# Exactly the same rules as arith.gra, but here we use infix notationn
# in the semantics.  (buildattrs assumes that non-alphabetic 
# symbols like "+" or "==>" are infix operators.)
# 
# Even though the input to the parser is in infix notation as well,
# the output is different: it is parenthesized in accordance with
# order of operations.  This is because buildattrs automatically
# inserts parentheses as necessary when substituting for x and y.  
# (It is not like #define in C!)
#
# The semantics for addition and subtraction put spaces around
# the "+" and "-" operators, so in this file, the value of the sem 
# attribute must be quoted (e.g. "x + y") to protect the spaces.

1 EXPR[sem="x + y"]	EXPR[sem=x] + TERM[sem=y]   
1 EXPR[sem="x - y"]	EXPR[sem=x] - TERM[sem=y]
1 EXPR[sem=x]		TERM[sem=x]

1 TERM[sem=1*3]	TERM * FACTOR
1 TERM[sem=1/3]	TERM / FACTOR
1 TERM[sem=1]	FACTOR

1 FACTOR[sem=1]		Num
1 FACTOR[sem=2]		{ EXPR }

1 FACTOR[sem=\/3]	sqrt { EXPR }   # \/ looks sort of like a sqrt symbol

1 ROOT[=1] 		EXPR

1 Num	0
1 Num	1
1 Num	2
1 Num	3
1 Num	4
1 Num	5
1 Num	6
1 Num	7
1 Num	8
1 Num	9
1 Num	pi
1 Num	e
1 Num	0.5