/*
* Expandable unordered list implementation.
* by David Lindquist <first name><at><last name><dot><net>
* See:
* http://www.gazingus.org/html/DOM-Scripted_Lists_Revisited.html
* Modifies unordered lists so that sublists can be hidden and shown
* by means of a switch. The switch is a node inserted into the DOM
* tree as the first child of the list item containing the sublist.
*/

// The script will only be applied to unordered lists containing
// this class name, e.g.: <ul class="foo expandable">...</ul>.
var CLASS_NAME = "expandable";

// This value is the assumed initial display style for a sublist
// when it cannot be determined by other means. See below.
var DEFAULT_DISPLAY = "none";

// The namespace to use when using this script in an XML context.
var XMLNS = "http://www.w3.org/1999/xhtml";

// Open and Closed symbols
var opensymbol = '+ ';
var closesymbol = "- ";


function initExpandableLists() {
if (!document.getElementsByTagName) return;

// Top-level function to accommodate browsers that do not register
// a click event when a link is activated by the keyboard.
switchNode = function(id) {
var node = document.getElementById(id);
if (node && /^switch /.test(node.className)) node.onclick();
}

// Top-level function to be assigned as the event handler for the
// switch. This could have been bound to the handler as a closure,
// but closures are associated with memory leak problems in IE.
actuate = function() {
var sublist = this.parentNode.getElementsByTagName("ul")[0];
if (sublist.style.display == "block") {
sublist.style.display = "none";
this.firstChild.data = opensymbol;
this.className = "switch off";
this.title = this.title.replace("collapse", "expand");
} else {
sublist.style.display = "block";
this.firstChild.data = closesymbol;
this.className = "switch on";
this.title = this.title.replace("expand", "collapse");
}
return false;
}

// Create switch node from which the others will be cloned.
if (typeof document.createElementNS == "function")
var template = document.createElementNS(XMLNS, "a");
else
var template = document.createElement("a");
template.appendChild(document.createTextNode(" "));

var list, i = 0;
var pattern = new RegExp("(^| )" + CLASS_NAME + "( |$)");

while ((list = document.getElementsByTagName("ul")[i++])) {
// Only lists with the given class name are processed.
if (pattern.test(list.className) == false) continue;

var item, j = 0;
while ((item = list.getElementsByTagName("li")[j++])) {
var sublist = item.getElementsByTagName("ul")[0];
// No sublist under this list item. Skip it.
if (sublist == null) continue;

// Attempt to determine initial display style of the
// sublist so the proper symbol is used.
var symbol;
switch (sublist.style.display) {
case "none" : symbol = opensymbol ; break;
case "block": symbol = closesymbol ; break;
default:
var display = DEFAULT_DISPLAY;
if (sublist.currentStyle) {
display = sublist.currentStyle.display;
} else if (document.defaultView &&
document.defaultView.getComputedStyle &&
document.defaultView.getComputedStyle(sublist, ""))
{
display = document.defaultView.
getComputedStyle(sublist, "").getPropertyValue("display");
}
symbol = (display == "none") ? opensymbol : closesymbol;
// Explicitly set the display style to make sure it is
// set for the next read. If it is somehow the empty
// string, use the default value from the (X)HTML DTD.
sublist.style.display = display || "block";
break;
}

var actuator = template.cloneNode(true);
var uid = "switch" + i + "-" + j; // a reasonably unique ID
actuator.id = uid;
actuator.href = "javascript:switchNode('" + uid + "')";
actuator.className = "switch " + ((symbol == opensymbol) ? "off" : "on");
actuator.title = ((symbol == opensymbol) ? "expand" : "collapse") + " list";
actuator.firstChild.data = symbol;
actuator.onclick = actuate;
item.insertBefore(actuator, item.firstChild);
}
}
}

// Props to Simon Willison:
// http://simon.incutio.com/archive/2004/05/26/addLoadEvent
var oldhandler = window.onload;
window.onload = (typeof oldhandler == "function")
? function() { oldhandler(); initExpandableLists(); }
: initExpandableLists;