class.js

/*
Copyright (c) 2005-2010 Sam Stephenson

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
/* Based on Alex Arnell's inheritance implementation. */
/** section: Language
 * class Class
 *
 *  Manages Prototype's class-based OOP system.
 *
 *  Refer to Prototype's web site for a [tutorial on classes and
 *  inheritance](http://prototypejs.org/learn/class-inheritance).
**/
(function(globalContext) {
/* ------------------------------------ */
/* Import from object.js                */
/* ------------------------------------ */
var _toString = Object.prototype.toString,
    NULL_TYPE = 'Null',
    UNDEFINED_TYPE = 'Undefined',
    BOOLEAN_TYPE = 'Boolean',
    NUMBER_TYPE = 'Number',
    STRING_TYPE = 'String',
    OBJECT_TYPE = 'Object',
    FUNCTION_CLASS = '[object Function]';
function isFunction(object) {
  return _toString.call(object) === FUNCTION_CLASS;
}
function extend(destination, source) {
  for (var property in source) if (source.hasOwnProperty(property)) // modify protect primitive slaughter
    destination[property] = source[property];
  return destination;
}
function keys(object) {
  if (Type(object) !== OBJECT_TYPE) { throw new TypeError(); }
  var results = [];
  for (var property in object) {
    if (object.hasOwnProperty(property)) {
      results.push(property);
    }
  }
  return results;
}
function Type(o) {
  switch(o) {
    case null: return NULL_TYPE;
    case (void 0): return UNDEFINED_TYPE;
  }
  var type = typeof o;
  switch(type) {
    case 'boolean': return BOOLEAN_TYPE;
    case 'number':  return NUMBER_TYPE;
    case 'string':  return STRING_TYPE;
  }
  return OBJECT_TYPE;
}
function isUndefined(object) {
  return typeof object === "undefined";
}
/* ------------------------------------ */
/* Import from Function.js              */
/* ------------------------------------ */
var slice = Array.prototype.slice;
function argumentNames(fn) {
  var names = fn.toString().match(/^[\s\(]*function[^(]*\(([^)]*)\)/)[1]
    .replace(/\/\/.*?[\r\n]|\/\*(?:.|[\r\n])*?\*\//g, '')
    .replace(/\s+/g, '').split(',');
  return names.length == 1 && !names[0] ? [] : names;
}
function wrap(fn, wrapper) {
  var __method = fn;
  return function() {
    var a = update([bind(__method, this)], arguments);
    return wrapper.apply(this, a);
  }
}
function update(array, args) {
  var arrayLength = array.length, length = args.length;
  while (length--) array[arrayLength + length] = args[length];
  return array;
}
function merge(array, args) {
  array = slice.call(array, 0);
  return update(array, args);
}
function bind(fn, context) {
  if (arguments.length < 2 && isUndefined(arguments[0])) return this;
  var __method = fn, args = slice.call(arguments, 2);
  return function() {
    var a = merge(args, arguments);
    return __method.apply(context, a);
  }
}

/* ------------------------------------ */
/* Import from Prototype.js             */
/* ------------------------------------ */
var emptyFunction = function(){};

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;
  })();
  
  /**
   *  Class.create([superclass][, methods...]) -> Class
   *    - superclass (Class): The optional superclass to inherit methods from.
   *    - methods (Object): An object whose properties will be "mixed-in" to the
   *        new class. Any number of mixins can be added; later mixins take
   *        precedence.
   *
   *  [[Class.create]] creates a class and returns a constructor function for
   *  instances of the class. Calling the constructor function (typically as
   *  part of a `new` statement) will invoke the class's `initialize` method.
   *
   *  [[Class.create]] accepts two kinds of arguments. If the first argument is
   *  a [[Class]], it's used as the new class's superclass, and all its methods
   *  are inherited. Otherwise, any arguments passed are treated as objects,
   *  and their methods are copied over ("mixed in") as instance methods of the
   *  new class. In cases of method name overlap, later arguments take
   *  precedence over earlier arguments.
   *
   *  If a subclass overrides an instance method declared in a superclass, the
   *  subclass's method can still access the original method. To do so, declare
   *  the subclass's method as normal, but insert `$super` as the first
   *  argument. This makes `$super` available as a method for use within the
   *  function.
   *
   *  To extend a class after it has been defined, use [[Class#addMethods]].
   *
   *  For details, see the
   *  [inheritance tutorial](http://prototypejs.org/learn/class-inheritance)
   *  on the Prototype website.
  **/
  function subclass() {};
  function create() {
    var parent = null, properties = [].slice.apply(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 = emptyFunction;

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

  /**
   *  Class#addMethods(methods) -> Class
   *    - methods (Object): The methods to add to the class.
   *
   *  Adds methods to an existing class.
   *
   *  [[Class#addMethods]] is a method available on classes that have been
   *  defined with [[Class.create]]. It can be used to add new instance methods
   *  to that class, or overwrite existing methods, after the class has been
   *  defined.
   *
   *  New methods propagate down the inheritance chain. If the class has
   *  subclasses, those subclasses will receive the new methods &mdash; even in
   *  the context of `$super` calls. The new methods also propagate to instances
   *  of the class and of all its subclasses, even those that have already been
   *  instantiated.
   *
   *  ##### Examples
   *
   *      var Animal = Class.create({
   *        initialize: function(name, sound) {
   *          this.name  = name;
   *          this.sound = sound;
   *        },
   *
   *        speak: function() {
   *          alert(this.name + " says: " + this.sound + "!");
   *        }
   *      });
   *
   *      // subclassing Animal
   *      var Snake = Class.create(Animal, {
   *        initialize: function($super, name) {
   *          $super(name, 'hissssssssss');
   *        }
   *      });
   *
   *      var ringneck = new Snake("Ringneck");
   *      ringneck.speak();
   *
   *      //-> alerts "Ringneck says: hissssssss!"
   *
   *      // adding Snake#speak (with a supercall)
   *      Snake.addMethods({
   *        speak: function($super) {
   *          $super();
   *          alert("You should probably run. He looks really mad.");
   *        }
   *      });
   *
   *      ringneck.speak();
   *      //-> alerts "Ringneck says: hissssssss!"
   *      //-> alerts "You should probably run. He looks really mad."
   *
   *      // redefining Animal#speak
   *      Animal.addMethods({
   *        speak: function() {
   *          alert(this.name + 'snarls: ' + this.sound + '!');
   *        }
   *      });
   *
   *      ringneck.speak();
   *      //-> alerts "Ringneck snarls: hissssssss!"
   *      //-> alerts "You should probably run. He looks really mad."
  **/
  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) &&
          argumentNames(value)[0] == "$super") {
        var method = value;
        value = wrap((function(m) {
          return function() { return ancestor[m].apply(this, arguments); };
        })(property), method);

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

    return this;
  }

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

if (globalContext.exports) {
  globalContext.exports.Class = Class;
}
else {
  globalContext.Class = Class;
}
})(this);