lsdks

/*
*Infiks to Postfiks
*Samuel Berkat Hulu
*Version 5.0 ETS Struktur Data
*
*/
class Ifikstopostfiks
{
    private stack theStack;
    private String input;
    private String output = "";
    public Ifikstopostfiks(String in)
    {
        input = in;
        int stackSize = input.length();
        theStack = new stack(stackSize);
    }
    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 '^':
                    gotOper(ch, 3);
                    break;
                case '(':
                    theStack.push(ch);
                    break;
                case ')':
                    gotParen(ch);
                    break;
                default:
                    output = output + ch;
            }
        }
        while( !theStack.isEmpty() )
        {
            output = output + theStack.pop();
        }
        return output;
    }
    //--------------------------------------------------------------
    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 if(opTop == '*' || opTop == '/')
                    prec2 = 2;
                else
                    prec2 = 3;
                if(prec2 < prec1)
                {
                    theStack.push(opTop);
                    break;
                }
                else
                    output = output + opTop;
            }
        }
        theStack.push(opThis);
    }

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