Synnefo

//     Backbone.js 0.5.3

//     (c) 2010 Jeremy Ashkenas, DocumentCloud Inc.

//     Backbone may be freely distributed under the MIT license.

//     For all details and documentation:

//     http://documentcloud.github.com/backbone

(function(){

  // Initial Setup

  // -------------

  // Save a reference to the global object.

  var root = this;

  // Save the previous value of the `Backbone` variable.

  var previousBackbone = root.Backbone;

  // Create a local reference to slice.

  var slice = Array.prototype.slice;

  // The top-level namespace. All public Backbone classes and modules will

  // be attached to this. Exported for both CommonJS and the browser.

  var Backbone;

  if (typeof exports !== 'undefined') {

    Backbone = exports;

  } else {

    Backbone = root.Backbone = {};

  }

  // Current version of the library. Keep in sync with `package.json`.

  Backbone.VERSION = '0.5.3';

  // Require Underscore, if we're on the server, and it's not already present.

  var _ = root._;

  if (!_ && (typeof require !== 'undefined')) _ = require('underscore')._;

  // For Backbone's purposes, jQuery, Zepto, or Ender owns the `$` variable.

  var $ = root.jQuery || root.Zepto || root.ender;

  // Runs Backbone.js in *noConflict* mode, returning the `Backbone` variable

  // to its previous owner. Returns a reference to this Backbone object.

  Backbone.noConflict = function() {

    root.Backbone = previousBackbone;

    return this;

  };

  // Turn on `emulateHTTP` to support legacy HTTP servers. Setting this option will

  // fake `"PUT"` and `"DELETE"` requests via the `_method` parameter and set a

  // `X-Http-Method-Override` header.

  Backbone.emulateHTTP = false;

  // Turn on `emulateJSON` to support legacy servers that can't deal with direct

  // `application/json` requests ... will encode the body as

  // `application/x-www-form-urlencoded` instead and will send the model in a

  // form param named `model`.

  Backbone.emulateJSON = false;

  // Backbone.Events

  // -----------------

  // A module that can be mixed in to *any object* in order to provide it with

  // custom events. You may `bind` or `unbind` a callback function to an event;

  // `trigger`-ing an event fires all callbacks in succession.

  //

  //     var object = {};

  //     _.extend(object, Backbone.Events);

  //     object.bind('expand', function(){ alert('expanded'); });

  //     object.trigger('expand');

  //

  Backbone.Events = {

    // Bind an event, specified by a string name, `ev`, to a `callback` function.

    // Passing `"all"` will bind the callback to all events fired.

    bind : function(ev, callback, context) {

      var calls = this._callbacks || (this._callbacks = {});

      var list  = calls[ev] || (calls[ev] = {});

      var tail = list.tail || (list.tail = list.next = {});

      tail.callback = callback;

      tail.context = context;

      list.tail = tail.next = {};

      return this;

    },

    // Remove one or many callbacks. If `callback` is null, removes all

    // callbacks for the event. If `ev` is null, removes all bound callbacks

    // for all events.

    unbind : function(ev, callback) {

      var calls, node, prev;

      if (!ev) {

        this._callbacks = null;

      } else if (calls = this._callbacks) {

        if (!callback) {

          calls[ev] = {};

        } else if (node = calls[ev]) {

          while ((prev = node) && (node = node.next)) {

            if (node.callback !== callback) continue;

            prev.next = node.next;

            node.context = node.callback = null;

            break;

          }

        }

      }

      return this;

    },

    // Trigger an event, firing all bound callbacks. Callbacks are passed the

    // same arguments as `trigger` is, apart from the event name.

    // Listening for `"all"` passes the true event name as the first argument.

    trigger : function(eventName) {

      var node, calls, callback, args, ev, events = ['all', eventName];

      if (!(calls = this._callbacks)) return this;

      while (ev = events.pop()) {

        if (!(node = calls[ev])) continue;

        args = ev == 'all' ? arguments : slice.call(arguments, 1);

        while (node = node.next) if (callback = node.callback) callback.apply(node.context || this, args);

      }

      return this;

    }

  };

  // Backbone.Model

  // --------------

  // Create a new model, with defined attributes. A client id (`cid`)

  // is automatically generated and assigned for you.

  Backbone.Model = function(attributes, options) {

    var defaults;

    attributes || (attributes = {});

    if (defaults = this.defaults) {

      if (_.isFunction(defaults)) defaults = defaults.call(this);

      attributes = _.extend({}, defaults, attributes);

    }

    this.attributes = {};

    this._escapedAttributes = {};

    this.cid = _.uniqueId('c');

    this.set(attributes, {silent : true});

    this._changed = false;

    this._previousAttributes = _.clone(this.attributes);

    if (options && options.collection) this.collection = options.collection;

    this.initialize(attributes, options);

  };

  // Attach all inheritable methods to the Model prototype.

  _.extend(Backbone.Model.prototype, Backbone.Events, {

    // Has the item been changed since the last `"change"` event?

    _changed : false,

    // The default name for the JSON `id` attribute is `"id"`. MongoDB and

    // CouchDB users may want to set this to `"_id"`.

    idAttribute : 'id',

    // Initialize is an empty function by default. Override it with your own

    // initialization logic.

    initialize : function(){},

    // Return a copy of the model's `attributes` object.

    toJSON : function() {

      return _.clone(this.attributes);

    },

    // Get the value of an attribute.

    get : function(attr) {

      return this.attributes[attr];

    },

    // Get the HTML-escaped value of an attribute.

    escape : function(attr) {

      var html;

      if (html = this._escapedAttributes[attr]) return html;

      var val = this.attributes[attr];

      return this._escapedAttributes[attr] = _.escape(val == null ? '' : '' + val);

    },

    // Returns `true` if the attribute contains a value that is not null

    // or undefined.

    has : function(attr) {

      return this.attributes[attr] != null;

    },

    // Set a hash of model attributes on the object, firing `"change"` unless you

    // choose to silence it.

    set : function(attrs, options) {

      // Extract attributes and options.

      options || (options = {});

      if (!attrs) return this;

      if (attrs.attributes) attrs = attrs.attributes;

      var now = this.attributes, escaped = this._escapedAttributes;

      // Run validation.

      if (!options.silent && this.validate && !this._performValidation(attrs, options)) return false;

      // Check for changes of `id`.

      if (this.idAttribute in attrs) this.id = attrs[this.idAttribute];

      // We're about to start triggering change events.

      var alreadyChanging = this._changing;

      this._changing = true;

      // Update attributes.

      for (var attr in attrs) {

        var val = attrs[attr];

        if (!_.isEqual(now[attr], val)) {

          now[attr] = val;

          delete escaped[attr];

          this._changed = true;

          if (!options.silent) this.trigger('change:' + attr, this, val, options);

        }

      }

      // Fire the `"change"` event, if the model has been changed.

      if (!alreadyChanging && !options.silent && this._changed) this.change(options);

      this._changing = false;

      return this;

    },

    // Remove an attribute from the model, firing `"change"` unless you choose

    // to silence it. `unset` is a noop if the attribute doesn't exist.

    unset : function(attr, options) {

      if (!(attr in this.attributes)) return this;

      options || (options = {});

      var value = this.attributes[attr];

      // Run validation.

      var validObj = {};

      validObj[attr] = void 0;

      if (!options.silent && this.validate && !this._performValidation(validObj, options)) return false;

      // changedAttributes needs to know if an attribute has been unset.

      (this._unsetAttributes || (this._unsetAttributes = [])).push(attr);

      // Remove the attribute.

      delete this.attributes[attr];

      delete this._escapedAttributes[attr];

      if (attr == this.idAttribute) delete this.id;

      this._changed = true;

      if (!options.silent) {

        this.trigger('change:' + attr, this, void 0, options);

        this.change(options);

      }

      return this;

    },

    // Clear all attributes on the model, firing `"change"` unless you choose

    // to silence it.

    clear : function(options) {

      options || (options = {});

      var attr;

      var old = this.attributes;

      // Run validation.

      var validObj = {};

      for (attr in old) validObj[attr] = void 0;

      if (!options.silent && this.validate && !this._performValidation(validObj, options)) return false;

      this.attributes = {};

      this._escapedAttributes = {};

      this._changed = true;

      if (!options.silent) {

        for (attr in old) {

          this.trigger('change:' + attr, this, void 0, options);

        }

        this.change(options);

      }

      return this;

    },

    // Fetch the model from the server. If the server's representation of the

    // model differs from its current attributes, they will be overriden,

    // triggering a `"change"` event.

    fetch : function(options) {

      options || (options = {});

      var model = this;

      var success = options.success;

      options.success = function(resp, status, xhr) {

        if (!model.set(model.parse(resp, xhr), options)) return false;

        if (success) success(model, resp);

      };

      options.error = wrapError(options.error, model, options);

      return (this.sync || Backbone.sync).call(this, 'read', this, options);

    },

    // Set a hash of model attributes, and sync the model to the server.

    // If the server returns an attributes hash that differs, the model's

    // state will be `set` again.

    save : function(attrs, options) {

      options || (options = {});

      if (attrs && !this.set(attrs, options)) return false;

      var model = this;

      var success = options.success;

      options.success = function(resp, status, xhr) {

        if (!model.set(model.parse(resp, xhr), options)) return false;

        if (success) success(model, resp, xhr);

      };

      options.error = wrapError(options.error, model, options);

      var method = this.isNew() ? 'create' : 'update';

      return (this.sync || Backbone.sync).call(this, method, this, options);

    },

    // Destroy this model on the server if it was already persisted. Upon success, the model is removed

    // from its collection, if it has one.

    destroy : function(options) {

      options || (options = {});

      if (this.isNew()) return this.trigger('destroy', this, this.collection, options);

      var model = this;

      var success = options.success;

      options.success = function(resp) {

        if (!options.silent) {

          model.trigger('destroy', model, model.collection, options);

        }

        if (success) success(model, resp);

      };

      options.error = wrapError(options.error, model, options);

      return (this.sync || Backbone.sync).call(this, 'delete', this, options);

    },

    // Default URL for the model's representation on the server -- if you're

    // using Backbone's restful methods, override this to change the endpoint

    // that will be called.

    url : function(options) {

      var base = getUrl(this.collection, options) || this.urlRoot || urlError();

      if (this.isNew()) return base;

      return base + (base.charAt(base.length - 1) == '/' ? '' : '/') + encodeURIComponent(this.id);

    },

    // **parse** converts a response into the hash of attributes to be `set` on

    // the model. The default implementation is just to pass the response along.

    parse : function(resp, xhr) {

      return resp;

    },

    // Create a new model with identical attributes to this one.

    clone : function() {

      return new this.constructor(this);

    },

    // A model is new if it has never been saved to the server, and lacks an id.

    isNew : function() {

      return this.id == null;

    },

    // Call this method to manually fire a `change` event for this model.

    // Calling this will cause all objects observing the model to update.

    change : function(options) {

      this.trigger('change', this, options);

      this._previousAttributes = _.clone(this.attributes);

      this._unsetAttributes = null;

      this._changed = false;

    },

    // Determine if the model has changed since the last `"change"` event.

    // If you specify an attribute name, determine if that attribute has changed.

    hasChanged : function(attr) {

      if (attr) return this._previousAttributes[attr] != this.attributes[attr];

      return this._changed;

    },

    // Return an object containing all the attributes that have changed, or false

    // if there are no changed attributes. Useful for determining what parts of a

    // view need to be updated and/or what attributes need to be persisted to

    // the server. Unset attributes will be set to undefined.

    changedAttributes : function(now) {

      now || (now = this.attributes);

      var old = this._previousAttributes, unset = this._unsetAttributes;

      var changed = false;

      for (var attr in now) {

        if (!_.isEqual(old[attr], now[attr])) {

          changed || (changed = {});

          changed[attr] = now[attr];

        }

      }

      if (unset) {

        changed || (changed = {});

        var len = unset.length;

        while (len--) changed[unset[len]] = void 0;

      }

      return changed;

    },

    // Get the previous value of an attribute, recorded at the time the last

    // `"change"` event was fired.

    previous : function(attr) {

      if (!attr || !this._previousAttributes) return null;

      return this._previousAttributes[attr];

    },

    // Get all of the attributes of the model at the time of the previous

    // `"change"` event.

    previousAttributes : function() {

      return _.clone(this._previousAttributes);

    },

    // Run validation against a set of incoming attributes, returning `true`

    // if all is well. If a specific `error` callback has been passed,

    // call that instead of firing the general `"error"` event.

    _performValidation : function(attrs, options) {

      var error = this.validate(attrs);

      if (error) {

        if (options.error) {

          options.error(this, error, options);

        } else {

          this.trigger('error', this, error, options);

        }

        return false;

      }

      return true;

    }

  });

  // Backbone.Collection

  // -------------------

  // Provides a standard collection class for our sets of models, ordered

  // or unordered. If a `comparator` is specified, the Collection will maintain

  // its models in sort order, as they're added and removed.

  Backbone.Collection = function(models, options) {

    options || (options = {});

    if (options.comparator) this.comparator = options.comparator;

    _.bindAll(this, '_onModelEvent', '_removeReference');

    this._reset();

    if (models) this.reset(models, {silent: true});

    this.initialize.apply(this, arguments);

  };

  // Define the Collection's inheritable methods.

  _.extend(Backbone.Collection.prototype, Backbone.Events, {

    // The default model for a collection is just a **Backbone.Model**.

    // This should be overridden in most cases.

    model : Backbone.Model,

    // Initialize is an empty function by default. Override it with your own

    // initialization logic.

    initialize : function(){},

    // The JSON representation of a Collection is an array of the

    // models' attributes.

    toJSON : function() {

      return this.map(function(model){ return model.toJSON(); });

    },

    // Add a model, or list of models to the set. Pass **silent** to avoid

    // firing the `added` event for every new model.

    add : function(models, options) {

      if (_.isArray(models)) {

        for (var i = 0, l = models.length; i < l; i++) {

          this._add(models[i], options);

        }

      } else {

        this._add(models, options);

      }

      return this;

    },

    // Remove a model, or a list of models from the set. Pass silent to avoid

    // firing the `removed` event for every model removed.

    remove : function(models, options) {

      if (_.isArray(models)) {

        for (var i = 0, l = models.length; i < l; i++) {

          this._remove(models[i], options);

        }

      } else {

        this._remove(models, options);

      }

      return this;

    },

    // Get a model from the set by id.

    get : function(id) {

      if (id == null) return null;

      return this._byId[id.id != null ? id.id : id];

    },

    // Get a model from the set by client id.

    getByCid : function(cid) {

      return cid && this._byCid[cid.cid || cid];

    },

    // Get the model at the given index.

    at : function(index) {

      return this.models[index];

    },

    // Force the collection to re-sort itself. You don't need to call this under normal

    // circumstances, as the set will maintain sort order as each item is added.

    sort : function(options) {

      options || (options = {});

      if (!this.comparator) throw new Error('Cannot sort a set without a comparator');

      this.models = this.sortBy(this.comparator);

      if (!options.silent) this.trigger('reset', this, options);

      return this;

    },

    // Pluck an attribute from each model in the collection.

    pluck : function(attr) {

      return _.map(this.models, function(model){ return model.get(attr); });

    },

    // When you have more items than you want to add or remove individually,

    // you can reset the entire set with a new list of models, without firing

    // any `added` or `removed` events. Fires `reset` when finished.

    reset : function(models, options) {

      models  || (models = []);

      options || (options = {});

      this.each(this._removeReference);

      this._reset();

      this.add(models, {silent: true});

      if (!options.silent) this.trigger('reset', this, options);

      return this;

    },

    // When you have an existing set of models in a collection, 

    // you can do in-place updates of these models, reusing existing instances.

    // - Items are matched against existing items in the collection by id

    // - New items are added

    // - matching models are updated using set(), triggers 'change'.

    // - existing models not present in the update are removed if 'removeMissing' is passed.

    // - a collection change event will be dispatched for each add() and remove()

    update : function(models, options) {

      models  || (models = []);

      options || (options = {});

      //keep track of the models we've updated, cause we're gunna delete the rest if 'removeMissing' is set.

      var updateMap = _.reduce(this.models, function(map, model){ map[model.id] = false; return map },{});

      _.each( models, function(model) {

        var idAttribute = this.model.prototype.idAttribute;

        var modelId = model[idAttribute];

        if ( modelId == undefined ) throw new Error("Can't update a model with no id attribute. Please use 'reset'.");

        if ( this._byId[modelId] ) {

          var attrs = (model instanceof Backbone.Model) ? _.clone(model.attributes) : _.clone(model);

          delete attrs[idAttribute];

          this._byId[modelId].set( attrs );

          updateMap[modelId] = true;

        }

        else {

          this.add( model );

        }

      }, this);

      if ( options.removeMissing ) {

        _.select(updateMap, function(updated, modelId){

          if (!updated) this.remove( modelId );

        }, this);

      }

      return this;

    },

    // Fetch the default set of models for this collection, resetting the

    // collection when they arrive. If `add: true` is passed, appends the

    // models to the collection instead of resetting.

    fetch : function(options) {

      options || (options = {});

      var collection = this;

      var success = options.success;

      options.success = function(resp, status, xhr) {

        collection[options.update ? 'update' : options.add ? 'add' : 'reset'](collection.parse(resp, xhr), options);

        if (success) success(collection, resp);

      };

      options.error = wrapError(options.error, collection, options);

      return (this.sync || Backbone.sync).call(this, 'read', this, options);

    },

    // Create a new instance of a model in this collection. After the model

    // has been created on the server, it will be added to the collection.

    // Returns the model, or 'false' if validation on a new model fails.

    create : function(model, options) {

      var coll = this;

      options || (options = {});

      model = this._prepareModel(model, options);

      if (!model) return false;

      var success = options.success;

      options.success = function(nextModel, resp, xhr) {

        coll.add(nextModel, options);

        if (success) success(nextModel, resp, xhr);

      };

      model.save(null, options);

      return model;

    },

    // **parse** converts a response into a list of models to be added to the

    // collection. The default implementation is just to pass it through.

    parse : function(resp, xhr) {

      return resp;

    },

    // Proxy to _'s chain. Can't be proxied the same way the rest of the

    // underscore methods are proxied because it relies on the underscore

    // constructor.

    chain : function () {

      return _(this.models).chain();

    },

    // Reset all internal state. Called when the collection is reset.

    _reset : function(options) {

      this.length = 0;

      this.models = [];

      this._byId  = {};

      this._byCid = {};

    },

    // Prepare a model to be added to this collection

    _prepareModel : function(model, options) {

      if (!(model instanceof Backbone.Model)) {

        var attrs = model;

        model = new this.model(attrs, {collection: this});

        if (model.validate && !model._performValidation(model.attributes, options)) model = false;

      } else if (!model.collection) {

        model.collection = this;

      }

      return model;

    },

    // Internal implementation of adding a single model to the set, updating

    // hash indexes for `id` and `cid` lookups.

    // Returns the model, or 'false' if validation on a new model fails.

    _add : function(model, options) {

      options || (options = {});

      model = this._prepareModel(model, options);

      if (!model) return false;

      var already = this.getByCid(model);

      if (already) throw new Error(["Can't add the same model to a set twice", already.id]);

      this._byId[model.id] = model;

      this._byCid[model.cid] = model;

      var index = options.at != null ? options.at :

                  this.comparator ? this.sortedIndex(model, this.comparator) :

                  this.length;

      this.models.splice(index, 0, model);

      model.bind('all', this._onModelEvent);

      this.length++;

      options.index = index;

      if (!options.silent) model.trigger('add', model, this, options);

      return model;

    },

    // Internal implementation of removing a single model from the set, updating

    // hash indexes for `id` and `cid` lookups.

    _remove : function(model, options) {

      options || (options = {});

      model = this.getByCid(model) || this.get(model);

      if (!model) return null;

      delete this._byId[model.id];

      delete this._byCid[model.cid];

      var index = this.indexOf(model);

      this.models.splice(index, 1);

      this.length--;

      options.index = index;

      if (!options.silent) model.trigger('remove', model, this, options);

      this._removeReference(model);

      return model;

    },

    // Internal method to remove a model's ties to a collection.

    _removeReference : function(model) {

      if (this == model.collection) {

        delete model.collection;

      }

      model.unbind('all', this._onModelEvent);

    },

    // Internal method called every time a model in the set fires an event.

    // Sets need to update their indexes when models change ids. All other

    // events simply proxy through. "add" and "remove" events that originate

    // in other collections are ignored.

    _onModelEvent : function(ev, model, collection, options) {

      if ((ev == 'add' || ev == 'remove') && collection != this) return;

      if (ev == 'destroy') {

        this._remove(model, options);

      }

      if (model && ev === 'change:' + model.idAttribute) {

        delete this._byId[model.previous(model.idAttribute)];

        this._byId[model.id] = model;

      }

      this.trigger.apply(this, arguments);

    }

  });

  // Underscore methods that we want to implement on the Collection.

  var methods = ['forEach', 'each', 'map', 'reduce', 'reduceRight', 'find', 'detect',

    'filter', 'select', 'reject', 'every', 'all', 'some', 'any', 'include',

    'contains', 'invoke', 'max', 'min', 'sortBy', 'sortedIndex', 'toArray', 'size',

    'first', 'rest', 'last', 'without', 'indexOf', 'lastIndexOf', 'isEmpty', 'groupBy'];

  // Mix in each Underscore method as a proxy to `Collection#models`.

  _.each(methods, function(method) {

    Backbone.Collection.prototype[method] = function() {

      return _[method].apply(_, [this.models].concat(_.toArray(arguments)));

    };

  });

  // Backbone.Router

  // -------------------

  // Routers map faux-URLs to actions, and fire events when routes are

  // matched. Creating a new one sets its `routes` hash, if not set statically.

  Backbone.Router = function(options) {

    options || (options = {});

    if (options.routes) this.routes = options.routes;

    this._bindRoutes();

    this.initialize.apply(this, arguments);

  };

  // Cached regular expressions for matching named param parts and splatted

  // parts of route strings.

  var namedParam    = /:([\w\d]+)/g;

  var splatParam    = /\*([\w\d]+)/g;

  var escapeRegExp  = /[-[\]{}()+?.,\\^$|#\s]/g;

  // Set up all inheritable **Backbone.Router** properties and methods.

  _.extend(Backbone.Router.prototype, Backbone.Events, {

    // Initialize is an empty function by default. Override it with your own

    // initialization logic.

    initialize : function(){},

    // Manually bind a single named route to a callback. For example:

    //

    //     this.route('search/:query/p:num', 'search', function(query, num) {

    //       ...

    //     });

    //

    route : function(route, name, callback) {

      Backbone.history || (Backbone.history = new Backbone.History);

      if (!_.isRegExp(route)) route = this._routeToRegExp(route);

      Backbone.history.route(route, _.bind(function(fragment) {

        var args = this._extractParameters(route, fragment);

        callback && callback.apply(this, args);

        this.trigger.apply(this, ['route:' + name].concat(args));

      }, this));

    },

    // Simple proxy to `Backbone.history` to save a fragment into the history.

    navigate : function(fragment, triggerRoute) {

      Backbone.history.navigate(fragment, triggerRoute);

    },

    // Bind all defined routes to `Backbone.history`. We have to reverse the

    // order of the routes here to support behavior where the most general

    // routes can be defined at the bottom of the route map.

    _bindRoutes : function() {

      if (!this.routes) return;

      var routes = [];

      for (var route in this.routes) {

        routes.unshift([route, this.routes[route]]);

      }

      for (var i = 0, l = routes.length; i < l; i++) {

        this.route(routes[i][0], routes[i][1], this[routes[i][1]]);

      }

    },

    // Convert a route string into a regular expression, suitable for matching

    // against the current location hash.

    _routeToRegExp : function(route) {

      route = route.replace(escapeRegExp, "\\$&")

                   .replace(namedParam, "([^\/]*)")

                   .replace(splatParam, "(.*?)");

      return new RegExp('^' + route + '$');

    },

    // Given a route, and a URL fragment that it matches, return the array of

    // extracted parameters.

    _extractParameters : function(route, fragment) {

      return route.exec(fragment).slice(1);

    }

  });

  // Backbone.History

  // ----------------

  // Handles cross-browser history management, based on URL fragments. If the

  // browser does not support `onhashchange`, falls back to polling.

  Backbone.History = function() {

    this.handlers = [];

    _.bindAll(this, 'checkUrl');

  };

  // Cached regex for cleaning hashes.

  var hashStrip = /^#*/;

  // Cached regex for detecting MSIE.

  var isExplorer = /msie [\w.]+/;

  // Has the history handling already been started?

  var historyStarted = false;

  // Set up all inheritable **Backbone.History** properties and methods.

  _.extend(Backbone.History.prototype, {

    // The default interval to poll for hash changes, if necessary, is

    // twenty times a second.

    interval: 50,

    // Get the cross-browser normalized URL fragment, either from the URL,

    // the hash, or the override.

    getFragment : function(fragment, forcePushState) {

      if (fragment == null) {

        if (this._hasPushState || forcePushState) {

          fragment = window.location.pathname;

          var search = window.location.search;

          if (search) fragment += search;

        } else {

          fragment = window.location.hash;

        }

      }

      fragment = decodeURIComponent(fragment.replace(hashStrip, ''));

      if (!fragment.indexOf(this.options.root)) fragment = fragment.substr(this.options.root.length);

      return fragment;

    },

    // Start the hash change handling, returning `true` if the current URL matches

    // an existing route, and `false` otherwise.

    start : function(options) {

      // Figure out the initial configuration. Do we need an iframe?

      // Is pushState desired ... is it available?

      if (historyStarted) throw new Error("Backbone.history has already been started");

      this.options          = _.extend({}, {root: '/'}, this.options, options);

      this._wantsPushState  = !!this.options.pushState;

      this._hasPushState    = !!(this.options.pushState && window.history && window.history.pushState);

      var fragment          = this.getFragment();

      var docMode           = document.documentMode;

      var oldIE             = (isExplorer.exec(navigator.userAgent.toLowerCase()) && (!docMode || docMode <= 7));

      if (oldIE) {

        this.iframe = $('<iframe src="javascript:0" tabindex="-1" />').hide().appendTo('body')[0].contentWindow;

        this.navigate(fragment);

      }

      // Depending on whether we're using pushState or hashes, and whether

      // 'onhashchange' is supported, determine how we check the URL state.

      if (this._hasPushState) {

        $(window).bind('popstate', this.checkUrl);

      } else if ('onhashchange' in window && !oldIE) {

        $(window).bind('hashchange', this.checkUrl);

      } else {

        setInterval(this.checkUrl, this.interval);

      }

      // Determine if we need to change the base url, for a pushState link

      // opened by a non-pushState browser.

      this.fragment = fragment;

      historyStarted = true;

      var loc = window.location;

      var atRoot  = loc.pathname == this.options.root;

      if (this._wantsPushState && !this._hasPushState && !atRoot) {

        this.fragment = this.getFragment(null, true);

        window.location.replace(this.options.root + '#' + this.fragment);

        // Return immediately as browser will do redirect to new url

        return true;

      } else if (this._wantsPushState && this._hasPushState && atRoot && loc.hash) {

        this.fragment = loc.hash.replace(hashStrip, '');

        window.history.replaceState({}, document.title, loc.protocol + '//' + loc.host + this.options.root + this.fragment);

      }

      if (!this.options.silent) {

        return this.loadUrl();

      }

    },

    // Add a route to be tested when the fragment changes. Routes added later may

    // override previous routes.

    route : function(route, callback) {

      this.handlers.unshift({route : route, callback : callback});

    },

    // Checks the current URL to see if it has changed, and if it has,

    // calls `loadUrl`, normalizing across the hidden iframe.

    checkUrl : function(e) {

      var current = this.getFragment();

      if (current == this.fragment && this.iframe) current = this.getFragment(this.iframe.location.hash);

      if (current == this.fragment || current == decodeURIComponent(this.fragment)) return false;

      if (this.iframe) this.navigate(current);

      this.loadUrl() || this.loadUrl(window.location.hash);

    },

    // Attempt to load the current URL fragment. If a route succeeds with a

    // match, returns `true`. If no defined routes matches the fragment,

    // returns `false`.

    loadUrl : function(fragmentOverride) {

      var fragment = this.fragment = this.getFragment(fragmentOverride);

      var matched = _.any(this.handlers, function(handler) {

        if (handler.route.test(fragment)) {

          handler.callback(fragment);

          return true;

        }

      });

      return matched;

    },

    // Save a fragment into the hash history. You are responsible for properly

    // URL-encoding the fragment in advance. This does not trigger

    // a `hashchange` event.

    navigate : function(fragment, triggerRoute) {

      var frag = (fragment || '').replace(hashStrip, '');

      if (this.fragment == frag || this.fragment == decodeURIComponent(frag)) return;

      if (this._hasPushState) {

        var loc = window.location;

        if (frag.indexOf(this.options.root) != 0) frag = this.options.root + frag;

        this.fragment = frag;

        window.history.pushState({}, document.title, loc.protocol + '//' + loc.host + frag);

      } else {

        window.location.hash = this.fragment = frag;

        if (this.iframe && (frag != this.getFragment(this.iframe.location.hash))) {

          this.iframe.document.open().close();

          this.iframe.location.hash = frag;

        }

      }

      if (triggerRoute) this.loadUrl(fragment);

    }

  });

  // Backbone.View

  // -------------

  // Creating a Backbone.View creates its initial element outside of the DOM,

  // if an existing element is not provided...

  Backbone.View = function(options) {

    this.cid = _.uniqueId('view');

    this._configure(options || {});

    this._ensureElement();

    this.delegateEvents();

    this.initialize.apply(this, arguments);

  };

  // Element lookup, scoped to DOM elements within the current view.

  // This should be prefered to global lookups, if you're dealing with

  // a specific view.

  var selectorDelegate = function(selector) {

    return $(selector, this.el);

  };

  // Cached regex to split keys for `delegate`.

  var eventSplitter = /^(\S+)\s*(.*)$/;

  // List of view options to be merged as properties.

  var viewOptions = ['model', 'collection', 'el', 'id', 'attributes', 'className', 'tagName'];

  // Set up all inheritable **Backbone.View** properties and methods.

  _.extend(Backbone.View.prototype, Backbone.Events, {

    // The default `tagName` of a View's element is `"div"`.

    tagName : 'div',

    // Attach the `selectorDelegate` function as the `$` property.

    $       : selectorDelegate,

    // Initialize is an empty function by default. Override it with your own

    // initialization logic.

    initialize : function(){},

    // **render** is the core function that your view should override, in order

    // to populate its element (`this.el`), with the appropriate HTML. The

    // convention is for **render** to always return `this`.

    render : function() {

      return this;

    },

    // Remove this view from the DOM. Note that the view isn't present in the

    // DOM by default, so calling this method may be a no-op.

    remove : function() {

      $(this.el).remove();

      return this;

    },

    // For small amounts of DOM Elements, where a full-blown template isn't

    // needed, use **make** to manufacture elements, one at a time.

    //

    //     var el = this.make('li', {'class': 'row'}, this.model.escape('title'));

    //

    make : function(tagName, attributes, content) {

      var el = document.createElement(tagName);

      if (attributes) $(el).attr(attributes);

      if (content) $(el).html(content);

      return el;

    },

    // Set callbacks, where `this.events` is a hash of

    //

    // *{"event selector": "callback"}*

    //

    //     {

    //       'mousedown .title':  'edit',

    //       'click .button':     'save'

    //     }

    //

    // pairs. Callbacks will be bound to the view, with `this` set properly.

    // Uses event delegation for efficiency.

    // Omitting the selector binds the event to `this.el`.

    // This only works for delegate-able events: not `focus`, `blur`, and

    // not `change`, `submit`, and `reset` in Internet Explorer.

    delegateEvents : function(events) {

      if (!(events || (events = this.events))) return;

      if (_.isFunction(events)) events = events.call(this);

      this.undelegateEvents();

      for (var key in events) {

        var method = this[events[key]];

        if (!method) throw new Error('Event "' + events[key] + '" does not exist');

        var match = key.match(eventSplitter);

        var eventName = match[1], selector = match[2];

        method = _.bind(method, this);

        eventName += '.delegateEvents' + this.cid;

        if (selector === '') {

          $(this.el).bind(eventName, method);

        } else {

          $(this.el).delegate(selector, eventName, method);

        }

      }

    },

    // Clears all callbacks previously bound to the view with `delegateEvents`.

    undelegateEvents : function() {

      $(this.el).unbind('.delegateEvents' + this.cid);

    },

    // Performs the initial configuration of a View with a set of options.

    // Keys with special meaning *(model, collection, id, className)*, are

    // attached directly to the view.

    _configure : function(options) {

      if (this.options) options = _.extend({}, this.options, options);

      for (var i = 0, l = viewOptions.length; i < l; i++) {

        var attr = viewOptions[i];

        if (options[attr]) this[attr] = options[attr];

      }

      this.options = options;

    },

    // Ensure that the View has a DOM element to render into.

    // If `this.el` is a string, pass it through `$()`, take the first

    // matching element, and re-assign it to `el`. Otherwise, create

    // an element from the `id`, `className` and `tagName` properties.

    _ensureElement : function() {

      if (!this.el) {

        var attrs = this.attributes || {};

        if (this.id) attrs.id = this.id;

        if (this.className) attrs['class'] = this.className;

        this.el = this.make(this.tagName, attrs);

      } else if (_.isString(this.el)) {

        this.el = $(this.el).get(0);

      }

    }

  });

  // The self-propagating extend function that Backbone classes use.

  var extend = function (protoProps, classProps) {

    var child = inherits(this, protoProps, classProps);

    child.extend = this.extend;

    return child;

  };

  // Set up inheritance for the model, collection, and view.

  Backbone.Model.extend = Backbone.Collection.extend =

    Backbone.Router.extend = Backbone.View.extend = extend;

  // Map from CRUD to HTTP for our default `Backbone.sync` implementation.

  var methodMap = {

    'create': 'POST',

    'update': 'PUT',

    'delete': 'DELETE',

    'read'  : 'GET',

    'head'  : 'HEAD'

  };

  // Backbone.sync

  // -------------

  // Override this function to change the manner in which Backbone persists

  // models to the server. You will be passed the type of request, and the

  // model in question. By default, makes a RESTful Ajax request

  // to the model's `url()`. Some possible customizations could be:

  //

  // * Use `setTimeout` to batch rapid-fire updates into a single request.

  // * Send up the models as XML instead of JSON.

  // * Persist models via WebSockets instead of Ajax.

  //

  // Turn on `Backbone.emulateHTTP` in order to send `PUT` and `DELETE` requests

  // as `POST`, with a `_method` parameter containing the true HTTP method,

  // as well as all requests with the body as `application/x-www-form-urlencoded` instead of

  // `application/json` with the model in a param named `model`.

  // Useful when interfacing with server-side languages like **PHP** that make

  // it difficult to read the body of `PUT` requests.

  Backbone.sync = function(method, model, options) {

    var type = methodMap[method];

    // Default JSON-request options.

    var params = {type : type, dataType : 'json'};

    // Ensure that we have a URL.

    if (!options.url) {

      params.url = getUrl(model, options) || urlError();

    }

    // Ensure that we have the appropriate request data.

    if (!options.data && model && (method == 'create' || method == 'update')) {

      params.contentType = 'application/json';

      params.data = JSON.stringify(model.toJSON());

    }

    // For older servers, emulate JSON by encoding the request into an HTML-form.

    if (Backbone.emulateJSON) {

      params.contentType = 'application/x-www-form-urlencoded';

      params.data = params.data ? {model : params.data} : {};

    }

    // For older servers, emulate HTTP by mimicking the HTTP method with `_method`

    // And an `X-HTTP-Method-Override` header.

    if (Backbone.emulateHTTP) {

      if (type === 'PUT' || type === 'DELETE') {

        if (Backbone.emulateJSON) params.data._method = type;

        params.type = 'POST';

        params.beforeSend = function(xhr) {

          xhr.setRequestHeader('X-HTTP-Method-Override', type);

        };

      }

    }

    // Don't process data on a non-GET request.

    if (params.type !== 'GET' && !Backbone.emulateJSON) {

      params.processData = false;

    }

    // Make the request, allowing the user to override any Ajax options.

    return $.ajax(_.extend(params, options));

  };

  // Helpers

  // -------

  // Shared empty constructor function to aid in prototype-chain creation.

  var ctor = function(){};

  // Helper function to correctly set up the prototype chain, for subclasses.

  // Similar to `goog.inherits`, but uses a hash of prototype properties and

  // class properties to be extended.

  var inherits = function(parent, protoProps, staticProps) {

    var child;

    // The constructor function for the new subclass is either defined by you

    // (the "constructor" property in your `extend` definition), or defaulted

    // by us to simply call `super()`.

    if (protoProps && protoProps.hasOwnProperty('constructor')) {

      child = protoProps.constructor;

    } else {

      child = function(){ return parent.apply(this, arguments); };

    }

    // Inherit class (static) properties from parent.

    _.extend(child, parent);

    // Set the prototype chain to inherit from `parent`, without calling

    // `parent`'s constructor function.