CodeAssist: Avoid pointless completion request after accepting item

Previously, accepting an item from the completion pop-up triggered
another completion request, but the result of that request was never
displayed since the inserted text was a perfect match.

Now, trigger another completion request only if the inserted text
matches the activation characters.

Change-Id: Ic8ed4139efb10aadc8d41105634fcc856e0a15be
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/texteditor/codeassist/codeassistant.cpp

@@ -104,6 +104,7 @@ private:
     IAssistProposalWidget *m_proposalWidget = nullptr;
     QScopedPointer<IAssistProposal> m_proposal;
     bool m_receivedContentWhileWaiting = false;
+    bool m_proposalItemProcessed = false;
     QTimer m_automaticProposalTimer;
     CompletionSettings m_settings;
     int m_abortedBasePosition = -1;
@@ -192,6 +193,13 @@ void CodeAssistantPrivate::requestProposal(AssistReason reason,
     if (m_editorWidget->hasBlockSelection())
         return; // TODO
 
+    if (m_proposalItemProcessed
+            && reason == IdleEditor
+            && m_assistKind == TextEditor::Completion
+            && !identifyActivationSequence()) {
+        return;
+    }
+
     if (!provider) {
         if (kind == Completion)
             provider = m_editorWidget->textDocument()->completionAssistProvider();
@@ -358,6 +366,15 @@ void CodeAssistantPrivate::processProposalItem(AssistProposalItemInterface *prop
     if (!proposalItem->isSnippet())
         process();
     m_editorWidget->encourageApply();
+    m_proposalItemProcessed = true;
+
+    auto connection = std::make_shared<QMetaObject::Connection>();
+    *connection = connect(m_editorWidget->textDocument(),
+                          &Core::IDocument::contentsChanged,
+                          this, [this, connection] {
+        m_proposalItemProcessed = false;
+        disconnect(*connection);
+    });
 }
 
 void CodeAssistantPrivate::handlePrefixExpansion(const QString &newPrefix)