Class QueryValueEvaluationStep.ConstantQueryValueEvaluationStep

java.lang.Object

org.eclipse.rdf4j.query.algebra.evaluation.QueryValueEvaluationStep.ConstantQueryValueEvaluationStep

All Implemented Interfaces:

QueryValueEvaluationStep

Enclosing interface:

QueryValueEvaluationStep

public static class QueryValueEvaluationStep.ConstantQueryValueEvaluationStep
extends Object
implements QueryValueEvaluationStep

A QueryValueEvalationStep that will return the same constant value throughout the query execution. As these rather result just in a value we set the value at precompile time.

Nested Class Summary

Nested classes/interfaces inherited from interface QueryValueEvaluationStep

QueryValueEvaluationStep.ApplyFunctionForEachBinding, QueryValueEvaluationStep.ConstantQueryValueEvaluationStep, QueryValueEvaluationStep.Fail, QueryValueEvaluationStep.Minimal

Modifier and Type	Interface	Description
static final class	QueryValueEvaluationStep.ApplyFunctionForEachBinding	A minimal implementation that falls calls a function that should return a value per passed in bindingsets.
static class	QueryValueEvaluationStep.ConstantQueryValueEvaluationStep	A QueryValueEvalationStep that will return the same constant value throughout the query execution.
static final class	QueryValueEvaluationStep.Fail	A minimal implementation that falls is known to throw an ValueExprEvaluationException.
static final class	QueryValueEvaluationStep.Minimal	A minimal implementation that falls back to calling evaluate in the strategy.

Constructor Summary

Constructors

Constructor	Description
ConstantQueryValueEvaluationStep(Value valueConstant)
ConstantQueryValueEvaluationStep(ValueConstant valueConstant)

Method Summary

Modifier and Type	Method	Description
Value	evaluate(BindingSet bindings)
boolean	isConstant()	If an value expression results in a constant then it may be executed once per query invocation.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface QueryValueEvaluationStep

asPredicate

Modifier and Type	Method	Description
default Predicate<BindingSet>	asPredicate()

Constructor Details

ConstantQueryValueEvaluationStep

public ConstantQueryValueEvaluationStep(ValueConstant valueConstant)

ConstantQueryValueEvaluationStep

public ConstantQueryValueEvaluationStep(Value valueConstant)

Method Details

evaluate

public Value evaluate(BindingSet bindings)
               throws QueryEvaluationException

Specified by:

evaluate in interface QueryValueEvaluationStep

Throws:

QueryEvaluationException

isConstant

public boolean isConstant()

Description copied from interface: QueryValueEvaluationStep

If an value expression results in a constant then it may be executed once per query invocation. This can reduce computation time significantly.

Specified by:

isConstant in interface QueryValueEvaluationStep

Returns:

if this ValueExpresionStep will always return the same value