org.eclipse.ocl.examples.impactanalyzer.instanceScope.unusedEvaluation

Class UnusedEvaluationRequest

java.lang.Object

org.eclipse.ocl.examples.impactanalyzer.instanceScope.unusedEvaluation.UnusedEvaluationRequest

public class UnusedEvaluationRequest
extends java.lang.Object

A largely immutable request to perform a (partial) evaluation (see also PartialEvaluatorImpl) of an OCLExpression, comparing the result with a given expected result or invalid. If the result compares equal, this indicates that the subexpression where the change occurred is not used, leading the traceback process to returning an empty set. The only modification allowed to a request is setting an inferred variable's value (see setInferredVariableValue(Variable, Object, UnusedEvaluationRequestFactory). Note that this assumes that invalid means "unused." This is the case for the currently known unused checks, in particular computing the condition of an IfExp, computing the source of a LoopExp and computing the argument of an ->at(...) OperationCallExp.

The request holds a number of slots for variable values inferred during the traceback process. If a new variable value is inferred for which this request has a slot, the value is entered into the slot and used for the partial evaluation.

If a variable for which this request has a slot changes scope, a new request is created in which the slot is removed, because we can't expect to infer the value for the right dynamic scope anymore.

Author:

Axel Uhl (D043530)

Field Summary

Fields

Modifier and Type	Field and Description
static int	evaluations
static int	evaluationsAbortedDueToUnknownVariable
static int	evaluationsSucceedingAndProvingUnused
static int	evaluationsSucceedingWithoutProvingUnused

Constructor Summary

Constructors

Modifier

Constructor and Description

protected

UnusedEvaluationRequest(OCLExpression expression, java.lang.Object resultIndicatingUnused, java.util.Map<Variable,java.lang.Object> inferredVariableValues, java.util.Set<Variable> slots, java.util.Set<VariableExp> inevitableVariableUsages) Must not be called from anywhere except UnusedEvaluationRequestFactory.getUnusedEvaluationRequest(OCLExpression, Object, Map, Set) because resulting instances need to be managed as their equality and hash code fall back to their identity.

Method Summary

Modifier and Type	Method and Description
protected PartialEvaluatorNoAllInstances	createPartialEvaluatorNoAllInstances(OppositeEndFinder oppositeEndFinder, OCLFactory oclFactory)
boolean	evaluate(OppositeEndFinder oppositeEndFinder, OCLFactory oclFactory) Tries a partial evaluation of the expression by setting the variable values inferred so far (see inferredVariableValues) in the evaluation environment.
boolean	hasOneOrMoreSlots()
boolean	hasSlotFor(Variable v)
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

evaluations

public static int evaluations

evaluationsAbortedDueToUnknownVariable

public static int evaluationsAbortedDueToUnknownVariable

evaluationsSucceedingAndProvingUnused

public static int evaluationsSucceedingAndProvingUnused

evaluationsSucceedingWithoutProvingUnused

public static int evaluationsSucceedingWithoutProvingUnused

Constructor Detail

UnusedEvaluationRequest

protected UnusedEvaluationRequest(OCLExpression expression,
                                  java.lang.Object resultIndicatingUnused,
                                  java.util.Map<Variable,java.lang.Object> inferredVariableValues,
                                  java.util.Set<Variable> slots,
                                  java.util.Set<VariableExp> inevitableVariableUsages)

Must not be called from anywhere except UnusedEvaluationRequestFactory.getUnusedEvaluationRequest(OCLExpression, Object, Map, Set) because resulting instances need to be managed as their equality and hash code fall back to their identity. Hence, equal objects in a given scope must be guaranteed to be identical. Such a scope is defined by the use of a UnusedEvaluationRequestFactory.

Parameters:

expression - the expression to evaluate

resultIndicatingUnused - if expression evaluates to this result, this request will return true from its evaluate(OppositeEndFinder, OCLFactory) method; as a special case, null will be considered "equal" to an empty collection as the result of evaluating expression

inferredVariableValues - may be null. In this case, a new Map is created internally.

slots - the variables currently within their dynamic scope such that, when a value is inferred for such a variable, it is correct to assign it for use in evaluating expression in this request

Method Detail

hasOneOrMoreSlots

public boolean hasOneOrMoreSlots()

hasSlotFor

public boolean hasSlotFor(Variable v)

evaluate

public boolean evaluate(OppositeEndFinder oppositeEndFinder,
                        OCLFactory oclFactory)
                 throws ValueNotFoundException

Tries a partial evaluation of the expression by setting the variable values inferred so far (see inferredVariableValues) in the evaluation environment. If this succeeds, the result is compared to resultIndicatingUnused. If successful, true is returned. If evaluation fails for an unknown variable, the ValueNotFoundException is simply passed through.

Callers should call checkValuePresentForAllRequiredVariables() before to see if it makes sense at all to attempt an evaluation or if a ValueNotFoundException would inevitably result. This saves the effort for a failing partial evaluation.

Throws:

ValueNotFoundException

createPartialEvaluatorNoAllInstances

protected PartialEvaluatorNoAllInstances createPartialEvaluatorNoAllInstances(OppositeEndFinder oppositeEndFinder,
                                                                              OCLFactory oclFactory)

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object