The package xxl.core.cursors.filters provides miscellaneous
implementations of filter operators on cursors. That means, the operators
provided in this package will evaluate a user defined predicate on the
elements of the given input iteration to decide how is to be dealt with
these elements. E.g., the predicate of a
{@link xxl.core.cursors.filters.Filter filter} decides whether an element
of the input iteration should be returned to the user or simply filtered
out. For compatibility reasons, all classes are able to handle user
defined boolean functions as well as predicates.