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;
	}
}