[antlr-interest] Context Sensitive Keyword Support?

[Terence Parr]

I also want to try a scannerless version of ANTLR.  Rats guy Robert Grimm has groovy combined language / modularity feature.
ter
On Feb 16, 2011, at 2:21 PM, Jim Idle wrote:

> I think that every time we talk about this, we realize that the problems
> lie in lookahead where you cannot decide what to do in certain cases. I
> think that the quantum token idea is a much better one in that a token can
> simultaneously be ID and WHERE or any other token that it is flagged as
> being possible to be. This removes context from the lexer and allows the
> parser to decide.
> 
> Predicates would still work and any other ambiguity should work out? It
> means that input.LA(n) would also need
> 
> input.LA(n, TYPE)
>  and perhaps
> input.LT(n).getType(TYPE)
> 
> which would return TYPE if LT(n)/LA(n) can be one, otherwise the main type
> that it actually is. Could have Boolean versions instead/as well of
> course.
> 
> WHERE :: ID, KEYWORD : 'WHERE' ;
> 
> Or something like that. I think that this is well worth looking in to.
> 
> 
> 
> Jim
> 
>> -----Original Message-----
>> From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-
>> bounces at antlr.org] On Behalf Of Terence Parr
>> Sent: Wednesday, February 16, 2011 2:09 PM
>> To: antlr-interest Interest
>> Subject: Re: [antlr-interest] Context Sensitive Keyword Support?
>> 
>> hiya. yep, i had a similar proposal way back when for v3.0 but I
>> abandoned; can't remember why at this point. i love idea but impl had
>> some issues.
>> ter
>> On Feb 16, 2011, at 2:02 PM, Scott Stanchfield wrote:
>> 
>>> Has anyone looked at the context-sensitive-scanning proposal I sent a
>>> while back?
>>> 
>>>   http://javadude.com/articles/antlr-context-sensitive-scanner.html
>>> 
>>> -- Scott
>>> 
>>> ----------------------------------------
>>> Scott Stanchfield
>>> http://javadude.com
>>> 
>>> 
>>> 
>>> On Wed, Feb 16, 2011 at 4:38 PM, Jim Idle <jimi at temporal-wave.com>
>> wrote:
>>>> No you do this in the parser by allowing the keywords where ID is
>>>> expected then by predicating the WHERE keyword in the LINQ rules:
>>>> 
>>>> 
>>>> .... ((WHERE)=>where_clause)? ....
>>>> 
>>>> 
>>>> id : ID | WHERE | ....
>>>> 
>>>> 
>>>> I have fully working C# lexer, parser, tree walker if that is what
>>>> you are trying to build. It is a commercial product though.
>>>> 
>>>> Jim
>>>> 
>>>>> -----Original Message-----
>>>>> From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-
>>>>> bounces at antlr.org] On Behalf Of chris king
>>>>> Sent: Wednesday, February 16, 2011 1:32 PM
>>>>> To: antlr-interest at antlr.org
>>>>> Subject: [antlr-interest] Context Sensitive Keyword Support?
>>>>> 
>>>>> Does ANTLR support context sensitive keywords? For example, in C#
>>>>> "where" is a keyword only in a LINQ expression. To support this
>>>>> ANTLR would need to change the lexer behavior given feedback from
>>>>> the parser letting it know what context it is in. From what I hear
>>>>> ANTLR lexes the entire file before passing it onto the parser. If
>>>>> that's true than I guess it doesn't support this language concept.
>>>>> In that case, is there a way to work around?
>>>>> 
>>>>> Thanks,
>>>>> Chris
>>>>> 
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