[antlr-interest] variables and keywords

[Anakreon]

Rene' Jansen wrote:
> In the NetRexx language, when a string is used as a variable, it cannot 
> be a keyword anymore.  This is a great feature, and it comes out of the 
> real life experience that newly added keywords in most environments 
> (languages and toolkits) break existing programs. Now I've read about 
> (and used a bit) the keywords literals feature of Antlr, but I am at a 
> loss of how to specify the NetRexx behaviour in a grammar. Does anyone 
> have any pointers on how to implement such a feature, if I were to, 
> ahem, for example trying to make an antlr grammar for NetRexx?
> 
> Rene Vincent Jansen. 
> 
I wrote an asp parser where activeX objects may have methods which can be 
keywords for the language.
To solve the problem, I declared the tokens for each keyword in the tokens 
section, and populated a Map with keyword's text as the key, and an Integer 
having the value for the corresponding token.
Exmaple:
map.put("for", new Integer(FOR));
Then from the lexer, when the IDENTIFIER rule is matched, I would search in the 
map if a key with that text exists.If it did, the value corresponding to that 
key was assigned as the token type.Otherwise the Token would be an IDENTIFIER.


 

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