[antlr-interest] Re: Does ANTLR *need* ASTNull?
open.zone at virgin.net
Thu Mar 20 20:26:03 PST 2003
> I have run into an issue with ASTNULL and hetero-ASTs using Java as
> the target language (IIRC C# doesn't have ASTNULL and it isn't an
> issue with C++).
My comments about C# is inaccurate - it does have ASTNULL and hence
the same problem.
In my limited analysis, ASTNULL seems to be used as a performance
optimization essentially. I guess my focus is now on ideas for
ensuring ASTNULL plays nice with hetero-AST usage.
Is anyone mixing TreeParsers and hetero-ASTs?. Any issues?.
> Specifically, there are a few situations where ASTNULL is assigned
> the value of a vriable then, an attempt is made to cast that
> whose value is ASTNULL to an hetero-AST class ==>
> Why does ANTLR-Java need ASTNULL?.
> Why isn't just "null" simply used as in ANTLR-C#?
The last question is misleading, ASTNULL is used in ANTL-C# too.
This issue only arises with TreeParsers incidentally and I've
inherited a few I could do without ;-)
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