Topic: What is the best parsing rule for an order-independent series of tokens?

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What is the best parsing rule for an order-independent series of tokens?

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Posted By: Brian_Sanders
Posted On: Tuesday, October 1, 2002 01:31 PM

My parser uses several rules expressed in the format

A : (X AND Y AND Z) | (X AND Z AND Y) | (Y AND X AND Z)...

where the general constraint is that tokens X, Y, and Z must exist exactly once, but in any order.

Is there a better way to express this constraint?

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Re: What is the best parsing rule for an order-independent series of tokens?

Posted By: Sam_Walker
Posted On: Tuesday, October 8, 2002 07:14 AM

How about this...


A: expr AND expr AND expr ;

expr: X | Y | Z ;

-Sam

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