package com.jclark.xsl.expr;

import com.jclark.xsl.om.*;

class DescendantOrSelfAxisExpr extends AxisExpr {
  public NodeIterator eval(Node node, ExprContext context) {
    return new DescendantsOrSelfNodeIterator(node);
  }
  int getOptimizeFlags() {
    return STAYS_IN_SUBTREE;
  }
  ConvertibleNodeSetExpr compose(ConvertibleNodeSetExpr expr) {
    Pattern pattern = expr.getChildrenNodePattern();
    if (pattern != null)
      return new NodeTestExpr(new DescendantAxisExpr(), pattern);
    if (expr.getClass() == ChildAxisExpr.class)
      return new DescendantAxisExpr();
    if ((expr.getOptimizeFlags() & STAYS_IN_SUBTREE) != 0)
      return new SubtreeExpr(expr);
    return super.compose(expr);
  }
}