class.js

/*
Based on Alex Arnell's inheritance implementation.
Ported by Christopher Blum (http://github.com/tiff) from Prototype (https://github.com/sstephenson/prototype) to be compatible with jQuery
*/

var Class = (function($) {
  
  // Some versions of JScript fail to enumerate over properties, names of which 
  // correspond to non-enumerable properties in the prototype chain
  var IS_DONTENUM_BUGGY = (function(){
    for (var p in { toString: 1 }) {
      // check actual property name, so that it works with augmented Object.prototype
      if (p === 'toString') return false;
    }
    return true;
  })();
  
  // Get argument names from method as array
  function getArgumentNames(method) {
    var names = method.toString().match(/^[\s\(]*function[^(]*\(([^)]*)\)/)[1]
      .replace(/\/\/.*?[\r\n]|\/\*(?:.|[\r\n])*?\*\//g, '')
      .replace(/\s+/g, '').split(',');
    return names.length == 1 && !names[0] ? [] : names;
  }
  
  // Wrap a given method
  function wrap(method, wrapper) {
    return function() {
      var args = $.makeArray(arguments);
      args.unshift($.proxy(method, this));
      return wrapper.apply(this, args);
    }
  }
  
  // Grab all keys from an object
  // keys({ a: 1, b: 2 }); // => ["a", "b"];
  function keys(object) {
    if (Object.keys) {
      return Object.keys(object);
    } else {
      var results = [];
      for (var property in object) {
        if (object.hasOwnProperty(property)) {
          results.push(property);
        }
      }
      return results;
    }
  }
  
  function subclass() {};
  function create() {
    var parent = null, properties = $.makeArray(arguments);
    if ($.isFunction(properties[0]))
      parent = properties.shift();

    function klass() {
      this.initialize.apply(this, arguments);
    }

    $.extend(klass, Class.Methods);
    klass.superclass = parent;
    klass.subclasses = [];

    if (parent) {
      subclass.prototype = parent.prototype;
      klass.prototype = new subclass;
      parent.subclasses.push(klass);
    }

    for (var i = 0, length = properties.length; i < length; i++)
      klass.addMethods(properties[i]);

    if (!klass.prototype.initialize)
      klass.prototype.initialize = $.noop;

    klass.prototype.constructor = klass;
    return klass;
  }

  function addMethods(source) {
    var ancestor   = this.superclass && this.superclass.prototype,
        properties = keys(source);

    // IE6 doesn't enumerate `toString` and `valueOf` (among other built-in `Object.prototype`) properties,
    // Force copy if they're not Object.prototype ones.
    // Do not copy other Object.prototype.* for performance reasons
    if (IS_DONTENUM_BUGGY) {
      if (source.toString != Object.prototype.toString)
        properties.push("toString");
      if (source.valueOf != Object.prototype.valueOf)
        properties.push("valueOf");
    }

    for (var i = 0, length = properties.length; i < length; i++) {
      var property = properties[i], value = source[property];
      if (ancestor && $.isFunction(value) &&
          getArgumentNames(value)[0] == "$super") {
        var method = value;
        value = wrap(function(m) {
          return function() { return ancestor[m].apply(this, arguments); };
        }(property), method);

        value.valueOf = $.proxy(method.valueOf, method);
        value.toString = $.proxy(method.toString, method);
      }
      this.prototype[property] = value;
    }

    return this;
  }

  return {
    create: create,
    keys: keys,
    Methods: {
      addMethods: addMethods
    }
  };
})(jQuery);