/*
Methods
The only property of sessvars you shouldn't tamper with is $, because it contains a number of helpful methods: 

sessvars.$.clearMem()
Clears the memory of sessvars. 

sessvars.$.usedMem()
Returns how much memory sessvars uses in Kb. 

sessvars.$.usedMemPercent()
Returns how much memory sessvars uses in % of the total memory allowed. 

sessvars.$.debug()
Shows a debug window at the top of the page (like in the example above). 

sessvars.$.flush()
Explicitly saves the current state of sessvars so that all data survives when you go to the next page. This should rarely be needed, as it is normally done automatically when the unload event fires. 

Preferences/flags
There are also some different flags you can set that governs how sessvars behaves: 

sessvars.$.prefs.memlimit
[2000 {default}]How many Kb of data you can store in sessvars. Defaults to 2000 Kb, because Opera 9.25 seems to have a limit just above that. IE7.0, Firefox 1.5/2.0 and Safari 3.0 all have higher limits – 10 MB is no problem in those browsers. 

sessvars.$.prefs.autoFlush
[true {default} /false]Determines whether sessvars should flush/save automatically (see methods). 

sessvars.$.prefs.crossDomain
[true/false {default}]If this flag is set to true the content of sessvars can be read across different domains (if both sites use sessvars.js). 

sessvars.$.prefs.includeFunctions
[true/false {default}]Determines whether sessvars remembers functions assigned to it across page loads. 

sessvars.$.prefs.includeProtos
[true/false {default}]If this flag is set to true sessvars remembers properties assigned to the prototype of different data/object types across page loads. Rarely needed.
*/

sessvars=function(){

	var x={};
	
	x.$={
		prefs:{
			memLimit:2000,
			autoFlush:true,
			crossDomain:false,
			includeProtos:false,
			includeFunctions:false
		},
		parent:x,
		clearMem:function(){
			for(var i in this.parent){if(i!="$"){this.parent[i]=undefined}};
			this.flush();
		},
		usedMem:function(){
			x={};
			return Math.round(this.flush(x)/1024);
		},
		usedMemPercent:function(){
			return Math.round(this.usedMem()/this.prefs.memLimit);
		},
		flush:function(x){
			var y,o={},j=this.$$;
			x=x||top;
			for(var i in this.parent){o[i]=this.parent[i]};
			o.$=this.prefs;
			j.includeProtos=this.prefs.includeProtos;
			j.includeFunctions=this.prefs.includeFunctions;
			y=this.$$.make(o);
			if(x!=top){return y.length};
			if(y.length/1024>this.prefs.memLimit){return false}
			x.name=y;
			return true;
		},
		getDomain:function(){
				var l=location.href
				l=l.split("///").join("//");
				l=l.substring(l.indexOf("://")+3).split("/")[0];
				while(l.split(".").length>2){l=l.substring(l.indexOf(".")+1)};
				return l
		},
		debug:function(t){
			var t=t||this,a=arguments.callee;
			if(!document.body){setTimeout(function(){a(t)},200);return};
			t.flush();
			var d=document.getElementById("sessvarsDebugDiv");
			if(!d){d=document.createElement("div");document.body.insertBefore(d,document.body.firstChild)};
			d.id="sessvarsDebugDiv";
			d.innerHTML='<div style="line-height:20px;padding:5px;font-size:11px;font-family:Verdana,Arial,Helvetica;'+
						'z-index:10000;background:#FFFFCC;border: 1px solid #333;margin-bottom:12px">'+
						'<b style="font-family:Trebuchet MS;font-size:20px">sessvars.js - debug info:</b><br/><br/>'+
						'Memory usage: '+t.usedMem()+' Kb ('+t.usedMemPercent()+'%)&nbsp;&nbsp;&nbsp;'+
						'<span style="cursor:pointer"><b>[Clear memory]</b></span><br/>'+
						top.name.split('\n').join('<br/>')+'</div>';
			d.getElementsByTagName('span')[0].onclick=function(){t.clearMem();location.reload()}
		},
		init:function(){
			var o={}, t=this;
			try {o=this.$$.toObject(top.name)} catch(e){o={}};
			this.prefs=o.$||t.prefs;
			if(this.prefs.crossDomain || this.prefs.currentDomain==this.getDomain()){
				for(var i in o){this.parent[i]=o[i]};
			}
			else {
				this.prefs.currentDomain=this.getDomain();
			};
			this.parent.$=t;
			t.flush();
			var f=function(){if(t.prefs.autoFlush){t.flush()}};
			if(window["addEventListener"]){addEventListener("unload",f,false)}
			else if(window["attachEvent"]){window.attachEvent("onunload",f)}
			else {this.prefs.autoFlush=false};
		}
	};
	
	x.$.$$={
		compactOutput:false, 		
		includeProtos:false, 	
		includeFunctions: false,
		detectCirculars:true,
		restoreCirculars:true,
		make:function(arg,restore) {
			this.restore=restore;
			this.mem=[];this.pathMem=[];
			return this.toJsonStringArray(arg).join('');
		},
		toObject:function(x){
			if(!this.cleaner){
				try{this.cleaner=new RegExp('^("(\\\\.|[^"\\\\\\n\\r])*?"|[,:{}\\[\\]0-9.\\-+Eaeflnr-u \\n\\r\\t])+?$')}
				catch(a){this.cleaner=/^(true|false|null|\[.*\]|\{.*\}|".*"|\d+|\d+\.\d+)$/}
			};
			if(!this.cleaner.test(x)){return {}};
			eval("this.myObj="+x);
			if(!this.restoreCirculars || !alert){return this.myObj};
			if(this.includeFunctions){
				var x=this.myObj;
				for(var i in x){if(typeof x[i]=="string" && !x[i].indexOf("JSONincludedFunc:")){
					x[i]=x[i].substring(17);
					eval("x[i]="+x[i])
				}}
			};
			this.restoreCode=[];
			this.make(this.myObj,true);
			var r=this.restoreCode.join(";")+";";
			eval('r=r.replace(/\\W([0-9]{1,})(\\W)/g,"[$1]$2").replace(/\\.\\;/g,";")');
			eval(r);
			return this.myObj
		},
		toJsonStringArray:function(arg, out) {
			if(!out){this.path=[]};
			out = out || [];
			var u; // undefined
			switch (typeof arg) {
			case 'object':
				this.lastObj=arg;
				if(this.detectCirculars){
					var m=this.mem; var n=this.pathMem;
					for(var i=0;i<m.length;i++){
						if(arg===m[i]){
							out.push('"JSONcircRef:'+n[i]+'"');return out
						}
					};
					m.push(arg); n.push(this.path.join("."));
				};
				if (arg) {
					if (arg.constructor == Array) {
						out.push('[');
						for (var i = 0; i < arg.length; ++i) {
							this.path.push(i);
							if (i > 0)
								out.push(',\n');
							this.toJsonStringArray(arg[i], out);
							this.path.pop();
						}
						out.push(']');
						return out;
					} else if (typeof arg.toString != 'undefined') {
						out.push('{');
						var first = true;
						for (var i in arg) {
							if(!this.includeProtos && arg[i]===arg.constructor.prototype[i]){continue};
							this.path.push(i);
							var curr = out.length; 
							if (!first)
								out.push(this.compactOutput?',':',\n');
							this.toJsonStringArray(i, out);
							out.push(':');                    
							this.toJsonStringArray(arg[i], out);
							if (out[out.length - 1] == u)
								out.splice(curr, out.length - curr);
							else
								first = false;
							this.path.pop();
						}
						out.push('}');
						return out;
					}
					return out;
				}
				out.push('null');
				return out;
			case 'unknown':
			case 'undefined':
			case 'function':
				if(!this.includeFunctions){out.push(u);return out};
				arg="JSONincludedFunc:"+arg;
				out.push('"');
				var a=['\n','\\n','\r','\\r','"','\\"'];
				arg+=""; for(var i=0;i<6;i+=2){arg=arg.split(a[i]).join(a[i+1])};
				out.push(arg);
				out.push('"');
				return out;
			case 'string':
				if(this.restore && arg.indexOf("JSONcircRef:")==0){
					this.restoreCode.push('this.myObj.'+this.path.join(".")+"="+arg.split("JSONcircRef:").join("this.myObj."));
				};
				out.push('"');
				var a=['\n','\\n','\r','\\r','"','\\"'];
				arg+=""; for(var i=0;i<6;i+=2){arg=arg.split(a[i]).join(a[i+1])};
				out.push(arg);
				out.push('"');
				return out;
			default:
				out.push(String(arg));
				return out;
			}
		}
	};
	
	x.$.init();
	return x;
}()