core: Add several QList::reserve() calls.

Reduces reallocations.

Change-Id: Ib63539fb690a80245d8fe81ff8468e79ffa8e57c
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

src/corelib/io/qresource.cpp

@@ -790,6 +790,7 @@ QStringList QResourceRoot::children(int node) const
         offset += 4;
         const int child_off = (tree[offset+0] << 24) + (tree[offset+1] << 16) +
                               (tree[offset+2] << 8) + (tree[offset+3] << 0);
+        ret.reserve(child_count);
         for(int i = child_off; i < child_off+child_count; ++i)
             ret << name(i);
     }

src/corelib/io/qsettings.cpp

@@ -357,6 +357,7 @@ void QSettingsPrivate::requestUpdate()
 QStringList QSettingsPrivate::variantListToStringList(const QVariantList &l)
 {
     QStringList result;
+    result.reserve(l.count());
     QVariantList::const_iterator it = l.constBegin();
     for (; it != l.constEnd(); ++it)
         result.append(variantToString(*it));
@@ -374,7 +375,9 @@ QVariant QSettingsPrivate::stringListToVariantList(const QStringList &l)
                 outStringList[i].remove(0, 1);
             } else {
                 QVariantList variantList;
-                for (int j = 0; j < l.count(); ++j)
+                const int stringCount = l.count();
+                variantList.reserve(stringCount);
+                for (int j = 0; j < stringCount; ++j)
                     variantList.append(stringToVariant(l.at(j)));
                 return variantList;
             }

src/corelib/io/qurlquery.cpp

@@ -642,6 +642,7 @@ QList<QPair<QString, QString> > QUrlQuery::queryItems(QUrl::ComponentFormattingO
     QList<QPair<QString, QString> > result;
     Map::const_iterator it = d->itemList.constBegin();
     Map::const_iterator end = d->itemList.constEnd();
+    result.reserve(d->itemList.count());
     for ( ; it != end; ++it)
         result << qMakePair(d->recodeToUser(it->first, encoding),
                             d->recodeToUser(it->second, encoding));

src/corelib/itemmodels/qabstractitemmodel.cpp

@@ -3222,6 +3222,7 @@ QModelIndexList QAbstractItemModel::persistentIndexList() const
 {
     Q_D(const QAbstractItemModel);
     QModelIndexList result;
+    result.reserve(d->persistent.indexes.count());
     for (QHash<QModelIndex, QPersistentModelIndexData *>::const_iterator it = d->persistent.indexes.constBegin();
          it != d->persistent.indexes.constEnd(); ++it) {
         QPersistentModelIndexData *data = *it;

src/corelib/itemmodels/qabstractproxymodel.cpp

@@ -379,6 +379,7 @@ QMimeData* QAbstractProxyModel::mimeData(const QModelIndexList &indexes) const
 {
     Q_D(const QAbstractProxyModel);
     QModelIndexList list;
+    list.reserve(indexes.count());
     foreach(const QModelIndex &index, indexes)
         list << mapToSource(index);
     return d->model->mimeData(list);

src/corelib/itemmodels/qidentityproxymodel.cpp

@@ -212,6 +212,7 @@ QItemSelection QIdentityProxyModel::mapSelectionFromSource(const QItemSelection&
 
     QItemSelection::const_iterator it = selection.constBegin();
     const QItemSelection::const_iterator end = selection.constEnd();
+    proxySelection.reserve(selection.count());
     for ( ; it != end; ++it) {
         Q_ASSERT(it->model() == d->model);
         const QItemSelectionRange range(mapFromSource(it->topLeft()), mapFromSource(it->bottomRight()));
@@ -234,6 +235,7 @@ QItemSelection QIdentityProxyModel::mapSelectionToSource(const QItemSelection& s
 
     QItemSelection::const_iterator it = selection.constBegin();
     const QItemSelection::const_iterator end = selection.constEnd();
+    sourceSelection.reserve(selection.count());
     for ( ; it != end; ++it) {
         Q_ASSERT(it->model() == this);
         const QItemSelectionRange range(mapToSource(it->topLeft()), mapToSource(it->bottomRight()));
@@ -269,6 +271,7 @@ QModelIndexList QIdentityProxyModel::match(const QModelIndex& start, int role, c
     QModelIndexList::const_iterator it = sourceList.constBegin();
     const QModelIndexList::const_iterator end = sourceList.constEnd();
     QModelIndexList proxyList;
+    proxyList.reserve(sourceList.count());
     for ( ; it != end; ++it)
         proxyList.append(mapFromSource(*it));
     return proxyList;

src/corelib/itemmodels/qsortfilterproxymodel.cpp

@@ -1011,6 +1011,7 @@ QModelIndexPairList QSortFilterProxyModelPrivate::store_persistent_indexes()
 {
     Q_Q(QSortFilterProxyModel);
     QModelIndexPairList source_indexes;
+    source_indexes.reserve(persistent.indexes.count());
     foreach (QPersistentModelIndexData *data, persistent.indexes) {
         QModelIndex proxy_index = data->index;
         QModelIndex source_index = q->mapToSource(proxy_index);
@@ -1030,7 +1031,10 @@ void QSortFilterProxyModelPrivate::update_persistent_indexes(
 {
     Q_Q(QSortFilterProxyModel);
     QModelIndexList from, to;
-    for (int i = 0; i < source_indexes.count(); ++i) {
+    const int numSourceIndexes = source_indexes.count();
+    from.reserve(numSourceIndexes);
+    to.reserve(numSourceIndexes);
+    for (int i = 0; i < numSourceIndexes; ++i) {
         QModelIndex source_index = source_indexes.at(i).second;
         QModelIndex old_proxy_index = source_indexes.at(i).first;
         create_mapping(source_index.parent());
@@ -2013,7 +2017,9 @@ QMimeData *QSortFilterProxyModel::mimeData(const QModelIndexList &indexes) const
 {
     Q_D(const QSortFilterProxyModel);
     QModelIndexList source_indexes;
-    for (int i = 0; i < indexes.count(); ++i)
+    const int numIndexes = indexes.count();
+    source_indexes.reserve(numIndexes);
+    for (int i = 0; i < numIndexes; ++i)
         source_indexes << mapToSource(indexes.at(i));
     return d->model->mimeData(source_indexes);
 }

src/corelib/itemmodels/qstringlistmodel.cpp

@@ -257,7 +257,9 @@ void QStringListModel::sort(int, Qt::SortOrder order)
     emit layoutAboutToBeChanged(QList<QPersistentModelIndex>(), VerticalSortHint);
 
     QList<QPair<QString, int> > list;
-    for (int i = 0; i < lst.count(); ++i)
+    const int lstCount = lst.count();
+    list.reserve(lstCount);
+    for (int i = 0; i < lstCount; ++i)
         list.append(QPair<QString, int>(lst.at(i), i));
 
     if (order == Qt::AscendingOrder)

src/corelib/json/qjsonarray.cpp

@@ -271,6 +271,7 @@ QVariantList QJsonArray::toVariantList() const
     QVariantList list;
 
     if (a) {
+        list.reserve(a->length);
         for (int i = 0; i < (int)a->length; ++i)
             list.append(QJsonValue(d, a, a->at(i)).toVariant());
     }

src/corelib/json/qjsonobject.cpp

@@ -274,7 +274,7 @@ QStringList QJsonObject::keys() const
         return QStringList();
 
     QStringList keys;
-
+    keys.reserve(o->length);
     for (uint i = 0; i < o->length; ++i) {
         QJsonPrivate::Entry *e = o->entryAt(i);
         keys.append(e->key());

src/corelib/kernel/qmimedata.cpp

@@ -354,7 +354,9 @@ void QMimeData::setUrls(const QList<QUrl> &urls)
 {
     Q_D(QMimeData);
     QList<QVariant> list;
-    for (int i = 0; i < urls.size(); ++i)
+    const int numUrls = urls.size();
+    list.reserve(numUrls);
+    for (int i = 0; i < numUrls; ++i)
         list.append(urls.at(i));
 
     d->setData(QLatin1String("text/uri-list"), list);

src/corelib/mimetypes/qmimedatabase.cpp

@@ -434,6 +434,7 @@ QList<QMimeType> QMimeDatabase::mimeTypesForFileName(const QString &fileName) co
     QStringList matches = d->mimeTypeForFileName(fileName);
     QList<QMimeType> mimes;
     matches.sort(); // Make it deterministic
+    mimes.reserve(matches.count());
     foreach (const QString &mime, matches)
         mimes.append(d->mimeTypeForName(mime));
     return mimes;

src/corelib/mimetypes/qmimeprovider.cpp

@@ -541,6 +541,7 @@ QList<QMimeType> QMimeBinaryProvider::allMimeTypes()
 {
     QList<QMimeType> result;
     loadMimeTypeList();
+    result.reserve(m_mimetypeNames.count());
 
     for (QSet<QString>::const_iterator it = m_mimetypeNames.constBegin();
           it != m_mimetypeNames.constEnd(); ++it)

src/corelib/plugin/qpluginloader.cpp

@@ -435,7 +435,9 @@ QObjectList QPluginLoader::staticInstances()
     QObjectList instances;
     const StaticPluginList *plugins = staticPluginList();
     if (plugins) {
-        for (int i = 0; i < plugins->size(); ++i)
+        const int numPlugins = plugins->size();
+        instances.reserve(numPlugins);
+        for (int i = 0; i < numPlugins; ++i)
             instances += plugins->at(i).instance();
     }
     return instances;

src/corelib/statemachine/qstatemachine.cpp

@@ -2454,6 +2454,7 @@ void QStateMachinePrivate::handleTransitionSignal(QObject *sender, int signalInd
     QMetaMethod method = meta->method(signalIndex);
     int argc = method.parameterCount();
     QList<QVariant> vargs;
+    vargs.reserve(argc);
     for (int i = 0; i < argc; ++i) {
         int type = method.parameterType(i);
         vargs.append(QVariant(type, argv[i+1]));

src/corelib/tools/qregularexpression.cpp

@@ -2128,7 +2128,8 @@ QStringRef QRegularExpressionMatch::capturedRef(const QString &name) const
 QStringList QRegularExpressionMatch::capturedTexts() const
 {
     QStringList texts;
-    for (int i = 0; i <= lastCapturedIndex(); ++i)
+    texts.reserve(d->capturedCount);
+    for (int i = 0; i < d->capturedCount; ++i)
         texts << captured(i);
     return texts;
 }

src/corelib/tools/qtimezoneprivate.cpp

@@ -700,6 +700,7 @@ QByteArray QUtcTimeZonePrivate::systemTimeZoneId() const
 QList<QByteArray> QUtcTimeZonePrivate::availableTimeZoneIds() const
 {
     QList<QByteArray> result;
+    result.reserve(utcDataTableSize);
     for (int i = 0; i < utcDataTableSize; ++i)
         result << utcId(utcData(i));
     std::sort(result.begin(), result.end()); // ### or already sorted??