/*
 * Stack.java
 *
 * Created on 13 de Maio de 2006, 14:55
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */

package calcpolonesa;

/**
 *
 * @author meiadmin
 */
public class Stack {
    /** Fields */
    private float[] data;
    private int top_index;
    /** Creates a new instance of Stack */
    public Stack(int size) {
        data = new float[size];
        top_index = -1;
    }
    public boolean isEmpty() { return top_index < 0; }
    public boolean isFull() { 
        return top_index == data.length -1; 
    }
    public void push(float n) throws StackException { 
      if( isFull() )
          throw new StackException("pilha cheia");
      data[++top_index] = n; 
    }
    public float pop() throws StackException { 
      if( isEmpty() )
         throw new StackException("pilha vazia");
      return data[top_index--]; 
    }
    public float top() throws StackException {
        if( isEmpty() )
          throw new StackException("pilha vazia");
        return data[top_index];
    } 
}

class StackException extends Exception {
  public StackException(String msg) {
    super(msg);
  }
}