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Validating x,y coordinates [message #1787047]

Thu, 17 May 2018 17:48

Jack Lee

Messages: 3
Registered: May 2018

Junior Member

Hello, I am working on an assignment and have a slight issue understanding something about validation and the grammar.

Currently this is my grammar (only showing relevant parts, ... is omitted code):

Game:
    'Game' name=ID grid=GridSize ...
;

GridSize:
   'Grid' 'size' size=Coordinates
;

Coordinates:
'('x=INT','y=INT')'
;
...

And this is my validation definition:

@Check
    def void checkGridCoordinates(Game game) {
    	val minValue = 1
    	val maxValue = 10
    	var x = game.grid.size.x
    	var y = game.grid.size.y
    	var literal = MetaGameLanguagePackage.Literals.GRID_SIZE__SIZE
    	
    	if(x < minValue || y < minValue){
    		error("Grid size must be at least 1.",literal)	
    	} else if(x > maxValue || y > maxValue) {
    		this.error("Grid size must be 10 or under.", literal)
    	}
    }

I get the following error, which happens if I try to set the grid x and y to be either 0 or under or above 10 (which is expected but I want it to display the error message and not fail to validate):

Description	Resource	Path	Location	Type
Error executing EValidator	TestingFile.gl	/IndividualExtension/src	/IndividualExtension/src/TestingFile.gl	GameLang Problem

Since this is an assignment I would appreciate it if you could hint me in a direction in which I can experiment, instead of handing me a solution :)

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Re: Validating x,y coordinates [message #1787090 is a reply to message #1787047]

Fri, 18 May 2018 16:30

Christian Dietrich

Messages: 14285
Registered: July 2009

Senior Member

first of all you should write a unit test for your validator
the classes parsehelper and validationtesthelper will help

@RunWith(XtextRunner)
@InjectWith(MyDslInjectorProvider)
class MyDslParsingTest {
	@Inject
	ParseHelper<Game> parseHelper
	
	@Inject
	extension ValidationTestHelper
	
	@Test
	def void loadModel() {
		val result = parseHelper.parse('''
			Game HelloWorld Grid size (1,11)
		''')
		Assert.assertNotNull(result)
		val errors = result.eResource.errors
		Assert.assertTrue('''Unexpected errors: «errors.join(", ")»''', errors.isEmpty)
		result.assertNoErrors // Triggers validation
	}
}

this will give you an actual stack trace (you would find it in the eclipse runtime error log too)
the stacktrace should hint you to your problem

Need professional support for Xtext, Xpand, EMF?
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Re: Validating x,y coordinates [message #1787114 is a reply to message #1787090]

Sat, 19 May 2018 04:05

Jack Lee

Messages: 3
Registered: May 2018

Junior Member

Thank you very much! Turns out the issue was I was in the wrong context and thus the feature was not being exposed. However as you can see in my below code I had to use eINSTANCE and not

MetaGameLanguagePackage.Literals.GRID_SIZE__SIZE

. I have yet to understand why Literals didn't do the job.

@Check
def void checkGridCoordinates(GridSize grid) {
    	// Variables
    	var minValue = 1
    	var maxValue = 10
    	var x = grid.size.x
    	var y = grid.size.y
    	var gridSize = MetaGameLanguagePackage.eINSTANCE.gridSize_Size
    	
    	if(x < minValue || y < minValue){
    		error("Grid size must be at least 1.", gridSize)	
    	} else if(x > maxValue || y > maxValue) {
			error("Grid size must be 10 or under.", gridSize)
    	}
    }

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