Page Comparison

tree grammar Simplify;
options {
    tokenVocab=VecMath;      // use tokens from VecMath.g
    ASTLabelType=CommonTree; // we're using CommonTree nodes
    output=AST;              // build ASTs from input AST
    filter=true;             // tree pattern matching, rewrited mode
}

topdown
    :   ^('*' INT ^(VEC (e+=.)+)) -> ^(VEC ^('*' INT $e)+)
    ;

bottomup
    :  ^('*' a=. b=INT {$b.int==0}?) -> $b // x*0 -> 0
    ;

$ cat t1
x = 4 * [0, 5*0, 3]
$ java Test < t1
Original tree: (= x (* 4 (VEC 0 (* 5 0) 3)))
(* 4 (VEC 0 (* 5 0) 3)) -> (VEC (* 4 0) (* 4 (* 5 0)) (* 4 3))
(* 4 0) -> 0
(* 5 0) -> 0
(* 4 0) -> 0
Simplified tree: (= x (VEC 0 0 (* 4 3)))
$