infixtopostfix

/**
 * Write a description of class infixtopostfix here.
 *
 * @author Samuel Berkat Hulu
 * @version 5.0 21-April-2021
 */
public class infixtopostfix
{
    private Stack theStack;
    private String input;
    private Queue queue;

    public infixtopostfix(String in)
    {
        input = in;
        int stackSize = input.length();
        int queueSize = input.length();
        queue = new Queue(queueSize);
        theStack = new Stack(stackSize);
    }

    //Lakukan terjemahan ke postfix
    public String doTrans()
    {
        for(int j=0; j<input.length(); j++)
        {
            char ch = input.charAt(j);
            switch(ch)
            {
                case '+':
                case '-':
                gotOper(ch, 1);
                break;
                case '*':
                case '/':
                gotOper(ch, 2);
                break;
                case '(':
                theStack.push(ch);
                break;
                case ')':
                gotParen(ch);
                break;
                default:
                queue.enqueue(ch);
                break;
            }
        }
        while( !theStack.isEmpty() )
        {
            queue.enqueue(theStack.pop());
        }
        return queue.getString();
    }

    public void gotOper(char opThis, int prec1)
    {
        while( !theStack.isEmpty() )
        {
            char opTop = theStack.pop();
            if( opTop == '(' )
            {
                theStack.push(opTop);
                break;
            }
            else
            {
                int prec2;
                if(opTop=='+' || opTop=='-')
                    prec2 = 1;
                else
                    prec2 = 2;
                if(prec2 < prec1)
                {
                    theStack.push(opTop);
                    break;
                }
                else
                    queue.enqueue(opTop);
            }
        }
        theStack.push(opThis);
    }


    public void gotParen(char ch)
    {
        while( !theStack.isEmpty() )
        {
            char chx = theStack.pop();
            if( chx == '(' )
                break;
            else
                queue.enqueue(chx);
        }
    }
}