Exercise 6
In the final task of this tutorial, we will look at various types of helper functions in YAMTL and use such functions to provide additional capabilties to model transformations.
Input Model
Source model representing the flowchart instance (in XMI format) conforming to the flowchart domain is as follows:
<?xml version="1.0" encoding="UTF-8"?>
<flowchart:Flowchart xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:flowchart="flowchart" xmi:id="_9mLMwDY6EeOwt8pm-kjW_Q" name="Wakeup">
<nodes xsi:type="flowchart:Action" xmi:id="_9mLMwTY6EeOwt8pm-kjW_Q" name="Wake up" outgoing="_9mLMxjY6EeOwt8pm-kjW_Q" incoming="_9mLMyDY6EeOwt8pm-kjW_Q _9mLz0TY6EeOwt8pm-kjW_Q"/>
<nodes xsi:type="flowchart:Decision" xmi:id="_9mLMwjY6EeOwt8pm-kjW_Q" name="Is it really too early?" outgoing="_9mLMxzY6EeOwt8pm-kjW_Q _9mLz0DY6EeOwt8pm-kjW_Q" incoming="_9mLMxjY6EeOwt8pm-kjW_Q"/>
<nodes xsi:type="flowchart:Action" xmi:id="_9mLMwzY6EeOwt8pm-kjW_Q" name="Sleep" outgoing="_9mLMyDY6EeOwt8pm-kjW_Q" incoming="_9mLMxzY6EeOwt8pm-kjW_Q"/>
<nodes xsi:type="flowchart:Action" xmi:id="_9mLMxDY6EeOwt8pm-kjW_Q" name="Get up" incoming="_9mLz0DY6EeOwt8pm-kjW_Q"/>
<nodes xsi:type="flowchart:Action" xmi:id="_9mLMxTY6EeOwt8pm-kjW_Q" name="begin" outgoing="_9mLz0TY6EeOwt8pm-kjW_Q"/>
<transitions xmi:id="_9mLMxjY6EeOwt8pm-kjW_Q" name="" source="_9mLMwTY6EeOwt8pm-kjW_Q" target="_9mLMwjY6EeOwt8pm-kjW_Q"/>
<transitions xmi:id="_9mLMxzY6EeOwt8pm-kjW_Q" name="Yes" source="_9mLMwjY6EeOwt8pm-kjW_Q" target="_9mLMwzY6EeOwt8pm-kjW_Q"/>
<transitions xmi:id="_9mLMyDY6EeOwt8pm-kjW_Q" name="Some Time Passes" source="_9mLMwzY6EeOwt8pm-kjW_Q" target="_9mLMwTY6EeOwt8pm-kjW_Q"/>
<transitions xmi:id="_9mLz0DY6EeOwt8pm-kjW_Q" name="No" source="_9mLMwjY6EeOwt8pm-kjW_Q" target="_9mLMxDY6EeOwt8pm-kjW_Q"/>
<transitions xmi:id="_9mLz0TY6EeOwt8pm-kjW_Q" name="start" source="_9mLMxTY6EeOwt8pm-kjW_Q" target="_9mLMwTY6EeOwt8pm-kjW_Q"/>
</flowchart:Flowchart>
Expected Output Model
<?xml version="1.0" encoding="ISO-8859-1"?>
<xmi:XMI xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns="HTML">
<H1 value="[Wake up, Sleep, Get up, begin]"/>
<H1 value="[Wake up, Sleep, Get up, begin]"/>
<H1 value="[Wake up, Sleep, Get up, begin]"/>
<H1 value="[Wake up, Sleep, Get up, begin]"/>
<H1 value="[Sleep, Get up]"/>
<H1 value="1. "/>
<H1 value="2. Yes"/>
<H1 value="3. Some Time Passes"/>
<H1 value="4. No"/>
<H1 value="5. start"/>
</xmi:XMI>
Task
A transformation script containing staticAttribute and staticOperation helper types has already been defined in the base transformation. Check out those helper functions and write the final helper type called contextualOperation that takes in two arguments: an object and an argument map, then returns the concatenation of the arguments map object's string value and the first argument object's name. Use this contextualOperation to create reusable function that appends an increment counter prefix to the name of the input object. Let's see how this can be done.
In Transition2Heading rule, set the value of h1 object to a function call c_op() (the returned value will be set as the h1.value). c_op(<object>, [<listOfArgumentMap>]) contains an <object> (in this case we need to pass the input object 't') and [<listOfArgumentMap>] (this has one key 'prefix' and a value as the increment counter i).
Create a new contextual operation helper function as contextualOperation('<operationName>', {obj, argsMapExpression}) within the helperStore(). <operationName> is the name of the operation that you want to define i.e. c_op. obj is the first argument passed into the function call within the Transition2Heading rule. argsMapExpression is a lambda expression as seen in the staticOperation before. You only need to define a single statement that returns the concatenation of the value of the key 'prefix' (which was passed into argsMap as a key-value pair before) and the name of the obj object.
That's all! Let's summarise the steps we did before. To set the value of h1 object of Transition2Heading, we called a helper function c_op and passed the input Transition object 't' and a list of arguments map with one key-value pair (specifically a variable i was provided to the function). Then we defined the contextual operation helper that returns the concatenated string of the calculation made with both arguments obj and map value. Remember, this function is reusable in any other rule which could lead to efficient code.
Base Transformation
Transformation class containing the MT definition. All rules are defined in the ruleStore().
package flowchartToHtmlExamples
import static yamtl.dsl.Helper.*
import static yamtl.dsl.Rule.*
import org.eclipse.emf.ecore.EClass
import org.eclipse.emf.ecore.EPackage
import yamtl.core.YAMTLModule
import yamtl.groovy.YAMTLGroovyExtensions_dynamicEMF
class Example6 extends YAMTLModule {
public int i = 1
public Example6(EPackage flowchartPk, EPackage htmlPk) {
YAMTLGroovyExtensions_dynamicEMF.init(this)
header().in('in', flowchartPk).out('out', htmlPk)
ruleStore([
rule('Action2Heading')
.in("a", flowchartPk.Action)
.out("h1", htmlPk.H1, {
h1.value = att.toString()
}),
rule('Decision2Heading')
.in("d", flowchartPk.Decision)
.out("h1", htmlPk.H1, {
h1.value = op(['obj': d])
}),
rule('Transition2Heading')
.in("t", flowchartPk.Transition)
.out("h1", htmlPk.H1, {
//TODO: Set value of h1 as the value returned from contextual operation
})
])
helperStore([
staticAttribute('att', {
def actionList = []
for (anAction in allInstances(flowchartPk.Action)) {
actionList.add(anAction.name)
}
//returns all instances of Action elements from the source model
return actionList
}),
staticOperation('op', { argsMap ->
def aTransition = (flowchartPk.Transition as EClass)
aTransition = argsMap.obj.outgoing
//The name of the target node of the outgoing transition from 'd' Decision element
return aTransition.target.name.toString()
}),
//TODO: Create a contextualOperation helper function that has 2 parameters
])
}
}
To solve this exercises interactively, go to the YAMTL playground.
A downloadable solution can be found here.