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

- Interface Summary
  Interface | Description
  --- | ---
  ICallDelegationStrategy | Function object that specifies how hints (including backend preferences) shall propagate through pattern calls.
  IMatcherCapability | Implementations of this interface can be used to decide whether a matcher created by an arbitrary backend can potentially be used as a substitute for another matcher.
  IQueryBackend | Internal interface for a VIATRA query specification.
  IQueryBackendFactory | A Query Backend Factory identifies a query evaluator implementation, and can create an evaluator instance (an `IQueryBackend`) tied to a specific VIATRA Query engine upon request.
  IQueryBackendFactoryProvider | A provider interface for `IQueryBackendFactory` instances.
  IQueryBackendHintProvider | Provides query evaluation hints consisting of the Engine default hints and the hints provided by the pattern itself.
  IQueryResultProvider | An internal interface of the query backend that provides results of a given query.
  IUpdateable | Internal interface for the query backend to singal an update to a query result.

- Class Summary
  Class | Description
  --- | ---
  CommonQueryHintOptions | Query evaluation hints applicable to any engine
  QueryEvaluationHint | Provides VIATRA Query with additional hints on how a query should be evaluated.
  QueryHintOption<HintValue> | Each instance of this class corresponds to a given hint option.
  ResultProviderRequestor | Uniform way of requesting result providers for pattern calls within queries.

- Enum Summary
  Enum | Description
  --- | ---
  QueryEvaluationHint.BackendRequirement |