XML::SAX::ParserFactory (3pm)

  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);

XML::SAX::ParserFactory is a factory class for providing an application with a Perl \s-1SAX2\s0 \s-1XML\s0 parser. It is akin to \s-1DBI\s0 - a front end for other parser classes. Each new \s-1SAX2\s0 parser installed will register itself with \s-1XML::SAX\s0, and then it will become available to all applications that use XML::SAX::ParserFactory to obtain a \s-1SAX\s0 parser.

Unlike \s-1DBI\s0 however, \s-1XML/SAX\s0 parsers almost all work alike (especially if they subclass XML::SAX::Base, as they should), so rather than specifying the parser you want in the call to \*(C`parser()\*(C', \s-1XML::SAX\s0 has several ways to automatically choose which parser to use:

• $XML::SAX::ParserPackage If this package variable is set, then this package is \*(C`require()\*(C'd and an instance of this package is returned by calling the \*(C`new()\*(C' class method in that package. If it cannot be loaded or there is an error, an exception will be thrown. The variable can also contain a version number: $XML::SAX::ParserPackage = "XML::SAX::Expat (0.72)"; And the number will be treated as a minimum version number.

• Required features It is possible to require features from the parsers. For example, you may wish for a parser that supports validation via a \s-1DTD\s0. To do that, use the following code: use XML::SAX::ParserFactory; my $factory = XML::SAX::ParserFactory->new(); $factory->require_feature('http://xml.org/sax/features/validation'); my $parser = $factory->parser(...); Alternatively, specify the required features in the call to the ParserFactory constructor: my $factory = XML::SAX::ParserFactory->new( RequiredFeatures => { 'http://xml.org/sax/features/validation' => 1, } ); If the features you have asked for are unavailable (for example the user might not have a validating parser installed), then an exception will be thrown. The list of known parsers is searched in reverse order, so it will always return the last installed parser that supports all of your requested features (Note: this is subject to change if someone comes up with a better way of making this work).

• \s-1SAX\s0.ini ParserFactory will search @INC for a file called \s-1SAX\s0.ini, which is in a simple format: # a comment looks like this, ; or like this, and are stripped anywhere in the file key = value # SAX.in contains key/value pairs. All whitespace is non-significant. This file can contain either a line: ParserPackage = MyParserModule (1.02) Where MyParserModule is the module to load and use for the parser, and the number in brackets is a minimum version to load. Or you can list required features: http://xml.org/sax/features/validation = 1 And each feature with a true value will be required.

• Fallback If none of the above works, the last parser installed on the user's system will be used. The \s-1XML::SAX\s0 package ships with a pure perl \s-1XML\s0 parser, XML::SAX::PurePerl, so that there will always be a fallback parser.

Matt Sergeant, [email protected]

This is free software, you may use it and distribute it under the same terms as Perl itself.