//----------------------------------------------------------------------------
// ArraySortedList3.java          by Dale/Joyce/Weems                Chapter 6
//
// Implements the ListInterface using an array. It is kept in increasing order
// as defined by the compareTo method of the added elements. Only Comparable
// elements may be added to a list.
//
// Null elements are not permitted on a list.
//
// Overrides the unsorted version of find with a recursive binary search
//
// ajg version: DWC, T extends Comparable, format, while-->for, new add()
//----------------------------------------------------------------------------

package ch06.lists;

public class ArraySortedList3<T extends Comparable<T>>
    extends ArrayUnsortedList<T> implements ListInterface<T> {

    public ArraySortedList3(T[] list) { super(list); }

    public void add(T element) {
 	if (numElements == list.length)
	    throw new ListOverflowException("Helpful message.");

	// slide existing elements down to make a slot for new element
	for (int location=numElements++; location>0; location--) {
	    if (element.compareTo(list[location-1]) >= 0)
		break;		// new element goes here
	    list[location] = list[location-1];
	}
	list[location] = element;
    }

    // Remove an element e such that e.equals(element).  Return outcome.
    public boolean remove (T element) {
	boolean found = find(element);
	if (found) {
	    for (int i=location; i <= numElements-2; i++)
		list[i] = list[i+1];
	    list[--numElements] = null;
	}
	return found;
    }

    // Recursive binary search
    protected boolean find(T target) { return find1 (target, 0, numElements-1); }

    private boolean find1 (T target, int lo, int hi) {
	if (lo > hi)
	    return false;
	location = (lo + hi) / 2;
	if (list[location].compareTo(target) == 0)  // found it
	    return true;
	if (list[location].compareTo(target) < 0)   // too small
	    return find1 (target, location+1, hi);
	return find1 (target, lo, hi-1);            // too big
    }
}
// Local Variables:
// compile-command: "cd ../..; javac ch06/lists/ArraySortedList3.java"
// End: