DescendantAxis.java :  » Scripting » Kawa » gnu » kawa » xml » Java Open Source

// Copyright (c) 2003  Per M.A. Bothner.
// This is free software;  for terms and warranty disclaimer see ./COPYING.

package gnu.kawa.xml;
import gnu.lists.*;

/** Used to implement a descendant:: step in a path expression. */

public class DescendantAxis extends TreeScanner
{
  public static DescendantAxis make (NodePredicate type)
  {
    DescendantAxis axis = new DescendantAxis();
    axis.type = type;
    return axis;
  }

  public void scan (AbstractSequence seq, int ipos, PositionConsumer out)
  {
    if (! (seq instanceof TreeList))
      { // AbstractSequence's nextMatching does not support descend.  FIXME.
  ipos = seq.firstChildPos(ipos);
  while (ipos != 0)
    {
      if (type.isInstancePos(seq, ipos))
        out.writePosition(seq, ipos);
      scan(seq, ipos, out);
      ipos = seq.nextPos(ipos);
    }
  return;
      }
    int limit = seq.nextPos(ipos);
    int child = ipos;
    for (;;)
      {
  child = seq.nextMatching(child, type, limit, true);
  if (child == 0)
    break;
  out.writePosition(seq, child);
      }
  }
}