remove length test add_class and remove_class

IPython/html/static/notebook/js/widgets/widget.js

@@ -1,326 +1,320
 //----------------------------------------------------------------------------
 //  Copyright (C) 2013 The IPython Development Team
 //
 //  Distributed under the terms of the BSD License.  The full license is in
 //  the file COPYING, distributed as part of this software.
 //----------------------------------------------------------------------------
 
 //============================================================================
 // Base Widget Model and View classes
 //============================================================================
 
 /**
  * @module IPython
  * @namespace IPython
  **/
 
 define(["notebook/js/widgetmanager",
         "underscore",
         "backbone"], 
 function(widget_manager, underscore, backbone){
     
     //--------------------------------------------------------------------
     // WidgetModel class
     //--------------------------------------------------------------------
     var WidgetModel = Backbone.Model.extend({
         constructor: function (widget_manager, model_id, comm) {
             // Construcctor
             //
             // Creates a WidgetModel instance.
             //
             // Parameters
             // ----------
             // widget_manager : WidgetManager instance
             // model_id : string
             //      An ID unique to this model.
             // comm : Comm instance (optional)
             this.widget_manager = widget_manager;
             this.pending_msgs = 0;
             this.msg_throttle = 3;
             this.msg_buffer = null;
             this.key_value_lock = null;
             this.id = model_id;
             this.views = [];
 
             if (comm !== undefined) {
                 // Remember comm associated with the model.
                 this.comm = comm;
                 comm.model = this;
 
                 // Hook comm messages up to model.
                 comm.on_close($.proxy(this._handle_comm_closed, this));
                 comm.on_msg($.proxy(this._handle_comm_msg, this));
             }
             return Backbone.Model.apply(this);
         },
 
         send: function (content, callbacks) {
             if (this.comm !== undefined) {
                 var data = {method: 'custom', custom_content: content};
                 this.comm.send(data, callbacks);
             }
         },
 
         // Handle when a widget is closed.
         _handle_comm_closed: function (msg) {
             this.trigger('comm:close');
             delete this.comm.model; // Delete ref so GC will collect widget model.
             delete this.comm;
             delete this.model_id; // Delete id from model so widget manager cleans up.
             // TODO: Handle deletion, like this.destroy(), and delete views, etc.
         },
 
 
         // Handle incoming comm msg.
         _handle_comm_msg: function (msg) {
             var method = msg.content.data.method;
             switch (method) {
                 case 'update':
                     this.apply_update(msg.content.data.state);
                     break;
                 case 'custom':
                     this.trigger('msg:custom', msg.content.data.custom_content);
                     break;
                 case 'display':
                     this.widget_manager.display_view(msg.parent_header.msg_id, this);
                     break;
             }
         },
 
 
         // Handle when a widget is updated via the python side.
         apply_update: function (state) {
             for (var key in state) {
                 if (state.hasOwnProperty(key)) {
                     var value = state[key];
                     this.key_value_lock = [key, value];
                     try {
                         this.set(key, state[key]);
                     } finally {
                         this.key_value_lock = null;
                     }
                 }
             }
             //TODO: are there callbacks that make sense in this case?  If so, attach them here as an option
             this.save();
         },
 
 
         _handle_status: function (msg, callbacks) {
             //execution_state : ('busy', 'idle', 'starting')
             if (this.comm !== undefined && msg.content.execution_state ==='idle') {
                 // Send buffer if this message caused another message to be
                 // throttled.
                 if (this.msg_buffer !== null &&
                     this.msg_throttle === this.pending_msgs) {
                     var data = {method: 'backbone', sync_method: 'update', sync_data: this.msg_buffer};
                     this.comm.send(data, callbacks);   
                     this.msg_buffer = null;
                 } else {
                     // Only decrease the pending message count if the buffer
                     // doesn't get flushed (sent).
                     --this.pending_msgs;
                 }
             }
         },
 
 
         // Custom syncronization logic.
         _handle_sync: function (method, options) {
             var model_json = this.toJSON();
             var attr;
 
             // Only send updated state if the state hasn't been changed 
             // during an update.
             if (this.comm !== undefined) {    
                 if (this.pending_msgs >= this.msg_throttle) {
                     // The throttle has been exceeded, buffer the current msg so
                     // it can be sent once the kernel has finished processing 
                     // some of the existing messages.
                     if (method=='patch') {
                         if (this.msg_buffer === null) {
                             this.msg_buffer = $.extend({}, model_json); // Copy
                         }
                         for (attr in options.attrs) {
                             var value = options.attrs[attr];
                             if (this.key_value_lock === null || attr != this.key_value_lock[0] || value != this.key_value_lock[1]) {
                                 this.msg_buffer[attr] = value;
                             }
                         }
                     } else {
                         this.msg_buffer = $.extend({}, model_json); // Copy
                     }
 
                 } else {
                     // We haven't exceeded the throttle, send the message like 
                     // normal.  If this is a patch operation, just send the 
                     // changes.
                     var send_json = model_json;
                     if (method =='patch') {
                         send_json = {};
                         for (attr in options.attrs) {
                             var value = options.attrs[attr];
                             if (this.key_value_lock === null || attr != this.key_value_lock[0] || value != this.key_value_lock[1]) {
                                 send_json[attr] = value;
                             }
                         }
                     }
 
                     var data = {method: 'backbone', sync_data: send_json};
                     this.comm.send(data, options.callbacks);
                     this.pending_msgs++;
                 }
             }
             
             // Since the comm is a one-way communication, assume the message 
             // arrived.
             return model_json;
         },
 
     });
 
 
     //--------------------------------------------------------------------
     // WidgetView class
     //--------------------------------------------------------------------
     var WidgetView = Backbone.View.extend({
         initialize: function(parameters) {
             this.model.on('change',this.update,this);
             this.options = parameters.options;
             this.child_views = [];
             this.model.views.push(this);
         },
 
         update: function(){
             // update view to be consistent with this.model
             // triggered on model change
         },
 
         child_view: function(model_id, options) {
             // create and return a child view, given a model id for a model and (optionally) a view name
             // if the view name is not given, it defaults to the model's default view attribute
             var child_model = this.widget_manager.get_model(model_id);
             var child_view = this.widget_manager.create_view(child_model, options);
             this.child_views[model_id] = child_view;
             return child_view;
         },
         
         update_child_views: function(old_list, new_list) {
             // this function takes an old list and new list of model ids
             // views in child_views that correspond to deleted ids are deleted
             // views corresponding to added ids are added child_views
         
             // delete old views
             _.each(_.difference(old_list, new_list), function(element, index, list) {
                 var view = this.child_views[element];
                 delete this.child_views[element];
                 view.remove();
             }, this);
             
             // add new views
             _.each(_.difference(new_list, old_list), function(element, index, list) {
                 // this function adds the view to the child_views dictionary
                 this.child_view(element);
             }, this);
         },
 
         callbacks: function(){
             return this.widget_manager.callbacks(this);
         },
 
         render: function(){
             // render the view.  By default, this is only called the first time the view is created
         },
         send: function (content) {
             this.model.send(content, this.callbacks());
         },
 
         touch: function () {
             this.model.save(this.model.changedAttributes(), {patch: true, callbacks: this.callbacks()});
         },
 
     });
 
     var DOMWidgetView = WidgetView.extend({
         initialize: function (options) {
             // TODO: make changes more granular (e.g., trigger on visible:change)
             this.model.on('change', this.update, this);
             this.model.on('msg:custom', this.on_msg, this);
             WidgetView.prototype.initialize.apply(this, arguments);
         },
         
         on_msg: function(msg) {
             switch(msg.msg_type) {
                 case 'add_class':
                     this.add_class(msg.selector, msg.class_list);
                     break;
                 case 'remove_class':
                     this.remove_class(msg.selector, msg.class_list);
                     break;
             }
         },
 
         add_class: function (selector, class_list) {
-            var elements = this._get_selector_element(selector);
-            if (elements.length > 0) {
-                elements.addClass(class_list);
-            }
+            this._get_selector_element(selector).addClass(class_list);
         },
         
         remove_class: function (selector, class_list) {
-            var elements = this._get_selector_element(selector);
-            if (elements.length > 0) {
-                elements.removeClass(class_list);
-            }
+            this._get_selector_element(selector).removeClass(class_list);
         },
     
         update: function () {
             // the very first update seems to happen before the element is finished rendering
             // so we use setTimeout to give the element time to render
             var e = this.$el;
             var visible = this.model.get('visible');
             setTimeout(function() {e.toggle(visible)},0);
      
             var css = this.model.get('_css');
             if (css === undefined) {return;}
             for (var selector in css) {
                 if (css.hasOwnProperty(selector)) {
                     // Apply the css traits to all elements that match the selector.
                     var elements = this._get_selector_element(selector);
                     if (elements.length > 0) {
                         var css_traits = css[selector];    
                         for (var css_key in css_traits) {
                             if (css_traits.hasOwnProperty(css_key)) {
                                 elements.css(css_key, css_traits[css_key]);
                             }
                         }
                     }
                 }
             }
         },
 
         _get_selector_element: function (selector) {
             // Get the elements via the css selector.  If the selector is
             // blank, apply the style to the $el_to_style element.  If
             // the $el_to_style element is not defined, use apply the 
             // style to the view's element.
             var elements;
             if (selector === undefined || selector === null || selector === '') {
                 if (this.$el_to_style === undefined) {
                     elements = this.$el;
                 } else {
                     elements = this.$el_to_style;
                 }
             } else {
                 elements = this.$el.find(selector);
             }
             return elements;
         },
     });
 
     IPython.WidgetModel = WidgetModel;
     IPython.WidgetView = WidgetView;
     IPython.DOMWidgetView = DOMWidgetView;
 
     return widget_manager;
 });