Author image יובל קוג'מן (Yuval Kogman)
and 1 contributors


XML::SAX::Expat::Incremental - XML::SAX::Expat subclass for non-blocking (incremental) parsing, with XML::Parser::ExpatNB.


        use XML::SAX::Expat::Incremental;

        # don't do this, use XML::SAX::ParserFactory
        my $p = XML::SAX::Expat::Incremental->new( Handler => MyHandler->new );


        while (<DATA>){
                $p->parse_more($_); # or $p->parse_string($_);



Most XML parsers give a callback interface within an encapsulated loop. That is, you call


And eventually, when $whatever is depleted by the parser, $p->parse will return.

Sometimes you don't want the parser to control the loop for you. For example, if you need to retrieve your XML in chunks in a funny way, you might need to do something like

        my $doc = '';
        while (defined(my $buffer = get_more_xml())) {
                $doc .= $buffer;


which is not very convenient, or efficient. You could use perltie to tie a filehandle which does this for you, but that only works some of the time (for example, say you have two inputs coming in simultaneously).

XML::Parser::ExpatNB solves this by providing three methods:


This interface lets you move the loop to outside the parser, retaining control.

The callbacks are executed in the same manner, just that now, when there is no left to parse, instead of taking more data from a source on it's own, the parser returns control to you.

        $p->parse_start; # you can omit this - parse_start will
                         # be called automatically as needed

        while(defined(my $buffer = get_more_xml())) {


This module is a subclass of XML::SAX::Expat which is to XML::Parser::ExpatXS as XML::SAX::Expat is to XML::Parser itself.


parse_string STRING
parse_more STRING

These have the same effect, except that parse_more actually calls parse_string with @_. You might want to use parse_string because in theory it's more efficient.

This simply continues parsing with the new string, and sends SAX events for the data that is complete in the string.


This calls parse_start on the underlying XML::Parser::ExpatNB object. It's called implicitly when you first call parse_string, though, so you don't have to worry about it.


This calls parse_done on the underlying XML::Parser::ExpatNB object. You use it to tell the parser you have no more data to give it.


This is used internally as a sort of parse-anything method. Don't use it, instead use parse_string, which invokes this method correctly, and takes simpler options.


XML::Parser, XML::SAX, XML::SAX::Expat, XML::SAX::ExpatNB


This module is maintained using Darcs. You can get the latest version from, and use darcs send to commit changes.


Yuval Kogman <>


        Copyright (c) 2005 Yuval Kogman. All rights reserved
        This program is free software; you can redistribute
        it and/or modify it under the same terms as Perl itself.