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Working with unordered groups [message #1798555]

Tue, 20 November 2018 07:14

Eclipse User

Hi,

My use case is; I have written a xtext grammar to create classes. The grammar looks like this:

RSELClass:
    'Class' name=ID ('subClassOf' '('subClassOf+=[RSELClass|QualifiedName]+ ')')? | {RSELClass}  ('instanceOf' '(' instanceOf=[RSELClass|QualifiedName] ')')? 
    '{'
    (   
     	('partitions'  partitions+=[RSELClass]+ EndStmt)? &
     	('subOrdinateTo' subOrdinateTo+=[RSELClass]+ EndStmt)? &
     	('disjointCategorizes'  disjointCategorizes+=[RSELClass]+ EndStmt)? &
     	('strongSubOrdinateTo' strongSubOrdinateTo+=[RSELClass]+ EndStmt)? 
    )
    '}';

EndStmt:
     ';'
;

The instance of this grammar looks like this:

Class class {
	
}

Class B {
	
}

Class A subClassOf (B) instanceOf (class) {
	
	partitions B;
	subOrdinateTo B;
	disjointCategorizes B;
	strongSubOrdinateTo B;	
}

The problem is:

When I am trying to write the code for validation in the RSELModelValidator.xtend, only class member "subClassOf" is getting populated in the instance of RSELClass A. Rest all data members "instanceOf", "partitions", "subOrdinateTo", "disjointCategorizes ", "strongSubOrdinateTo " are null.

However, when I change the grammar and set these elements (data members of class) as ordered:

RSELClass:
    'Class' name=ID ('subClassOf' '('subClassOf+=[RSELClass|QualifiedName]+ ')')?  ('instanceOf' '(' instanceOf=[RSELClass|QualifiedName] ')')? 
    '{'
    (   
     	('partitions'  partitions+=[RSELClass]+ EndStmt)? 
     	('subOrdinateTo' subOrdinateTo+=[RSELClass]+ EndStmt)? 
     	('disjointCategorizes'  disjointCategorizes+=[RSELClass]+ EndStmt)? 
     	('strongSubOrdinateTo' strongSubOrdinateTo+=[RSELClass]+ EndStmt)? 
    )
    '}';

EndStmt:
     ';'
;

It works fine. i.e. all the data members are populated.

Can anyone please guide me what I am missing/doing wrong? Is it a bug in Xtext/Xtend? I want these data members to be unordered.

Any help is much appreciated.

Regards,
Yash

Re: Working with unordered groups [message #1798556 is a reply to message #1798555]

Tue, 20 November 2018 07:21

Eclipse User

"Class A subClassOf (B) instanceOf (class) {"

is not allowed by this grammar. did you check eResource.getErrors() for parse errors?

Re: Working with unordered groups [message #1798567 is a reply to message #1798556]

Tue, 20 November 2018 08:33

Eclipse User

Thanks Christian for the reply.

No, rselClass.eResource.getErrors() does not return any error.

On further investigation, I have observed that it's the OR between subClassOf and instanceOf is creating issue.

RSELClass:
'Class' name=ID ('subClassOf' '('subClassOf+=[RSELClass|QualifiedName]+ ')')? | {RSELClass} ('instanceOf' '(' instanceOf=[RSELClass|QualifiedName] ')')?

If there's no OR here, the data members are populated otherwise they are null. I don't understand what's the magic here.

Re: Working with unordered groups [message #1798570 is a reply to message #1798567]

Tue, 20 November 2018 08:39

Eclipse User

A|B says

either parse a A or parse a B
but you have A B in your model

=> do you want to have both? then you should use an unordered group here too.
also the position of the | is bogus and the {RSELClass}

can you please example what should be possible?

'Class' name=ID (('subClassOf' '('subClassOf+=[RSELClass|QualifiedName]+ ')')? & ('instanceOf' '(' instanceOf=[RSELClass|QualifiedName] ')')? )

????

Re: Working with unordered groups [message #1798571 is a reply to message #1798570]

Tue, 20 November 2018 09:16

Eclipse User

Probably I misunderstood the use of | here.

I came across another follow problem after making the changes are you suggested.

The grammar for RSELClass looks like this (I have removed the un-necessary parts):

RSELClass:
     'Class' name=ID ('instanceOf' '(' instanceOf=[RSELClass|QualifiedName] ')')? 
    //name=ID ('instanceOf' instanceOf+=[RSELClass|QualifiedName] (',' instanceOf+=[RSELClass|QualifiedName])* )?
    //('subClassOf' subClassOf+=[RSELClass|QualifiedName] (',' subClassOf+=[RSELClass|QualifiedName])*)? 
    '{'
      	 
        (
        ('subClassOf' '(' subClassOf+=[RSELClass|QualifiedName]+ ')' EndStmt)? &	   
       	('attribute' '{'
       		attributes+=RSELAttribute+ 
       		'}'
     	)? &
     	('deep_instantiation' body=RSELBlock)? 
     )
    '}';
   
RSELBlock:
    {RSELBlock}  '{' statements+=RSELStatement* '}';

RSELStatement:
    RSELExpression ';' ;
        
RSELExpression:
    RSELAssignment;

RSELAssignment returns RSELExpression:
    RSELSelectionExpression
    ({RSELAssignment.left=current} '=' right=RSELTerminalExpression)?; // Right associativity

RSELSelectionExpression returns RSELExpression:
    {RSELExpression} (
     [color=red]   attribute+=[RSELAttribute][/color]
    )*;

RSELTerminalExpression returns RSELExpression:
    {RSELStringConstant} value=STRING |
    {RSELIntConstant} value=INT |
    {RSELPropFormula} value=ReqExpr |
    {RSELBoolConstant} value=('true' | 'false') |
    {RSELNull} 'null' |
    '(' RSELExpression ')';

The instance of this grammar looks like this:

Class class instanceOf (class) {
	
}

Class B instanceOf (class){
	
}

Class A  instanceOf (class) {
	
	subClassOf (C);
	partitions B;
	subOrdinateTo B;
	
	
	disjointCategorizes B;
	strongSubOrdinateTo B;	
	
	attribute {
		name : String [1..*];
	}
	
	deep_instantiation {
		name = "Yash";
	}
	
}

Class C  instanceOf (class){
	deep_instantiation {
		name = "Yash";  //It shows an error that name cannot be resolved. 
	}
	
}

However, this scoping error was not there when I was mistakenly using | between subClassOf and instanceOf.

Sorry, I am exploring xtext and may be doing a blunder here with scoping. Thanks for your patience.

Re: Working with unordered groups [message #1798573 is a reply to message #1798571]

Tue, 20 November 2018 09:23

Eclipse User

please open the model element dialog crtl+shift+f3 or navifate menu to find out how the names of the attributes are.
i dont know how the rules in your case are. how do you want to reference?
simple name / qualified name?
you can either adapt your name provider or scoping.
unfort. your snippets are not in a way to try out (e.g. grammar incomplete. dont see where name is defined in the snippet.

Re: Working with unordered groups [message #1798574 is a reply to message #1798571]

Tue, 20 November 2018 09:25

Eclipse User

Also this might be useful:


RSELAttribute:
     name=ID ':' type=Type  cardinality=Cardinality? EndStmt
;


enum Cardinality:
	ExactlyOne='[1]' | OneorMore='[1..*]' | ZeroOrMore='[*]' | ZeroOrOne='[0..1]'
;

Type:
    IntegerType | StringType | BooleanType | ClassType | JVMType | PropFormula | PredFormula
;

IntegerType:
    id='Integer'
;

StringType:
    id='String'
;

BooleanType:
    id='Boolean'
;

ClassType:
    id=[RSELClass|QualifiedName]
;

PropFormula:
	id='PropFormula'
;

PredFormula:
	id='PredFormula'
;

Re: Working with unordered groups [message #1798575 is a reply to message #1798574]

Tue, 20 November 2018 10:21

Eclipse User

Please find attached grammar file and corresponding instance.

The problem is:

When I am having | between subClassOf and instanceOf (as shown in the previous snippets) on opening the model element dialog using cntrl+shft+f3
the attributes names are name and sn

index.php/fa/34377/0/

However when making the changes as suggested by you. (The attached grammar file contains these changes) these attributes names are A.name and A.sn .

index.php/fa/34376/0/

How is this getting impacted?

All I want is to be able to access these attributes from other class as well.

Attachment: MyDsl.xtext
(Size: 1.62KB, Downloaded 127 times)
Attachment: model.mydsl
(Size: 0.31KB, Downloaded 98 times)
Attachment: ModelElementView.PNG
(Size: 17.58KB, Downloaded 193 times)
Attachment: ModelElementViewWithOR.PNG
(Size: 17.08KB, Downloaded 232 times)

[Updated on: Tue, 20 November 2018 10:22] by Moderator

Re: Working with unordered groups [message #1798579 is a reply to message #1798575]

Tue, 20 November 2018 10:45

Eclipse User

as i said. if you want simple name (bogus from my perspective) you need to adapt the name provider.
without my change it seems to be working by accident (cause the part that gives the bad parent name = the class) is skipped
(you should see the classes having no name too - in fact you should have a class with the name and one without)

Re: Working with unordered groups [message #1798629 is a reply to message #1798579]

Wed, 21 November 2018 06:12

Eclipse User

"you need to adapt the name provider."

Any tips how can I do that? Code snippet for that? and where should I write that code?

Re: Working with unordered groups [message #1798634 is a reply to message #1798629]

Wed, 21 November 2018 07:39

Eclipse User

there should be gazillions of examples in the forum and there is this old blogpost
https://www.dietrich-it.de/xtext/2011/07/16/iqualifiednameproviders-in-xtext-2-0.html

Re: Working with unordered groups [message #1798661 is a reply to message #1798634]

Thu, 22 November 2018 05:57

Eclipse User

Thanks a lot Christian :)