package dk.itu.oop.lecture5;

public class StringList {
	private ListElement head;
	private ListElement tail;
	
	private class ListElement{
		private String value;
		private ListElement next;
		
		ListElement(String val, ListElement elm){
			value = val; next = elm;
		}
		ListElement(String val){
			this(val,null);
		}
	}
	
	public boolean isEmpty(){
		return head == null;
	}
	
	public void insertFirst(String s){
		head = new ListElement(s,head);
		if (tail == null) 
			tail = head;
	}
	
	public void insertLast(String s){
		ListElement newOne = new ListElement(s);
		if (head == null)
			head = tail = newOne;
		else
			tail = tail.next = new ListElement(s);
	}
	
	public void insertInOrder(String s){
		if ( isEmpty() )
			insertFirst(s);
		else {
			ListElement before=null;
			ListElement after =head;
			while(after != null && after.value.compareToIgnoreCase(s)<0 ){
				// all elements from head to before (not incl) are less than s
				// after is the element after before
				before = after;
				after = after.next;
			}
			if (before == null)
				head = new ListElement(s,head);
			else
				before.next = new ListElement(s,after);
		}
	}
}