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Xtext Grammar - Referencing [message #1044805]

Fri, 19 April 2013 11:14

rohit ahuja

Messages: 27
Registered: February 2013

Junior Member

I need something like what we do in a programming language, wherein we define a variable and then assign some value to it later.(i need only type int for now)

int a;
int b;

//some functions/other statements etc
....
....

//

a=10;
b=10;

Leaving aside the functions and other statements that may exist, i wrote something like,

Model:
Defintion|Assignment|OtherStatements;

Definition:
'int' name=ID ';

OtherStatements :
//TODO, for now think it is only a name=ID
name=ID
;

Assignment:
definition=[Definition] '=' INT ';'

I have a problem in here. Since the assignment can come anywhere after the Definition how do i ensure that it comes only after definition..

So something like definition followed by assignment
works, which is correct..

int a;
int b;

//other statements
...
...

a=10;

-----------------------------------------------------------------------------

This also works,i.e the definition after assignment
a=10;

...
...

int a;

which is obviously incorrect.

I think there must be some way to resolve it. Can anyone please help as i am relatively new to Xtext.

Thanks in Advance.

Rohit

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Re: Xtext Grammar - Referencing [message #1044821 is a reply to message #1044805]

Fri, 19 April 2013 11:34

Christian Dietrich

Messages: 13316
Registered: July 2009

Senior Member

HI,

you have to customize scoping or introduce a semantic validation for that

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

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Re: Xtext Grammar - Referencing [message #1044827 is a reply to message #1044805]

Fri, 19 April 2013 11:40

Steve Kallestad

Messages: 62
Registered: March 2013

Member

That's something that you probably don't want to define in your grammar specifically.

It's possible if you define all declarations to occur before all assignment calls and link the two, but that means inline declarations are out the window.

It's usually better if you handle such a thing within your validation routines. You can leverage INode.getStartLine and INode.getEndLine to check the line numbers of nodes, and you can access nodes using the NodeModelUtils set of routines.

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Re: Xtext Grammar - Referencing [message #1046623 is a reply to message #1044827]

Mon, 22 April 2013 06:35

rohit ahuja

Messages: 27
Registered: February 2013

Junior Member

Thanks Steve and Chreistian.. I wrote a custom validator instead.

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