Left recursion still not working

[JFinis]

Hi,

the latest early access (built from latest commit d378469) is still not able to handle a (non-mutually) left recursive grammar. The following simple grammar yields the error:

qualifiedName returns [Object res]  
    : name=ID 
            { return null; }

    | (scope=qualifiedName '.') name=ID 
            { return null; }
    ;

ID 
    : '0'..'9'+;

the resulting error is error(119): ... ::: The following sets of rules are mutually left-recursive [qualifiedName]

[parrt]

That doesn't fit the pattern. why do you have extra parens?

[JFinis]

oh, the parens are the problem? They are superfluous, agree. A relic of the non-left recursive (name .)* name form. However, should the parser rely on simple pattern matching for detecting mutual left recursion? I dont think that extra parens should ever change the semantics of a grammar file.

[parrt]

Hi. No doubt the computation is undecidable or close for arbitrary grammars. I am doing a pattern match for only those grammars that will work with the generated code pattern. It is a fairly complicated precedence parsing mechanism. I must be able to determine the operators, which would be quite difficult for arbitrary grammars.