[antlr-interest] rough idea of exceptions vs no-exceptions backtracking in v3

Sohail Somani sohail at taggedtype.net
Tue Jan 3 16:44:27 PST 2006


On Tue, 2006-01-03 at 16:21 -0800, Terence Parr wrote:
> howdy,
> 
> I am doing some fuzzy parsing in the lexer using v3.  The basic trick  
> of "try to match and if you fail, throw an exception, skip a char and  
> retry" works.  It's pretty slow though it turns out.  The exceptions  
> per char kill you.  I then tried backtracking using the non-exception  
> mechanism in v3 and it's like 5x faster :)
> 
> Heh heh heh...thanks to all of you that badgered me into trying to  
> build backtracking w/o exceptions. :)

I'm glad you took the time to do this. That being said, its not as if
this result was at all unexpected :)



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