[antlr-interest] Token/TOKENS Rewrite Bug

[ANTLR Mailing List]

Hello there. I'm not sure if this has been fixed, but I have a simple
grammar that ANTLR (in 3.0 or some dev version) generates incorrectly in
Java. It's an easy manual fix, but I'd thought I'll let you know.

Here's my grammar, it's a simple variation of the Expr grammar:

grammar ExprTree;
options {
    // language=ActionScript;
    output=AST;
    ASTLabelType=CommonTree; // type of $stat.tree ref etc...
}

tokens {
    SET_VARIABLE = 'SetVariable';
    GET_VARIABLE = 'GetVariable';
    PUSH = 'Push';
    PLUS = '+';
    MINUS = '-';
    STAR = '*';
    SLASH = '/';
    PERCENT = '%';
}

prog:   ( stat { System.out.println ( $stat.tree.toStringTree ( ) ); } )+ ;

stat:   expr NEWLINE        -> expr
    |   ID '=' expr NEWLINE -> ^(ID expr SET_VARIABLE)
    |   NEWLINE             ->
    ;

expr:   v1=multExpr (op=(PLUS|MINUS) v2=multExpr)? -> ^($v1 ($v2 $op)?);

multExpr
    :   v1=atom (op=(STAR|SLASH|PERCENT) v2=atom)? -> ^($v1 ($v2 $op)?);

atom:   INT
    |   ID -> ^(ID GET_VARIABLE)
    |   '('! expr ')'!
    ;

ID  :   ('a'..'z'|'A'..'Z')+ ;
INT :   '0'..'9'+ ;
NEWLINE: ';' ;
WS  :   (' '|  '\t')+ { $channel=HIDDEN; } ;

The problem happens in expr and multExpr; the rewrite of $op. It gets caught
up in PLUS or MINUS (or STAR, SLASH or PERCENT) that it forgets to set op.
Inside the alternative switch statement that sets op, we have this:

switch (alt3) {
    case 1 :
    // ExprTree.g:25:26: PLUS
    {
        PLUS9=Token(input.LT(1));
        matchStream(input,PLUS,FOLLOW_PLUS_in_expr198);
        stream_PLUS.add(PLUS9);
    }
    break;
    case 2 :
    // ExprTree.g:25:31: MINUS
    {
        MINUS10=Token(input.LT(1));
        matchStream(input,MINUS,FOLLOW_MINUS_in_expr200);
        stream_MINUS.add(MINUS10);
   }
   break;
}

It sets PLUS9 and MINUS10 without setting op, but op is referenced when
doing the rewrite. The op is just a simple fix of setting op at the same
time it sets PLUS9 (or MINUS10).

Also, Terr, I am interested in developing the ActionScript target (I have
already talked to George Scott). What would I need to do to get my
credentials added?
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