[antlr-interest] "An Introduction to ANTLR" presentation slides

[Terence Parr]

On Feb 28, 2008, at 9:41 AM, Matt Benson wrote:

>
> --- Andy Tripp <antlr at jazillian.com> wrote:
>
>> Terence Parr wrote:
>>>
>>> A syn pred simply specifies the sytnactic context
>> that must be true
>>> for the parser (or lexer or tree parser) to pass.
>>
>> Ah, OK. So my slide is wrong.
>>
>> I guess I tend to wrongly equate "syntax" with a
>> lexer and "semantics"
>> with a parser.
>>
>> So a syntactic predicate can apply to lexer, parser,
>> or treewalker.
>> And I guess a syntactic predicate is a specific kind
>> of semantic
>> predicate. Whereas a sem pred is
>> any boolean expression that must be true to match, a
>> syn pred is one
>> that simply says
>> "look ahead and see if we'll match X".
>
> I don't think it's correct to say that a syntactic
> predicate is a type of semantic predicate.  I think
> the nomenclature here directly reflects the difference
> between syntax and semantics:  respectively, the
> legality of the communication medium vs. the
> sensicality (?) of the content.
>
> Opinions?  Yea/nay?
>
> -Matt

Syn preds are actually impl. as sem preds as Andy says.  The diff is  
as you say syntax vs semantics (at least by intention)

Ter