Token.java

package dataStructure_7_PreAndPost;

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

public 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);
	}
	
	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 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("number can't compare priority");
		}
		return priorities.get(this.value) - priorities.get(t.value) > 0;
	}
	
	
	
	
	
	
	
	
	
	
	
	
	
	
}