Re: When %dprec and %merge aren't enough...

[Hans Aberg]

On 17 Nov 2008, at 20:48, Marcel Laverdet wrote:

> So I ended up solving this by basically copy and pasting my  
> expression grammar sans the expressions that begin with t_LCURLY.  
> Then an expression_statement must be an expression_no_statement  
> t_SEMICOLON, where expression_no_statement is the copy and pasted  
> grammar.
>
> ES-262 recommends a similar technique to deal with the ambiguity  
> that comes up by using the `in` operator in a `for` loop initializer.
> http://www.mozilla.org/js/language/E262-3.pdf
> The madness begins on page 167, each rule is repeated once with  
> `in` and once without it. What I'm doing is identical except with  
> '{' and `function` instead of `in`.
>
> On the plus side, though, with the modifications there are 0  
> conflicts so I don't need %glr-parser anymore. On the down side  
> that introduced about 50 redundant rules and added 300 lines to my  
> grammar.

Good, if you have solved your problem; one can often handle  
ambiguities by other techniques than GLR. Getting it to work is the  
number one priority of course, but it is important to keep it  
maintainable, and structure is important for that. So you might still  
check if some of the other techniques help with that.

> Thanks for the help Hans!

You are welcome.

  Hans