rustlr 0.3.7

LR parser generator that can automatically create ASTs
Documentation 
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# ambiguous grammar for online calculator, enum Expr defined in exprtrees.rs

!use crate::exprtrees::*;
!use crate::exprtrees::Expr::*;
!use rustlr::{LBox,makelbox};

absyntype Expr
nonterminal E
nonterminal ES
terminal + - * / ( ) ;
terminal int
topsym ES
resync ;

left * 500
left / 500
left + 400
left - 400

E --> int:m {m /* should be a Val(n) */}
E --> E:e1 + E:e2 { Plus(makelbox!(_e1_,e1),makelbox!(_e2_,e2)) }
E --> E:e1 - E:e2 { Minus(makelbox!(_e1_,e1),makelbox!(_e2_,e2)) }
E --> E:e1 / E:e2 { Divide(makelbox!(_e1_,e1),makelbox!(_e2_,e2)) }
E --> E:e1 * E:e2 { Times(makelbox!(_e1_,e1),makelbox!(_e2_,e2)) }
E --> - E:e { Negative(makelbox!(_e_,e)) }
E --> ( E:e )  { e }
ES --> E:n ; { Seq(vec![parser.lb(n)]) }
ES ==> ES:es@Seq(ref mut v)@  E:e ;  {
   v.push( makelbox!(_e_,e) );
   es
 } <==

# ==> and <== are required for rules spanning multiple lines

EOF

What could be better syntax than makelbox! ?
Plus(parser.lbox(0,e1), parser.lbox(2,e2)) ??

ZCParser can have a vector of (line,col) values popped off from the
stack in a separate vector that's clearly before each reduce. - the vector
will be in reverse.