Provided by: libxml-dt-perl_0.69-2_all 
NAME
XML::DT - a package for down translation of XML files
SYNOPSIS
use XML::DT;
%xml=( 'music' => sub{"Music from: $c\n"},
'lyrics' => sub{"Lyrics from: $v{name}\n"},
'title' => sub{ uc($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())<4] ".{1,4}"
//aaa[string-length(name())>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 Simões, <albie@alfarrabio.di.uminho.pt>
ACKNOWLEDGEMENTS
Michel Rodriguez <mrodrigu@ieee.org>
José 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.