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lib/AI/Categorizer/Document/XML.pm  view on Meta::CPAN

package AI::Categorizer::Document::XML;

use strict;
use AI::Categorizer::Document;
use base qw(AI::Categorizer::Document);
use XML::SAX;

__PACKAGE__->contained_objects
  (
   xml_handler => 'AI::Categorizer::Document::XML::Handler',
  );

### Constructors

sub parse {
  my ($self, %args) = @_;

  # it is a string which contains the content of XML
  my $body= $args{content};			

  # it is a hash which includes a pair of <elementName, weight>
  my $elementWeight= $args{elementWeight};	

  # construct Handler which receive event of element, data, comment, processing_instruction
  # And convert their values into a sequence  of string and save it into buffer
  my $xmlHandler = $self->create_contained_object('xml_handler', weights => $elementWeight);

  # construct parser
  my $xmlParser= XML::SAX::ParserFactory->parser(Handler => $xmlHandler);

  # let's start parsing XML, where the methids of Handler will be called
  $xmlParser->parse_string($body);

  # extract the converted string from Handler
  $body= $xmlHandler->getContent;

  # Now, construct Document Object and return it
  return { body => $body };
}

##########################################################################
package AI::Categorizer::Document::XML::Handler;
use strict;
use base qw(XML::SAX::Base);

# Input: a hash which is weights of elements
# Output: object of this class
# Description: this is constructor
sub new{
  my ($class, %args) = @_;

  # call super class such as XML::SAX::Base
  my $self = $class->SUPER::new;

  # save weights of elements which is a hash for pairs <elementName, weight>
  # weight is times duplication of corresponding element
  # It is provided by caller(one of parameters) at construction, and
  # we must save it in order to use doing duplication at end_element
  $self->{weightHash} = $args{weights};

  # It is storage to store the data produced by Text, CDataSection and etc.
  $self->{content} = '';

  # This array is used to store the data for every element from root to the current visiting element.
  # Thus, data of 0~($levelPointer-1)th in the array is only valid.
  # The array which store the starting location(index) of the content for an element, 
  # From it, we can know all the data produced by an element at the end_element
  # It is needed at the duplication of the data produced by the specific element
  $self->{locationArray} = [];

  return $self;
}
	
# Input: None
# Output: None
# Description:
# 	it is called whenever the parser meets the document
# 	it will be called at once
#	Currently, confirm if the content buffer is an empty
sub start_document{
  my ($self, $doc)= @_;

  # The level(depth) of the last called element in XML tree
  # Calling of start_element is the preorder of the tree traversal.
  # The level is the level of current visiting element in tree.
  # the first element is 0-level
  $self->{levelPointer} = 0;

  # all data will be saved into here, initially, it is an empty
  $self->{content} = "";

  #$self->SUPER::start_document($doc);
}

# Input: None
# Output: None
# Description:
# 	it is called whenever the parser ends the document
# 	it will be called at once
#	Nothing to do
sub end_document{
  my ($self, $doc)= @_;

  #$self->SUPER::end_document($doc);
}

# Input
#	LocalName: 	$el->{LocalName}
#	NamespaceURI: 	$el->{NamespaceURI}
#	Name		$el->{Name}
#	Prefix		$el->{Prefix}
#	Attributes	$el->{Attributes}
#	for each attribute
#		LocalName: 	$el->{LocalName}
#		NamespaceURI: 	$el->{NamespaceURI}
#		Name		$el->{Name}