Token.java

package stack.expr;

import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

class Token {
	public static final List<String> OPERATORS = Arrays.asList("+", "-", "*", "/", "(", ")");
	private static final Map<String,Integer> priorities = new HashMap<>();
	static {
		priorities.put("+", 1);
		priorities.put("-", 1);
		priorities.put("*", 2);
		priorities.put("/", 2);
		priorities.put("(", 0);
		priorities.put(")", 3);
	}
	static final int OPERATOR = 1;
	static final int NUMBER = 2;
	String value;
	int type;
	public Token(int type, String value){
		this.type = type;
		this.value = value;
	}		

	public boolean isNumber() {
		return type == NUMBER;
	}

	public boolean isOperator() {
		return type == OPERATOR;
	}
	
	public boolean isLeftSquare() {
		if (!isOperator()) {
			return false;
		}

		return priorities.get(this.value) == 0;
	}
	
	public boolean isRightSquare() {
		if (!isOperator()) {
			return false;
		}

		return priorities.get(this.value) == 3;
	}

	public int getIntValue() {
		return Integer.valueOf(value).intValue();
	}
	public String toString(){
		return value;
	}
	
	
	
	public boolean hasHigherPriority(Token t){
		if(!this.isOperator() && !t.isOperator()){
			throw new RuntimeException("numbers can't compare priority");
		}
		return priorities.get(this.value) - priorities.get(t.value) > 0;
	}

	public boolean isSquare() {
		
		return isLeftSquare() || isRightSquare();
	}


	
	

}