org.openrdf.query.algebra.evaluation
Interface EvaluationStrategy

All Known Implementing Classes:

EvaluationStrategyImpl

public interface EvaluationStrategy

Evaluates TupleExprs and ValueExprs.

Author:

Arjohn Kampman, James Leigh

Method Summary

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.
boolean	isTrue(ValueExpr expr, BindingSet bindings) Evaluates the boolean expression on the supplied TripleSource object.

Method Detail

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