[antlr-interest] Right-to-left binding (was RE: Problem with AST)

[Marcin Rzeźnicki]

Bryan Ewbank wrote:
> Hi Marcin,
> 
> I struggled with how to do right-to-left operator evaluations as well, and
> the examples sidestep it by stopping the calculator example
> at multiplication (exponentiation is right-to-left).  What I figured out
> was:
> 
> For a left-to-right operator, you use the standard production:
> 
> 	left_to_right:	operand ( OP^ operand )*
> 
> For a right-to-left operator, you use recursion on the rightmost element;
> also notice that the production
> uses a "?" instead of a "*" - A "*" is ambiguous because ANTLR can't know
> whether to recurse, or return:
> 
> 	right_to_left:	operand ( OP^ right_to_left )?


Hello Bryan,
You are right, second pattern does the right thing. Thank you very much 
for your help
--
Greetings
Marcin Rzeźnicki




 
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