# Package org.eclipse.viatra.query.runtime.matchers.context

- Interface Summary
  Interface | Description
  --- | ---
  IInputKey | An input key identifies an input (extensional) relation, such as the instance set of a given node or edge type, or the direct containment relation.
  IPosetComparator | Implementations of this interface aid the query engine with the ordering of poset elements.
  IQueryBackendContext | This interface is a collector which holds every API that is provided by the engine to control the operation of the backends.
  IQueryCacheContext | Provides information on already cached queries to query evaluator backends at runtime.
  IQueryMetaContext | Provides metamodel information (relationship of input keys) to query evaluator backends at runtime and at query planning time.
  IQueryResultProviderAccess | This interface exposes API to request `IQueryResultProvider` for `PQuery` instances.
  IQueryRuntimeContext | Provides instance model information (relations corresponding to input keys) to query evaluator backends at runtime.
  IQueryRuntimeContextListener | Listens for changes in the runtime context.

- Class Summary
  Class | Description
  --- | ---
  AbstractQueryMetaContext | Common abstract class for implementers of `IQueryMetaContext`
  AbstractQueryRuntimeContext | This class is intended to be extended by implementors.
  InputKeyImplication | Data object representing the implication of an input key, in use cases including edge supertypes, edge opposites, node type constraints, etc.

- Enum Summary
  Enum | Description
  --- | ---
  IndexingService | These are the different services which can be provided by an `IQueryRuntimeContext` implementation.