A query can be used as an expression if it is enclosed in asterisked parentheses (* and *). Theses symbols are also used to declare context in a query but the concept is different. A query expression enables to execute the query in an imperative context (e.g. in a java block). Thus, the query can be used combined with other imperative statements (e.g. methods, aggregators, …). The query expression is a Node generator and can be used as such.

Query expressions finds all matches of the pattern and yields the currently bound value of the right-most non-bracketed node pattern.