[antlr-interest] "An Introduction to ANTLR" presentation slides
Terence Parr
parrt at cs.usfca.edu
Wed Feb 27 12:49:56 PST 2008
On Feb 27, 2008, at 12:45 PM, Andy Tripp wrote:
> Hi Matt,
>
> Thanks. Yea, I was very hesitant to put that sentence in, as I
> wasn't sure it was
> correct. I'd appreciate it if anyone could clarify this for me.
hi gang. A semantic predicate is a boolean expression that must be
true for the parse to pass over it; any kind of recognizer. A gated
sem pred is one that forces alts to be turned on or off at run time.
A syn pred simply specifies the sytnactic context that must be true
for the parser (or lexer or tree parser) to pass. I.e., if you see X,
then Y will match:
a : (X)=> Y
| ...
;
preds order the alts. first one that matches wins.
Ter
>
>
> Andy
>
> Matt Benson wrote:
>>
>> “Syntactic Predicate" is just some "Symantic
>> Predicate" that happens to be in a lexer
>> rule rather than a parser rule.
>>
>>
>
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