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Re: shift/reduce conflict with unary
From: |
cwcaceres |
Subject: |
Re: shift/reduce conflict with unary |
Date: |
Wed, 22 Aug 2007 05:11:06 -0700 (PDT) |
But I'm not trying to list. I'm trying to do the add operation. So the
expression "5 6 +4" wouldn't be valid. An example of a valid operation would
be "+5 + -6 - -2" which should have an output of 1. My grammar file
currently outputs the correct result.
I agree with trying to remove the conflict but I'm putting that on hold for
now since I can't think of how to remove it.
Thanks for trying to help.
Camille
Evan Lavelle-2 wrote:
>
> Actually, it turns out that the conflict is pretty obvious even without
> the debug output. consider this input:
>
> "5 6 +4"
>
> How do you expect this to be scanned? Does it contain 3
> summation_expressions ("5", "6", "+4") or 2 ("5", "6+4")? There's an
> ambiguity - you haven't defined an expression list in an unambiguuous way.
>
> this is a very common problem - how do you define a list of something
> complex? Can you define expression lists to require a separator? How about
>
> "5, 6, +4" -> 3 expressions
> "5, 6 +4" -> 2 expressions
>
>
>
>> Is
>> it okay if I disregard the conflict if the grammar works anyway?
>
> I personally think that this is a mistake, but it is commonly done. The
> problems are that you may not understand why there is a conflict in the
> first place, and any subsequent maintainers certainly won't understand;
> I prefer to try to remove the conflict.
>
> Evan
>
>
> _______________________________________________
> address@hidden http://lists.gnu.org/mailman/listinfo/help-bison
>
>
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- Re: shift/reduce conflict with unary, (continued)
- Re: Top Dowm Variable Communication, Evan Lavelle, 2007/08/22
- Message not available
- Re: Top Dowm Variable Communication, lfinsto1, 2007/08/22
- Re: Top Dowm Variable Communication, Ramón García, 2007/08/24
- Re: shift/reduce conflict with unary, Evan Lavelle, 2007/08/22
- Re: shift/reduce conflict with unary, cwcaceres, 2007/08/22
- Re: shift/reduce conflict with unary, Evan Lavelle, 2007/08/22
- Re: shift/reduce conflict with unary,
cwcaceres <=
- Re: shift/reduce conflict with unary, Evan Lavelle, 2007/08/22