XML::DT(3pm)						User Contributed Perl Documentation					      XML::DT(3pm)

NAME

       XML::DT - a package for down translation of XML files

SYNOPSIS

	use XML::DT;

	%xml=( 'music'	  => sub{"Music from: $c
"},
	       'lyrics'   => sub{"Lyrics from: $v{name}
"},
	       'title'	  => sub{ uc($c) },
	       '-userdata => { something => 'I like' },
	       '-default' => sub{"$q:$c"} );

	print dt($filename,%xml);

ABSTRACT

       This module is a XML down processor. It maps tag (element) names to functions to process that element and respective contents.

DESCRIPTION

       This module processes XML files with an approach similar to OMNIMARK. As XML parser it uses XML::LibXML module in an independent way.

       You can parse HTML files as if they were XML files. For this, you must supply an extra option to the hash:

	%hander = ( -html => 1,
		    ...
		  );

       You can also ask the parser to recover from XML errors:

	%hander = ( -recover => 1,
		    ...
		  );

Functions
   dt
       Down translation function "dt" receives a filename and a set of expressions (functions) defining the processing and associated values for
       each element.

   dtstring
       "dtstring" works in a similar way with "dt" but takes input from a string instead of a file.

   dturl
       "dturl" works in a similar way with "dt" but takes input from an Internet url instead of a file.

   pathdt
       The "pathdt" function is a "dt" function which can handle a subset of XPath on handler keys. Example:

	%handler = (
	  "article/title"	 => sub{ toxml("h1",{},$c) },
	  "section/title"	 => sub{ toxml("h2",{},$c) },
	  "title"		 => sub{ $c },
	  "//image[@type='jpg']" => sub{ "JPEG: <img src="$c">" },
	  "//image[@type='bmp']" => sub{ "BMP: sorry, no bitmaps on the web" },
	)

	pathdt($filename,%handler);

       Here are some examples of valid XPath expressions under XML::DT:

	/aaa
	/aaa/bbb
	//ccc				- ccc somewhere (same as "ccc")
	/*/aaa/*
	//*				- same as "-default"
	/aaa[@id]			- aaa with an attribute id
	/*[@*]				- root with an attribute
	/aaa[not(@name)]		- aaa with no attribute "name"
	//bbb[@name='foo']		- ... attribute "name" = "foo"
	/ccc[normalize-space(@name)='bbb']
	//*[name()='bbb']		- complex way of saying "//bbb"
	//*[starts-with(name(),'aa')]	- an element named "aa.*"
	//*[contains(name(),'c')]	- an element	   ".*c.*"
	//aaa[string-length(name())=4]			   "...."
	//aaa[string-length(name())&lt;4]		   ".{1,4}"
	//aaa[string-length(name())&gt;5]		   ".{5,}"

       Note that not all XPath is currently handled by XML::DT. A lot of XPath will never be added to XML::DT because is not in accordance with
       the down translation model. For more documentation about XPath check the specification at http://www.w3c.org or some tutorials under
       http://www.zvon.org

   pathdtstring
       Like the "dtstring" function but supporting XPath.

   pathdturl
       Like the "dturl" function but supporting XPath.

   ctxt
       Returns the context element of the currently being processed element. So, if you call ctxt(1) you will get your father element, and so on.

   inpath
       "inpath(pattern)" is true if the actual element path matches the provided pattern. This function is meant to be used in the element
       functions in order to achieve context dependent processing.

   inctxt
       "inctxt(pattern)" is true if the actual element father matches the provided pattern.

   toxml
       This is the default "-default" function. It can be used to generate XML based on $c $q and %v variables. Example: add a new attribute to
       element "ele1" without changing it:

	  %handler=( ...
	    ele1 => sub { $v{at1} = "v1"; toxml(); },
	  )

       "toxml" can also be used with 3 arguments: tag, attributes and contents

	  toxml("a",{href=> "http://local/f.html"}, "example")

       returns:

	<a href='http://local/f.html'>example</a>

       Empty tags are written as empty tags. If you want an empty tag with opening and closing tags, then use the "tohtml".

   tohtml
       See "toxml".

   xmltree
       This simple function just makes a HASH reference:

	{ -c => $c, -q => $q, all_the_other_attributes }

       The function "toxml" understands this structure and makes XML with it.

   mkdtskel
       Used by the mkdtskel script to generate automatically a XML::DT perl script file based on an XML file. Check "mkdtskel" manpage for
       details.

   mkdtskel_fromDTD
       Used by the mkdtskel script to generate automatically a XML::DT perl script file based on an DTD file. Check "mkdtskel" manpage for
       details.

   mkdtdskel
       Used by the mkdtskel script to generate automatically a XML::DT perl script file based on a DTD file. Check "mkdtdskel" manpage for
       details.

Accessing parents
       With XML::DT you can access an element parent (or grand-parent) attributes, till the root of the XML document.

       If you use c<$dtattributes[1]{foo} = 'bar'> on a processing function, you are defining the attribute "foo" for that element parent.

       In the same way, you can use $dtattributes[2] to access the grand-parent. $dtattributes[-1] is, as expected, the XML document root element.

       There are some shortcuts:

       "father"
       "gfather"
       "ggfather"
	   You can use these functions to access to your "father", grand-father ("gfather") or great-grand-father ("ggfather"):

	      father("x"); # returns value for attribute "x" on father element
	      father("x", "value"); # sets value for attribute "x" on father
					    # element

	   You can also use it directly as a reference to @dtattributes:

	      father->{"x"};	       # gets the attribute
	      father->{"x"} = "value"; # sets the attribute
	      $attributes = father;	       # gets all attributes reference

       "root"
	   You can use it as a function to access to your tree root element.

	      root("x");	  # gets attribute C<x> on root element
	      root("x", "value"); # sets value for attribute C<x> on root

	   You can also use it directly as a reference to $dtattributes[-1]:

	      root->{"x"};	     # gets the attribute x
	      root->{"x"} = "value"; # sets the attribute x
	      $attributes = root;    # gets all attributes reference

User provided element processing functions
       The user must provide an HASH with a function for each element, that computes element output. Functions can use the element name $q, the
       element content $c and the attribute values hash %v.

       All those global variables are defined in $CALLER::.

       Each time an element is find the associated function is called.

       Content is calculated by concatenation of element contents strings and interior elements return values.

   "-default" function
       When a element has no associated function, the function associated with "-default" called. If no "-default" function is defined the default
       function returns a XML like string for the element.

       When you use "/-type" definitions, you often need do set "-default" function to return just the contents: "sub{$c}".

   "-outputenc" option
       "-outputenc" defines the output encoding (default is Unicode UTF8).

   "-inputenc" option
       "-inputenc" forces a input encoding type. Whenever that is possible, define the input encoding in the XML file:

	<?xml version='1.0' encoding='ISO-8859-1'?>

   "-pcdata" function
       "-pcdata" function is used to define transformation over the contents.  Typically this function should look at context (see "inctxt"
       function)

       The default "-pcdata" function is the identity

   "-cdata" function
       You can process "<CDATA"> in a way different from pcdata. If you define a "-cdata" method, it will be used. Otherwise, the "-pcdata" method
       is called.

   "-begin" function
       Function to be executed before processing XML file.

       Example of use: initialization of side-effect variables

   "-end" function
       Function to be executed after processing XML file.  I can use $c content value.	The value returned by "-end" will be the "dt" return
       value.

       Example of use: post-processing of returned contents

   "-recover" option
       If set, the parser will try to recover in XML errors.

   "-html" option
       If set, the parser will try to recover in errors. Note that this differs from the previous one in the sense it uses some knowledge of the
       HTML structure for the recovery.

   "-userdata" option
       Use this to pass any information you like to your handlers. The data structure you pass in this option will be available as $u in your
       code. -- New in 0.62.

Elements with values other than strings (";-type")
       By default all elements return strings, and contents ($c) is the concatenation of the strings returned by the sub-elements.

       In some situations the XML text contains values that are better processed as a structured type.

       The following types (functors) are available:

       THE_CHILD
	   Return the result of processing the only child of the element.

       LAST_CHILD
	   Returns the result of processing the last child of the element.

       STR concatenates all the sub-elements returned values (DEFAULT) all the sub-element should return strings to be concatenated;

       SEQ makes an ARRAY with all the sub elements contents; attributes are ignored (they should be processed in the sub-element). (returns a
	   ref) If you have different types of sub-elements, you should use SEQH

       SEQH
	   makes an ARRAY of HASH with all the sub elements (returns a ref); for each sub-element:

	    -q	=> element name
	    -c	=> contents
	    at1 => at value1	for each attribute

       MAP makes an HASH with the sub elements; keys are the sub-element names, values are their contents. Attributes are ignored. (they should be
	   processed in the sub-element) (returns a ref)

       MULTIMAP
	   makes an HASH of ARRAY; keys are the sub-element names; values are lists of contents; attributes are ignored (they should be processed
	   in the sub-element); (returns a ref)

       MMAPON(element-list)
	   makes an HASH with the sub-elements; keys are the sub-element names, values are their contents; attributes are ignored (they should be
	   processed in the sub-element); for all the elements contained in the element-list, it is created an ARRAY with their contents. (returns
	   a ref)

       XML return a reference to an HASH with:

	    -q	=> element name
	    -c	=> contents
	    at1 => at value1	for each attribute

       ZERO
	   don't process the sub-elements; return ""

       When you use "/-type" definitions, you often need do set "-default" function returning just the contents "sub{$id}".

   An example:
	use XML::DT;
	%handler = ( contacts => sub{ [ split(";",$c)] },
		     -default => sub{$c},
		     -type    => { institution => 'MAP',
				   degrees     =>  MMAPON('name')
				   tels        => 'SEQ' }
		   );
	$a = dt ("f.xml", %handler);

       with the following f.xml

	<degrees>
	   <institution>
	      <id>U.M.</id>
	      <name>University of Minho</name>
	      <tels>
		 <item>1111</item>
		 <item>1112</item>
		 <item>1113</item>
	      </tels>
	      <where>Portugal</where>
	      <contacts>J.Joao; J.Rocha; J.Ramalho</contacts>
	   </institution>
	   <name>Computer science</name>
	   <name>Informatica </name>
	   <name> history </name>
	</degrees>

       would make $a

	{ 'name' => [ 'Computer science',
		      'Informatica ',
		      ' history ' ],
	  'institution' => { 'tels' => [ 1111, 1112, 1113 ],
			     'name' => 'University of Minho',
			     'where' => 'Portugal',
			     'id' => 'U.M.',
			     'contacts' => [ 'J.Joao',
				      ' J.Rocha',
				      ' J.Ramalho' ] } };

DT Skeleton generation
       It is possible to build an initial processor program based on an example

       To do this use the function "mkdtskel(filename)".

       Example:

	perl -MXML::DT -e 'mkdtskel "f.xml"' > f.pl

DTD skeleton generation
       It makes a naive DTD based on an example(s).

       To do this use the function "mkdtdskel(filename*)".

       Example:

	perl -MXML::DT -e 'mkdtdskel "f.xml"' > f.dtd

SEE ALSO

       mkdtskel(1) and mkdtdskel(1)

AUTHORS

       Home for XML::DT;

       http://natura.di.uminho.pt/~jj/perl/XML/

       Jose Joao Almeida, <jj@di.uminho.pt>

       Alberto Manuel Simo~es, <albie@alfarrabio.di.uminho.pt>

ACKNOWLEDGEMENTS

       Michel Rodriguez    <mrodrigu@ieee.org>

       Jose Carlos Ramalho <jcr@di.uminho.pt>

       Mark A. Hillebrand

COPYRIGHT AND LICENSE

       Copyright 1999-2012 Project Natura.

       This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

perl v5.14.2							    2012-06-25							      XML::DT(3pm)