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package visitor.typecase;
import enumeration.Op;
public class Main {
public static void main (String[] args) {
Expr one = new Const(1);
Expr onePtwo = new BinOp (new Const(1), Op.ADD, new Const(2));
Expr threeMfour = new BinOp (new Const(3), Op.MUL, new Const(4));
Expr m = new BinOp (onePtwo, Op.SUB, threeMfour);
Expr n = new BinOp (m, Op.DIV, new Const(5));
System.out.println (PostorderPrint.run(n));
System.out.println ("Value: " + Eval.run(n));
}
}
class PostorderPrint {
private PostorderPrint() {}
static private StringBuilder b = new StringBuilder();
static private StringBuilder runConst(int c) {
b.append(c + " ");
return b;
}
static private StringBuilder runBinOp(Expr l, Op op, Expr r) {
run(l); run(r); b.append(op + " ");
return b;
}
static public StringBuilder run(Expr e) {
if (e instanceof BinOp) {
BinOp x = (BinOp) e;
return runBinOp(x.l, x.op, x.r);
} else {
Const x = (Const) e;
return runConst(x.c);
}
}
}
class Eval {
private Eval() {}
static private Integer runConst(int c) {
return c;
}
static private Integer runBinOp(Expr l, Op op, Expr r) {
return op.eval(run(l), run(r));
}
static public Integer run(Expr e) {
if (e instanceof BinOp) {
BinOp x = (BinOp) e;
return runBinOp(x.l, x.op, x.r);
} else {
Const x = (Const) e;
return runConst(x.c);
}
}
}
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