[antlr-interest] AST for repeated occurrences of binary operators

[Jim Idle]

expr : ^(OR expr expr)

          | ^(AND expr expr)

          | atoms

          ;

 

Jim

 

From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-bounces at antlr.org] On Behalf Of Caetano Sauer
Sent: Tuesday, November 24, 2009 5:34 AM
To: antlr-interest at antlr.org
Subject: [antlr-interest] AST for repeated occurrences of binary operators

 

Hello everyone,

I am trying to generate an AST node for a logical OR operator. This would be a parent OrExpr token with all the operands as children, for example:

a OR b OR c -> ^(OrExpr a b c)

My question is not how to do it, but I am wondering if the solution I found is the best, since similar situations occur quite often in my grammar. Here is the rule;

orExpr
    :    firstOperand=andExpr
        (OR furtherOperands+=andExpr)*
        -> { furtherOperands != null }? ^(OrExpr andExpr+)
        -> $firstOperand
    ;

The important thing here is that I want it to skip straight to andExpr in case there is no OR token.

Thank you very much and regards,
Caetano.



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