DevTools: Autocomplete class names in ClassesPaneWidget

third_party/WebKit/Source/devtools/front_end/elements/ClassesPaneWidget.js

 // Copyright (c) 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @constructor
  * @extends {WebInspector.Widget}
  */
 WebInspector.ClassesPaneWidget = function()
 {
     WebInspector.Widget.call(this);
     this.element.className = "styles-element-classes-pane";
     var container = this.element.createChild("div", "title-container");
-    this._input = container.createChild("input", "new-class-input monospace");
-    this._input.placeholder = WebInspector.UIString("Add new class");
-    this._input.addEventListener("keydown", this._onKeyDown.bind(this), false);
+    this._input = container.createChild("div", "new-class-input monospace");
+    this._input.setAttribute("placeholder", WebInspector.UIString("Add new class"));
     this.setDefaultFocusedElement(this._input);
     this._classesContainer = this.element.createChild("div", "source-code");
     this._classesContainer.classList.add("styles-element-classes-container");
+    this._prompt = new WebInspector.ClassesPaneWidget.ClassNamePrompt();
+    this._prompt.setAutocompletionTimeout(0);
+    this._prompt.renderAsBlock();
+
+    var proxyElement = this._prompt.attach(this._input);
+    proxyElement.addEventListener("keydown", this._onKeyDown.bind(this), false);
 
     WebInspector.targetManager.addModelListener(WebInspector.DOMModel, WebInspector.DOMModel.Events.DOMMutated, this._onDOMMutated, this);
     /** @type {!Set<!WebInspector.DOMNode>} */
     this._mutatingNodes = new Set();
     WebInspector.context.addFlavorChangeListener(WebInspector.DOMNode, this._update, this);
 }
 
 WebInspector.ClassesPaneWidget._classesSymbol = Symbol("WebInspector.ClassesPaneWidget._classesSymbol");
 
 WebInspector.ClassesPaneWidget.prototype = {
     /**
      * @param {!Event} event
      */
     _onKeyDown: function(event)
     {
-        var text = event.target.value;
+        var text = event.target.textContent;
         if (isEscKey(event)) {
-            event.target.value = "";
+            event.target.textContent = "";
             if (!text.isWhitespace())
                 event.consume(true);
             return;
         }
 
         if (!isEnterKey(event))
             return;
         var node = WebInspector.context.flavor(WebInspector.DOMNode);
         if (!node)
             return;
 
-        event.target.value = "";
+        this._prompt.clearAutocomplete();
+        event.target.textContent = "";
         var classNames = text.split(/[.,\s]/);
         for (var className of classNames) {
             var className = className.trim();
             if (!className.length)
                 continue;
             this._toggleClass(node, className, true);
         }
         this._installNodeClasses(node);
         this._update();
         event.consume(true);
@@ skipping 144 matching lines @@
 
     /**
      * @override
      * @return {!WebInspector.ToolbarItem}
      */
     item: function()
     {
         return this._button;
     }
 }
+
+/**
+ * @constructor
+ * @extends {WebInspector.TextPrompt}
+ */
+WebInspector.ClassesPaneWidget.ClassNamePrompt = function()
+{
+    WebInspector.TextPrompt.call(this, this._buildClassNameCompletions.bind(this), " ");
+    this.setSuggestBoxEnabled(true);
+    this.disableDefaultSuggestionForEmptyInput();
+    this._lastQuery = "";
+    this._selectedFrameId = "";
+    this._completions = new Set();
+}
+
+WebInspector.ClassesPaneWidget.ClassNamePrompt.prototype = {
+    /**
+     * @param {!Element} proxyElement
+     * @param {!Range} wordRange
+     * @param {boolean} force
+     * @param {function(!Array.<string>, number=)} completionsReadyCallback
+     */
+    _buildClassNameCompletions: function(proxyElement, wordRange, force, completionsReadyCallback)
+    {
+        var prefix = wordRange.toString();
+        var selectedNode = WebInspector.context.flavor(WebInspector.DOMNode);
+        if (!selectedNode || (!prefix && !force && !proxyElement.textContent.length)) {
+            completionsReadyCallback([]);
+            return;
+        }
+
+        var promises = [];
+        if (this._selectedFrameId !== selectedNode.frameId() || !prefix.startsWith(this._lastQuery)) {
+            this._completions = new Set();

[lushnikov, 2016/09/29 16:03:15]

We usually employ promises to cache values. One great benefit is that It makes
code more modular and easier to read.

With this approach, this "if" statement will look like this:

    if (!this._classNamesPromise || this._selectedFrameId !==
selectedNode.frameId() || !prefxis.startsWith(this._lastQuery))
        this._classNamesPromise = this._getClassNames();
    
    this._classNamesPromise.then(completions => completionsReadyCallback(<filter
completions>));

The "_getClassNames" function does not mutate state of the object.
Instead, it returns a promise which resolves with fetched completions:

    /**
     * @return {!Promise<!Set<string>>}
     */
    _getClassNames: function()
    {
        var completions = new Set();
        .... the code ....
        return Promise.all(promises).then(() => completions);
    }

[ahmetemirercin, 2016/09/29 19:25:36]

I just see that promises are used like this after your comment. Thanks.

+            this._selectedFrameId = selectedNode.frameId() || WebInspector.ResourceTreeModel.fromTarget(selectedNode.target()).mainFrame.id;
+
+            var cssModel = WebInspector.CSSModel.fromTarget(selectedNode.target());
+            var allStyleSheets = cssModel.allStyleSheets();
+            for (var stylesheet of allStyleSheets) {
+                if (stylesheet.frameId !== this._selectedFrameId)
+                    continue;
+                var cssPromise = cssModel.classNamesPromise(stylesheet.id).then(classes => this._completions.addAll(classes));
+                promises.push(cssPromise);
+            }
+
+            var domPromise = selectedNode.domModel().classNamesPromise(selectedNode.ownerDocument.id).then(classes => this._completions.addAll(classes));
+            promises.push(domPromise);
+        }
+        this._lastQuery = prefix;
+
+        Promise.all(promises).then(() => {
+            var results = [];
+            this._completions.valuesArray().forEach((value) => {
+                if (prefix.substring(0, 1) === ".")
+                    value = "." + value;

[lushnikov, 2016/09/29 16:03:15]

i agree with this

+                if (value.startsWith(prefix))
+                    results.push(value);
+            });
+            completionsReadyCallback(results, 0);
+        });
+    },
+
+    __proto__: WebInspector.TextPrompt.prototype
+}