LinkedList<Token> tokens = new LinkedList<Token>();
int pos = 0;
char currChar;
StringBuilder tk = new StringBuilder();
TypeEnum type = null;
int initIndex = pos;
while (pos < this.expression.length()) {
currChar = this.expression.charAt(pos);
if (Character.toLowerCase(currChar) >= 'a' && Character.toLowerCase(currChar) <= 'z') {