samer@0: package samer.silk;
samer@0: import java.util.*;
samer@0: import jscheme.*;
samer@0: 
samer@0: public class SchemeList extends AbstractSequentialList {
samer@0: 	SchemePair	head;
samer@0: 
samer@0: 	public SchemeList(SchemePair pair) { head=pair; }
samer@0: 
samer@0: 	public ListIterator listIterator(int index) {
samer@0: 		return new Iterator(head,index);
samer@0: 	}
samer@0: 
samer@0: 	public int size() {
samer@0: 		int i=0;
samer@0: 		for (SchemePair p=head; !p.isEmpty(); p=(SchemePair)p.getRest()) i++;
samer@0: 		return i;
samer@0: 	}
samer@0: 
samer@0: 	class Iterator implements ListIterator {
samer@0: 		SchemePair	current, previous=null;
samer@0: 		int			index=0;
samer@0: 
samer@0: 		public Iterator(SchemePair head, int index) { 
samer@0: 			current=head;
samer@0: 			for (int i=0; i<index; i++) next();
samer@0: 		}
samer@0: 
samer@0: 		public void add(Object o) { 
samer@0: 			if (previous==null) no();
samer@0: 			current=new jsint.Pair(o,current);
samer@0: 			previous.setRest(current);
samer@0: 		}
samer@0: 
samer@0: 		public void remove() { no(); }
samer@0: //			if (previous==null) no();
samer@0: //			previous.setRest(current.getRest());
samer@0: //			current=(SchemePair)current.getRest();
samer@0: //		}
samer@0: 
samer@0: 		public void set(Object o) { previous.setFirst(o); }
samer@0: 
samer@0: 		public boolean hasNext() {
samer@0: 			return !current.isEmpty();
samer@0: 		}
samer@0: 
samer@0: 		public Object next() {
samer@0: 			Object rc=current.getFirst();
samer@0: 			previous=current;
samer@0: 			current=(SchemePair)current.getRest();
samer@0: 			index++;
samer@0: 			return rc;
samer@0: 		}
samer@0: 
samer@0: 		public int nextIndex() { return index; }
samer@0: 		public boolean hasPrevious() { no(); return false; }
samer@0: 		public Object previous() { no(); return null; }
samer@0: 		public int previousIndex() { no(); return 0; }
samer@0: 
samer@0: 		private void no() { throw new Error("Unsupported"); }
samer@0: 	}
samer@0: }