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Can Ecore::EString be used in XText? [message #1834708]

Mon, 16 November 2020 16:39

John Henbergs

Messages: 227
Registered: October 2020

Senior Member

Hi guys,

I have generated an XText grammar from an ecore model and the grammar that I got is the following:

grammar org.xtext.example.mydsl16.MyDsl with org.eclipse.xtext.common.Terminals

generate myDsl "http://www.xtext.org/example/mydsl16/MyDsl"
import "http://www.eclipse.org/emf/2002/Ecore" as ecore

WorldMap returns WorldMap:
	'WorldMap'
	'{'
		'WorldMap' WorldMap=EString
		'countrycorona'  countrycorona+=CountryCorona ( "," countrycorona+=CountryCorona)*  
	'}';


CountryCorona returns CountryCorona:
	'CountryCorona'
	'{'
		'CountryCorona' CountryCorona=EString
		'population' population=EInt
		'continent' continent=EString
		'infectedPopulation' infectedPopulation=EInt
		'zonelabel' zonelabel=zonelabelcolour
	
	'}';

EString returns ecore::EString:
	STRING | ID;

EInt returns ecore::EInt:
	'-'? INT;

enum zonelabelcolour returns zonelabelcolour:
				red = 'red' | orange = 'orange' | yellow = 'yellow' | green = 'green' | white = 'white';

My issue is that when I try write a model for this grammar, I usually use CTRL Space, to get the suggestion for the following token. However after I write WorldMap { WorldMap, I get

no viable alternative at input '<EOF>'

Furthermore, I do not get a suggestion that the next token should be an EString. Refering to XText documentation I should be able to use this EString, but apparently I can't. Do you know what might be the issue?

Thank you!

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Re: Can Ecore::EString be used in XText? [message #1834710 is a reply to message #1834708]

Mon, 16 November 2020 16:42

Christian Dietrich

Messages: 14497
Registered: July 2009

Senior Member

if you have a datatype rule (in your case EString), you have to override and implement
the corresponding complete_XXXX method yourself inside YourDslProposalProvider

Need professional support for Xtext, Xpand, EMF?
Go to: https://www.itemis.com/en/it-services/methods-and-tools/xtext
Twitter : @chrdietrich
Blog : https://www.dietrich-it.de

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Re: Can Ecore::EString be used in XText? [message #1834711 is a reply to message #1834710]

Mon, 16 November 2020 16:51

John Henbergs

Messages: 227
Registered: October 2020

Senior Member

Hi Christian,

Thank you for your answer! Could you be a bit more specific on the steps that I should follow to do that?

I thought that adding

EString returns ecore::EString:
	STRING | ID;

would be enough

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Re: Can Ecore::EString be used in XText? [message #1834712 is a reply to message #1834711]

Mon, 16 November 2020 17:05

Christian Dietrich

Messages: 14497
Registered: July 2009

Senior Member

grammar != content assist

so implement complete_EString
and create the proposals you want to have

public class MyDslProposalProvider extends AbstractMyDslProposalProvider {
	
	@Override
	public void complete_EString(EObject model, RuleCall ruleCall, ContentAssistContext context,
			ICompletionProposalAcceptor acceptor) {
		acceptor.accept(createCompletionProposal("NiceID", context));
		acceptor.accept(createCompletionProposal("\"NiceString\"", context));
	}
}

Need professional support for Xtext, Xpand, EMF?
Go to: https://www.itemis.com/en/it-services/methods-and-tools/xtext
Twitter : @chrdietrich
Blog : https://www.dietrich-it.de

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Re: Can Ecore::EString be used in XText? [message #1834715 is a reply to message #1834712]

Mon, 16 November 2020 18:14

John Henbergs

Messages: 227
Registered: October 2020

Senior Member

When I try it, I get this error

Multiple markers at this line
	- ContentAssistContext cannot be resolved to a 
	 type
	- RuleCall cannot be resolved to a type
	- EObject cannot be resolved to a type

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Re: Can Ecore::EString be used in XText? [message #1834716 is a reply to message #1834715]

Mon, 16 November 2020 18:21

John Henbergs

Messages: 227
Registered: October 2020

Senior Member

Managed to fix it, thanks!

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Re: Can Ecore::EString be used in XText? [message #1834720 is a reply to message #1834716]

Mon, 16 November 2020 19:18

Ed Willink

Messages: 7598
Registered: July 2009

Senior Member

Hi

You should not rely on Completion Assist. It can be very useful, but most tools try to prioritize good suggestions over a ridiculous volume of suggestions. Unfortunately if your prevailing text has typos that point the tool in the 'wrong' direction, you will get 'wrong' suggestions. Also the completion coding often involves manual contributions that are hard to debug thoroughly, so you often encounter bugs, particularly where incremental update is needed to accommodate changes in referenced resources.

Regards

Ed Willink

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