filter

This base class provides the all-important "filter" method that you really don't want to implement yourself. Instead, you should provide one of these methods:

filter_text

This should simply modify $_. It's called once for each representation, with the representation as the first parameter to the method.

filter_node

This gets called as

        $class->filter_node($args, $node)

for every textual node, and is expected to return one or more modified node objects.

There's also "filter_group" which you may want to provide, which does the same but for "Group" objects.

filter_anynode

This is the same, but gets called for both Group and Node objects.