[antlr-interest] grammar for jdk1.5 parameterized types

Terence Parr parrt at antlr.org
Thu Sep 18 12:01:44 PDT 2003

For some reason my last post didn't appear.

See the C++ templates added to Java solution by Jamie Herre on the 
antlr site.  Not sure what he did any more.  However, it's a simple 
matter in the lexer to track a tiny bit of context I think (i.e., did I 
see "class" or a class name)?  It means the lexer needs access to the 
symbol table.  I think Jamie did something clever, but can't remember.  
Perhaps my audio lectures have the answer ;)


On Thursday, September 18, 2003, at 11:55 AM, John P N Pybus wrote:

> mzukowski at yci.com wrote:
>> You can't switch your lexer from the parser safely.  ANTLR doesn't 
>> work that
>> way (infinite lookahead and all that).  I suggest getting rid of ">>" 
>> as a
>> token and making the parser look for '>' '>' as GT.
>> Monty
> Hmm, with the lexer ignoring Whitespace wouldn't the parser then allow
> "n > > 3" as well as "n >> 3"?
> I'd suggest using lookahead in the lexer to define 3 tokens GT_GT,
> GT_EQ, and GT corresponding to a '>' directly followed by another '>';
> '>' followed by '=' and all other '>' chars, respectively.
> You can use ( GT | GT_GT ) in your parser rules for generics, and can
> define the various shift operators as GT_GT GT; GT_GT GT_EQ EQ etc...
> I haven't done this with the antlr java grammar myself, but I believe
> I've seen this approach used in other java1.5 recognisers (sorry no
> reference handy).
> Hope this makes some sense.
> Yours,
> John
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