# Package org.eclipse.rdf4j.query.algebra.helpers

- Class Summary
  Class | Description
  --- | ---
  AbstractQueryModelVisitor<X extends Exception> | Base class for `QueryModelVisitor`s.
  BGPCollector<X extends Exception> | Basic graph pattern collector.
  QueryModelNodeReplacer | Deprecated.
  QueryModelTreePrinter | QueryModelVisitor implementation that "prints" a tree representation of a query model.
  QueryModelTreeToGenericPlanNode | Convert TupleExpr (QueryModelNode) to GenericPlanNode for the Query.explain(...) feature.
  QueryModelVisitorBase<X extends Exception> | Deprecated. since 2.0.
  StatementPatternCollector | A QueryModelVisitor that collects StatementPattern's from a query model.
  TupleExprs | Utility methods for `TupleExpr` objects.
  VarNameCollector | A QueryModelVisitor that collects the names of (non-constant) variables that are used in a query model.