On Tue, 2007-10-30 at 23:26 -0500, Angela Zhu wrote:

> /***** Precedence Rules  *****/
> ...
> %left PLUS MINUS
> %left STAR DIVIDE
> %left ATOB

> Can any one help me to see why it happens? Why the precedence rules
> doesn't work?

> Precedences also can be created by sophisticated
> organization of the grammar rules.
> But I want to avoid this.

DO NOT USE THEM. The rules are hard to explain and very badly
designed, in other words, they're a hack. Ocaml provides
them for compatibility with older yacc like tools.

Write your grammar properly instead, in pseudo code:

	term = factor | term + factor
	factor = atom | factor * atom
	atom = INTEGER | ( term )


gives the precedence of * over + and left associativity,
without using incomprehensible precedence rules. 


-- 
John Skaller <skaller at users dot sf dot net>
Felix, successor to C++: http://felix.sf.net