package com.jclark.xsl.expr;

import com.jclark.xsl.om.*;

abstract class ReverseAxisExpr extends AxisExpr {
  ConvertibleNodeSetExpr makeDocumentOrderExpr(final ConvertibleNodeSetExpr expr) {
    return new ConvertibleNodeSetExpr() {
      public NodeIterator eval(Node node, ExprContext context) throws XSLException {
	return reverse(expr.eval(node, context));
      }
    };
  }

  private static NodeIterator reverse(NodeIterator iter) throws XSLException {
    Node nodes[] = new Node[10];
    int off = nodes.length;
    for (;;) {
      Node node = iter.next();
      if (node == null)
	break;
      if (off == 0) {
	Node oldNodes[] = nodes;
	nodes = new Node[oldNodes.length * 2];
	System.arraycopy(oldNodes, 0, nodes, oldNodes.length, oldNodes.length);
	off = oldNodes.length;
      }
      nodes[--off] = node;
    }
    return new ArrayNodeIterator(nodes, off, nodes.length);
  }
}