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/*
        common, version 1.0.4 (2005/06/05)
        Copyright 2005, Dean Edwards
        License: http://creativecommons.org/licenses/LGPL/2.1/
*/

// this function may be used to cast any javascript object
//  to a common object
function ICommon(that) {
        if (that != null) {
                that.inherit = Common.prototype.inherit;
                that.specialize = Common.prototype.specialize;
        }
        return that;
};

// sub-classing
ICommon.specialize = function($prototype, $constructor) {
        // initialise class properties
        if (!$prototype) $prototype = {};
        if (!$constructor) $constructor = $prototype.constructor;
        if ($constructor == {}.constructor) $constructor = new Function;
        // build the inheritance chain
        //  insert a dummy constructor between the ancestor
        //  and the new constructor. this allows standard
        //  prototype inheritance plus chained constructor
        //  functions.
        $constructor.valueOf = new Function("return this");
        $constructor.valueOf.prototype = new this.valueOf;
        $constructor.valueOf.prototype.specialize($prototype);
        $constructor.prototype = new $constructor.valueOf;
        $constructor.valueOf.prototype.constructor =
        $constructor.prototype.constructor = $constructor;
        $constructor.ancestor = this;
        $constructor.specialize = arguments.callee;
        $constructor.ancestorOf = this.ancestorOf;
        return $constructor;
};

// root of the inheritance chain
ICommon.valueOf = new Function("return this");

// common interface
ICommon.valueOf.prototype = {
constructor: ICommon,
inherit: function() {
//-
//   Call this method from any other method to call that method's ancestor.
//   If there is no ancestor function then this function will throw an error.
//-
        return arguments.callee.caller.ancestor.apply(this, arguments);
},
specialize: function(that) {
//-
//   Add the interface of another object to this object
//-
        // if this object is the prototype then specialize the /real/ prototype
        if (this == this.constructor.prototype && this.constructor.specialize) {
                return this.constructor.valueOf.prototype.specialize(that);
        }
        // add each of one of the source object's properties to this object
        for (var i in that) {
                switch (i) {
                        case "constructor": // don't do this one!
                        case "toString":    // do this one maually
                        case "valueOf":     // ignore this one...
                                continue;
                }
                // implement inheritance
                if (typeof that[i] == "function" && that[i] != this[i]) {
                        that[i].ancestor = this[i];
                }
                // add the property
                this[i] = that[i];
        }
        // do the "toString" function manually
        if (that.toString != this.toString && that.toString != {}.toString) {
                that.toString.ancestor = this.toString;
                this.toString = that.toString;
        }
        return this;
}};

// create the root
function Common() {
//--
//   empty constructor function
//--
};
this.Common = ICommon.specialize({
constructor: Common,
toString: function() {
    return "[common " + (this.constructor.className || "Object") + "]";
},
instanceOf: function(klass) {
    return this.constructor == klass || klass.ancestorOf(this.constructor);
}
});
Common.className = "Common";
Common.ancestor = null;
Common.ancestorOf = function(klass) {
        // Is this class an ancestor of the supplied class?
        while (klass && klass.ancestor != this) klass = klass.ancestor;
        return Boolean(klass);
};

// preserve the common prototype so that we can tell when a
//  property of the root class has changed
Common.valueOf.ancestor = ICommon;

// c'est fini!