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Xtext [message #1858942]

Tue, 02 May 2023 15:23

Luong Tiet

Messages: 4
Registered: May 2023

Junior Member

Hi,

The grammar

Instruction:
	from=Identifier '->' to=Identifier
	| 'stack' stack+=Identifier+
;
Execute: 'exec' '{' instructions+=Instruction+ '}';
Identifier: name=ID ( '(' index=Identifier ')' )?;

works fine.

But if I add an inactive rule like:

Instruction:
	from=Identifier '->' to=Identifier
	| 'stack' stack+=Identifier+
;
Execute: 'exec' '{' instructions+=Instruction+ '}';
Identifier: name=ID ( '(' index=Identifier ')' )?;
RuleInError: Execute; // <-- error at generation time with this rule

at generation time, i have the following error:

rule ruleInstruction has non-LL(*) decision due to recursive rule invocations reachable from alts 1,2. Resolve by left-factoring or using syntactic predicates or using backtrack=true option

What is my mistake?

Best regards.

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Re: Xtext [message #1858992 is a reply to message #1858942]

Thu, 04 May 2023 12:30

Christian Dietrich

Messages: 14665
Registered: July 2009

Senior Member

have no idea
maybe you can generate a debug grammar and alayze with antlr works

side question: why do you introduce the uncalled rule? to change type hierarchy?

Twitter : @chrdietrich
Blog : https://www.dietrich-it.de

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Re: Xtext [message #1859113 is a reply to message #1858992]

Fri, 12 May 2023 08:59

Luong Tiet

Messages: 4
Registered: May 2023

Junior Member

Hi Christian,

Called or uncalled rule does not change the problem. I simplified the exposed case for clarity. This is part of a project to convert programs written on mainframe to java. The uncalled rule shown is used for later scoping. Maybe i'm wrong but i think i have to solve this simplified case before generalizing.

I come from mainframe and I'm newcomer to new technologies. Any tips for generating a debug grammar and antlr works?

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Re: Xtext [message #1859117 is a reply to message #1859113]

Fri, 12 May 2023 09:49

Christian Dietrich

Messages: 14665
Registered: July 2009

Senior Member

if you want to work on type hierarchy of inferred metamodel you can do this in your example instead

Execute returns RuleInError : {Execute} 'exec' '{' instructions+=Instruction+ '}';

Twitter : @chrdietrich
Blog : https://www.dietrich-it.de

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