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Entities extend other entities [message #756597]

Mon, 14 November 2011 13:27

Mikka Missing name

Messages: 2
Registered: November 2011

Junior Member

Hi,

I have a problem with the classes generated by xtext using my grammar definition. Some classes extend other classes and 'steal' their properties and I have absolutely no idea why.

This is an extract of the used grammar definition:

Probassigns:
	probassign+=Probassign ('+' probassign+=Probassign)*;

Probassign:
	(Probability ':')? nextstateassign+=Nextstateassign ('&'nextstateassign+=Nextstateassign)*;

Probability:
	mult+=Mult (('+'|'-') mult+=Mult)*;
	
Mult:
	sign+=Sign (('*'|'/') sign+=Sign)*;

Sign:
	('+'|'-')* Prob;

Prob:
	name+=Name | Val | '('probability+=Probability')';

Nextstateassign:
	('(' newstate+=Newstate '=' stateexpr+=Stateexpr ')')+;

As you can see the 'Probassigns' rule contains the 'Probassign' rule, which contains the 'Nextstateassign' rule. So I expect the generated 'Probassign' class to contain a 'getNextstateassigns()' method, that returns a list of 'NextStateAssigns' objects.
But instead of this the 'Probassign' class is empty, the 'Probability' class extends the 'Probassign' class and contains the 'getNextstateassigns()' method, as you can see in the attached screenshot.

Why is the the 'Probability' class extending the 'Probassign' class? Could it be caused by the circle in the grammar (Probassign -> Probability -> Mult -> Sign -> Prob -> Probability)?

In the manual i found this:
"Manual - 7.3.2."

Furthermore, each type that is added to the currently possible return types automatically extends the current return type of the parser rule.

I first thought that this is the reason, but i guess I just misunderstood it, because other classes are not extended by classes that are contained in the rules.

It would be great if somebody can tell me why the inheritance is happening. Let me know if further information is required.

Attachment: xtext_extends.png
(Size: 13.25KB, Downloaded 90 times)

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Re: Entities extend other entities [message #756626 is a reply to message #756597]

Mon, 14 November 2011 14:29

Sven Efftinge

Messages: 1823
Registered: July 2009

Senior Member

The feature must be part of Probability, since the the result of Probassign will be an instance of Probability if the first optional group matches.
If that was not your intention you might want to assign Probability to a feature :

Probassign:
(probability=Probability ':')? nextstateassign+=Nextstateassign ('&'nextstateassign+=Nextstateassign)*;

Probability:
mult+=Mult (('+'|'-') mult+=Mult)*;

[Updated on: Mon, 14 November 2011 14:30]

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