Package handling the compilation of queries. Provides compilation of "string-based" queries. Provides handling for different query languages such as JDOQL, JPQL and SQL(simplified). Compilation of a string-based query results in a tree of expressions. From this tree the evaluation process can be configured to convert it into the native query language for the datastore; this part is handled within each datastore plugin. From this tree an in-memory evaluation can be performed. This is provided in the org.datanucleus.query.evaluator package and subpackage(s).