package com.jclark.xsl.expr;

import com.jclark.xsl.om.*;

class PrecedingSiblingAxisExpr extends ReverseAxisExpr {
  public NodeIterator eval(Node node, ExprContext context) throws XSLException {
    return precedingSiblings(node);
  }

  static NodeIterator precedingSiblings(Node node) throws XSLException {
    if (node.getType() == Node.ATTRIBUTE)
      return null;
    Node tem = node.getParent();
    if (tem == null)
      return new SingleNodeIterator(null);
    NodeIterator iter = tem.getChildren();
    tem = iter.next();
    if (tem.equals(node))
      return new SingleNodeIterator(null);
    Node[] nodes = new Node[1];
    int off = nodes.length;
    nodes[--off] = tem;
    for (tem = iter.next(); !tem.equals(node); tem = iter.next()) {
      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] = tem;
    }
    return new ArrayNodeIterator(nodes, off, nodes.length);
  }
  int getOptimizeFlags() {
    return SINGLE_LEVEL;
  }
}