[antlr-interest] grammar for jdk1.5 parameterized types
mzukowski at yci.com
mzukowski at yci.com
Thu Sep 18 11:57:13 PDT 2003
Yep, you're right!
Monty
-----Original Message-----
From: John P N Pybus [mailto:john-yahoo at pybus.org]
Sent: Thursday, September 18, 2003 11:56 AM
To: antlr-interest at yahoogroups.com
Subject: Re: [antlr-interest] grammar for jdk1.5 parameterized types
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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