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von raredesign | Dez 3, 2019 | Allgemein | 0 Kommentare

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Current File : //usr/share/doc/libxml-perl/UsingPerlSAX.pod

=head1 Using PerlSAX

Working with PerlSAX involves using two classes (packages), a PerlSAX
parser that generates parsing events and a class that you write that
will receive those parsing events, the ``handler''.  This guide will
use the XML::Parser::PerlSAX parser that uses Clark Cooper's
XML::Parser module.

The handler class implements the PerlSAX handler methods that you are
interested in.  The following example, MyHandler.pm, prints a message
every time an element starts or ends:

    package MyHandler;

    sub new {
        my ($type) = @_;
        return bless {}, $type;
    }

    sub start_element {
        my ($self, $element) = @_;

        print "Start element: $element->{Name}\n";
    }

    sub end_element {
        my ($self, $element) = @_;

        print "End element: $element->{Name}\n";
    }

    1;

To use your handler you will need to have a script, myhandler.pl, that
loads and creates your handler and the parser, and then calls the
parser to parse the XML instance and send events to your handler:

    use XML::Parser::PerlSAX;
    use MyHandler;

    my $my_handler = MyHandler->new;
    my $parser = XML::Parser::PerlSAX->new( Handler => $my_handler );

    foreach my $instance (@ARGV) {
        $parser->parse(Source => { SystemId => $instance });
    }

Given this XML instance, myhandler.xml:

    <?xml version="1.0"?>

    <article>
    <title>Using PerlSAX</title>
    <paragraph>Working with PerlSAX ...</paragraph>
    </article>

Running myhandler.pl like this:

    perl myhandler.pl myhandler.xml

will produce this output:

    Start element: article
    Start element: title
    End element: title
    Start element: paragraph
    End element: paragraph
    End element: article

=head2 For More Information

PerlSAX.pod describes the PerlSAX interface.  Each parser module
describes it's individual capabilities.  XML::Parser::PerlSAX is the
most commonly used PerlSAX implementation.

The files described in this doc are in the `examples' directory.  A
more complete implementation of the very simple handler above is in
the module XML::Handler::Sample.  Other, more complex handlers are in
the XML::Handler directory as well.

Another hands-on doc for PerlSAX is the XML-Parser-and-PerlSAX.pod.
This doc describes the difference between and the purpose of PerlSAX
with respect to XML::Parser.

This document was inspired by and uses the code examples from David
Megginson's ``Quick Start for SAX Application Writers.''
<http://www.megginson.com/SAX/quickstart.html>

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