/* File: ArrayStack.java - April 2015 */
package l12;

/**
 * Stack implementation backed by an array.
 *
 * @author Michael Albert
 *
 */
 
public class ArrayStack<T> implements Stack241<T> {

  public static final int DEFAULT_CAPACITY = 10;
  private T[] stack;
  private int count;
  
  // Create an empty stack
  @SuppressWarnings("unchecked")
   public ArrayStack() {
  	this.stack = (T[]) new Object[DEFAULT_CAPACITY];
  	count = 0;
  }

  public void push(T element) {
  	if (count >= stack.length) {
  		stack = java.util.Arrays.copyOf(stack, 2*stack.length);
  	}
  	stack[count] = element; // Deal with size issue later
  	count++;
  }
  
  public T pop() {
  	if (this.isEmpty()) {
  		throw new StackException("Pop from empty stack");
  	}
  	count--;
  	return stack[count];
  }
  
  public T peek() {
  	if (this.isEmpty()) {
  		throw new StackException("Peek on empty stack");
  	}
  	return stack[count-1];
  }
  
  public boolean isEmpty() {
  	return count <= 0;
  }
  
  public int size() {
  	return count;
  }
  
  public String toString() {
  	return "Stack(" + count + "): " + java.util.Arrays.toString(stack);
  }

}