[antlr-interest] Newbie: NoViableAltException
Buck, Robert
rbuck at verisign.com
Tue Jul 24 18:13:05 PDT 2007
It clarified things for me quite a bit. Not quite sure how I'd write a
parser in ANTLR for the sort of syntax, if its possible, but now I
understand the issue.
Bob
> -----Original Message-----
> From: antlr-interest-bounces at antlr.org
> [mailto:antlr-interest-bounces at antlr.org] On Behalf Of
> Cameron Esfahani
> Sent: Tuesday, July 24, 2007 8:12 PM
> To: antlr-interest at antlr.org
> Subject: Re: [antlr-interest] Newbie: NoViableAltException
>
> Ah, I was trying to come up with a good explanation and
> Randall's is so much better...
>
> On Jul 24, 2007, at 5:10 PM, Randall R Schulz wrote:
>
>
> I still don't get it.
>
>
>
>
> Don't the parser rules indicate what lexer rule
> to use? If you have
>
> the following:
>
>
>
>
> Nope. Again, the lexical analyzer operates
> independently and essentially
>
> asynchronously w.r.t. the parser. The parser _DOES NOT_
> direct the
>
> actions of the scanner.
>
>
>
>
>
>
>
> IDENT EQUALS (PCHAR)*
>
>
>
>
> The IDENT lexer rule would not get called for
> any tokens to the RHS
>
> of the EQUALS sign, right? I declared it only
> gets called for the
>
> LHS.
>
>
>
>
> Scanner rules are NOT "called" by the parser. They are
> used to partition
>
> the input stream and assign token type codes to each
> sub-sequence of
>
> the input. Then, when that's all done and the entire
> input is broken
>
> into tokens, the parser starts in on those tokens.
>
>
>
>
>
> Cameron Esfahani
> dirty at apple.com
>
> "Americans are very skilled at creating a custom meaning from
> something that's mass-produced."
>
> Ann Powers
>
>
>
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