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Re: [xtext-dev] Xtext grammar translation bug?
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| Hi Oleg,
the EOF is necessary to detect superfluous tokens at the end of the document, e.g. a file with a grammar like this:
Model: name = ID;
is invalid if it has this content:
Foo Bar Zonk
Such error would remain undetected. Same applies for partial parsing, too. When you edit a file, Xtext will usually not reparse the complete file but only a necessary part of it (depending on the grammar and the amount of changes). The entry rules allow to do this.
You are right, I was tricked by the Antlr works bug. Nevertheless, the grammar looks valid to me and should not produce an error in Antlr. So the only valid solution is to refactor it in a way that allow to parse your files without that pattern.
Best regards, Sebastian
On 14.01.2014, at 13:50, Oleg Bolshakov wrote: Hello, Sebastian.
> entryRules describe a complete document from the beginning to the end. Therefore the EOF token is used in these rules.
But is it normal that entryRules were generated for each of my Xtext parser rules?
> They serve as parser rules if partial parsing is applied during editing of a file.
why?.. What problem does "EOF" in entry rules solve in the case of partial parsing?
>In your particular example it seems to be a bug in Antlr, e.g. if I
manually edit the generated grammar and put meaningless parentheses
> around the the subrule for id1 = ID?, I don't the the error anymore.
Could you please send my this grammar? Because when I try to put meaningless parentheses around lv_id1_1_0=RULE_ID nothing happens (and especially if I put them for Xtext grammar id1 = ID?). I do it with antlr.3.2 in command line mode. Because I have seen some very strange problem with antlrWorks (a gui for antlr): when I open the program and check the grammar for the first time it shows THE error ("bla bla RULE_ID EOF EOF"), but when I click it once again it never shows that and it seems to be a bug! Maybe you worked in AntlrWorks and you didn't get the error for the second time just because it just never shows up in this case?... I will write to antlr support as soon as I got to know your workflow in which you managed to avoid the error.
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