XML::Parser

Overview

XML::Parser is an event-based parser, which means that you must register event handlers (callbacks) with the parser to process an XML document. As the document is parsed, the event handlers are called when the corresponding events are detected.

There are several handlers, but most applications will only need the Start, End, and Char handlers. See the module documentation for a list of all the handlers.

Download

• XML::Parser

Requirements

• Perl 5.004 or greater
• expat (1.95.0 or greater)

Installation

expat

% ./configure
% make
# make install

XML::Parser

% perl Makefile.PL
% make
% make test
# make install

Parsing a Simple XML Document

country.xml

<?xml version="1.0"?>
<country>
  <name abbrv="fr">France</name>
  <capital>Paris</capital>
  <language>French</language>
</country>

xmlparser1.pl

#!/usr/bin/perl -w
use strict;
use XML::Parser;

die "Usage: xmlparser1.pl " unless @ARGV == 1;

my $file = shift;

die qq!Can't find file "$file"! unless -f $file;

my $parser = new XML::Parser(
	Handlers => {Start => \&start_handler,
                     End   => \&end_handler,
                     Char  => \&char_handler));

$parser->parsefile($file);

##########################
# Handlers               #
##########################
sub start_handler {
    my $expat = shift;
    my $element = shift;
 
    print "START: $element\n";

    # Handle the attributes
    while (@_) {
        my $attr = shift;
        my $val = shift;
        print qq!ATTR: $attr="$val"\n!;
    }

}

sub end_handler {
    my($expat, $element) = @_;
    print "END: $element\n";

}

sub char_handler {
    my($expat, $data) = @_;
    return if $data =~ /^\s+$/;
    print "CHAR: $data\n";

}

% perl xmlparser1.pl country.xml

START: country
START: name
ATTR: abbrv="fr"
CHAR: France
END: name
START: capital
CHAR: Paris
END: capital
START: language
CHAR: French
END: language
END: country

Converting XML to Text

xmlparser2.pl

#!/usr/bin/perl -w
use strict;
use XML::Parser;

die "Usage: xmlparser1.pl " unless @ARGV == 1;

my $file = shift;

die qq!Can't find file "$file"! unless -f $file;

my $parser = new XML::Parser(ErrorContext => 2);
$parser->setHandlers(Start => \&start_handler,
                     End   => \&end_handler,
                     Char  => \&char_handler);

$parser->parsefile($file);

##########################
# Handlers               #
##########################
sub start_handler {
    my $expat = shift;
    my $element = shift;
    my %attribs = @_;

    if ( $element =~ /\bfirst\b/i ) {
        print "First Name: ";
    } elsif ( $element =~ /\blast\b/i ) {
        print "Last Name: ";
    } elsif ( $element =~ /\bstreet\b/i ) {
        print "Street: ";
    } elsif ( $element =~ /\bcity\b/i ) {
        print "City: ";
    } elsif ( $element =~ /\bstate\b/i ) {
        print "State: ";
    } elsif ( $element =~ /\bzip\b/i ) {
        print "Zip: ";
    } elsif ( $element =~ /\btel\b/i ) {
        print "Phone ($attribs{'type'}): ";
    } elsif ( $element =~ /\bemail\b/i ) {
        print "Email: ";
    }

}

sub end_handler {
    my($expat, $element) = @_;

    if ( $element =~ /\bcontact\b/i ) {
        print "\n";
    }

}

sub char_handler {
    my($expat, $data) = @_;
    return if $data =~ /^\s+$/;
    print "$data\n";

}

Converting XML to HTML

Resources

• XML.com - Using The Perl XML::Parser Module
• Clark Cooper's XML::Parser page
• XML::Parser (2.30) manpage