text: //     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;
  
    // 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 or Zepto owns the `$` variable.
    var $ = root.jQuery || root.Zepto;
  
    // 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] = []);
        list.push([callback, context]);
        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;
        if (!ev) {
          this._callbacks = {};
        } else if (calls = this._callbacks) {
          if (!callback) {
            calls[ev] = [];
          } else {
            var list = calls[ev];
            if (!list) return this;
            for (var i = 0, l = list.length; i < l; i++) {
              if (list[i] && callback === list[i][0]) {
                list[i] = 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 list, calls, ev, callback, args;
        var both = 2;
        if (!(calls = this._callbacks)) return this;
        while (both--) {
          ev = both ? eventName : 'all';
          if (list = calls[ev]) {
            for (var i = 0, l = list.length; i < l; i++) {
              if (!(callback = list[i])) {
                list.splice(i, 1); i--; l--;
              } else {
                args = both ? Array.prototype.slice.call(arguments, 1) : arguments;
                callback[0].apply(callback[1] || 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, {
  
      // A snapshot of the model's previous attributes, taken immediately
      // after the last `"change"` event was fired.
      _previousAttributes : null,
  
      // 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] = escapeHTML(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;
  
        // 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) {
          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() {
        var base = getUrl(this.collection) || 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._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.
      changedAttributes : function(now) {
        now || (now = this.attributes);
        var old = this._previousAttributes;
        var changed = false;
        for (var attr in now) {
          if (!_.isEqual(old[attr], now[attr])) {
            changed = changed || {};
            changed[attr] = now[attr];
          }
        }
        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;
      },
  
      // 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.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(attrs, 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++;
        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];
        this.models.splice(this.indexOf(model), 1);
        this.length--;
        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.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;
            if (fragment.indexOf(this.options.root) == 0) fragment = fragment.substr(this.options.root.length);
          } else {
            fragment = window.location.hash;
          }
        }
        return decodeURIComponent(fragment.replace(hashStrip, ''));
      },
  
      // 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.callbacks` 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.el).unbind('.delegateEvents' + this.cid);
        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);
          }
        }
      },
  
      // 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` proeprties.
      _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'
    };
  
    // 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, uses 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 = _.extend({
        type:         type,
        dataType:     'json'
      }, options);
  
      // Ensure that we have a URL.
      if (!params.url) {
        params.url = getUrl(model) || urlError();
      }
  
      // Ensure that we have the appropriate request data.
      if (!params.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.
      return $.ajax(params);
    };
  
    // 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.
      ctor.prototype = parent.prototype;
      child.prototype = new ctor();
  
      // Add prototype properties (instance properties) to the subclass,
      // if supplied.
      if (protoProps) _.extend(child.prototype, protoProps);
  
      // Add static properties to the constructor function, if supplied.
      if (staticProps) _.extend(child, staticProps);
  
      // Correctly set child's `prototype.constructor`.
      child.prototype.constructor = child;
  
      // Set a convenience property in case the parent's prototype is needed later.
      child.__super__ = parent.prototype;
  
      return child;
    };
  
    // Helper function to get a URL from a Model or Collection as a property
    // or as a function.
    var getUrl = function(object) {
      if (!(object && object.url)) return null;
      return _.isFunction(object.url) ? object.url() : object.url;
    };
  
    // Throw an error when a URL is needed, and none is supplied.
    var urlError = function() {
      throw new Error('A "url" property or function must be specified');
    };
  
    // Wrap an optional error callback with a fallback error event.
    var wrapError = function(onError, model, options) {
      return function(resp) {
        if (onError) {
          onError(model, resp, options);
        } else {
          model.trigger('error', model, resp, options);
        }
      };
    };
  
    // Helper function to escape a string for HTML rendering.
    var escapeHTML = function(string) {
      return string.replace(/&(?!\w+;|#\d+;|#x[\da-f]+;)/gi, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;').replace(/"/g, '&quot;').replace(/'/g, '&#x27;').replace(/\//g,'&#x2F;');
    };
  
  }).call(this);
  