de.uka.ipd.sdq.beagle.core.analysis

Interface ProposedExpressionAnalyser

public interface ProposedExpressionAnalyser

An analyser that contributes EvaluableExpressions to the Blackboard by analysing EvaluableExpressions. This analyser can use measurement results and already proposed EvaluableExpressions to propose new EvaluableExpressions. Analysers that only use measurement results should implement MeasurementResultAnalyser instead of this interface. For more details, look for the Blackboard layers in the Design and Architecture document in chapter 2. Tools wishing to conduct measurements on software are advised to implement MeasurementTool instead of this interface.

Proposed expression analysers need a public zero argument constructor for the instantiation, because they are loaded through eclipse extension points.

Method Summary

Modifier and Type	Method and Description
boolean	canContribute(ReadOnlyProposedExpressionAnalyserBlackboardView blackboard) Determines whether this analyser can potentially contribute knowledge in the moment.
void	contribute(ProposedExpressionAnalyserBlackboardView blackboard) Contributes this analyser’s knowledge to the passed blackboard.

Method Detail

canContribute

boolean canContribute(ReadOnlyProposedExpressionAnalyserBlackboardView blackboard)

Determines whether this analyser can potentially contribute knowledge in the moment. If true is returned, the analyser can potentially contribute, but might still be unable to generate meaningful results when being executed. If false is returned, calling contribute(de.uka.ipd.sdq.beagle.core.analysis.ProposedExpressionAnalyserBlackboardView) will not yield any new results. Calling this method has no implications on whether or when contribute(de.uka.ipd.sdq.beagle.core.analysis.ProposedExpressionAnalyserBlackboardView) will be called. Passing a blackboard that was last modified by this analyser’s contribute(de.uka.ipd.sdq.beagle.core.analysis.ProposedExpressionAnalyserBlackboardView) must always result in false .

This method must behave entirely stateless, meaning that its result do not depend on any prior calls to any method but only on the passed blackboard. Furthermore, calls with equal blackboard contents must always result in the same value.

Parameters:

blackboard - The current blackboard.

Returns:

true only if contribute(de.uka.ipd.sdq.beagle.core.analysis.ProposedExpressionAnalyserBlackboardView) may be called.

contribute

void contribute(ProposedExpressionAnalyserBlackboardView blackboard)

Contributes this analyser’s knowledge to the passed blackboard.

Calling this method with a blackboard for which canContribute(de.uka.ipd.sdq.beagle.core.analysis.ReadOnlyProposedExpressionAnalyserBlackboardView) returns false results in undefined behaviour. This method must

• behave entirely stateless, meaning that its result do not depend on any prior calls to any method (especially not canContribute(de.uka.ipd.sdq.beagle.core.analysis.ReadOnlyProposedExpressionAnalyserBlackboardView)) but only on the passed blackboard.
• store all its results on the passed blackboard.
• assure that if canContribute(de.uka.ipd.sdq.beagle.core.analysis.ReadOnlyProposedExpressionAnalyserBlackboardView) is called with the blackboard like its left by this method, it will return false.

Implementing BlackboardStorer and using Blackboard.writeFor(Class, java.io.Serializable) is, if needed, the recommended way to achieve the behaviour described above.

Parameters:

blackboard - The current blackboard.