/* CSS-related javascript functions
by Fred Bird http://fredbird.org
License : Public Domain

file version 16/09/2005 09:30:45
*/

/* has the DOM object a certain class ?
	obj = DOM object, cName = a class name
*/
function hasClass(obj,cName) {
	return new RegExp('\\b'+cName+'\\b').test(obj.className);
}
/* has the DOM object a set of classes ?
	obj = DOM object, classes=array of class names
*/
function hasClasses(obj,classes) {
	for (f=0; f<classes.length; f++) {
		if (!hasClass(obj,classes[i])) return false;
	}
	return true;
}
/* add a class to a DOM object if necessary
	obj = DOM object, cName = a class name
*/
function addClass(obj,cName) {
	if (!hasClass(obj,cName)) {
		obj.className+=obj.className?' '+cName:cName;
	}
	return true;
}
/* removes a class from a DOM object
	obj = DOM object, cName = a class name
*/
function removeClass(obj,cName) {
	if (!hasClass(obj,cName)) return false;
	var rep=obj.className.match(' '+cName)?' '+cName:cName;
	obj.className=obj.className.replace(rep,'');
	return true;
}
/* swap two classes for a DOM object, whatever provided order
*/
function swapClasses(obj,class1,class2) {
	if (hasClass(obj,class1)) {
		removeClass(obj,class1);
		addClass(obj,class2);
		return true;
	}
	if (hasClass(obj,class2)) {
		removeClass(obj,class2);
		addClass(obj,class1);
		return true;
	}
	return false;
}
/* sets class 'to' to the DOM object obj, removes class 'from' if necessary
*/
function switchClass(obj,to,from) {
	if (hasClass(obj,from)) removeClass(obj,from);
	addClass(obj,to);
	return true;
}

/* returns an array of DOM objects having the provided class name
within object 'container' and with tag name 'tag'
some code from http://www.webmasterworld.com/forum91/1757.htm (unbugged)
*/
function getElementsByClassName(className,container,tag) {
	// default container to document
	container=container||document;
	// default tag to *
	tag=tag||'*';
	// listing container descendants
	if(tag=='*'&&container.all)
		var all = container.all;
	else
		var all = container.getElementsByTagName(tag);
	var found=new Array();
	// searching for targets
	for (f=0; f<all.length; f++) {
		var el=all[f];
		if (hasClass(all[f],className)) {
			found.push(all[f]);
		}
	}
	return found;
}