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package visitor.expr;
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 (n.accept(new PostorderToString()));
System.out.println ("Value: " + n.accept(new Eval()));
}
}
class Eval implements ExprVisitor<Integer> {
public Integer visitConst(int c) {
return c;
}
public Integer visitBinOp(Expr l, Op op, Expr r) {
return op.eval(l.accept(this), r.accept(this));
}
}
class PostorderToString implements ExprVisitor<StringBuilder> {
StringBuilder b = new StringBuilder();
public StringBuilder visitConst(int c) {
b.append (c + " ");
return b;
}
public StringBuilder visitBinOp(Expr l, Op op, Expr r) {
l.accept(this); r.accept(this); b.append (op + " ");
return b;
}
}
class PreOrderToString implements ExprVisitor<StringBuilder> {
StringBuilder b = new StringBuilder();
public StringBuilder visitConst(int c) {
b.append (c + " ");
return b;
}
public StringBuilder visitBinOp(Expr l, Op op, Expr r) {
b.append (op + " "); l.accept(this); r.accept(this);
return b;
}
}
class InOrderToString implements ExprVisitor<StringBuilder> {
StringBuilder b = new StringBuilder();
public StringBuilder visitConst(int c) {
b.append (c + " ");
return b;
}
public StringBuilder visitBinOp(Expr l, Op op, Expr r) {
l.accept(this); b.append (op + " "); r.accept(this);
return b;
}
}
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