package com.jclark.xsl.expr;

import com.jclark.xsl.om.*;

public class DifferenceNodeIterator implements NodeIterator {
  private NodeIterator iter1;
  private NodeIterator iter2;
  private Node node1;
  private Node node2;

  public DifferenceNodeIterator(NodeIterator iter1, NodeIterator iter2) throws XSLException {
    this.iter1 = iter1;
    this.iter2 = iter2;
    this.node1 = iter1.next();
    this.node2 = iter2.next();
  }

  public Node next() throws XSLException {
    while (node1 != null) {
      if (node2 == null) {
	Node tem = node1;
	node1 = iter1.next();
	return tem;
      }
      int cmp = node1.compareTo(node2);
      if (cmp < 0) {
	Node tem = node1;
	node1 = iter1.next();
	return tem;
      }
      if (cmp == 0) {
	node1 = iter1.next();
	node2 = iter2.next();
      }
      else
	node2 = iter2.next();
    }
    return null;
  }
}