public class Tokenizer {
    private Class<? extends Token>[] tokens;
    private Tokenizer(Class<? extends Token>[] tokens) {
        this.tokens = tokens;
    }

    public Tokenizer() {
        this(new Class<? extends Token>[]{
            AsteriskToken,
            LParenToken,
            MinusToken,
            NumberToken,
            PlusToken,
            RParenToken,
            SlashToken,
            Token
        });
    }
}

[
     ['[0-9]', TokenType.Number],
     ['\+|-', TokenType.Operator],
]

enum Token {
    NUMBER('\d'),
    OPERATOR('[-+]');

    private String regex;

    Token (String regex) { this.regex = regex; }

    string getRegex () { return regex; }
}

func power(int x, int y) -> int:
  int temp = 1

  for int n -> range(y):
    temp *= x

  return temp

import tokenizer.*;
import java.util.Stack;

public class Parser {
    public Stack<Token> parse(Stack<Token> tokens) {
        Stack<Token> output = new Stack<Token>();
        Stack<Token> operatorStack = new Stack<Token>();

        while (!tokens.empty()) {
            Token token = tokens.pop();

            if (token.getType() == TokenType.NUMBER) output.push(token);
            if (token.getType() == TokenType.OPERATOR) {
                int precedence = TokenType.getPrecedence(token.getValue());