org.openrdf.query.algebra.evaluation

Interface EvaluationStrategy

All Superinterfaces:

FederatedServiceResolver

All Known Implementing Classes:

EvaluationStrategyImpl, LimitedSizeEvaluationStrategy

public interface EvaluationStrategy
extends FederatedServiceResolver

Evaluates TupleExprs and ValueExprs.

Author:

Arjohn Kampman, James Leigh

Method Summary

Modifier and Type	Method and Description
CloseableIteration<BindingSet,QueryEvaluationException>	evaluate(Service expr, String serviceUri, CloseableIteration<BindingSet,QueryEvaluationException> bindings) Evaluates the tuple expression against the supplied triple source with the specified set of variable bindings as input.
CloseableIteration<BindingSet,QueryEvaluationException>	evaluate(TupleExpr expr, BindingSet bindings) Evaluates the tuple expression against the supplied triple source with the specified set of variable bindings as input.
Value	evaluate(ValueExpr expr, BindingSet bindings) Gets the value of this expression.
FederatedService	getService(String serviceUrl) Retrieve the FederatedService registered for serviceUrl.
boolean	isTrue(ValueExpr expr, BindingSet bindings) Evaluates the boolean expression on the supplied TripleSource object.

Method Detail

getService

FederatedService getService(String serviceUrl)
                     throws QueryEvaluationException

Retrieve the FederatedService registered for serviceUrl. If there is no service registered for serviceUrl, a new SPARQLFederatedService is created and registered.

Specified by:

getService in interface FederatedServiceResolver

Parameters:

serviceUrl - URL of the service.

Returns:

the FederatedService registered for the serviceUrl.

Throws:

QueryEvaluationException

See Also:

FederatedServiceResolver.getService(java.lang.String)

evaluate

CloseableIteration<BindingSet,QueryEvaluationException> evaluate(Service expr,
                                                                 String serviceUri,
                                                                 CloseableIteration<BindingSet,QueryEvaluationException> bindings)
                                                          throws QueryEvaluationException

Evaluates the tuple expression against the supplied triple source with the specified set of variable bindings as input.

Parameters:

expr - The Service Expression to evaluate

serviceUri - TODO

bindings - The variables bindings iterator to use for evaluating the expression, if applicable.

Returns:

A closeable iterator over all of variable binding sets that match the tuple expression.

Throws:

QueryEvaluationException

evaluate

CloseableIteration<BindingSet,QueryEvaluationException> evaluate(TupleExpr expr,
                                                                 BindingSet bindings)
                                                          throws QueryEvaluationException

Evaluates the tuple expression against the supplied triple source with the specified set of variable bindings as input.

Parameters:

expr - The Tuple Expression to evaluate

bindings - The variables bindings to use for evaluating the expression, if applicable.

Returns:

A closeable iterator over the variable binding sets that match the tuple expression.

Throws:

QueryEvaluationException

evaluate

Value evaluate(ValueExpr expr,
               BindingSet bindings)
        throws ValueExprEvaluationException,
               QueryEvaluationException

Gets the value of this expression.

Parameters:

bindings - The variables bindings to use for evaluating the expression, if applicable.

Returns:

The Value that this expression evaluates to, or null if the expression could not be evaluated.

Throws:

ValueExprEvaluationException

QueryEvaluationException

isTrue

boolean isTrue(ValueExpr expr,
               BindingSet bindings)
        throws ValueExprEvaluationException,
               QueryEvaluationException

Evaluates the boolean expression on the supplied TripleSource object.

Parameters:

bindings - The variables bindings to use for evaluating the expression, if applicable.

Returns:

The result of the evaluation.

Throws:

ValueExprEvaluationException - If the value expression could not be evaluated, for example when comparing two incompatible operands. When thrown, the result of the boolean expression is neither true nor false , but unknown.

QueryEvaluationException