main.cpp

//
// main.cpp
//
// --------------------------------------------------------------------------
// Attribution: "Programming Abstractions in C++" by Eric Roberts
// Chapter 19, Exercise 07
// Stanford University, Autumn Quarter 2012
// http://web.stanford.edu/class/archive/cs/cs106b/cs106b.1136/materials/CS106BX-Reader.pdf
// --------------------------------------------------------------------------
//
// Created by Glenn Streiff on 3/27/17
// Copyright © 2017 Glenn Streiff. All rights reserved.
//

#include <iostream>
#include <string>
#include "error.h"
#include "exp.h"
#include "parser.h"
#include "tokenscanner.h"
using namespace std;

const std::string HEADER = "CS106B Programming Abstractions in C++: Ex 19.07\n";
const std::string DETAIL = "Inheritance: Arithmetic interpreter with % operator";
const std::string BANNER = HEADER + DETAIL;

const std::string PROMPT = "=> ";

// Main program

int main() {
    cout << BANNER << endl << endl;
    cout << "Enter an arithmetic expression to evaluate (e.g., x = 3 + 4)";
    cout << endl;
    
    EvaluationContext context;
    TokenScanner scanner;
    
    scanner.ignoreWhitespace();
    scanner.scanNumbers();
    
    while (true) {
        Expression* exp = NULL;
        try {
            string line;
            cout << PROMPT;
            getline(cin, line);
            if (line == "quit") break;
            scanner.setInput(line);
            exp = parseExp(scanner);
            int value = exp->eval(context);
            cout << value << endl;
        } catch (ErrorException& ex) {
            cerr << "Error: " << ex.getMessage() << endl;
        }
        if (exp != NULL) delete exp;
    }
    return 0;
}