/**
 * Throughout, whitespace is defined as one of the characters
 *  "\t" TAB \u0009
 *  "\n" LF  \u000A
 *  "\r" CR  \u000D
 *  " "  SPC \u0020
 *
 * This does not use Javascript's "\s" because that includes non-breaking
 * spaces (and also some other characters).
 */


/**
 * Determine whether a node's text content is entirely whitespace.
 *
 * @param nod  A node implementing the |CharacterData| interface (i.e.,
 *             a |Text|, |Comment|, or |CDATASection| node
 * @return     True if all of the text content of |nod| is whitespace,
 *             otherwise false.
 */
function is_all_ws( nod )
{
  // Use ECMA-262 Edition 3 String and RegExp features
  return !(/[^\t\n\r ]/.test(nod.data));
}


/**
 * Determine if a node should be ignored by the iterator functions.
 *
 * @param nod  An object implementing the DOM1 |Node| interface.
 * @return     true if the node is:
 *                1) A |Text| node that is all whitespace
 *                2) A |Comment| node
 *             and otherwise false.
 */

function is_ignorable( nod )
{
  return ( nod.nodeType == 8) || // A comment node
         ( (nod.nodeType == 3) && is_all_ws(nod) ); // a text node, all ws
}

/**
 * Version of |previousSibling| that skips nodes that are entirely
 * whitespace or comments.  (Normally |previousSibling| is a property
 * of all DOM nodes that gives the sibling node, the node that is
 * a child of the same parent, that occurs immediately before the
 * reference node.)
 *
 * @param sib  The reference node.
 * @return     Either:
 *               1) The closest previous sibling to |sib| that is not
 *                  ignorable according to |is_ignorable|, or
 *               2) null if no such node exists.
 */
function node_before( sib )
{
  while ((sib = sib.previousSibling)) {
    if (!is_ignorable(sib)) return sib;
  }
  return null;
}

/**
 * Version of |nextSibling| that skips nodes that are entirely
 * whitespace or comments.
 *
 * @param sib  The reference node.
 * @return     Either:
 *               1) The closest next sibling to |sib| that is not
 *                  ignorable according to |is_ignorable|, or
 *               2) null if no such node exists.
 */
function node_after( sib )
{
  while ((sib = sib.nextSibling)) {
    if (!is_ignorable(sib)) return sib;
  }
  return null;
}

/**
 * Version of |lastChild| that skips nodes that are entirely
 * whitespace or comments.  (Normally |lastChild| is a property
 * of all DOM nodes that gives the last of the nodes contained
 * directly in the reference node.)
 *
 * @param sib  The reference node.
 * @return     Either:
 *               1) The last child of |sib| that is not
 *                  ignorable according to |is_ignorable|, or
 *               2) null if no such node exists.
 */
function last_child( par )
{
  var res=par.lastChild;
  while (res) {
    if (!is_ignorable(res)) return res;
    res = res.previousSibling;
  }
  return null;
}

/**
 * Version of |firstChild| that skips nodes that are entirely
 * whitespace and comments.
 *
 * @param sib  The reference node.
 * @return     Either:
 *               1) The first child of |sib| that is not
 *                  ignorable according to |is_ignorable|, or
 *               2) null if no such node exists.
 */
function first_child(par)
{
  if (par.firstChild){
    var res=par.firstChild;
    while (res) {
    if (!is_ignorable(res)) return res;
    res = res.nextSibling;
    }
  }
  return null;
}

/**
 * Version of |data| that doesn't include whitespace at the beginning
 * and end and normalizes all whitespace to a single space.  (Normally
 * |data| is a property of text nodes that gives the text of the node.)
 *
 * @param txt  The text node whose data should be returned
 * @return     A string giving the contents of the text node with
 *             whitespace collapsed.
 */
//retourne false quand le noeud passé n'est pas du bon type
//retourne null quand y'a pas de données ex: <noeud />
function data_of(txt)
{
  if (txt){
    //Vérifie qu'on a bien un noeud de type textNode(3)
    if(txt.nodeType != "3"){
		  alert("Seuls des textNode peuvent être passé dans cette fonction");
		  return false;
    }
    //ça plante quand le noeud = <noeud />
    try{
  	  var data = txt.data;
	  // Use ECMA-262 Edition 3 String and RegExp features
  	  data = data.replace(/[\t\n\r ]+/g, " ");
    }catch(e){
	    var err = new String(e);
		  if(err.indexOf("txt has no properties")){
			return null;
		  }else{
		  	return e;
		  }
	  }
	
	  if (data.charAt(0) == " ")
	    data = data.substring(1, data.length);
	  if (data.charAt(data.length - 1) == " ")
	    data = data.substring(0, data.length - 1);
	  return data;
  }
  else return ''
}