[antlr-interest] Fwd: ANTLRWorks bug: Remove Left Recursion with comments in grammar

[The Researcher]

I forgot to give credit where credit is due.

This grammar is from

Aho, A. V., Lam, M. S., Sethi, R., & Ullman, J. D. (2007) Compilers:
principles, techniques, & tools (2nd ed.). Boston: Pearson/Addison Wesley.
pg. 47, Example 2.5





---------- Forwarded message ----------
From: The Researcher <researcher0x00 at gmail.com>
Date: Mon, Sep 26, 2011 at 1:51 PM
Subject: ANTLRWorks bug: Remove Left Recursion with comments in grammar
To: antlr-interest at antlr.org


grammar Ambiguious001;



string      : string Plus string

            | string Minus string

            | Digit

            ;



Digit       : '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' ;

Minus       : '-' ;

Plus        : '+' ;



Remove All Left Recursion or Remove Left Recursion produces

grammar Ambiguious001;



string      : (Digit) (Plus string | Minus string)*

            ;



Digit       : '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' ;

Minus       : '-' ;

Plus        : '+' ;



However

grammar Ambiguious001;



// Parser



string      : string Plus string

            | string Minus string

            | Digit

            ;



// Lexer



Digit       : '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' ;

Minus       : '-' ;

Plus        : '+' ;



Remove All Left Recursion or Remove Left Recursion produces



grammar Ambiguious001;



// Parser



string      : (Digit

            ;) (Plus string | Minus string)*



// Lexer



Digit       : '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' ;

Minus       : '-' ;

Plus        : '+' ;

  It's the first time I have ever had an error wink at me.

Eric