net.ontopia.topicmaps.query.impl.utils

Class CostEstimator

java.lang.Object

net.ontopia.topicmaps.query.impl.utils.CostEstimator

Direct Known Subclasses:

PredicateDrivenCostEstimator, SimpleCostEstimator

public abstract class CostEstimator
extends Object

Constructor Summary

Constructors

Constructor and Description
CostEstimator()

Method Summary

Modifier and Type	Method and Description
abstract int	computeCost(Set context, AbstractClause clause, Set literalvars, String rulename) INTERNAL: Computes the cost of evaluating the given clause in the given context of variable bindings.

Methods inherited from class java.lang.Object

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

Constructor Detail

CostEstimator

public CostEstimator()

Method Detail

computeCost

public abstract int computeCost(Set context,
                                AbstractClause clause,
                                Set literalvars,
                                String rulename)

INTERNAL: Computes the cost of evaluating the given clause in the given context of variable bindings. The cost largely depends on the number of unbound variables in the clause.

Parameters:

context - A set of bound variables.

clause - The clause whose cost we want to compute.

literalvars - Contains the variables representing literals. Only an issue in rules.

rulename - The name of the current rule (so we can delay recursive evaluation).