Dictionary.java

// Kimberley Ni and Eylul Oktay

import java.util.HashMap;
import java.util.Map.Entry;

public class Dictionary {
    public static HashMap<String, Expression> map;
    public static String lastResultString;

    public Dictionary() {
        map = new HashMap<>();
        lastResultString = "";
    }

    public static void addVals(String storedVarStr, Expression storedExp) {
        if (!map.containsKey(storedVarStr)) {
            map.put(storedVarStr, storedExp);
            lastResultString = "Added " + storedExp.toString() + " as " + storedVarStr + ".";
        } else {
            lastResultString = storedVarStr + " is already defined.";
        }
    }

    public static Boolean containsKey(String storedVarStr) {
        return map.containsKey(storedVarStr);
    }

    public static Expression get(String storedVarStr) {
        return map.get(storedVarStr);
    }

    public static Expression getKey(Expression exp) {
        for (Entry<String, Expression> entry : map.entrySet()) {
            if (exp.equals(entry.getValue())) {
                return new Variable(entry.getKey());
            }
        }
        return exp;
    }

    /*
	 * Logging from Dictionary, namely "Added value as variable"
	 * Alternatively, string could be "variable is already defined."
	 */
    public static String lastVariableAssignResult() {
        return lastResultString;
    }
}