package com.jclark.xsl.expr;

import com.jclark.xsl.om.*;

class NodeTestExpr extends ConvertibleNodeSetExpr {
  private final Pattern nodeTest;
  private final ConvertibleNodeSetExpr expr;

  NodeTestExpr(ConvertibleNodeSetExpr expr, Pattern nodeTest) {
    this.expr = expr;
    this.nodeTest = nodeTest;
  }

  public NodeIterator eval(Node node, final ExprContext context) throws XSLException {
    final NodeIterator iter = expr.eval(node, context);
    return new NodeIterator() {
      public Node next() throws XSLException {
	for (;;) {
	  Node tem = iter.next();
	  if (tem == null)
	    break;
	  if (nodeTest.matches(tem, context))
	    return tem;
	}
	return null;
      }
    };
  }
  int getOptimizeFlags() {
    return expr.getOptimizeFlags();
  }

  Pattern getChildrenNodePattern() {
    if (expr.getClass() == ChildAxisExpr.class)
      return nodeTest;
    return null;
  }
}