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

use XML::DT;

%xml=( 'music' => sub{Music from: CW$c\n}, 'lyrics' => sub{Lyrics from: CW$v{name}\n}, 'title' => sub{ uc($c) }, '-default' => sub{$q:$c} );

print dt($filename,%xml);

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

This module processes XML files with an approach similar to OMNIMARK. As XML parser it uses XML::Parser or XML::LibXML module in an independent way. At configure stage, you should choose one of the back-ends.

If you use XML::LibXML module as backend, 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, ... ); Down translation function CWdt receives a filename and a set of expressions (functions) defining the processing and associated values for each element. CWdtstring works in a similar way with CWdt but takes input from a string instead of a file. CWdturl works in a similar way with CWdt but takes input from an Internet url instead of a file. The CWpathdt function is a CWdt 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{ CW$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 Like the CWdtstring function but supporting XPath. Like the CWdturl function but supporting XPath. CWinctxt(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. This is the default -default function. It can be used to generate XML based on CW$c CW$q and CW%v variables. Example: add a new attribute to element CWele1 without changing it:

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

CWtoxml 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> This simple function just makes a HASH reference:

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

The function CWtoxml understands this structure and makes XML with it.

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

All those global variables are defined in CW$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. When a element has no associated function, the function associated with CW-default called. If no CW-default function is defined the default function returns a XML like string for the element.

When you use CW/-type definitions, you often need do set CW-default function to return just the contents: CWsub{$id}. CW-outputenc defines the output encoding (default is Unicode UTF8). CW-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'?> CW-pcdata function is used to define transformation over the contents. Typically this function should look at context (see CWinctxt function)

The default CW-pcdata function is the identity Function to be executed before processing XML file.

Example of use: initialization of side-effect variables Function to be executed after processing XML file. I can use CW$c content value. The value returned by CW-end will be the CWdt return value.

Example of use: post-processing of returned contents By default all elements return strings, and contents (CW$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:

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 CW/-type definitions, you often need do set CW-default function returning just the contents CWsub{$id}.

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

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

To do this use the function CWmkdtskel(filename).

Example:

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

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

To do this use the function CWmkdtdskel(filename*).

Example:

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

mkdtskel(1) and mkdtdskel(1)

Home for XML::DT;

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

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

Alberto Manuel Simões, <albie@alfarrabio.di.uminho.pt>

thanks to

Michel Rodriguez <mrodrigu@ieee.org> José Carlos Ramalho <jcr@di.uminho.pt> Mark A. Hillebrand