package rebelsky.list;

/**
 * An array-based implementation of simple lists.
 *
 * @author CSC152 2004F
 */
public class ArrayBasedSimpleList
	implements SimpleList
{
// +--------+------------------------------------------------------------
// | Fields |
// +--------+

	/**
	 * The values in the list.
	 */
	Object[] contents;
	
	/**
	 * The number of values in the list.
	 */
	int n;
	

// +--------------+------------------------------------------------------
// | Constructors |
// +--------------+

	/**
	 * Build a new empty list.
	 */
	public ArrayBasedSimpleList()
	{
		this.contents = new Object[3]; 
		this.n = 0;
	} // ArrayBasedSimpleList

	
// +---------+-----------------------------------------------------------
// | Methods |
// +---------+

	/**
	 * Add object addMe somewhere in the list.
	 *
	 * @post
	 *   The list now contains an additional copy of addMe.
	 */
	public void add(Object addMe)
	{
		// Warning!  We have not yet handled arrays that fill.
		if (this.contents.length == this.n) {
			Object[] bigger = new Object[this.contents.length*2];
			for (int i = 0; i < this.contents.length; i++) {
				// copy contents at position i
				bigger[i] = this.contents[i];
			}
			this.contents = bigger;
		}
		this.contents[this.n] = addMe;
		++this.n;
	} // add(Object)

	/**
	 * Get a new cursor for the list.
	 */
	public Cursor getCursor()
	{
		return new ArrayBasedCursor(this);
	} // getCursor()

	/**
	 * Get a new cursor for the list.
	 */
	public SimpleCursor getSimpleCursor()
	{
		return new ArrayBasedSimpleCursor(this);
	} // getCursor()

	/**
	 * Remove the object last returned by cursor c.
	 */
	public void remove(SimpleCursor c)
	{
		// The thing to remove is at c.p - 1.  (Problem if at start of list, but
		// fails precondition.)  We shove the last thing there.
		this.contents[((ArrayBasedSimpleCursor) c).p - 1] = this.contents[this.n-1];
		this.contents[this.n-1] = null;
		this.n--;
	} // remove(SimpleCursor)

	/**
	 * Convert this list to a string for ease of printing.
	 */
	public String toString()
	{
		// Special case: Empty list.
		if (this.n == 0)
			return "[]";
		String result = "[";
		for (int i = 0; i < this.n-1; i++)
			result = result + this.contents[i].toString() + " ";
		result = result + this.contents[this.n-1];
		result = result + "]";
		return result;
	} // toString()
} // class ArrayBasedSimpleList