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

Interface IQueryBackend

All Known Implementing Classes:

LocalSearchBackend, ReteEngine

public interface IQueryBackend

Internal interface for a VIATRA query specification. Each query is associated with a pattern. Methods instantiate a matcher of the pattern with various parameters.

Since:

0.9

Method Summary

Modifier and Type	Method and Description
void	dispose() Disposes the query backend.
void	flushUpdates() Propagates all pending updates in this query backend.
IQueryResultProvider	getResultProvider(PQuery query) Returns a result provider for a given query.
IQueryResultProvider	getResultProvider(PQuery query, QueryEvaluationHint hints) Returns a result provider for a given query.
boolean	isCaching()
IQueryResultProvider	peekExistingResultProvider(PQuery query) Returns an existing result provider for a given query, if it was previously constructed, returns null otherwise.

Method Detail

isCaching

boolean isCaching()

Returns:

true iff this backend is incremental, i.e. it caches the results of queries for quick retrieval, and can provide update notifications on result set changes.

getResultProvider

IQueryResultProvider getResultProvider(PQuery query)
                                throws QueryProcessingException

Returns a result provider for a given query. Repeated calls may return the same instance.

Throws:

QueryProcessingException

getResultProvider

IQueryResultProvider getResultProvider(PQuery query,
                                       QueryEvaluationHint hints)
                                throws QueryProcessingException

Returns a result provider for a given query. Repeated calls may return the same instance.

Parameters:

optional - hints that may override engine and query defaults (as provided by IQueryBackendHintProvider). Can be null.

Throws:

QueryProcessingException

Since:

1.4

peekExistingResultProvider

IQueryResultProvider peekExistingResultProvider(PQuery query)

Returns an existing result provider for a given query, if it was previously constructed, returns null otherwise. Will not construct and initialize new result providers.

flushUpdates

void flushUpdates()

Propagates all pending updates in this query backend. The implementation of this method is optional, and it can be ignored entirely if the backend does not delay updates.

Since:

1.6

dispose

void dispose()

Disposes the query backend.