#ifndef EXPRESSION_TREE_H
#define EXPRESSION_TREE_H

#include <iostream>
#include "Token.h"
#include "BinaryTree.h"

class ExpressionTree : public BinaryTree<Token> {


 public:
  /*
   * Default constructor (for convenience).  No need to implement.
   */
  ExpressionTree() {};

  /*
   * Constructor to build an Expression Tree based upon an array of
   * 'tokens'
   */
  ExpressionTree(int numTokens, const Token tokens[]);


  /*
   * Evaluate the underlying expression, returning the result of that evaluation.
   */
  int evaluate() const;


  /*
   * EXTRA CREDIT version of constructor to build an Expression Tree
   * based upon an array of 'tokens'.
   *
   * This version handles more general syntax which may not be fully
   * parenthesized or which may include unary negation.
   *
   * Furthermore, it throws and InvalidExpressionException in the
   * case where the input has invalid syntax.
   */
  ExpressionTree(const Token tokens[], int numTokens);


   /* 
    * You will likely need to define your own recursive functions.
    * You can decide whether the design makes sense to have each as
    * public or private.
    */

};


/*
 *  Overloaded output operator should result in echoing the underlying
 *  arithemtic expression in fully-parenthesized form.
 */
std::ostream& operator<<(std::ostream& out, const ExpressionTree& T);

#endif