QtBase: avoid uses of Java-style iterators [QHash, QMap]

Java-style iterators are slower than STL-style ones, so
they should not be used in library code.

Replaced them with C++11 range-for, STL iterators or, in
one case, qDeleteAll().

In one case, avoid a double hash lookup by using erase(it)
instead of remove(it.key()), which we can now do without
detaching, due to the new erase() taking const_iterator.

Change-Id: I96174657fed70f76120b2c9d8190b4e70d5d8179
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>

3 files changed, 6 insertions, 20 deletions

diff --git a/qmake/generators/win32/msvc_vcproj.cpp b/qmake/generators/win32/msvc_vcproj.cpp
index d473f3df9f..6219252161 100644
--- a/qmake/generators/win32/msvc_vcproj.cpp
+++ b/qmake/generators/win32/msvc_vcproj.cpp
@@ -685,9 +685,7 @@ void VcprojGenerator::writeSubDirs(QTextStream &t)
 
     t << _slnGlobalBeg;
 
-    QHashIterator<VcsolutionDepend *, QStringList> extraIt(extraSubdirs);
-    while (extraIt.hasNext()) {
-        extraIt.next();
+    for (auto extraIt = extraSubdirs.cbegin(), end = extraSubdirs.cend(); extraIt != end; ++extraIt) {
         for (const QString &depend : extraIt.value()) {
             if (!projGuids[depend].isEmpty()) {
                 extraIt.key()->dependencies << projGuids[depend];
diff --git a/src/network/access/qnetworkdiskcache.cpp b/src/network/access/qnetworkdiskcache.cpp
index eb66a1a6a4..5d38ebcd86 100644
--- a/src/network/access/qnetworkdiskcache.cpp
+++ b/src/network/access/qnetworkdiskcache.cpp
@@ -114,11 +114,7 @@ QNetworkDiskCache::QNetworkDiskCache(QObject *parent)
 QNetworkDiskCache::~QNetworkDiskCache()
 {
     Q_D(QNetworkDiskCache);
-    QHashIterator<QIODevice*, QCacheItem*> it(d->inserting);
-    while (it.hasNext()) {
-        it.next();
-        delete it.value();
-    }
+    qDeleteAll(d->inserting);
 }
 
 /*!
@@ -319,13 +315,11 @@ bool QNetworkDiskCache::remove(const QUrl &url)
     Q_D(QNetworkDiskCache);
 
     // remove is also used to cancel insertions, not a common operation
-    QHashIterator<QIODevice*, QCacheItem*> it(d->inserting);
-    while (it.hasNext()) {
-        it.next();
+    for (auto it = d->inserting.cbegin(), end = d->inserting.cend(); it != end; ++it) {
         QCacheItem *item = it.value();
         if (item && item->metaData.url() == url) {
             delete item;
-            d->inserting.remove(it.key());
+            d->inserting.erase(it);
             return true;
         }
     }
@@ -559,10 +553,7 @@ qint64 QNetworkDiskCache::expire()
         QFile file(name);
 
         if (name.contains(PREPARED_SLASH)) {
-            QHashIterator<QIODevice*, QCacheItem*> iterator(d->inserting);
-            while (iterator.hasNext()) {
-                iterator.next();
-                QCacheItem *item = iterator.value();
+            for (QCacheItem *item : qAsConst(d->inserting)) {
                 if (item && item->file && item->file->fileName() == name) {
                     delete item->file;
                     item->file = 0;
diff --git a/src/widgets/itemviews/qcolumnview.cpp b/src/widgets/itemviews/qcolumnview.cpp
index bc8a9d38d8..cba7e8aacc 100644
--- a/src/widgets/itemviews/qcolumnview.cpp
+++ b/src/widgets/itemviews/qcolumnview.cpp
@@ -793,11 +793,8 @@ void QColumnView::initializeColumn(QAbstractItemView *column) const
     column->setModel(model());
 
     // Copy the custom delegate per row
-    QMapIterator<int, QPointer<QAbstractItemDelegate> > i(d->rowDelegates);
-    while (i.hasNext()) {
-        i.next();
+    for (auto i = d->rowDelegates.cbegin(), end = d->rowDelegates.cend(); i != end; ++i)
         column->setItemDelegateForRow(i.key(), i.value());
-    }
 
     // set the delegate to be the columnview delegate
     QAbstractItemDelegate *delegate = column->itemDelegate();