Sort the items lazily.

src/plugins/cpptools/cppcodecompletion.cpp

@@ -69,6 +69,7 @@
 #include <QtCore/QDebug>
 #include <QtCore/QMap>
 #include <QtCore/QFile>
+#include <QtCore/QtConcurrentRun>
 #include <QtGui/QAction>
 #include <QtGui/QApplication>
 #include <QtGui/QDesktopWidget>
@@ -652,11 +653,22 @@ bool CppCodeCompletion::triggersCompletion(TextEditor::ITextEditable *editor)
     return false;
 }
 
+static QList<TextEditor::CompletionItem> sortCompletionItems(QList<TextEditor::CompletionItem> items)
+{
+    qStableSort(items.begin(), items.end(), CppCodeCompletion::completionItemLessThan);
+    return items;
+}
+
 int CppCodeCompletion::startCompletion(TextEditor::ITextEditable *editor)
 {
     int index = startCompletionHelper(editor);
-    if (index != -1)
-        qStableSort(m_completions.begin(), m_completions.end(), completionItemLessThan);
+    if (index != -1) {
+        m_sortedCompletions = QtConcurrent::run(sortCompletionItems, m_completions);
+
+        if (m_completions.size() < 1000)
+            m_completions = m_sortedCompletions;
+    }
+
     return index;
 }
 
@@ -1568,8 +1580,14 @@ void CppCodeCompletion::completions(QList<TextEditor::CompletionItem> *completio
 
     const QString key = m_editor->textAt(m_startPosition, length);
 
+    QList<TextEditor::CompletionItem> currentCompletion;
+    if (m_sortedCompletions.isFinished())
+        currentCompletion = m_sortedCompletions;
+    else
+        currentCompletion = m_completions;
+
     if (length == 0)
-        *completions = m_completions;
+        *completions = currentCompletion;
     else if (length > 0) {
         /* Close on the trailing slash for include completion, to enable the slash to
          * trigger a new completion list. */
@@ -1578,12 +1596,12 @@ void CppCodeCompletion::completions(QList<TextEditor::CompletionItem> *completio
             return;
 
         if (m_completionOperator != T_LPAREN) {
-            filter(m_completions, completions, key);
+            filter(currentCompletion, completions, key);
 
         } else if (m_completionOperator == T_LPAREN ||
                    m_completionOperator == T_SIGNAL ||
                    m_completionOperator == T_SLOT) {
-            foreach (const TextEditor::CompletionItem &item, m_completions) {
+            foreach (const TextEditor::CompletionItem &item, currentCompletion) {
                 if (item.text.startsWith(key, Qt::CaseInsensitive)) {
                     completions->append(item);
                 }
@@ -1742,6 +1760,7 @@ bool CppCodeCompletion::partiallyComplete(const QList<TextEditor::CompletionItem
 
 void CppCodeCompletion::cleanup()
 {
+    m_sortedCompletions.cancel();
     m_completions.clear();
 
     // Set empty map in order to avoid referencing old versions of the documents

src/plugins/cpptools/cppcodecompletion.h

@@ -40,6 +40,7 @@
 
 #include <QtCore/QObject>
 #include <QtCore/QPointer>
+#include <QtCore/QFuture>
 
 QT_BEGIN_NAMESPACE
 class QTextCursor;
@@ -149,6 +150,7 @@ private:
     QPointer<FunctionArgumentWidget> m_functionArgumentWidget;
 
     QList<TextEditor::CompletionItem> m_completions;
+    QFuture<QList<TextEditor::CompletionItem> > m_sortedCompletions;
 };
 
 } // namespace Internal