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# $Id$
package XML::SAX;
use strict;
use vars qw($VERSION @ISA @EXPORT_OK);
$VERSION = '1.02';
use Exporter ();
@ISA = ('Exporter');
@EXPORT_OK = qw(Namespaces Validation);
use File::Basename qw(dirname);
use File::Spec ();
use Symbol qw(gensym);
use XML::SAX::ParserFactory (); # loaded for simplicity
use constant PARSER_DETAILS => "ParserDetails.ini";
use constant Namespaces => "http://xml.org/sax/features/namespaces";
use constant Validation => "http://xml.org/sax/features/validation";
my $known_parsers = undef;
# load_parsers takes the ParserDetails.ini file out of the same directory
# that XML::SAX is in, and looks at it. Format in POD below
=begin EXAMPLE
[XML::SAX::PurePerl]
http://xml.org/sax/features/namespaces = 1
http://xml.org/sax/features/validation = 0
# a comment
# blank lines ignored
[XML::SAX::AnotherParser]
http://xml.org/sax/features/namespaces = 0
http://xml.org/sax/features/validation = 1
=end EXAMPLE
=cut
sub load_parsers {
my $class = shift;
my $dir = shift;
# reset parsers
$known_parsers = [];
# get directory from wherever XML::SAX is installed
if (!$dir) {
$dir = $INC{'XML/SAX.pm'};
$dir = dirname($dir);
}
my $fh = gensym();
if (!open($fh, File::Spec->catfile($dir, "SAX", PARSER_DETAILS))) {
XML::SAX->do_warn("could not find " . PARSER_DETAILS . " in $dir/SAX\n");
return $class;
}
$known_parsers = $class->_parse_ini_file($fh);
return $class;
}
sub _parse_ini_file {
my $class = shift;
my ($fh) = @_;
my @config;
my $lineno = 0;
while (defined(my $line = <$fh>)) {
$lineno++;
my $original = $line;
# strip whitespace
$line =~ s/\s*$//m;
$line =~ s/^\s*//m;
# strip comments
$line =~ s/[#;].*$//m;
# ignore blanks
next if $line =~ /^$/m;
# heading
if ($line =~ /^\[\s*(.*)\s*\]$/m) {
push @config, { Name => $1 };
next;
}
# instruction
elsif ($line =~ /^(.*?)\s*?=\s*(.*)$/) {
unless(@config) {
push @config, { Name => '' };
}
$config[-1]{Features}{$1} = $2;
}
# not whitespace, comment, or instruction
else {
die "Invalid line in ini: $lineno\n>>> $original\n";
}
}
return \@config;
}
sub parsers {
my $class = shift;
if (!$known_parsers) {
$class->load_parsers();
}
return $known_parsers;
}
sub remove_parser {
my $class = shift;
my ($parser_module) = @_;
if (!$known_parsers) {
$class->load_parsers();
}
@$known_parsers = grep { $_->{Name} ne $parser_module } @$known_parsers;
return $class;
}
sub add_parser {
my $class = shift;
my ($parser_module) = @_;
if (!$known_parsers) {
$class->load_parsers();
}
# first load module, then query features, then push onto known_parsers,
my $parser_file = $parser_module;
$parser_file =~ s/::/\//g;
$parser_file .= ".pm";
require $parser_file;
my @features = $parser_module->supported_features();
my $new = { Name => $parser_module };
foreach my $feature (@features) {
$new->{Features}{$feature} = 1;
}
# If exists in list already, move to end.
my $done = 0;
my $pos = undef;
for (my $i = 0; $i < @$known_parsers; $i++) {
my $p = $known_parsers->[$i];
if ($p->{Name} eq $parser_module) {
$pos = $i;
}
}
if (defined $pos) {
splice(@$known_parsers, $pos, 1);
push @$known_parsers, $new;
$done++;
}
# Otherwise (not in list), add at end of list.
if (!$done) {
push @$known_parsers, $new;
}
return $class;
}
sub save_parsers {
my $class = shift;
# get directory from wherever XML::SAX is installed
my $dir = $INC{'XML/SAX.pm'};
$dir = dirname($dir);
my $file = File::Spec->catfile($dir, "SAX", PARSER_DETAILS);
chmod 0644, $file;
unlink($file);
my $fh = gensym();
open($fh, ">$file") ||
die "Cannot write to $file: $!";
foreach my $p (@$known_parsers) {
print $fh "[$p->{Name}]\n";
foreach my $key (keys %{$p->{Features}}) {
print $fh "$key = $p->{Features}{$key}\n";
}
print $fh "\n";
}
print $fh "\n";
close $fh;
return $class;
}
sub do_warn {
my $class = shift;
# Don't output warnings if running under Test::Harness
warn(@_) unless $ENV{HARNESS_ACTIVE};
}
1;
__END__
=head1 NAME
XML::SAX - Simple API for XML
=head1 SYNOPSIS
use XML::SAX;
# get a list of known parsers
my $parsers = XML::SAX->parsers();
# add/update a parser
XML::SAX->add_parser(q(XML::SAX::PurePerl));
# remove parser
XML::SAX->remove_parser(q(XML::SAX::Foodelberry));
# save parsers
XML::SAX->save_parsers();
=head1 DESCRIPTION
XML::SAX is a SAX parser access API for Perl. It includes classes
and APIs required for implementing SAX drivers, along with a factory
class for returning any SAX parser installed on the user's system.
=head1 USING A SAX2 PARSER
The factory class is XML::SAX::ParserFactory. Please see the
documentation of that module for how to instantiate a SAX parser:
L<XML::SAX::ParserFactory>. However if you don't want to load up
another manual page, here's a short synopsis:
use XML::SAX::ParserFactory;
use XML::SAX::XYZHandler;
my $handler = XML::SAX::XYZHandler->new();
my $p = XML::SAX::ParserFactory->parser(Handler => $handler);
$p->parse_uri("foo.xml");
# or $p->parse_string("<foo/>") or $p->parse_file($fh);
This will automatically load a SAX2 parser (defaulting to
XML::SAX::PurePerl if no others are found) and return it to you.
In order to learn how to use SAX to parse XML, you will need to read
L<XML::SAX::Intro> and for reference, L<XML::SAX::Specification>.
=head1 WRITING A SAX2 PARSER
The first thing to remember in writing a SAX2 parser is to subclass
XML::SAX::Base. This will make your life infinitely easier, by providing
a number of methods automagically for you. See L<XML::SAX::Base> for more
details.
When writing a SAX2 parser that is compatible with XML::SAX, you need
to inform XML::SAX of the presence of that driver when you install it.
In order to do that, XML::SAX contains methods for saving the fact that
the parser exists on your system to a "INI" file, which is then loaded
to determine which parsers are installed.
The best way to do this is to follow these rules:
=over 4
=item * Add XML::SAX as a prerequisite in Makefile.PL:
WriteMakefile(
...
PREREQ_PM => { 'XML::SAX' => 0 },
...
);
Alternatively you may wish to check for it in other ways that will
cause more than just a warning.
=item * Add the following code snippet to your Makefile.PL:
sub MY::install {
package MY;
my $script = shift->SUPER::install(@_);
if (ExtUtils::MakeMaker::prompt(
"Do you want to modify ParserDetails.ini?", 'Y')
=~ /^y/i) {
$script =~ s/install :: (.*)$/install :: $1 install_sax_driver/m;
$script .= <<"INSTALL";
install_sax_driver :
\t\@\$(PERL) -MXML::SAX -e "XML::SAX->add_parser(q(\$(NAME)))->save_parsers()"
INSTALL
}
return $script;
}
Note that you should check the output of this - \$(NAME) will use the name of
your distribution, which may not be exactly what you want. For example XML::LibXML
has a driver called XML::LibXML::SAX::Generator, which is used in place of
\$(NAME) in the above.
=item * Add an XML::SAX test:
A test file should be added to your t/ directory containing something like the
following:
use Test;
BEGIN { plan tests => 3 }
use XML::SAX;
use XML::SAX::PurePerl::DebugHandler;
XML::SAX->add_parser(q(XML::SAX::MyDriver));
local $XML::SAX::ParserPackage = 'XML::SAX::MyDriver';
eval {
my $handler = XML::SAX::PurePerl::DebugHandler->new();
ok($handler);
my $parser = XML::SAX::ParserFactory->parser(Handler => $handler);
ok($parser);
ok($parser->isa('XML::SAX::MyDriver');
$parser->parse_string("<tag/>");
ok($handler->{seen}{start_element});
};
=back
=head1 EXPORTS
By default, XML::SAX exports nothing into the caller's namespace. However you
can request the symbols C<Namespaces> and C<Validation> which are the
URIs for those features, allowing an easier way to request those features
via ParserFactory:
use XML::SAX qw(Namespaces Validation);
my $factory = XML::SAX::ParserFactory->new();
$factory->require_feature(Namespaces);
$factory->require_feature(Validation);
my $parser = $factory->parser();
=head1 AUTHOR
Current maintainer: Grant McLean, grantm@cpan.org
Originally written by:
Matt Sergeant, matt@sergeant.org
Kip Hampton, khampton@totalcinema.com
Robin Berjon, robin@knowscape.com
=head1 LICENSE
This is free software, you may use it and distribute it under
the same terms as Perl itself.
=head1 SEE ALSO
L<XML::SAX::Base> for writing SAX Filters and Parsers
L<XML::SAX::PurePerl> for an XML parser written in 100%
pure perl.
L<XML::SAX::Exception> for details on exception handling
=cut
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