// mozilla white space handling functions, from http://www.mozilla.org/docs/dom/technote/whitespace/

function node_before(sib)
{
  while ((sib = sib.previousSibling)) {
    if (!is_ignorable(sib)) return sib;
  }
  return null;
}
function node_after(sib)
{
  while ((sib = sib.nextSibling)) {
    if (!is_ignorable(sib)) return sib;
  }
  return null;
}
function first_child( par )
{
  var res=par.firstChild;
  while (res) {
    if (!is_ignorable(res)) return res;
    res = res.nextSibling;
  }
  return null;
}
// helpers
function is_all_ws( nod )
{
  // Use ECMA-262 Edition 3 String and RegExp features
  return !(/[^\t\n\r ]/.test(nod.data));
}
function is_ignorable( nod )
{
  return ( nod.nodeType == 8) || // A comment node
         ( (nod.nodeType == 3) && is_all_ws(nod) ); // a text node, all ws
}