Operator precedence

[Andrew Cooke <andrew@intertrader.com>]

	Hi,

	Has anyone got any quick tips on implementing several layers
	of operator precedence?

	Yacc has %prec which helps reduce conflicts, but SableCC seems
	to expect me to do this in the grammar.  The thesis includes an
	example where * and / take precedence over + and - so I am
	going to see if I can extend this to have more "layers"
	( http://www.sable.mcgill.ca/sablecc/thesis.html#PAGE26 ), but
	if anyone has any simple advice or pointers they would be
	appreciated...

	To put this in context: I am writing an interpreter (for "fun")
	and it needs to parse something like:

	z + 2 < 3 * y + 1 and x > y > z

	so I need the following precendence:

	* > + > ">" > and  (and then there's "not" to add in).

	Cheers,
	Andrew

	PS.  x > y > z is interesting when it comes to storing temporary results
	by node :-)

	PPS.  I guess one could implement this later using rotations to arrange
	the tree as required, but that seems like a lot of work!