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• All references to EObjects in EObjectWrapper are references to a copy of the original EObject. This allows to represent immutable mapping. To reidentify corresponding EObjects TransformationTreeExtensions provides search functions which will check for structural matching models.
• Models in TransformationTrees may be transient. This indicates that all references to EObjects in all Elements of the transient model are removed. Thus these models can't be source of a new appended transformation and can not be associated with it's original model. The main propose of this feature is to improve scalability of TransformationTrees by removing unnecessary references to internal model, but preserve traversing functionality of the object-mapping.
• Mappings can be incomplete causing resulting transfromation tree to be incomplete. A incomplete tree does not represent every object in a model with a corresponding Element. This may break some paths of element transformations, but allows to omit model-immanent objects like annotations from mapping. TranformationMapping extension provies a function to check completeness of mapping against its models.

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Example

In this example we will perform some transformations on SCCharts.

The source chart is a ABO, the "Hello World" of SCCharts.

ABO is already a CoreSCChart, so we will perform normalization and a transformation to SCG.

Creating Mapping during Transformation

The following code is a modifcation of the tranformation "Spilt Trigger and Effects" of SCCharts.In order to note every single element transformation of a model transformation, we use the TransformationMapping extension.

After each creation of new Objects for transformed model the mapping must be updated with it's origin information.

The codeblock blow show a snipped of SCChartCoreTransformation with additional mapping registration.

package de.cau.cs.kieler.ktm.test.transformations
import com.google.inject.Inject
import de.cau.cs.kieler.ktm.extensions.TransformationMapping
import de.cau.cs.kieler.sccharts.Region
import de.cau.cs.kieler.sccharts.Transition
import de.cau.cs.kieler.sccharts.extensions.SCChartsExtension
/**
 * @author als
 */
class SCChartTestTransformation {
    @Inject
    extension TransformationMapping
    @Inject
    extension SCChartsExtension  @Inject
    extension TransformationMapping

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    // NEW - Mapping access delegation  
    def extractMapping() {
        extractMappingData;
    }

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    //-------------------------------------------------------------------------
    //--                 S P L I T   T R A N S I T I O N                     --
    //-------------------------------------------------------------------------
    // For every transition T that has both, a trigger and an effect do the following:
    //   For every effect:
    //     Create a conditional C and add it to the parent of T's source state S_src.
    //     create a new true triggered immediate effect transition T_eff and move all effects of T to T_eff.
    //     Set the T_eff to have T's target state. Set T to have the target C.
    //     Add T_eff to C's outgoing transitions. 
    def Region transformTriggerEffect(Region rootRegion) {
        clearMapping; //NEW - clear previous mapping information to assure a single consistent mapping
        // Clone the complete SCCharts region 
        var targetRootRegion = rootRegion.mappedCopy; //NEW - mapping information (changed copy to mappedCopy)
        // Traverse all transitions
        for (targetTransition : targetRootRegion.getAllContainedTransitions) {
            targetTransition.transformTriggerEffect(targetRootRegion);
        }
        //check if mapping is complete (only for test proposes)
        val diffcompleteness = rootRegion.checkMappingCompleteness(rootRegion, targetRootRegion);
 //NEW       if (diff.key.empty && diff.value.empty) {- DEBUG
            targetRootRegion;
        } else {
            null
        }
    }
    def void transformTriggerEffect(Transition transition, Region targetRootRegion) {
        // Only apply this to transition that have both, a trigger (or is a termination) and one or more effects 
        if (((transition.trigger != null || !transition.immediate || transition.typeTermination) && !transition.effects.nullOrEmpty) ||
            transition.effects.size > 1) {
            val targetState = transition.targetState
            val parentRegion = targetState.parentRegion
            val transitionOriginalTarget = transition.targetState
            var Transition lastTransition = transition
            val firstEffect = transition.effects.head
            for (effect : transition.effects.immutableCopy) {
                 // Optimization: Prevent transitions without a trigger
                 if(transition.immediate && transition.trigger == null && firstEffect == effect) {
                        // skip
                 } else { 
                    val effectState = parentRegion.createState(targetState.idGENERATED_PREFIX + effect.id"S")
                    effectState.mapParents(transition.mappedParents); //NEW - mapping information
                    effectState.setTypeConnectoruniqueName
                    val effectTransition = createImmediateTransition.addEffect(effect)
                    effectTransition.mapParents(transition.mappedParents); //NEW - mapping information
                    
                    effectTransition.setSourceState(effectState)
                    lastTransition.setTargetState(effectState)
                    lastTransition = effectTransition
                 }
            }
            lastTransition.setTargetState(transitionOriginalTarget)
        }
    }
}

Create TransformationTree

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To test the transformation and mapping we will transform th following ABO-SCChart.

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The following code snipped performs the transformation on our ABO-example, extracts the mapping and creates will now perform each transformation stepwise and updates a transformation tree each step.

 

Code Block
theme Eclipse language java title Transform and create TranformationTree firstline 1 linenumbers true collapse true
aboSplitTE = transformationSCCtransformation.transformTriggerEffect(abo); ModelModelWrapper aboSplitTEModel = transformationTreeExtensions.initializeTransformationTree( transformationtransformationTree.initializeTransformationTree(SCCtransformation.extractMapping(), "TriggerEffect", abo, "splitTriggerEffect", "coreSCChart", aboSplitTE, "coreSCChart-splitTriggerEffect"); aboNormalized = SCCtransformation.transformSurfaceDepth(aboSplitTE); ModelWrapper aboNormalizedModel = transformationTree.addTransformationToTree(SCCtransformation.extractMapping(), aboSplitTEModel, "SurfaceDepth", aboaboSplitTE, aboNormalized, "coreSCChartnormalizedCoreSCChart",); aboSCG = SCGtransformation.transformSCG(aboNormalized); ModelWrapper aboSCGModel = transformationTree.addTransformationToTree(SCGtransformation.extractMapping(), aboNormalizedModel, "SCC2SCG", aboSplitTE, "coreSCChart-splitTriggerEffectaboNormalized, aboSCG,"SCG"); tranformationTreetree = transformationTreeExtensionstransformationTree.root(aboSplitTEModelaboSCGModel);

 

The result of transformation is the following SCChart. ABO-splitTriggerEffect.

Image Removed

Resulting TransformationTree has following structure.

Image Removedresulting TransformationTree has following structure and representing each step and model of the transformation.

 

Image Added
Image Added	Image Added	Image Added	Image Added

 

Furthermore the TransformationTree now contains the following mapping information for the whole transformation chain.

Image Removed

Here you can see the effect of the transformation causing the transformation to split up.

Image RemovedNow we can use an additional feature of KTM, the resolving of mappings between arbitary models.

The following code has starts with an instance of the initial ABO SCChart and SCG, along with the TranformationTree above.

 

Code Block
theme Eclipse language java title resolveMapping firstline 1 linenumbers true collapse true
@Inject extension TransformationTreeExtensions //Find nodes of model instances in tree val aboSCCModelWrapper = transformationTree.findModel(aboSCC,"coreSCChart"); val aboSCGModelWrapper = transformationTree.findModel(aboSCG,"SCG"); //resolve val mapping = resolvemapping(aboSCCModelWrapper, aboSCC, aboSCGModelWrapper, aboSCG);

 

The returned mapping is a multi mapping between all object in aboSCC and their resulting objects in aboSCG.