[antlr-interest] Discarding characters in lexer

[Loring Craymer]

Oliver--

v2 lexers had very poor performance because they copied characters.  ANTLR 3 does not do this, and lexer performance is much improved.  It is possible to efficiently implement ! in v3--I've done a preliminary implementation for Yggdrasil--but Ter has not yet gotten that far.  I would expect this feature to return after ANTLR 3 is implemented in ANTLR 3; there has not yet been enough attention paid to lexer features and there are some important features (use of follow sets to do true LL*, lexer states) that are on the "to do" list.

--Loring

----- Original Message ----
From: Olivier Lefevre <lefevrol at yahoo.com>
To: antlr-interest at antlr.org
Sent: Sunday, March 30, 2008 6:41:32 PM
Subject: Re: [antlr-interest] Discarding characters in lexer

> In v3, the ! operator only works in the parser (and affects AST 
> generation).  You can't use it in the lexer any more.

Any idea why this was done? That was a useful feature.

-- O.L.







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