DevTools: Fix flickering hint when typing in TextPrompt

third_party/WebKit/Source/devtools/front_end/ui/TextPrompt.js

Index: third_party/WebKit/Source/devtools/front_end/ui/TextPrompt.js
diff --git a/third_party/WebKit/Source/devtools/front_end/ui/TextPrompt.js b/third_party/WebKit/Source/devtools/front_end/ui/TextPrompt.js
index ffd47423e462767910bb2081411566c8cbaf4850..aa2cba77b643ca9e6b61476e0083c59a5f123881 100644
--- a/third_party/WebKit/Source/devtools/front_end/ui/TextPrompt.js
+++ b/third_party/WebKit/Source/devtools/front_end/ui/TextPrompt.js
@@ -45,6 +45,7 @@ WebInspector.TextPrompt = function(completions, stopCharacters)
     this._completionStopCharacters = stopCharacters || " =:[({;,!+-*/&|^<>.";
     this._autocompletionTimeout = WebInspector.TextPrompt.DefaultAutocompletionTimeout;
     this._title = "";
+    this._previousText = "";
 }
 
 WebInspector.TextPrompt.DefaultAutocompletionTimeout = 250;
@@ -189,6 +190,7 @@ WebInspector.TextPrompt.prototype = {
         } else {
             this._element.textContent = x;
         }
+        this._previousText = this.userEnteredText();
 
         this.moveCaretToEndOfPrompt();
         this._element.scrollIntoView();
@@ -281,7 +283,22 @@ WebInspector.TextPrompt.prototype = {
      */
     _updateAutoComplete: function(force)
     {
-        this.clearAutoComplete();
+        var clearHint = true;
+        if (this.autoCompleteElement) {
+            var text = this.userEnteredText();
+            if (this._previousText === text.substring(0, text.length - 1)) {
+                this._hintPrefix += this.autoCompleteElement.textContent.charAt(0);
+                this.autoCompleteElement.textContent = this.autoCompleteElement.textContent.substring(1);
+                clearHint = false;
+            } else if (this._previousText.substring(0, this._previousText.length - 1) === text) {

[lushnikov, 2016/09/07 22:11:01]

let's use .startsWith?

[einbinder, 2016/10/18 00:57:33]

Done.

+                this.autoCompleteElement.textContent = this._hintPrefix.charAt(this._hintPrefix.length - 1) + this.autoCompleteElement.textContent;
+                this._hintPrefix = this._hintPrefix.substring(0, this._hintPrefix.length - 1);
+                clearHint = false;
+            }
+        }
+        if (clearHint)
+            this.clearAutoComplete();
+        delete this._waitingForCompletions;

[lushnikov, 2016/09/07 22:11:01]

why would you need to delete this?

The _waitingForCompletions flag also doesn't do its job properly - it is
supposed to cancel the 
completionsReady callback, but it is not hard to model the situation when it
doesn't.

Let's fix in a separate patch?

[einbinder, 2016/10/18 00:57:33]

Done.

         this.autoCompleteSoon(force);
     },
 
@@ -355,6 +372,7 @@ WebInspector.TextPrompt.prototype = {
     {
         if (this._needUpdateAutocomplete)
             this._updateAutoComplete();
+        this._previousText = this.userEnteredText();
     },
 
     /**
@@ -376,10 +394,8 @@ WebInspector.TextPrompt.prototype = {
         if (this.isSuggestBoxVisible())
             this._suggestBox.hide();
 
-        if (this._completeTimeout) {
-            clearTimeout(this._completeTimeout);
-            delete this._completeTimeout;
-        }
+        this._clearAutocompleteTimeout();
+
         delete this._waitingForCompletions;
 
         if (!this.autoCompleteElement)
@@ -391,6 +407,14 @@ WebInspector.TextPrompt.prototype = {
         delete this._userEnteredText;
     },
 
+    _clearAutocompleteTimeout: function()
+    {
+        if (this._completeTimeout) {
+            clearTimeout(this._completeTimeout);
+            delete this._completeTimeout;
+        }
+    },
+
     /**
      * @param {boolean=} force
      */
@@ -407,7 +431,7 @@ WebInspector.TextPrompt.prototype = {
      */
     complete: function(force, reverse)
     {
-        this.clearAutoComplete();
+        this._clearAutocompleteTimeout();
         var selection = this._element.getComponentSelection();
         var selectionRange = selection && selection.rangeCount ? selection.getRangeAt(0) : null;
         if (!selectionRange)
@@ -422,7 +446,7 @@ WebInspector.TextPrompt.prototype = {
         else if (!force) {
             // BUG72018: Do not show suggest box if caret is followed by a non-stop character.
             var wordSuffixRange = selectionRange.startContainer.rangeOfWord(selectionRange.endOffset, this._completionStopCharacters, this._element, "forward");
-            if (wordSuffixRange.toString().length)
+            if (wordSuffixRange.toString().length + this.userEnteredText().length - this.text().length)
                 shouldExit = true;
         }
         if (shouldExit) {
@@ -560,8 +584,10 @@ WebInspector.TextPrompt.prototype = {
             var prefixTextNode = createTextNode(prefixText);
             fullWordRange.insertNode(prefixTextNode);
 
-            this.autoCompleteElement = createElementWithClass("span", "auto-complete-text");
+            if (!this.autoCompleteElement)
+                this.autoCompleteElement = createElementWithClass("span", "auto-complete-text");
             this.autoCompleteElement.textContent = suffixText;
+            this._hintPrefix = completionText.substring(0, wordPrefixLength);
 
             prefixTextNode.parentNode.insertBefore(this.autoCompleteElement, prefixTextNode.nextSibling);