QtWidgets: replace some index-based for loops with C++11 range-for

This needs to be handled a bit carefully, because Qt containers
will detach upon being iteratoed over using range-for.

In the cases of this patch, that cannot happen, because all
containers are marked as const (either by this patch or before).

Separate patches will deal with other situations.

Apart from being more readable, range-for loops are also the
most efficient for loop.

This patch shaves almost 2K of text size off an optimized Linux
AMD64 GCC 4.9 build.

Change-Id: I53810c7b25420b4fd449d20c90c07503c5e76a66
Reviewed-by: Edward Welbourne <edward.welbourne@theqtcompany.com>
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>

6 files changed, 45 insertions, 51 deletions

diff --git a/src/widgets/dialogs/qfiledialog.cpp b/src/widgets/dialogs/qfiledialog.cpp
index 1f832abf78..1bf5691837 100644
--- a/src/widgets/dialogs/qfiledialog.cpp
+++ b/src/widgets/dialogs/qfiledialog.cpp
@@ -2587,7 +2587,7 @@ void QFileDialog::accept()
         return;
     }
 
-    QStringList files = selectedFiles();
+    const QStringList files = selectedFiles();
     if (files.isEmpty())
         return;
     QString lineEditText = d->lineEdit()->text();
@@ -2657,10 +2657,10 @@ void QFileDialog::accept()
 
     case ExistingFile:
     case ExistingFiles:
-        for (int i = 0; i < files.count(); ++i) {
-            QFileInfo info(files.at(i));
+        for (const auto &file : files) {
+            QFileInfo info(file);
             if (!info.exists())
-                info = QFileInfo(d->getEnvironmentVariable(files.at(i)));
+                info = QFileInfo(d->getEnvironmentVariable(file));
             if (!info.exists()) {
 #ifndef QT_NO_MESSAGEBOX
                 QString message = tr("%1\nFile not found.\nPlease verify the "
@@ -3444,15 +3444,13 @@ void QFileDialogPrivate::_q_autoCompleteFileName(const QString &text)
         return;
     }
 
-    QStringList multipleFiles = typedFiles();
+    const QStringList multipleFiles = typedFiles();
     if (multipleFiles.count() > 0) {
         QModelIndexList oldFiles = qFileDialogUi->listView->selectionModel()->selectedRows();
         QModelIndexList newFiles;
-        for (int i = 0; i < multipleFiles.count(); ++i) {
-            QModelIndex idx = model->index(multipleFiles.at(i));
-            if (oldFiles.contains(idx))
-                oldFiles.removeAll(idx);
-            else
+        for (const auto &file : multipleFiles) {
+            QModelIndex idx = model->index(file);
+            if (oldFiles.removeAll(idx) == 0)
                 newFiles.append(idx);
         }
         for (int i = 0; i < newFiles.count(); ++i)
@@ -3479,7 +3477,7 @@ void QFileDialogPrivate::_q_updateOkButton()
     bool enableButton = true;
     bool isOpenDirectory = false;
 
-    QStringList files = q->selectedFiles();
+    const QStringList files = q->selectedFiles();
     QString lineEditText = lineEdit()->text();
 
     if (lineEditText.startsWith(QLatin1String("//")) || lineEditText.startsWith(QLatin1Char('\\'))) {
@@ -3538,10 +3536,10 @@ void QFileDialogPrivate::_q_updateOkButton()
         }
         case QFileDialog::ExistingFile:
         case QFileDialog::ExistingFiles:
-            for (int i = 0; i < files.count(); ++i) {
-                QModelIndex idx = model->index(files.at(i));
+            for (const auto &file : files) {
+                QModelIndex idx = model->index(file);
                 if (!idx.isValid())
-                    idx = model->index(getEnvironmentVariable(files.at(i)));
+                    idx = model->index(getEnvironmentVariable(file));
                 if (!idx.isValid()) {
                     enableButton = false;
                     break;
@@ -3682,14 +3680,14 @@ void QFileDialogPrivate::_q_useNameFilter(int index)
 void QFileDialogPrivate::_q_selectionChanged()
 {
     const QFileDialog::FileMode fileMode = q_func()->fileMode();
-    QModelIndexList indexes = qFileDialogUi->listView->selectionModel()->selectedRows();
+    const QModelIndexList indexes = qFileDialogUi->listView->selectionModel()->selectedRows();
     bool stripDirs = (fileMode != QFileDialog::DirectoryOnly && fileMode != QFileDialog::Directory);
 
     QStringList allFiles;
-    for (int i = 0; i < indexes.count(); ++i) {
-        if (stripDirs && model->isDir(mapToSource(indexes.at(i))))
+    for (const auto &index : indexes) {
+        if (stripDirs && model->isDir(mapToSource(index)))
             continue;
-        allFiles.append(indexes.at(i).data().toString());
+        allFiles.append(index.data().toString());
     }
     if (allFiles.count() > 1)
         for (int i = 0; i < allFiles.count(); ++i) {
diff --git a/src/widgets/dialogs/qfileinfogatherer.cpp b/src/widgets/dialogs/qfileinfogatherer.cpp
index 92d6b8f3be..d99e3df802 100644
--- a/src/widgets/dialogs/qfileinfogatherer.cpp
+++ b/src/widgets/dialogs/qfileinfogatherer.cpp
@@ -282,8 +282,8 @@ void QFileInfoGatherer::getFileInfos(const QString &path, const QStringList &fil
             infoList = QDir::drives();
         } else {
             infoList.reserve(files.count());
-            for (int i = 0; i < files.count(); ++i)
-                infoList << QFileInfo(files.at(i));
+            for (const auto &file : files)
+                infoList << QFileInfo(file);
         }
         for (int i = infoList.count() - 1; i >= 0; --i) {
             QString driveName = translateDriveName(infoList.at(i));
diff --git a/src/widgets/dialogs/qfilesystemmodel.cpp b/src/widgets/dialogs/qfilesystemmodel.cpp
index 3c154c3dbb..c1d0ecf33b 100644
--- a/src/widgets/dialogs/qfilesystemmodel.cpp
+++ b/src/widgets/dialogs/qfilesystemmodel.cpp
@@ -1562,10 +1562,9 @@ void QFileSystemModel::setNameFilters(const QStringList &filters)
         d->bypassFilters.clear();
         // We guarantee that rootPath will stick around
         QPersistentModelIndex root(index(rootPath()));
-        QModelIndexList persistantList = persistentIndexList();
-        for (int i = 0; i < persistantList.count(); ++i) {
-            QFileSystemModelPrivate::QFileSystemNode *node;
-            node = d->node(persistantList.at(i));
+        const QModelIndexList persistentList = persistentIndexList();
+        for (const auto &persistentIndex : persistentList) {
+            QFileSystemModelPrivate::QFileSystemNode *node = d->node(persistentIndex);
             while (node) {
                 if (d->bypassFilters.contains(node))
                     break;
@@ -1579,9 +1578,8 @@ void QFileSystemModel::setNameFilters(const QStringList &filters)
     d->nameFilters.clear();
     const Qt::CaseSensitivity caseSensitive =
         (filter() & QDir::CaseSensitive) ? Qt::CaseSensitive : Qt::CaseInsensitive;
-    for (int i = 0; i < filters.size(); ++i) {
-        d->nameFilters << QRegExp(filters.at(i), caseSensitive, QRegExp::Wildcard);
-    }
+    for (const auto &filter : filters)
+        d->nameFilters << QRegExp(filter, caseSensitive, QRegExp::Wildcard);
     d->forceSort = true;
     d->delayedSort();
 #endif
@@ -1734,9 +1732,9 @@ void QFileSystemModelPrivate::addVisibleFiles(QFileSystemNode *parentNode, const
     if (parentNode->dirtyChildrenIndex == -1)
         parentNode->dirtyChildrenIndex = parentNode->visibleChildren.count();
 
-    for (int i = 0; i < newFiles.count(); ++i) {
-        parentNode->visibleChildren.append(newFiles.at(i));
-        parentNode->children.value(newFiles.at(i))->isVisible = true;
+    for (const auto &newFile : newFiles) {
+        parentNode->visibleChildren.append(newFile);
+        parentNode->children.value(newFile)->isVisible = true;
     }
     if (!indexHidden)
       q->endInsertRows();
@@ -1779,10 +1777,10 @@ void QFileSystemModelPrivate::_q_fileSystemChanged(const QString &path, const QV
     QStringList newFiles;
     QFileSystemModelPrivate::QFileSystemNode *parentNode = node(path, false);
     QModelIndex parentIndex = index(parentNode);
-    for (int i = 0; i < updates.count(); ++i) {
-        QString fileName = updates.at(i).first;
+    for (const auto &update : updates) {
+        QString fileName = update.first;
         Q_ASSERT(!fileName.isEmpty());
-        QExtendedInformation info = fileInfoGatherer.getInfo(updates.at(i).second);
+        QExtendedInformation info = fileInfoGatherer.getInfo(update.second);
         bool previouslyHere = parentNode->children.contains(fileName);
         if (!previouslyHere) {
             addNode(parentNode, fileName, info.fileInfo());
@@ -1971,8 +1969,8 @@ bool QFileSystemModelPrivate::passNameFilters(const QFileSystemNode *node) const
 
     // Check the name regularexpression filters
     if (!(node->isDir() && (filters & QDir::AllDirs))) {
-        for (int i = 0; i < nameFilters.size(); ++i) {
-            QRegExp copy = nameFilters.at(i);
+        for (const auto &nameFilter : nameFilters) {
+            QRegExp copy = nameFilter;
             if (copy.exactMatch(node->fileName))
                 return true;
         }
diff --git a/src/widgets/dialogs/qmessagebox.cpp b/src/widgets/dialogs/qmessagebox.cpp
index 76a9de0f1c..704883b5c6 100644
--- a/src/widgets/dialogs/qmessagebox.cpp
+++ b/src/widgets/dialogs/qmessagebox.cpp
@@ -1047,26 +1047,26 @@ void QMessageBoxPrivate::detectEscapeButton()
     }
 
     // if the message box has one RejectRole button, make it the escape button
-    for (int i = 0; i < buttons.count(); i++) {
-        if (buttonBox->buttonRole(buttons.at(i)) == QDialogButtonBox::RejectRole) {
+    for (auto *button : buttons) {
+        if (buttonBox->buttonRole(button) == QDialogButtonBox::RejectRole) {
             if (detectedEscapeButton) { // already detected!
                 detectedEscapeButton = 0;
                 break;
             }
-            detectedEscapeButton = buttons.at(i);
+            detectedEscapeButton = button;
         }
     }
     if (detectedEscapeButton)
         return;
 
     // if the message box has one NoRole button, make it the escape button
-    for (int i = 0; i < buttons.count(); i++) {
-        if (buttonBox->buttonRole(buttons.at(i)) == QDialogButtonBox::NoRole) {
+    for (auto *button : buttons) {
+        if (buttonBox->buttonRole(button) == QDialogButtonBox::NoRole) {
             if (detectedEscapeButton) { // already detected!
                 detectedEscapeButton = 0;
                 break;
             }
-            detectedEscapeButton = buttons.at(i);
+            detectedEscapeButton = button;
         }
     }
 }
@@ -1506,8 +1506,7 @@ void QMessageBox::keyPressEvent(QKeyEvent *e)
         int key = e->key() & ~Qt::MODIFIER_MASK;
         if (key) {
             const QList<QAbstractButton *> buttons = d->buttonBox->buttons();
-            for (int i = 0; i < buttons.count(); ++i) {
-                QAbstractButton *pb = buttons.at(i);
+            for (auto *pb : buttons) {
                 QKeySequence shortcut = pb->shortcut();
                 if (!shortcut.isEmpty() && key == int(shortcut[0] & ~Qt::MODIFIER_MASK)) {
                     pb->animateClick();
diff --git a/src/widgets/dialogs/qsidebar.cpp b/src/widgets/dialogs/qsidebar.cpp
index f883705cc3..58a92800f4 100644
--- a/src/widgets/dialogs/qsidebar.cpp
+++ b/src/widgets/dialogs/qsidebar.cpp
@@ -103,9 +103,9 @@ Qt::ItemFlags QUrlModel::flags(const QModelIndex &index) const
 QMimeData *QUrlModel::mimeData(const QModelIndexList &indexes) const
 {
     QList<QUrl> list;
-    for (int i = 0; i < indexes.count(); ++i) {
-        if (indexes.at(i).column() == 0)
-           list.append(indexes.at(i).data(UrlRole).toUrl());
+    for (const auto &index : indexes) {
+        if (index.column() == 0)
+           list.append(index.data(UrlRole).toUrl());
     }
     QMimeData *data = new QMimeData();
     data->setUrls(list);
@@ -125,8 +125,8 @@ bool QUrlModel::canDrop(QDragEnterEvent *event)
         return false;
 
     const QList<QUrl> list = event->mimeData()->urls();
-    for (int i = 0; i < list.count(); ++i) {
-        QModelIndex idx = fileSystemModel->index(list.at(0).toLocalFile());
+    for (const auto &url : list) {
+        const QModelIndex idx = fileSystemModel->index(url.toLocalFile());
         if (!fileSystemModel->isDir(idx))
             return false;
     }
diff --git a/src/widgets/dialogs/qwizard.cpp b/src/widgets/dialogs/qwizard.cpp
index c050b5b097..6add83e135 100644
--- a/src/widgets/dialogs/qwizard.cpp
+++ b/src/widgets/dialogs/qwizard.cpp
@@ -3622,9 +3622,8 @@ void QWizardPage::cleanupPage()
 {
     Q_D(QWizardPage);
     if (d->wizard) {
-        QVector<QWizardField> &fields = d->wizard->d_func()->fields;
-        for (int i = 0; i < fields.count(); ++i) {
-            const QWizardField &field = fields.at(i);
+        const QVector<QWizardField> &fields = d->wizard->d_func()->fields;
+        for (const auto &field : fields) {
             if (field.page == this)
                 field.object->setProperty(field.property, field.initialValue);
         }