synonym: e Synonym: name Args: Return: element str Example: $element = $struct->element returns the element name of the current node. This is illustrated in the different representation formats below sxpr (element "data") or (element (sub_element "...")) xml data or ... perl [element => $data ] or [element => [ [sub_element => "..." ]]] itext element: data or element: sub_element: ... kids (k children) Title: kids Synonym: k Synonym: children Args: Return: ANY or ANY[] Example: @nodes = $person->kids Example: $name = $namestruct->kids returns the data value(s) of the current node; if it is a terminal node, returns a single value which is the data. if it is non-terminal, returns an array of nodes addkid (ak addchild) Title: addkid Synonym: ak Synonym: addchild Args: kid node Return: ANY Example: $person->addkid('job', $job); adds a new child node to a non-terminal node, after all the existing child nodes subnodes Title: subnodes Args: Return: ANY[] Example: @nodes = $person->subnodes returns the non-terminal data value(s) of the current node; QUERYING AND ADVANCED DATA MANIPULATION ijoin (j) Title: ijoin Synonym: j Synonym: ij Args: element str, key str, data Node Return: undef does a relational style inner join - see previous example in this doc key can either be a single node name that must be shared (analagous to SQL INNER JOIN .. USING), or a key1=key2 equivalence relation (analagous to SQL INNER JOIN ... ON) qmatch (qm) Title: qmatch Synonym: qm Args: return-element str, match-element str, match-value str Return: node[] Example: @persons = $s->qmatch('person', 'name', 'fred'); Example: @persons = $s->qmatch('person', (job=>'bus driver')); queries the node tree for all elements that satisfy the specified key=val match - see previous example in this doc for those inclined to thinking relationally, this can be thought of as a query that returns a stag object: SELECT FROM WHERE = this always returns an array; this means that calling in a scalar context will return the number of elements; for example $n = $s->qmatch('person', (name=>'fred')); the value of $n will be equal to the number of persons called fred tmatch (tm) Title: tmatch Synonym: tm Args: element str, value str Return: bool Example: @persons = grep {$_->tmatch('name', 'fred')} @persons returns true if the the value of the specified element matches - see previous example in this doc tmatchhash (tmh) Title: tmatchhash Synonym: tmh Args: match hashref Return: bool Example: @persons = grep {$_->tmatchhash({name=>'fred', hair_colour=>'green'})} @persons returns true if the node matches a set of constraints, specified as hash. tmatchnode (tmn) Title: tmatchnode Synonym: tmn Args: match node Return: bool Example: @persons = grep {$_->tmatchnode([person=>[[name=>'fred'], [hair_colour=>'green']]])} @persons returns true if the node matches a set of constraints, specified as node cmatch (cm) Title: cmatch Synonym: cm Args: element str, value str Return: bool Example: $n_freds = $personset->cmatch('name', 'fred'); counts the number of matches where (w) Title: where Synonym: w Args: element str, test CODE Return: Node[] Example: @rich_persons = $data->where('person', sub {shift->get_salary > 100000}); the tree is queried for all elements of the specified type that satisfy the coderef (must return a boolean) my @rich_dog_or_cat_owners = $data->where('person', sub {my $p = shift; $p->get_salary > 100000 && $p->where('pet', sub {shift->get_type =~ /(dog|cat)/})}); iterate (i) Title: iterate Synonym: i Args: CODE Return: Node[] Example: $data->iterate(sub { my $stag = shift; my $parent = shift; if ($stag->element eq 'pet') { $parent->set_pet_name($stag->get_name); } }); iterates through whole tree calling the specified subroutine. the first arg passed to the subroutine is the stag node representing the tree at that point; the second arg is for the parent. for instance, the example code above would turn this (person (name "jim") (pet (name "fluffy"))) into this (person (name "jim") (pet_name "fluffy") (pet (name "fluffy"))) MISCELLANEOUS METHODS duplicate (d) Title: duplicate Synonym: d Args: Return: Node Example: $node2 = $node->duplicate; does a deep copy of a stag structure isanode Title: isanode Args: Return: bool Example: if (stag_isanode($node)) { ... } hash Title: hash Args: Return: hash Example: $h = $node->hash; turns a tree into a hash. all data values will be arrayrefs pairs Title: pairs turns a tree into a hash. all data values will be scalar (IMPORTANT: this means duplicate values will be lost) write Title: write Args: filename str, format str[optional] Return: Example: $node->write("myfile.xml"); Example: $node->write("myfile", "itext"); will try and guess the format from the extension if not specified xml Title: xml Args: filename str, format str[optional] Return: Example: $node->write("myfile.xml"); Example: $node->write("myfile", "itext"); Args: Return: xml str Example: print $node->xml; XML METHODS sax Title: sax Args: saxhandler SAX-CLASS Return: Example: $node->sax($mysaxhandler); turns a tree into a series of SAX events xpath (xp tree2xpath) Title: xpath Synonym: xp Synonym: tree2xpath Args: Return: xpath object Example: $xp = $node->xpath; $q = $xp->find($xpathquerystr); xpquery (xpq xpathquery) Title: xpquery Synonym: xpq Synonym: xpathquery Args: xpathquery str Return: Node[] Example: @nodes = $node->xqp($xpathquerystr); STAG SCRIPTS The following scripts come with the stag module stag-autoschema.pl writes the implicit stag-schema for a stag file stag-db.pl persistent storage and retrieval for stag data (xml, sxpr, itext) stag-diff.pl finds the difference between two stag files stag-drawtree.pl draws a stag file (xml, itext, sxpr) as a PNG diagram stag-filter.pl filters a stag file (xml, itext, sxpr) for nodes of interest stag-findsubtree.pl finds nodes in a stag file stag-flatten.pl turns stag data into a flat table stag-grep.pl filters a stag file (xml, itext, sxpr) for nodes of interest stag-handle.pl streams a stag file through a handler into a writer stag-join.pl joins two stag files together based around common key stag-mogrify.pl mangle stag files stag-parse.pl parses a file and fires events (e.g. sxpr to xml) stag-query.pl aggregare queries stag-split.pl splits a stag file (xml, itext, sxpr) into multiple files stag-splitter.pl splits a stag file into multiple files stag-view.pl draws an expandable Tk tree diagram showing stag data To get more documentation, type stag_