[antlr-interest] Confused about backtracking in lexer rules

[Jim Idle]

On Mon, 2008-11-17 at 07:44 +1300, Gavin Lambert wrote:

> At 01:39 17/11/2008, William Rose wrote:
>  >What I'm finding is that the lexer starts matching the URL,
>  >gets to a point where it can't match the character, then



>               ;
> TEXT : (URL) => URL { $type = URL; }
>       | ~(COLON | SLASH | HYPHEN | ASTERISK | SPACE | TAB | CR | 
> LF)*
>       ;


Remember that lexer rules that can effectively match a zero length
string are meaningless. That * would have to be + :-)

To be honest I think that wiki syntax is so bad (I don't even find it
that helpful to marking things up), that a grammar to parser such a
thing is going to be so full of exceptions and hacks that it probably
isn't worth it. 

Jim
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