import java.util.*;

public class FunCall extends Expression {
	private List<Expression> operands = new ArrayList<Expression>();
	private String operator = "?";
	public String getOperator() { return operator; }
	public static Expression parse(Scanner tokens) throws Exception {
		FunCall result = new FunCall();
		tokens.next(); // toss left paren
		result.operator = tokens.next();
		while (!tokens.hasNext("\\)")) {  // parse operands until closing right paren encountered
			result.operands.add(Expression.parse(tokens));
		}
		tokens.next(); // toss right paren
		return result;
	}

	public void accept(ExpVisitor v) { v.visit(this); }

	public Iterator<Expression> iterator() {
		return operands.iterator();
	}
	public String toString() {
		String result = "(";
		for(Expression node: operands) {
			result = result + node + " ";
		}
		return result + ")";
	}
	public double eval() throws Exception {
		double result = 0;
		List<Double> args = new ArrayList<Double>();
		for(Expression operand: operands) {
			args.add(operand.eval());
		}
		if (operator.equals("+")) {
			for(Double arg: args) {
				result += arg;
			}
		} else if (operator.equals("*")) {
			result = 1;
			for(Double arg: args) {
				result *= arg;
			}
		} else {
			throw new Exception("unrecognized operator: " + operator);
		}
		return result;
	}
}