Backport PR #8131: handle undefined when sorting quick help

Since undefined is neither less than nor greater than anything in Javascript, the sort function was treating it as equal to everything, causing inconsistent behavior depending on the sort algorithm of the browser.

closes  #8089

This ensures undefined elements are sorted last in the sequence.

IPython/html/static/base/js/keyboard.js

@@ -1,454 +1,454 b''
 // Copyright (c) IPython Development Team.
 // Distributed under the terms of the Modified BSD License.
 /**
  *
  *
  * @module keyboard
  * @namespace keyboard
  * @class ShortcutManager
  */
 
 define([
     'base/js/namespace',
     'jquery',
     'base/js/utils',
     'underscore',
 ], function(IPython, $, utils, _) {
     "use strict";
 
 
     /**
      * Setup global keycodes and inverse keycodes.
      * 
      * See http://unixpapa.com/js/key.html for a complete description. The short of
      * it is that there are different keycode sets. Firefox uses the "Mozilla keycodes"
      * and Webkit/IE use the "IE keycodes". These keycode sets are mostly the same
      * but have minor differences.
      **/
 
      // These apply to Firefox, (Webkit and IE)
      // This does work **only** on US keyboard.
     var _keycodes = {
         'a': 65, 'b': 66, 'c': 67, 'd': 68, 'e': 69, 'f': 70, 'g': 71, 'h': 72, 'i': 73,
         'j': 74, 'k': 75, 'l': 76, 'm': 77, 'n': 78, 'o': 79, 'p': 80, 'q': 81, 'r': 82,
         's': 83, 't': 84, 'u': 85, 'v': 86, 'w': 87, 'x': 88, 'y': 89, 'z': 90,
         '1 !': 49, '2 @': 50, '3 #': 51, '4 $': 52, '5 %': 53, '6 ^': 54,
         '7 &': 55, '8 *': 56, '9 (': 57, '0 )': 48, 
         '[ {': 219, '] }': 221, '` ~': 192,  ', <': 188, '. >': 190, '/ ?': 191,
         '\\ |': 220, '\' "': 222,
         'numpad0': 96, 'numpad1': 97, 'numpad2': 98, 'numpad3': 99, 'numpad4': 100,
         'numpad5': 101, 'numpad6': 102, 'numpad7': 103, 'numpad8': 104, 'numpad9': 105,
         'multiply': 106, 'add': 107, 'subtract': 109, 'decimal': 110, 'divide': 111,
         'f1': 112, 'f2': 113, 'f3': 114, 'f4': 115, 'f5': 116, 'f6': 117, 'f7': 118,
         'f8': 119, 'f9': 120, 'f11': 122, 'f12': 123, 'f13': 124, 'f14': 125, 'f15': 126,
         'backspace': 8, 'tab': 9, 'enter': 13, 'shift': 16, 'ctrl': 17, 'alt': 18,
         'meta': 91, 'capslock': 20, 'esc': 27, 'space': 32, 'pageup': 33, 'pagedown': 34,
         'end': 35, 'home': 36, 'left': 37, 'up': 38, 'right': 39, 'down': 40,
         'insert': 45, 'delete': 46, 'numlock': 144,
     };
     
     // These apply to Firefox and Opera
     var _mozilla_keycodes = {
         '; :': 59, '= +': 61, '- _': 173, 'meta': 224
     };
     
     // This apply to Webkit and IE
     var _ie_keycodes = {
         '; :': 186, '= +': 187, '- _': 189
     };
     
     var browser = utils.browser[0];
     var platform = utils.platform;
     
     if (browser === 'Firefox' || browser === 'Opera' || browser === 'Netscape') {
         $.extend(_keycodes, _mozilla_keycodes);
     } else if (browser === 'Safari' || browser === 'Chrome' || browser === 'MSIE') {
         $.extend(_keycodes, _ie_keycodes);
     }
 
     var keycodes = {};
     var inv_keycodes = {};
     for (var name in _keycodes) {
         var names = name.split(' ');
         if (names.length === 1) {
             var n = names[0];
             keycodes[n] = _keycodes[n];
             inv_keycodes[_keycodes[n]] = n;
         } else {
             var primary = names[0];
             var secondary = names[1];
             keycodes[primary] = _keycodes[name];
             keycodes[secondary] = _keycodes[name];
             inv_keycodes[_keycodes[name]] = primary;
         }
     }
 
     var normalize_key = function (key) {
         return inv_keycodes[keycodes[key]];
     };
 
     var normalize_shortcut = function (shortcut) {
         /**
          * @function _normalize_shortcut
          * @private
          * return a dict containing the normalized shortcut and the number of time it should be pressed:
          *
          * Put a shortcut into normalized form:
          * 1. Make lowercase
          * 2. Replace cmd by meta
          * 3. Sort '-' separated modifiers into the order alt-ctrl-meta-shift
          * 4. Normalize keys
          **/
         if (platform === 'MacOS') {
             shortcut = shortcut.toLowerCase().replace('cmdtrl-', 'cmd-');
         } else {
             shortcut = shortcut.toLowerCase().replace('cmdtrl-', 'ctrl-');
         }
 
         shortcut = shortcut.toLowerCase().replace('cmd', 'meta');
         shortcut = shortcut.replace(/-$/, '_');  // catch shortcuts using '-' key
         shortcut = shortcut.replace(/,$/, 'comma');  // catch shortcuts using '-' key
         if(shortcut.indexOf(',') !== -1){
             var sht = shortcut.split(',');
             sht = _.map(sht, normalize_shortcut);
             return shortcut;
         }
         shortcut = shortcut.replace(/comma/g, ',');  // catch shortcuts using '-' key
         var values = shortcut.split("-");
         if (values.length === 1) {
             return normalize_key(values[0]);
         } else {
             var modifiers = values.slice(0,-1);
             var key = normalize_key(values[values.length-1]);
             modifiers.sort();
             return modifiers.join('-') + '-' + key;
         }
     };
 
     var shortcut_to_event = function (shortcut, type) {
         /**
          * Convert a shortcut (shift-r) to a jQuery Event object
          **/
         type = type || 'keydown';
         shortcut = normalize_shortcut(shortcut);
         shortcut = shortcut.replace(/-$/, '_');  // catch shortcuts using '-' key
         var values = shortcut.split("-");
         var modifiers = values.slice(0,-1);
         var key = values[values.length-1];
         var opts = {which: keycodes[key]};
         if (modifiers.indexOf('alt') !== -1) {opts.altKey = true;}
         if (modifiers.indexOf('ctrl') !== -1) {opts.ctrlKey = true;}
         if (modifiers.indexOf('meta') !== -1) {opts.metaKey = true;}
         if (modifiers.indexOf('shift') !== -1) {opts.shiftKey = true;}
         return $.Event(type, opts);
     };
 
     var only_modifier_event = function(event){
         /**
          * Return `true` if the event only contains modifiers keys.
          * false otherwise
          **/
         var key = inv_keycodes[event.which];
         return ((event.altKey || event.ctrlKey || event.metaKey || event.shiftKey) && 
          (key === 'alt'|| key === 'ctrl'|| key === 'meta'|| key === 'shift'));
 
     };
 
     var event_to_shortcut = function (event) {
         /**
          * Convert a jQuery Event object to a normalized shortcut string (shift-r)
          **/
         var shortcut = '';
         var key = inv_keycodes[event.which];
         if (event.altKey && key !== 'alt') {shortcut += 'alt-';}
         if (event.ctrlKey && key !== 'ctrl') {shortcut += 'ctrl-';}
         if (event.metaKey && key !== 'meta') {shortcut += 'meta-';}
         if (event.shiftKey && key !== 'shift') {shortcut += 'shift-';}
         shortcut += key;
         return shortcut;
     };
 
     // Shortcut manager class
 
     var ShortcutManager = function (delay, events, actions, env) {
         /**
          * A class to deal with keyboard event and shortcut
          *
          * @class ShortcutManager
          * @constructor
          */
         this._shortcuts = {};
         this.delay = delay || 800; // delay in milliseconds
         this.events = events;
         this.actions = actions;
         this.actions.extend_env(env);
         this._queue = [];
         this._cleartimeout = null;
         Object.seal(this);
     };
 
     ShortcutManager.prototype.clearsoon = function(){
         /**
          * Clear the pending shortcut soon, and cancel previous clearing
          * that might be registered.
          **/ 
          var that = this;
          clearTimeout(this._cleartimeout);
          this._cleartimeout = setTimeout(function(){that.clearqueue();}, this.delay);
     };
 
 
     ShortcutManager.prototype.clearqueue = function(){
         /**
          * clear the pending shortcut sequence now. 
          **/
         this._queue = [];
         clearTimeout(this._cleartimeout);
     };
 
 
     var flatten_shorttree = function(tree){
         /**
          * Flatten a tree of shortcut sequences. 
          * use full to iterate over all the key/values of available shortcuts.
          **/
         var  dct = {};
         for(var key in tree){
             var value = tree[key];
             if(typeof(value) === 'string'){
                 dct[key] = value;
             } else {
                 var ftree=flatten_shorttree(value);
                 for(var subkey in ftree){
                     dct[key+','+subkey] = ftree[subkey];
                 }
             } 
         }
         return dct;
     };
 
     ShortcutManager.prototype.help = function () {
         var help = [];
         var ftree = flatten_shorttree(this._shortcuts);
         for (var shortcut in ftree) {
             var action = this.actions.get(ftree[shortcut]);
             var help_string = action.help||'== no help ==';
             var help_index = action.help_index;
             if (help_string) {
                 var shortstring = (action.shortstring||shortcut);
                 help.push({
                     shortcut: shortstring,
                     help: help_string,
                     help_index: help_index}
                 );
             }
         }
         help.sort(function (a, b) {
-            if (a.help_index > b.help_index){
-                return 1;
+            if (a.help_index === b.help_index) {
+                return 0;
             }
-            if (a.help_index < b.help_index){
-                return -1;
+            if (a.help_index === undefined || a.help_index > b.help_index){
+                return 1;
             }
-            return 0;
+            return -1;
         });
         return help;
     };
 
     ShortcutManager.prototype.clear_shortcuts = function () {
         this._shortcuts = {};
     };
 
     ShortcutManager.prototype.get_shortcut = function (shortcut){
         /**
          * return a node of the shortcut tree which an action name (string) if leaf,
          * and an object with `object.subtree===true`
          **/
         if(typeof(shortcut) === 'string'){
             shortcut = shortcut.split(',');
         }
         
         return this._get_leaf(shortcut, this._shortcuts);
     };
 
 
     ShortcutManager.prototype._get_leaf = function(shortcut_array, tree){
         /**
          * @private
          * find a leaf/node in a subtree of the keyboard shortcut
          *
          **/
         if(shortcut_array.length === 1){
             return tree[shortcut_array[0]];
         } else if(  typeof(tree[shortcut_array[0]]) !== 'string'){
             return this._get_leaf(shortcut_array.slice(1), tree[shortcut_array[0]]);
         }
         return null;
     };
 
     ShortcutManager.prototype.set_shortcut = function( shortcut, action_name){
         if( typeof(action_name) !== 'string'){ throw('action is not a string', action_name);}
         if( typeof(shortcut) === 'string'){
             shortcut = shortcut.split(',');
         }
         return this._set_leaf(shortcut, action_name, this._shortcuts);
     };
 
     ShortcutManager.prototype._is_leaf = function(shortcut_array, tree){
         if(shortcut_array.length === 1){
            return(typeof(tree[shortcut_array[0]]) === 'string');
         } else {
             var subtree = tree[shortcut_array[0]];
             return this._is_leaf(shortcut_array.slice(1), subtree );
         }
     };
 
     ShortcutManager.prototype._remove_leaf = function(shortcut_array, tree, allow_node){
         if(shortcut_array.length === 1){
             var current_node = tree[shortcut_array[0]];
             if(typeof(current_node) === 'string'){
                 delete tree[shortcut_array[0]];
             } else {
                 throw('try to delete non-leaf');
             }
         } else {
             this._remove_leaf(shortcut_array.slice(1),  tree[shortcut_array[0]], allow_node);
             if(_.keys(tree[shortcut_array[0]]).length === 0){
                 delete tree[shortcut_array[0]];
             }
         }
     };
 
     ShortcutManager.prototype._set_leaf = function(shortcut_array, action_name, tree){
         var current_node = tree[shortcut_array[0]];
         if(shortcut_array.length === 1){
             if(current_node !== undefined && typeof(current_node) !== 'string'){
                 console.warn('[warning], you are overriting a long shortcut with a shorter one');
             }
             tree[shortcut_array[0]] = action_name;
             return true;
         } else {
             if(typeof(current_node) === 'string'){
                 console.warn('you are trying to set a shortcut that will be shadowed'+
                              'by a more specific one. Aborting for :', action_name, 'the follwing '+
                              'will take precedence', current_node);
                 return false;
             } else {
                 tree[shortcut_array[0]] = tree[shortcut_array[0]]||{};
             }
             this._set_leaf(shortcut_array.slice(1), action_name, tree[shortcut_array[0]]);
             return true;
         }
     };
 
     ShortcutManager.prototype.add_shortcut = function (shortcut, data, suppress_help_update) {
         /**
          * Add a action to be handled by shortcut manager. 
          * 
          * - `shortcut` should be a `Shortcut Sequence` of the for `Ctrl-Alt-C,Meta-X`...
          * - `data` could be an `action name`, an `action` or a `function`.
          *   if a `function` is passed it will be converted to an anonymous `action`. 
          *
          **/
         var action_name = this.actions.get_name(data);
         if (! action_name){
             throw('does nto know how to deal with ', data);
         }
         
         shortcut = normalize_shortcut(shortcut);
         this.set_shortcut(shortcut, action_name);
 
         if (!suppress_help_update) {
             // update the keyboard shortcuts notebook help
             this.events.trigger('rebuild.QuickHelp');
         }
     };
 
     ShortcutManager.prototype.add_shortcuts = function (data) {
         /**
          * Convenient methods to call `add_shortcut(key, value)` on several items
          * 
          *  data : Dict of the form {key:value, ...}
          **/
         for (var shortcut in data) {
             this.add_shortcut(shortcut, data[shortcut], true);
         }
         // update the keyboard shortcuts notebook help
         this.events.trigger('rebuild.QuickHelp');
     };
 
     ShortcutManager.prototype.remove_shortcut = function (shortcut, suppress_help_update) {
         /**
          * Remove the binding of shortcut `sortcut` with its action.
          * throw an error if trying to remove a non-exiting shortcut
          **/
         shortcut = normalize_shortcut(shortcut);
         if( typeof(shortcut) === 'string'){
             shortcut = shortcut.split(',');
         }
         this._remove_leaf(shortcut, this._shortcuts);
         if (!suppress_help_update) {
             // update the keyboard shortcuts notebook help
             this.events.trigger('rebuild.QuickHelp');
         }
     };
 
 
 
     ShortcutManager.prototype.call_handler = function (event) {
         /**
          * Call the corresponding shortcut handler for a keyboard event
          * @method call_handler
          * @return {Boolean} `true|false`, `false` if no handler was found, otherwise the  value return by the handler. 
          * @param event {event}
          *
          * given an event, call the corresponding shortcut. 
          * return false is event wan handled, true otherwise 
          * in any case returning false stop event propagation
          **/
 
 
         this.clearsoon();
         if(only_modifier_event(event)){
             return true;
         }
         var shortcut = event_to_shortcut(event);
         this._queue.push(shortcut);
         var action_name = this.get_shortcut(this._queue);
 
         if (typeof(action_name) === 'undefined'|| action_name === null){
             this.clearqueue();
             return true;
         }
         
         if (this.actions.exists(action_name)) {
             event.preventDefault();
             this.clearqueue();
             return this.actions.call(action_name, event);
         }
 
         return false;
     };
 
 
     ShortcutManager.prototype.handles = function (event) {
         var shortcut = event_to_shortcut(event);
         var action_name = this.get_shortcut(this._queue.concat(shortcut));
         return (typeof(action_name) !== 'undefined');
     };
 
     var keyboard = {
         keycodes : keycodes,
         inv_keycodes : inv_keycodes,
         ShortcutManager : ShortcutManager,
         normalize_key : normalize_key,
         normalize_shortcut : normalize_shortcut,
         shortcut_to_event : shortcut_to_event,
         event_to_shortcut : event_to_shortcut,
     };
 
     // For backwards compatibility.
     IPython.keyboard = keyboard;
 
     return keyboard;
 });