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how to enable backtracking [message #876414]

Thu, 24 May 2012 14:47

dav dav

Messages: 5
Registered: May 2012

Junior Member

Hi,

How does one enable backtracking in xtext? From what I've researched I uncommented antlr fragment in mwe2 file, that is this:

fragment = parser.antlr.XtextAntlrGeneratorFragment {
options = {
backtrack = true
memoize=true
}
}

However, I still get 'Resolve by left-factoring or using syntactic predicates or using backtrack=true option' errors. Is there something I've overlooked ?

Thanks for any help,
Dav

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Re: how to enable backtracking [message #876447 is a reply to message #876414]

Thu, 24 May 2012 15:52

Christian Dietrich

Messages: 13669
Registered: July 2009

Senior Member

Hi maybe The error message comes from the antlr UI fragment

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Re: how to enable backtracking [message #877284 is a reply to message #876414]

Sat, 26 May 2012 10:35

dav dav

Messages: 5
Registered: May 2012

Junior Member

Hi,

Actually yes , it is. Clearly I'm missing something obvious, but I'm still not very skilled with xtext. Can you point me where I can find more info on this, or tell me whats wrong ?

Thanks,
Dav

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Re: how to enable backtracking [message #877295 is a reply to message #877284]

Sat, 26 May 2012 11:00

Christian Dietrich

Messages: 13669
Registered: July 2009

Senior Member

Hi,

you have to enable backtracking there too

fragment = parser.antlr.XtextAntlrUiGeneratorFragment {
            	options = {
            		backtrack = true
            	}
            }

~Christian

P.S: if you grammar is actually left recusive you have to solve the left recursion.

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

[Updated on: Sat, 26 May 2012 11:06]

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