T.J. Mather

NAME

XML::Filter::SAXT - Replicates SAX events to several SAX event handlers

SYNOPSIS

 $saxt = new XML::Filter::SAXT ( { Handler => $out1 },
                                 { DocumentHandler => $out2 },
                                 { DTDHandler => $out3,
                                   Handler => $out4 
                                 }
                               );

 $perlsax = new XML::Parser::PerlSAX ( Handler => $saxt );
 $perlsax->parse ( [OPTIONS] );

DESCRIPTION

SAXT is like the Unix 'tee' command in that it multiplexes the input stream to several output streams. In this case, the input stream is a PerlSAX event producer (like XML::Parser::PerlSAX) and the output streams are PerlSAX handlers or filters.

The SAXT constructor takes a list of hash references. Each hash specifies an output handler. The hash keys can be: DocumentHandler, DTDHandler, EntityResolver or Handler, where Handler is a combination of the previous three and acts as the default handler. E.g. if DocumentHandler is not specified, it will try to use Handler.

EXAMPLE

In this example we use XML::Parser::PerlSAX to parse an XML file and to invoke the PerlSAX callbacks of our SAXT object. The SAXT object then forwards the callbacks to XML::Checker, which will 'die' if it encounters an error, and to XML::Handler::BuildDOM, which will store the XML in an XML::DOM::Document.

 use XML::Parser::PerlSAX;
 use XML::Filter::SAXT;
 use XML::Handler::BuildDOM;
 use XML::Checker;

 my $checker = new XML::Checker;
 my $builder = new XML::Handler::BuildDOM (KeepCDATA => 1);
 my $tee = new XML::Filter::SAXT ( { Handler => $checker },
                                   { Handler => $builder } );

 my $parser = new XML::Parser::PerlSAX (Handler => $tee);
 eval
 {
    # This is how you set the error handler for XML::Checker
    local $XML::Checker::FAIL = \&my_fail;

    my $dom_document = $parser->parsefile ("file.xml");
    ... your code here ...
 };
 if ($@)
 {
    # Either XML::Parser::PerlSAX threw an exception (bad XML)
    # or XML::Checker found an error and my_fail died.
    ... your error handling code here ...
 }

 # XML::Checker error handler
 sub my_fail
 {
   my $code = shift;
   die XML::Checker::error_string ($code, @_)
        if $code < 200;   # warnings and info messages are >= 200
 }

CAVEATS

This is still alpha software. Package names and interfaces are subject to change.

AUTHOR

Enno Dersken is the original author.

Send bug reports, hints, tips, suggestions to T.J. Mather at <tjmather@tjmather.com>.