# Package org.eclipse.rdf4j.federated.algebra

- Interface Summary
  Interface | Description
  --- | ---
  BoundJoinTupleExpr | Marker interface indicating that instances are applicable for bound join processing (see `ControlledWorkerBoundJoin`
  EmptyResult | A generic interface to mark some TupleExpr as empty.
  ExclusiveTupleExpr | Interface representing nodes that can exclusively be evaluated at a single `StatementSource`.
  ExclusiveTupleExprRenderer | A specialization of `ExclusiveTupleExpr` which provides definitions how the expressions can be rendered to a sub-query.
  FedXTupleExpr | Interface marking known FedX algebra nodes.
  FilterTuple | Expressions implementing this interface can apply some `FilterValueExpr` during evaluation.
  FilterValueExpr | Interface to indicate filter expressions.
  QueryRef | Interface to access the `QueryInfo` from all FedX Algebra nodes.
  StatementTupleExpr | Interface for any expression that can be evaluated
  VariableExpr | Interface for algebra nodes that can return the free variables of the expression.

- Class Summary
  Class | Description
  --- | ---
  BoundFiltersNode | A `QueryModelNode` for printing the bound filter vars (e.g.
  CheckStatementPattern | A statement pattern with no free variables when provided with some particular BindingSet in evaluate.
  ConjunctiveFilterExpr | ConjunctiveFilterExpr maintains a list of conjunctive (i.e.
  EmptyNJoin | Algebra construct representing an empty join.
  EmptyNUnion | Algebra construct representing an empty union.
  EmptyStatementPattern | EmptyStatementPattern represents a statement that cannot produce any results for the registered endpoints.
  ExclusiveArbitraryLengthPath | An `ArbitraryLengthPath` node which can be evaluated at a single node.
  ExclusiveGroup | Represents a group of `ExclusiveTupleExpr` that can only produce results at a single endpoint, the `StatementSource`.
  ExclusiveStatement | Represents a StatementPattern that can only produce results at a single endpoint, the owner.
  FederatedDescribeOperator | Specialized `DescribeOperator` Node for maintaining `QueryInfo`.
  FedXLeftJoin | Abstraction of `LeftJoin` to maintain the `QueryInfo`.
  FedXService |
  FedXStatementPattern | Base class providing all common functionality for FedX StatementPatterns
  FilterExpr | FilterExpr maintains information for a particular FILTER expression.
  NJoin | A tuple expression that represents an nary-Join.
  NodeFactory | A factory that produces globally unique IDS which are used as node identifiers, e.g.
  NTuple | Base class for any nary-tuple expression
  NUnion | A tuple expression that represents an nary-Union.
  PassThroughTupleExpr | Marker `TupleExpr` that is used from `FedXTupleQuery.evaluate(TupleQueryResultHandler)` to allow for passing through of results to the handler.
  PrecompiledQueryNode | Node representing a precompiled query.
  SingleSourceQuery | A query which has a single relevant source.
  StatementSource | A structure representing a relevant source for some expression.
  StatementSourcePattern | Represents statements that can produce results at a some particular endpoints, the statement sources.
  TrueStatementPattern | A TrueStatementPattern represents a stmt with no free variables which in addition is available at one of the provided sources.

- Enum Summary
  Enum | Description
  --- | ---
  StatementSource.StatementSourceType |