Use QStringRef to optimize memory allocation

Replace substring functions that return QString with
corresponding functions that return QStringRef where
it's possible.

Create QString from QStringRef only where necessary.

While touching the code, also port loops to C++11 style.

Change-Id: I04c99b24ea6afd3715e3edf9ea00bfab838fd53c
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>
Reviewed-by: Frank Meerkoetter <frank.meerkoetter@basyskom.com>
Reviewed-by: Shawn Rutledge <shawn.rutledge@theqtcompany.com>
Reviewed-by: Robin Burchell <robin.burchell@viroteck.net>

4 files changed, 35 insertions, 34 deletions

diff --git a/src/plugins/qmltooling/qmldbg_debugger/qqmlenginedebugservice.cpp b/src/plugins/qmltooling/qmldbg_debugger/qqmlenginedebugservice.cpp
index a9996da7f4..ff4e30835d 100644
--- a/src/plugins/qmltooling/qmldbg_debugger/qqmlenginedebugservice.cpp
+++ b/src/plugins/qmltooling/qmldbg_debugger/qqmlenginedebugservice.cpp
@@ -683,11 +683,13 @@ bool QQmlEngineDebugServiceImpl::resetBinding(int objectId, const QString &prope
     QQmlContext *context = qmlContext(object);
 
     if (object && context) {
-        QString parentProperty = propertyName;
-        if (propertyName.indexOf(QLatin1Char('.')) != -1)
-            parentProperty = propertyName.left(propertyName.indexOf(QLatin1Char('.')));
+        QStringRef parentPropertyRef(&propertyName);
+        const int idx = parentPropertyRef.indexOf(QLatin1Char('.'));
+        if (idx != -1)
+            parentPropertyRef = parentPropertyRef.left(idx);
 
-        if (object->property(parentProperty.toLatin1()).isValid()) {
+        const QByteArray parentProperty = parentPropertyRef.toLatin1();
+        if (object->property(parentProperty).isValid()) {
             QQmlProperty property(object, propertyName);
             QQmlPropertyPrivate::removeBinding(property);
             if (property.isResettable()) {
@@ -700,7 +702,7 @@ bool QQmlEngineDebugServiceImpl::resetBinding(int objectId, const QString &prope
                 // overwrite with default value
                 if (QQmlType *objType = QQmlMetaType::qmlType(object->metaObject())) {
                     if (QObject *emptyObject = objType->create()) {
-                        if (emptyObject->property(parentProperty.toLatin1()).isValid()) {
+                        if (emptyObject->property(parentProperty).isValid()) {
                             QVariant defaultValue = QQmlProperty(emptyObject, propertyName).read();
                             if (defaultValue.isValid()) {
                                 setBinding(objectId, propertyName, defaultValue, true);
diff --git a/src/plugins/qmltooling/qmldbg_debugger/qqmlnativedebugservice.cpp b/src/plugins/qmltooling/qmldbg_debugger/qqmlnativedebugservice.cpp
index 877821e03f..a9b9587aa9 100644
--- a/src/plugins/qmltooling/qmldbg_debugger/qqmlnativedebugservice.cpp
+++ b/src/plugins/qmltooling/qmldbg_debugger/qqmlnativedebugservice.cpp
@@ -704,7 +704,7 @@ bool NativeDebugger::reallyHitTheBreakPoint(const QV4::Function *function, int l
         const BreakPoint &bp = m_service->m_breakHandler->m_breakPoints.at(i);
         if (bp.lineNumber == lineNumber) {
             const QString fileName = function->sourceFile();
-            const QString base = fileName.mid(fileName.lastIndexOf('/') + 1);
+            const QStringRef base = fileName.midRef(fileName.lastIndexOf('/') + 1);
             if (bp.fileName.endsWith(base)) {
                 if (bp.condition.isEmpty() || checkCondition(bp.condition)) {
                     BreakPoint &mbp = m_service->m_breakHandler->m_breakPoints[i];
diff --git a/src/plugins/qmltooling/qmldbg_native/qqmlnativedebugconnector.cpp b/src/plugins/qmltooling/qmldbg_native/qqmlnativedebugconnector.cpp
index cc0118f0c2..3145601612 100644
--- a/src/plugins/qmltooling/qmldbg_native/qqmlnativedebugconnector.cpp
+++ b/src/plugins/qmltooling/qmldbg_native/qqmlnativedebugconnector.cpp
@@ -49,6 +49,7 @@
 #include <QtCore/qjsonobject.h>
 #include <QtCore/qjsonvalue.h>
 #include <QtCore/qpointer.h>
+#include <QtCore/qvector.h>
 
 //#define TRACE_PROTOCOL(s) qDebug() << s
 #define TRACE_PROTOCOL(s)
@@ -182,24 +183,21 @@ QQmlNativeDebugConnector::QQmlNativeDebugConnector()
     : m_blockingMode(false)
 {
     const QString args = commandLineArguments();
-    const QStringList lstjsDebugArguments = args.split(QLatin1Char(','));
+    const auto lstjsDebugArguments = args.splitRef(QLatin1Char(','));
     QStringList services;
-    QStringList::const_iterator argsItEnd = lstjsDebugArguments.cend();
-    QStringList::const_iterator argsIt = lstjsDebugArguments.cbegin();
-    for (; argsIt != argsItEnd; ++argsIt) {
-        const QString strArgument = *argsIt;
+    for (const QStringRef &strArgument : lstjsDebugArguments) {
         if (strArgument == QLatin1String("block")) {
             m_blockingMode = true;
         } else if (strArgument == QLatin1String("native")) {
             // Ignore. This is used to signal that this connector
             // should be loaded and that has already happened.
         } else if (strArgument.startsWith(QLatin1String("services:"))) {
-            services.append(strArgument.mid(9));
+            services.append(strArgument.mid(9).toString());
         } else if (!services.isEmpty()) {
-            services.append(strArgument);
+            services.append(strArgument.toString());
         } else {
             qWarning("QML Debugger: Invalid argument \"%s\" detected. Ignoring the same.",
-                     qUtf8Printable(strArgument));
+                     strArgument.toUtf8().constData());
         }
     }
     setServices(services);
diff --git a/src/plugins/qmltooling/qmldbg_server/qqmldebugserver.cpp b/src/plugins/qmltooling/qmldbg_server/qqmldebugserver.cpp
index 28213e7b56..a6d93e85ae 100644
--- a/src/plugins/qmltooling/qmldbg_server/qqmldebugserver.cpp
+++ b/src/plugins/qmltooling/qmldbg_server/qqmldebugserver.cpp
@@ -53,6 +53,7 @@
 #include <QtCore/QDir>
 #include <QtCore/QPluginLoader>
 #include <QtCore/QStringList>
+#include <QtCore/QVector>
 #include <QtCore/qwaitcondition.h>
 
 QT_BEGIN_NAMESPACE
@@ -345,40 +346,40 @@ void QQmlDebugServerImpl::parseArguments()
     QString fileName;
     QStringList services;
 
-    const QStringList lstjsDebugArguments = args.split(QLatin1Char(','));
-    QStringList::const_iterator argsItEnd = lstjsDebugArguments.cend();
-    QStringList::const_iterator argsIt = lstjsDebugArguments.cbegin();
-    for (; argsIt != argsItEnd; ++argsIt) {
-        const QString strArgument = *argsIt;
+    const auto lstjsDebugArguments = args.splitRef(QLatin1Char(','));
+    for (auto argsIt = lstjsDebugArguments.begin(), argsItEnd = lstjsDebugArguments.end(); argsIt != argsItEnd; ++argsIt) {
+        const QStringRef &strArgument = *argsIt;
         if (strArgument.startsWith(QLatin1String("port:"))) {
-            portFrom = strArgument.midRef(5).toInt(&ok);
+            portFrom = strArgument.mid(5).toInt(&ok);
             portTo = portFrom;
-            QStringList::const_iterator argsNext = argsIt + 1;
+            const auto argsNext = argsIt + 1;
             if (argsNext == argsItEnd)
                 break;
-            const QString nextArgument = *argsNext;
-
-            // Don't use QStringLiteral here. QRegExp has a global cache and will save an implicitly
-            // shared copy of the passed string. That copy isn't properly detached when the library
-            // is unloaded if the original string lives in the library's .rodata
-            if (ok && nextArgument.contains(QRegExp(QLatin1String("^\\s*\\d+\\s*$")))) {
-                portTo = nextArgument.toInt(&ok);
-                ++argsIt;
+            if (ok) {
+                const QString nextArgument = argsNext->toString();
+
+                // Don't use QStringLiteral here. QRegExp has a global cache and will save an implicitly
+                // shared copy of the passed string. That copy isn't properly detached when the library
+                // is unloaded if the original string lives in the library's .rodata
+                if (nextArgument.contains(QRegExp(QLatin1String("^\\s*\\d+\\s*$")))) {
+                    portTo = nextArgument.toInt(&ok);
+                    ++argsIt;
+                }
             }
         } else if (strArgument.startsWith(QLatin1String("host:"))) {
-            hostAddress = strArgument.mid(5);
+            hostAddress = strArgument.mid(5).toString();
         } else if (strArgument == QLatin1String("block")) {
             block = true;
         } else if (strArgument.startsWith(QLatin1String("file:"))) {
-            fileName = strArgument.mid(5);
+            fileName = strArgument.mid(5).toString();
             ok = !fileName.isEmpty();
         } else if (strArgument.startsWith(QLatin1String("services:"))) {
-            services.append(strArgument.mid(9));
+            services.append(strArgument.mid(9).toString());
         } else if (!services.isEmpty()) {
-            services.append(strArgument);
+            services.append(strArgument.toString());
         } else {
             const QString message = tr("QML Debugger: Invalid argument \"%1\" detected."
-                                       " Ignoring the same.").arg(strArgument);
+                                       " Ignoring the same.").arg(strArgument.toString());
             qWarning("%s", qPrintable(message));
         }
     }